Sciencemadness Discussion Board

Catechol preparation

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madscientist - 12-11-2002 at 16:37

I have been interested in preparing Benzene-1,2-diol (catechol) for some time. Here's the route of synthesis that I think would be viable for the amateur chemist.

Step one: hydrolyze acetylsalicylic acid to yield salicylic acid. Acetic acid will be another product of the reaction.

Step two: react salicylic acid with carbamide to yield salicylamide. Ammonia and carbon dioxide gas will be evolved by this reaction.

Step three: perform a Hofmann elimination on salicylamide with calcium hypochlorite to yield 1-hydroxyl-2-aminobenzene. Carbon dioxide will be evolved, and calcium chloride will form as well.

Step four: add sodium nitrite to 1-hydroxyl-2-aminobenzene to yield the monosodium salt of Benzene-1,2-diol. This works by the acidic hydroxyl group reacting with the sodium nitrite to form nitrous acid, which then performs a diazotation on the amino group, yielding the desired hydroxyl group.

Step five: add hydrochloric acid to yield Benzene-1,2-diol. Sodium chloride will obviously be the other product.

Step six: boil off all water, add toluene in which the Benzene-1,2-diol will dissolve; pour the toluene through a filter (to catch any sodium chloride crystals that may have broken off into the toluene); distill off the toluene, leaving Benzene-1,2-diol crystals.


The_Cutting_Crew - 13-11-2002 at 03:54

It`s a good base-stuff for stabilising-agents than
3,5-di-tertbutyl-1,2-benzenediol or to build other
Have You a idea whats the synthesis-way when
adding HCl to
hydro-sodium-pyrocatechol-3,5-disulfonate ?

C6H4O8S2Na2 + HCl ???

tiron.jpg - 4kB

IodineForLunch - 13-11-2002 at 16:41

Are you on drugs?

madscientist - 13-11-2002 at 18:01

Adding HCl to the molecule you shared a diagram of should yield the free acid of that salt: 4,5-Dihydroxy-benzene-1,3-disulfonic acid.

Perhaps I misunderstood what you said? :)

KABOOOM(pyrojustforfun) - 21-11-2002 at 18:03

I think this method would be easier:
dissolve phenol in excess conc H2SO4 at low temperatures to get ortho-phenolsulfonic acid (high temp leads into parapheolsufonic acid)
add exact calculated amount of NaOH needed, then gently warm it to evaporate all the water so that a solid stuff remains.
attack a condenser to the flask, and heat to 240°C(bp of catechol) and keep on this temperature until no more catechol is distilled.
C6H5OH + H2SO4 => HOC6H4SO3H + H2O
HOC6H4SO3H + NaOH => NaHSO3 + C6H4(OH)2

madscientist - 27-11-2002 at 21:45

Are you sure that reacting sodium hydroxide with an aromatic sulfonic acid causes the oxidation state of the sulfur to drop? Seems mighty strange to me.

I thought of another, more economical idea for synthesizing catechol (since acetylsalicylic acid isn't exactly inexpensive). Toluolsulfonic acid can be hydrated to yield toluene and sulfuric acid by heating with water. The ortho form of toluolsulfonic acid is prepared by reacting concentrated sulfuric acid with toluene. So, perhaps 2-hydroxyltoluene could be prepared by reacting concentrated sulfuric acid with toluene; purifying the toluolsulfonic acid crystals; heating with hydrogen peroxide; and then extracting and purifying the 2-hydroxyltoluene. The 2-hydroxyltoluene would be oxidized, then reacted with urea, then treated with calcium hypochlorite, and then diazotized with nitrous acid to yield catechol.

Marvin - 30-11-2002 at 12:59

Concentrated sulphuric acid is actually half decent oxidising agent, the method stated is not disimilar to one of the methods for making phenol. Conc sulphuric with a catalyst will even oxidise napthalene to pthallic acid.

I'm very bothered by the idea of using hoffman rearangement to make an aryl amine, do we have any reliable information of this being done?

KABOOOM(pyrojustforfun) - 9-12-2002 at 18:16

madscientist the method I mentioned was right except the mistake about temperature

pyrocatechol (ortho-dihydroxybenzene; catechol)
Properties: Colorless crystals; discolors to brown on
exposure to air and light, espesially when moist; sp.
gr. 1.371; m.p. 104°C; b.p. 245°C, sublimes; soluble
in water, alcohol, ether, benzene and chloroform,
also in pyridine and aqueous alkaline solutions.
Combustible. Flash point 261°F (127°C) (C.C).
Derivation: (a) By fusion of ortho-phenolsulfonic
acid with caustic potash at 350°C. (b) By heating
guaiacol with hydroiodic acid.
Grades: Technical; C.P.; resublimed.
Containers: 25- to 200-lb drums.
Hazard: Strong irritiant. Toxic. Tolerance, 5 ppm in
Uses: Antiseptic; photography; dyestuffs; electro-
plating; specialty inks; antioxidants and light stabil-
izers; organic synthesis.

I also have "Dictionary of Chemistry" (by David William Arthur Sharp) that mentions melting ortho-benzene-disulphonic acid with NaOH

Ritter - 28-6-2008 at 17:18

Catechol (along with hydroquinone) are made industrially via hydrogen peroxide oxidation of phenol.

stoichiometric_steve - 28-6-2008 at 23:25

why not just buy the stuff, it's dead cheap - 250g 30 USD...

YT2095 - 29-6-2008 at 00:50


what are using as the medium to perform these reactions in?
it looks like a very Simple straightforwards procedure and one I would like to try myself even though I already have Catechol.
I would be starting from the Salicylic acid stage, and this doesn`t dissolve in water very well.

Klute - 29-6-2008 at 04:51

That hydroxide fusion cannot be performed in usual glassware, it will etch any pyrex within minutes...

A dakin reaction on salicylaldheyde should yield the deired compound in ratehr high yields. Salicylaldehyde can be produced from phenol in 84% yields via Mg(OCH3)/(H2CO)n formylation, or by a riemer-tieman formylation.

You would have to compare with the direct H2O2 oxidation of phenol, although the two step preparation above yields only one isomer.

For the amide formation, you might better be off forming the ester and reacting it with alcoholic ammonia, a bit longer but less decomposition products. I know the hofmann degradation works for nitrobenzamide for sure, but don't know how well it would perform here. Check the litterature.

smuv - 29-6-2008 at 08:44

A cool and stupid easy way of making chloramides for the hofmann degradation involves stirring the amide with TCCA in MeOH and allowing the cyanuric acid to percipitate out as the amide is chlorinated. I tried this with urea as a substrate and it worked just as described in the article attached below.

I think though, your method would not be very efficient as I would worry about ring chlorination. Phenols have a pretty activated nucleus, and the conditions for the classic Hofmann degradation would certainly halogenate it. Although maybe your method with straight calcium hypochlorite instead of the classic Br2 and then NaOH/Heat may not suffer this problem.

Attachment: N-Chloroamides_via_TCCA.pdf (113kB)
This file has been downloaded 2952 times

Ritter - 29-6-2008 at 08:48

Originally posted by stoichiometric_steve
why not just buy the stuff, it's dead cheap - 250g 30 USD...

This is the same question I ask about subscribers who post elaborate & expensive schemes to make very inexpensive chemicals. In most cases it is intellectual curiosdity rather than economics, I would guess.

ScienceSquirrel - 29-6-2008 at 10:22

I think you will find that the easiest way from OTC chemicals is;

1) Aspirin to salicylic acid

2) Salicyclic acid to phenol-2-sulphonic acid with concentrated sulphuric acid ( ipso substitution )

3) Fusion with caustic potash to yield catechol

Klute - 29-6-2008 at 16:49

IMHO, hydroxide fusion isn't avery practical reaction: it can't be done in conventional borosilicate glassware without causing excessive damage (risk or breaking the beaker/flask once the glassware has been significantly etched), and melting an alkali hydroxide in a crucible or such is very hazardous.
It would be great if there was a way of performing this reaction in less extreme ways.

ScienceSquirrel - 1-7-2008 at 05:15

Here is an elegant method using the Dakin reaction

Phenol -> Salicylaldehyde - > Catechol

Maybe someone could post the full paper

One-pot synthesis of substituted catechols from the corresponding phenols

Tetrahedron Letters, Volume 46, Issue 19, 9 May 2005, Pages 3357-3358

FreedomFighter - 1-7-2008 at 06:38

Take a look at US patent 4465864, may be you can apply it to phenol and get pyrocatechol.

Mush - 19-8-2009 at 09:12

Methyl salicylate -> salicylamide


Problem in the diazotation:

"Due to the adjacency of the amino and hydroxyl groups, 2-aminophenol readily forms heterocycles."


Another route:

Benzene (nitration)-> nitrobenze (reduction) ->
aniline (diazotation) ->phenol (Reimer-Tiemann formylation)
mostly o-salicylaldehyde (Dakin Reaction)-> pyrocatechol

Vogel, Practical Organic Chemistry, 5 th ed., p 854

This preparation should be conducted in an efficient fume cupboard.
Place 50 g (35 mL, c. 0.5 mol)of concentrated nitric acid in a 500-mL round-bottomed flask,
and add, in portions with shaking, 74 g (40 mL) of concentrated sulfuric acid. Keep the
mixture cool during the addition by immersing the flak in cold water. Place a thermometer
(110 °C range) in the acid mixture. Introduce 26 g (30 mL, 0.33 mol of benzene (CAUTION)
in portions of 2 - 3 mL; shake the flask well to ensure thorough mixing, after each addition
of benzene. Do not allow the temperature to rise over 55 °C; immerse the flask, if necessary,
in cold water or in ice water. When all the benzene has been added, fit a reflux condenser
to the flask and heat it in a water bath maintained at 60 °C (but not appreciably higher)
for 40 - 45 minutes; remove the flask from time to time and shake it vigorously to ensure
good mixing of the immiscible layers. Pour the contents of the flask into about 500 mL of
cold water in a beaker, stir the mixture well in order to wash out as much acid as possible
from the nitrobenzene and allow to stand. When the nitrobenzene has settled to the bottom,
pour of the acid liquor as completely as possible, and transfer the residual liquid to a
separatory funnel. Run off the lower layer of nitrobenzene and reject the upper aqueous
layer; return the nitrobenzene to the separatory funnel and shake it vigorously with about
50 mL of water. Separate the nitrobenzene as completely as possible and rin it into a small
conical flask containing about 5 g of anhydrous calcium chloride. If the nitrobenzene does
not become clear because of the presence of emulsified water, warm the mixture, with shaking,
for a short period on a water bath; the cloudiness will soon disappear. Filter the cold product
through a small fluted filter paper into a small (50- or 100-mL)distilling flask and attach
a still-head and air condenser. Heat the flask on a ceramic-centred wire gauze or preferably
in an air bath, and collect the fraction which boils at 206 - 211 °C. (1). Do not distill
quite to dryness nor allow the temperature to rise above 214 °C, for there may be a residue
of m-dinitrobenzene or higher nitro compounds and an explosion may result. The yield of
nitrobenzene is 35 g (85 %). Pure nitrobenzene is a clear, pale yellow liquid, B.P. = 210 °C.

(1) Nitrobenzene is appreciably toxic and its vapour should not be allowed to escape into
the atmosphere of the laboratory. Site the distillation apparatus in a fume cupboard, use
the receiver assembly illustrated in fig. 2.98, and attach to the outlet of the receiver
adapter a piece of rubber tubing leading to the extraction system. The liquid is also a
skin poison, if accidentally spilled on the skin, it should be removed by washing with a
little methylated spirit, followed by soap and warm water.

Nitrobenzene Synthesis (alternative)
Prepare a mixture of 82 mL of 95-100% sulfuric acid and 71 mL of 70% nitric acid in a 500-mL
flask. Stir well and allow the mixture to cool to room temperature in a cold water bath.
Gradually add 57 mL of benzene to the acid with frequent shaking. If the temperature rises
above 50-60 °C during the benzene addition, stop adding benzene and cool the flask in a
cold water bath until the temperature has lowered. After all of the benzene has been added,
reflux the flask in a water bath at 60 °C for 1 hour. The temperature of the water bath
should be 60 °C, not the contents of the flask. Shake the flask frequently during reflux.
After heating, allow the flask to cool, two layers should form. Transfer the contents
to a separatory funnel and drain off the bottom layer of sulfuric and nitric acids; the
top layer contains the nitrobenzene. The bottom layer can be disposed of. The nitrobenzene
is then vigorously shaken in the separatory funnel several times with water. After each shaking,
allow the layers to separate, the nitrobenzene will now be the bottom layer, dispose of the
top water layer. After washing, place the nitrobenzene in a dry Erlenmeyer flask with some
calcium chloride. Heat this flask on a steam bath, it will first be milky, then it will
go clear, stop when it is clear. The nitrobenzene is now purified by simple distillation.
Yield is about 60-70 g.

Vogel, Practical Organic Chemistry, 5 th ed., p 892

Into a 500-mL round bottomed flask equipped with a reflux condenser place 25 g (21 mL, 0.25 mol) of nitrobenzene and 45 g (0.38 mol) of granulated tin. Measure out 100 mL of concentrated hydrochloric acid. Pour about 15 mL of this acid down the condenser and shake the contents of the flask steadily. The mixture becomes warm and before long the reaction should be quite vigorous; if it boils very vigorously, moderate the reduction somewhat by temporarily immersing the flask in cold water. When the initial reaction slackens of its own accord, pour another 15 mL of hydrochloric acid down the condenser, shake the flask steadily to ensure thorough mixing and cool again if the reduction becomes too violent. Do not cool more than is necessary to keep the reaction under control; keep the mixture well shaken. Proceed in this way until all 100 mL of acid has been added. Finally heat the mixture on a boiling water bath for 30 - 60 minutes, i.e. until the odour of nitrobenzene is no longer perceptible and a few drops of the reaction mixture when diluted with water yield a perfectly clear solution. During the course of the reduction, particularly during the cooling, aniline chlorostannate may separate as a white or yellow crystalline complex. Cool the reaction mixture to room temperature and add gradually a solution of 75 g of sodium hydroxide in 125 mL of water; if the reaction mixture boils during the addition of alkali, cool again. The hydroxide of tin which is first precipitated should all dissolve and the solution should be strongly alkaline: the aniline separates as an oil. Equip the flask for steam distillation, and pass steam into the warm mixture until, after the distillate has ceased to pass over as a turbid liquid, a further 120 mL of clear liquid are collected. Since aniline is appreciably soluble (c. 3 %) in water, it must be 'salted out' by saturating the distillate with salt. Use about 20 g of commercial salt for each 100 mL of liquid. Transfer the distillate, saturated with salt, to a separatory funnel, add about 40 mL of ether and shake to ensure intimate mixing of the solution and the ether; relive the pressure within the funnel by momentarily lifting the stopper. (All flames in the vicinity must be extinguished during the extraction ... :-) you must be joking ...). Allow the two layers to separate; run off the lower aqueous layer into a beaker, and pour the ethereal layer through the mounth of the funnel into a 200-mL flask. Return the aqueous solution to the funnel and extract with a further 40 mL of ether. Proceed as before, and pour the ethereal extract into the flask. Dry the combined ethereal solutions with a few grams of anhydrous potassium carbonate (1): shake the well-stoppered flask for several minutes. Filter the ethereal solution through a fluted filter paper and remove the ether by flash distillation, using a 50-ml round-bottomed flask to which has been added a few boiling chips. Since ether is extremely volatile and also highly flammable, the flask must be heated by means of an electrically heated water bath. When all the ethereal solution has been introduced into the flask, and no more ether distilson the boiling water bath, run out the water from the condenser, and distil the aniline either by direct heating over a wire gauze or, preferably, using an air bath. A small quantity of ether may pass over during the early part of the distillation; it is therefore advisable to interpose a uralite board between the receiver and the flame. Collect the fraction B.P. 180 - 184 °C, in a weighed conical flask. The yield of aniline is 18 g (97 %).

Phenol (with diazotation)
Attachment: Organikum (2001), p637-638 Phenol preparation.rar (250kB)
This file has been downloaded 1105 times

Simply heat up your reaction mixture till
nitrogen formation subside to get phenol.

Reimer-Tiemann formylation process for producing aldehydes


100.cm3 of chloroform, 9.4 g of phenol, 20 g of anhydrous sodium hydroxide and 3.6 cm3
of water are placed in a 250 cm3 reactor provided with a coolant, a mechanical stirrer
and a thermometer, and the reaction medium temperature is thermostatically maintained
at 50° C. These conditions of the initial mixture correspond to a hydration rate of
0.4 moles of water per mole of sodium hydroxide (2 moles of water per mole of initial
compound) and to 12.6 times as much chloroform as initial compound (expressed in moles).
Thereupon the temperature of the reaction medium is raised to 58° C. for one hour.
Next 12 g of sodium hydroxide in powdered form are progressively added over a period of
two hours, the temperature being kept constant at 58° C. The reaction proceeds for 1
hour. At the end of the reaction, the initial phenol has completely disappeared.
The residual chloroform is recovered and recycled. The mixture of aldehydes is
obtained in sodium form. It is neutralized until a neutral brine is obtained.
The salicylaldehyde can be recovered in conventional manner at a yield close to 77% (9.4 g)
with respect to the initial phenol by carrier vapor distillation or by ether extraction.
The p-hydroxybenzaldehyde is recovered at a yield of 17% (2 g) by ether extraction from
the acidified residual brine to pH of 1.

Catechol (pyrocatechol)
Organic Syntheses, Coll. Vol. 1, p.149 (1941); Vol. 3, p.28 (1923).

To a solution of 122 g. (1 mole) of pure salicylaldehyde (Note 1) in 1000 cc. of normal
sodium hydroxide solution at room temperature, is added 1420 g. (1.2 moles) of 3 per cent
hydrogen peroxide. The mixture darkens slightly in color and the temperature rises to 45–50°.
The solution is allowed to stand for fifteen to twenty hours, whereupon a few drops of
acetic acid are added in order to neutralize any excess alkali, and the solution evaporated
to complete dryness on the water bath under reduced pressure.
The solid residue is finely crushed and warmed nearly to boiling with 500 cc. of toluene;
the mixture is then poured into the folded filter paper of an extraction apparatus (p. 375)
and extracted with boiling toluene for five hours. The toluene is allowed to cool and is
decanted from the catechol, which crystallizes out. The insoluble material is again ground
up and extracted in the apparatus with the decanted toluene. The combined product,
weighing 70–76 g., consists of light brown plates melting at 104°, and is thus pure enough
for many purposes. A further 6–12 g. of catechol can be obtained on distilling off the bulk
of the toluene from the mother liquor. In order to obtain an entirely pure product, the
crude catechol should be distilled under reduced pressure, when it passes over entirely at
119–121° /10 mm. (or 113–115° /8 mm.), and the distillate recrystallized from about five
times its weight of toluene. In this way, colorless plates melting at 104–105° are obtained.
The yield of the purified product is 76–80 g. (69–73 per cent of the theoretical amount) (Note 2).

1. A considerably lower yield is obtained (50 per cent or less) if technical salicylaldehyde
(not purified through the bisulfite compound) is employed.
2. The procedure described is applicable to almost all hydroxyaldehydes in which the hydroxyl
and carbonyl groups occupy ortho or para positions relatively to each other;1 in the latter
case derivatives of hydroquinone are produced. When the hydroxyl and carbonyl groups occupy
the meta position with respect to each other, no reaction takes place, as is also the case
with certain ortho and para compounds containing nitro groups and iodine atoms.
o-Hydroxyacetophenone and p-hydroxyacetophenone are also capable of yielding catechol
and hydroquinone, respectively, under the above conditions.
3. Catechol may also be produced from salicylaldehyde by the use of certain derivatives
of hydrogen peroxide, such as persulfates or sodium peroxide, but the method is far less convenient.

[Edited on 19-8-2009 by Mush]

JohnWW - 19-8-2009 at 16:07

Quote: Originally posted by Mush  
Methyl salicylate -> salicylamide
US2570502 (cut)
- try instead
Quote: Originally posted by Mush  

Another route:
Benzene (nitration)-> nitrobenze (reduction) ->
aniline (diazotation) ->phenol (Reimer-Tiemann formylation)
mostly o-salicylaldehyde (Dakin Reaction)-> pyrocatechol
Vogel, Practical Organic Chemistry, 5 th ed., p 854 (cut)
Vogel, Practical Organic Chemistry, 5 th ed., p 892 (cut)

- See the References section for the complete book by Vogel.
Quote: Originally posted by Mush  

Reimer-Tiemann formylation process for producing aldehydes
(US4755613) (cut)

- try instead

unome - 22-11-2009 at 20:49

Why would diazotization be necessary? There are several papers where p/m/o-amino groups have been removed during heating of compounds with syrupy phosphoric acid (granted most are involving modified Fischer cyclization), but suffice to say, the relevant amino groups have been removed in essentially quantitive yield.

If that were the case, the only remaining issue I can see is the possibility of dimer/trimer formation, plus the fact I haven't seen any mention of a Hoffman rearrangement of 2-hydroxybenzamide in any literature (which might lead suspicious minds to suspect there are workup problems of one form or another)...

It would be nice if the Reimer-Tiemann could be avoided, but if not, then I really want catechol simply because of the ease of forming the benzodioxole without needing inert atmospheres/etc.

PS I am in Australia and there is no really cheap source of photochems, the one decent source is overly inquisitive, prone to reporting suspicious purchases and not at all pleasant to deal with. As for importing ANY chemical, no chance in hell.

unome - 24-11-2009 at 00:57

Have to double-post (must have missed the deadline) but for anyone here who (1) speaks German; and (2) has access to Ber. this reference apparently (according to page 291 of Organic Reactions, Vol 3 - this sites library) details the formation of 2-hydroxyaniline from salicylamide via an intermediate 4,5-benzoxazole (??)

Graebe and Rostowzev, Ber. 35, 2747 (1902)

Details (and especially a translation) would be gratefully accepted

PS The relevant article is now attached (with many thanks to Java/Solo) if any of the German speakers could help out, the problem might well me capable of being solved:)

[Edited on 24-11-2009 by unome]

Attachment: phpuFO2fA (401kB)
This file has been downloaded 1495 times

something_sinister - 16-6-2010 at 18:14

Quote: Originally posted by unome  

PS I am in Australia and there is no really cheap source of photochems, the one decent source is overly inquisitive, prone to reporting suspicious purchases and not at all pleasant to deal with. As for importing ANY chemical, no chance in hell., is an excellent Australian photochemical site. I just got my order of mercuric chloride, sodium bromide and potassium iodide today. Catechol per 100gm $60. suspicious/no chance in hell... Your just not looking hard enough mate. Australia may seem like one of the most restricted places on earth, but theres still hope for those chemists who persevere.

Panache - 18-6-2010 at 04:02

Eugenol will demethylate to catechol in a NaCl/AlCl3 melt (i think the proportions for the eutetic are 3:1) at ~175C. Yields are terrible, around 20% however the reagants are cheap (assuming you make your own AlCl3, purity of the Alcl3 is not paramount). Also the reaction is quick and simple...form the eutetic in a beaker raise to 200C, drip in the eugenol as quickly as possible without bombing out the temperature (and whilst standing back as it hisses and fizzes), once the eugenol has been added, leave at temperature for a few minutes then pour the vile tarry mess into an excess of ice water. The fun really begins now as the workup is tedious.
It will appear to run unsuccessfully many times and suddenly the tarry vile mess will almosty seem pure, in stark contrast to most runs, the reason for this is luck (or maybe Jesus helping out). Interestingly although far more pleasant to workup the yeilds are not any better on these hail mary runs, and once the workup is grasped the reaction runs well.
Vac distill the eugenol prior to use as this tends to render the workup simplier, i am assuming the myriad of natural poroducts present in small quantites in eugenol wreac havoc with the cataechol formed generating messy complexes with the aluminium.

i just made up a chemistry joke
q.did you hear about the chemist demethylating eugenol out in the snow
a;he caught a cold! (catecol, LMOA, ROFL, LOL, Ha!, teet)

peach - 19-6-2010 at 15:29

Interesting about a melt and the eutectic point. Personally, I've never had any luck with the stuff even when simply using AlCl3 in a polar aprotic or none polar solvent. Usually ends up with a nice tarry mess. And what's worse, it starts forming the second the first drop hits the solution (I can see the solution darkening to 'that color' we all know and love).

I've even tried AlI3 in none polar solvent with a PTC under argon. It yielded a quantity of thick, lightly green colored resinous material that became considerably tough after cooling in the fridge (I could leave the flask on it's side for a few hours and it wouldn't move). When back at room temperature, it'd flow a few mm if left on it's side for hours. The amount of product, this time, was more in line with the quantity of substrate used. Importantly, it wasn't the color of a smokers lungs (my poor, poor lungs). If I poked at the resin like material, I could leave impressions in it's surface and it wouldn't stick to the poking instrument. Over time, exposed to the atmosphere, it appeared to darken to a more greeny brown color.

I also tried said AlI3 method using DCM, producing an odd result that was damn near IMPOSSIBLE to filter. By that I mean, I had to leave it for two days to collect tens of mls. I could swirl it and scrape at the filter paper all I liked. Nothing. And the filtrate seemed to refuse to boil at room temperature when down around 40mBar, despite being full of DCM. I abandoned the filtrate but left it to stand in the sunlight, exposed to the atmosphere. It gradually turned almost black over a few days. Hmmm... interesting!

When I was trying to demethylate with AlCl3, I noticed what I am sure where HCl fumes slowly leaving the flask on addition. I am sure they were HCl due to the acrid nature, smell, taste and brass around them turning green. This may have been water in the substrate. I'm fairly sure this substrate has been vacuum distilled prior to me getting hold of it, and it hasn't been left open. So it's unlikely to have much water in it. And the amount of fuming seemed out of proportion to any realistic water content of the oil. I also agree that using raw oil is probably a bad idea, since caryophyllene (one of it's other components) features a few double bonds, which will likely be getting intimately involved with the acid, in a bad way (eugenol is enough of a bastard child on it's own). I tried A/B extracting the raw oil and received a product that was still a significantly brown/orange color with a complex aroma. The distillate is near colorless and has a very simple aroma.

On hydrolysing AlCl3 runs, there would inevitably be a large amount of HCl produced, far more than when adding the eugenol. This was done in an ice bath with ice cooled water. The aluminum would also go into solution in the aqueous phase.

AlI3 runs were different. Here, adding the eugenol produced significantly more fuming. I also suspect this was HI. It would immediately begin turning the solution opaque. On heating, the solution would immediately thicken and begin turning gray. After ten or so minutes at only the reflux point of DCM, it would form a solid grey sludge and cake up, jamming a 70mm odd sized stir bar in an erlenmeyer. The cakeyness (advanced SI terminology :D) would actually form a skin and form 'crevices' through it's self, like an over baked milky pudding. At hydrolysis, absolutely nothing would happen. No fuming, no breakdown of the cake. I had to warm the solution to just above room temperature. Again, no evolution of gas. But the cake would then breakdown into fine grains of aluminum.

I've tried AlCl3 in DCM in a salt/ice bath, same tarryness on addition.

As I say, the AlI3 methods are stupidly difficult to filter. I can pick the filter paper up and hold it there for a minute and nothing will come through. Same for swirling and stirring. It seems, ironically, easier when using a higher BP solvent, and virtually impossible when using something as free flowing as DCM.

With regards to AlCl3 purity, I've bought CP grade before and it's literally been dirt brown. After leaving it to sit in some DCM for a few weeks, I just about managed to clean most of it off. Some of the crystals were also tinted yellow. That's suggesting the aluminum was contaminated with iron. How on earth it got that dirty is something I'm still not sure of. It looked like they'd scraped the aluminum up off the sides of the electrolytic cells.

Intriguing my dear Watsons, intriguiging.

As for synthesizing the stuff through a method as long as the original post... darn! Time to switch your developing solutions if it's for anything other than the fun of playing. :P

If you're considering something featuring as many stage as that, you could also look to guaiacol, which will probably be easy to demethylate to catechol and occurs in both the plant guaiacum and wood creasote (tar). Interesting facts about each... the wood from guaiacum is the hardest known. It lives around the Carribean and northern South America. Don't know if it's native to the land of girls, sunshine, beaches and positivity but the climate is about right. Not worth growing it since it's a slow grower. Wood creosote is used to preserve wood furniture or other timber in the garden. I'm pretty sure you could find a gigantic 25l container of it if you ask at the timber yards. They may try selling you expensive, proprietary, brand name timber solutions. Answers;

"I like the smell of creosote in the morning"
"My [boss, strange brother, farther, alter ego, someone who knows lots about wood] sent me here and, I have no idea why, but he specifically demanded wood creosote"
"I'm making my own photodeveloper" (wood creosote actually changes color when exposed to light I think)

You want WOOD creosote, not coal creosote. Coal creosote doesn't have the guaiacol in it and it's full of things like PAHs (a primary carcinogen found in cigarette smoke). It does make nice smelling soap however.

The number of steps involved in what you're thinking of is already a good few. If you were going on from there to something else via a few more stages, that would be one heavy and involved workload, possibly resulting in horrendously poor yields.

[edit]I'm looking at a 25l container of creosote now and it's about $95 AUD. Also, be advised that creosote is usually used by people with experience when it comes to timber, so making out like you're the one using it in the garden and then having no idea what you're talking about when they ask you about timber may encourage them to question your ability to use it in the first place. e.g. "What's your stock? (Good sir, what wood is it that you will be using this fine product upon?" "Erm.........."[/edit]

[Edited on 20-6-2010 by peach]

ThatchemistKid - 13-10-2010 at 13:02

I have thought about making catechol myself from methyl salicylate using the Bouveault Blanc reduction I do not have any literature references for this, I have talked to a professor about it though, they said that the Lithium or sodium in ethanol should not be strong enough to reduce the benzene ring.

any reason or something that I am ignorant to why this reaction will not work or has not been suggested for making catechol?

ThatchemistKid - 13-10-2010 at 13:19

Here is the reference to a paper about the reaction.. it mentions that aromatics are not reduced and phenols and Carboxylic acids were tolerated.

DJF90 - 13-10-2010 at 14:10

Well for a start, bouvealt-blanc reduction will take the ester to the alcohol. All gravy, but then you've got a benzylic alcohol and not a phenol. I suppose oxidation to the aldehyde and subsequent Dakin reaction would work but it sounds like alot of hassle to me.

peach - 13-10-2010 at 15:24

This entire thread depends on why you're doing it.

If it's for the fun of it and to get a pure reference, yeah, go heavy duty on the ground up method.

If it's for a bit of fun, use one of the naturally occurring close variants like guaiacol and demethylate it. Blasting it with a hard lewis acid will be fairly simple compared to other demethylations.

If it's to get something working, just buy a bottle of the crap. The photography guys have some if you don't have a supplier account.

If it's a scheme to an unlimited supply of drugs.... it's probably not going to happen. Acid and cocaine can both be made from very basic beginnings. The 12 step process and 1% yield, involving some seriously tricky chemistry along the way, means no one has bothered. Despite people wanting them enough to kill each other.

[Edited on 13-10-2010 by peach]

ThatchemistKid - 13-10-2010 at 16:04

"subsequent Dakin reaction" after oxidation to the aldehyde...
yes yes.. sorry
I agree

sorry idk how that even slipped my mind, and I was even TAing organic lab at the time I feel..blegh XD

[Edited on 14-10-2010 by ThatchemistKid]

ThatchemistKid - 13-10-2010 at 16:17

well.. wait a moment that is counter productive.. can the bouvealt-blanc reduction not be adjusted to give the aldehyde?
It takes two equivalents of the alkali metal to reduce the acid all the way to the alcohol. an intermediate in the mechanism is the aldehyde, can it not be stopped there if the conditions are controlled.. say a little excess Salicylic acid to only about 1 equivalent of alkali-metal? ... essentially we would be going through Salicylaldehyde as mentioned in some of the other procedures here but we would be skipping the Reimer-Tiemann formylation ( if phenol or benzene was your starting material) and going straight to the dakin reaction.

It would also avoid the salicylamide formation and the hoffman degradation and subsequent diazotization.

DJF90 - 14-10-2010 at 14:42

Nope - think electrophilicity of the species in question. Its the same reason LAH reduction of esters can't be stopped at the aldehyde.

[Edited on 14-10-2010 by DJF90]

ThatchemistKid - 14-10-2010 at 22:38

Well is there a milder reducing that will take the ester only to the aldehyde?

hopefully ones that are more common and accessible than diisobutylaluminum hydride? ( which is done at -70C), although if this last method is of interest to anyone I have uploaded here a good paper that I found about the subject.

And I figured that the electrophilicity might be an issue as with LAH reductions but I have no experience as of yet with the reaction so I did not actually know.

Attachment: Dibalh salts reduction of esters to aldehydes.pdf (354kB)
This file has been downloaded 988 times

DJF90 - 15-10-2010 at 04:14

DIBAL-H and the salts that paper mentions (which work far better than DIBAL-H itself for the Ester=>Aldehyde transformation) are typically what are used, and I'm not sure there is another *direct* alternative. LAH reduction of the corresponding acyl aziridines, acyl imidazoles, or weinreb amides should also furnish the aldehyde. Take your pick, but its all alot of hassle for a commercially available material.

ThatchemistKid - 15-10-2010 at 08:05

Note by common and accessible I meant to the home amature XD

although I do know that the synthesis of LAH and its derivatives is not to terribly difficult that someone with a little skill, and possibly a glovebox, may achieve it at home...I have yet to do I do not think I am that skilled yet.

[Edited on 15-10-2010 by ThatchemistKid]

DJF90 - 15-10-2010 at 09:34

Then the Bouvealt-Blanc is probably the best bet. Catechol should still be accessible to you though, especially if you can get sodium.

Natures Natrium - 15-10-2010 at 21:44

Just wanted to pop in and comment on this necromantic thread.

Seems to me that to go from salicylic acid to catechol, the simplest route would be:

1. Mix with CaOH, heat and decarboxylate to phenol.
2. Treat phenol with Fenton's Reagent to generate a mixture of dihydroxybenzenes.
3. Separate via vacuum distillation.

Found a rather detailed site on Fenton's Reagent, here:

As a surprisingly simple alternative to Fenton's, I found a patent detailing the use of SO2 or SeO2 and H2O2, without the need for any sort of co-catalyst and using n-propyl acetate as a solvent:

Interestingly enough, they don't report any m-dihydroxybeneze as a result of this method. Unfortunately, most of their examples do use >70% H2O2 solutions.

Oh, and no, I have not personally tried any of these reactions, so I cannot offer specific advice.

RiP057 - 26-10-2010 at 18:28

Quote: Originally posted by peach  
just buy a bottle of the crap.
[Edited on 13-10-2010 by peach]

seriously that is an enormous amount of work for next to nothing.... maybe fun but purchase... there are a million different sources.

Random - 14-12-2010 at 14:53

Is there some alternative to fenton's reagent that doesn't use h2o2?

not_important - 14-12-2010 at 15:43

Fenton's depends on the OH radical, and peroxides are the common/easiest way to get that. As the pH is slightly acid, various peroxide salts might be usable - don't know for certain.

There's not much else that does a decent job, the OH radical is a very strong oxidiser. I believe Ce(IV) salts can give similar oxidations, but without very decent yields. Most of the bacteria that chomp on aromatic rings use peroxide.

Try a bit of searching for aromatic ring oxidations.

[Edited on 14-12-2010 by not_important]

Random - 21-12-2010 at 15:31

There is also way to make salicylamide from phenol, urea and ZnO catalyst so then I could make catechol from salicylamide with steps written in the first post of this thread. All without H2O2 :D

Sandmeyer - 23-12-2010 at 18:01

Random, are you talking about this method: 10.1016/j.catcom.2007.11.006

Random - 24-12-2010 at 17:07

Yes, that is the reaction I am talking about.

not_important - 24-12-2010 at 17:39

Quote: Originally posted by Random  
There is also way to make salicylamide from phenol, urea and ZnO catalyst so then I could make catechol from salicylamide with steps written in the first post of this thread. All without H2O2 :D

Did you note the conditions for such reactions?

Clipboard01.png - 47kB

205C, 12 hours, 16% yield.

Satan - 25-12-2010 at 06:01

Another table, this time from 10.1016/j.catcom.2007.11.006 :

table.GIF - 27kB

Ephoton - 25-12-2010 at 11:47

A note on using. Li and alcohol.

Your professor never tried this or
We would have used it for claisen
Years ago.

It makes hydroxides not alkoxides the
Electrons are held too tight.

Plus I tried many times.

atomicfire - 8-3-2011 at 12:57

Sorry for digging this up, but I was looking at synthesizing catechol from phenol and have come across many varying methods. Has anyone found a simple yet effective treatment of phenol to catechol?

I would like to try the direct hydroxylation of phenol via hydrogen peroxide but what type of catalyst would I need? I have seen the use of many exotic ones, but what is the reason?


dean stark - 18-3-2011 at 00:55

Okay, so not terribly straightforward but...

Aspirin to 3-acetylsalicylic acid via ortho-Fries arrangement*, followed by decarboxylation and Dakin oxidation, not necessarily in that order.

In this* paper (which I don't have electronically), they perform ortho-Fries rearrangement on 2-acetoxynitrobenzene by microwaving for a few minutes with zinc dust in DMF.

Seems the hardest part would be decarboxylation. Would simple heating work or would it require something like Quinoline?

bbartlog - 18-3-2011 at 04:11

The Fries rearrangement adds a hydroxyl group to the ring, and attaches the alkyl part of the ester directly to the ring (in the 2 or 4 position apparently). So the closest you could get to 3-acetylsalicylic acid would be maybe 2-hydroxybenzaldehyde, but that would be if you *started* with the methyl ester of phenol, not aspirin. Fries rearrangement on aspirin (if it even worked, which I doubt) would give you a triply substituted ring and leave you no closer to catechol than before.
Decarboxylating salicylic acid can apparently be done via simple heating, but I haven't had any success doing it preparatively at temperatures up to 195C (including attempts with copper catalyst). Probably not hot enough, may need something like 230C to proceed at a reasonable rate. Anyway if you did that you would have phenol, which as some others have suggested might be a route to catechol.
There is a patent out there somewhere on the oxidative (via air) decarboxylation of aromatics using copper catalysts; in that process the carboxyl group ends up replaced by a hydroxyl one. So if this worked on salicylic acid, it would provide a direct route to catechol. However as I recall their process didn't work well at all when there was an ortho-hydroxy substituent, so it's not really applicable here.

dean stark - 18-3-2011 at 04:35

Pretty sure the ortho-Fries rearrangement of Aspirin IS 3-acetylsalicylic acid (unless I'm getting the numbering wrong, and BTW I'm using acetyl in the sense of acetylbenzene which is acetophenone...).

The Fries rearrangement doesn't ADD a hydroxyl group - it's already there. From Wikipedia: The Fries rearrangement ... is a rearrangement reaction of a phenyl ester to a hydroxy aryl ketone by catalysis of lewis acids.

So the acid part of the ester, which is acetic in this case, migrates to the aromatic nucleus.

More details and diagrams from the paper are available from the Organic Chemistry Portal.

bbartlog - 18-3-2011 at 06:21

Ah, you're right. My bad. Fair enough; I guess you can get 3-acetylsalicylic acid that way. I remain skeptical about this being a usable precursor for catechol, though.

Nicodem - 19-3-2011 at 01:51

The only mention related to the Fries rearrangement of aspirin that I could find is in some old article in a Romanian journal. HClO4 is used for in situ O-acylation and subsequent Fries rearrangement of various phenols, salicylic acid included. Yields are low and I doubt they would be much better by starting from aspirin directly. Unfortunately, the journal only has electronic issues starting from 2006, so unless you get in in a library, the CA abstract is the only info available:

Fries rearrangement. Leonte, Mircea; Beschia, Magda; Pascaru, Elvira; Stoica, Maria. Polytech. Inst., Galati, Rom. Studia Universitatis Babes-Bolyai, Chemia (1963), 8(1), 291-6. CODEN: SUBCAB ISSN: 1224-7154. Journal language unavailable. CAN 61:68907 AN 1964:468907 CAPLUS


Starting from the hypothesis that the strength of the acid catalysts plays an essential role in the initiation of the Fries rearrangement, the capacity of 70% HClO4 to catalyze the reaction of phenol acylation was investigated, since the only case of the use of this acid was the unsuccessful attempt of Dorofeenko (CA 55, 24518i) to acylate phenol and resorcinol, which gave the esters instead of the ketones. Phenol (50 g.) was treated with 45 cc. Ac2O and 10 cc. 70% HClO4, the mixt. heated 30 min. on a water bath, left 24 h. at room temp., neutralized with 20% Na2CO3, 20 g. NaOH in 100 cc. H2O added, the aq. alk. soln. extd. with ether, then neutralized with 20% HCl, reextd. with ether, the ether evapd., and the product distd. to give 51% 2-hydroxyacetophenone, b7 86, and the distn. residue dissolved in 20% NaOH, boiled 30 min., cooled, pptd. with 10% HCl, and recrystd. from H2O with animal charcoal, to give 20.5% 4-hydroxyacetophenone, m. 108-9. Parallel Fries rearrangement of PhOAc under the same conditions gave the o- and p-isomers in 38 and 19% yields, resp., thus confirming that the ester was formed at first and was then rearranged to the corresponding ketone. Similar treatment of o-cresol (3 h. at 120) gave 55.5% 2-hydroxy-3-methylacetophenone, b10 105, 31% 3-methyl-4-hydroxyacetophenone. Treatment of m-cresol (1 h. with no external heating, then 48 h. at room temp.) gave the o- and p-isomers, 62.8% 2-hydroxy-4-methyl- and 6% 4-hydroxy-2-methylacetophenone, b7 103, and m. 128% resp. Similar treatment of p-cresol (heating 1 h. at 100 then keeping 48 h. at room temp.) gave 53% 2-hydroxy-5-methylacetophenone, b7 101-3. Treatment of resorcinol (cooling, strong agitation, then 24 h. at room temp.) gave after neutralization with Na2CO3 90% 2,4-dihydroxyacetophenone; similar treatment of resorcinol monoacetate gave 83% same product. Treatment of pyrocatechol (refluxing 3 h. on a water bath) gave 58% light-violet 2,3-dihydroxyacetophenone, m. 97.
Identical treatment of pyrogallol gave 44% 2,3,4-trihydroxyacetophenone, m. 173. Treatment of .alpha.-naphthol (1 h. at 115-20 on a sand bath) gave after steam-distn. part of the 1-hydroxy-2-acetylnaphthalene formed, m. 100; further boiling of the resinous residue 1 h. in NaOH, neutralization, and steam-distn. gave some further product, for a total yield of 40%. Salicylic acid was first dissolved in Ac2O-HClO4 at 100, the mixt. kept 0.5 h. at 120-30, cooled, H2O added, and the ppt. filtered off and recrystd. (H2O) to give 20-5% 3-carboxy-4-hydroxyacetophenone, m. 209-10, phenylhydrazone m. 260; semicarbazone m. 222. Heating the reaction mixt. 1.5-2 h. at 120-30 and similar purifn. gave 71% 2-hydroxy-3-carboxyacetophenone, m. 148-9; phenylhydrazone m. 218; semicarbazone m. 240. The cause for the limited usefulness of HClO4 as a catalyst in the Fries rearrangement was hence attributed to the oxidizing nature of this acid, which appeared only >170 for long durations in the case of phenol acylation, but did not appear when the reaction temp. was kept <140 in the case of the Fries rearrangement. Its advantages over other acid catalysts were: low amt. needed (0.1-0.2 mol per mol phenol compared to 1-2 mol AlCl3); no solvent needed as is the case with AlCl3 (the use of solvents in the case of HClO4 did not improve the yields); and the preferential catalysis to the o-isomer, which in the case of some phenols-pyrocatechol, pyrogallol, and salicylic acid-was the only isomer obtained, in contrast to the p-isomer obtained when AlCl3 was used, while in the other cases the yields of o-isomer were greater than and the yields of p-isomer smaller than when AlCl3 was used as catalyst.

Whatever conditions are to be used, the Fries rearrangement of para-unsubstituted acyloxybenzenes rarely gives a clean ortho-rearrangement.
There are however a few examples of the Fries rearrangement of 5-substituted acylsalicylic acids in the literature, however these all have the para-position in respect to the acyloxy group blocked (with Me, Et, F or I):
Inorganic Chemistry, 41 (2002) 3673-3683. (AlCl3)
J. Ind. Chem. Soc., 41 (1964) 833.
Journal of Medicinal Chemistry, 29 (1986) 538-549. (same method as ref above)
Journal of Chemical Research, Synopses (1985) 372-373. (AlCl3/MeNO2)

About the decarboxylation... The retro-Kolbe-Schmitt reaction procceds best the more hydroxy groups there are on the aromatic ring and the more electron withdrawing groups there are para/ortho to these hydroxy groups. 3-Acetylsalicylic acid is barelly souitable, but might undergo such decarboxylation under proper conditions. The literature is however more aboundant with Cu-catalysed decarboxylation of substituted salicylic acids (eg, Helvetica Chimica Acta, 68 (1985) 945-948 where Cu2O/bipyridine/diglyme is used).

Also, making something as interesting as 3-acetylsalicylic acid just to decompose it to something as trivial and cheap as ortho-hydroxyacetophenone or catechol is a bit dumb in my opinion. Both of these can be simply bought, as they are neither toxic or controled in any way, nor are they prohibitively expensive. On the other hand 3-acetylsalicylic acid is not commercially available and its syntheses described in the literature are all quite tedious.

dean stark - 19-3-2011 at 03:00

Thanks Nicodem.

The Fries rearrangement in the paper I mentioned seems to be selective to some degree depending on whether it is MWed or simply heated.

Now that I have the m.p. (from your quote), it should at least be possible to see if it works. 13 minutes in the microwave isn't too bad...

I will check out your suggestions for decarboxylation. Something's gotta work.

As for price and availability, my options are pretty limited for the time being.

adianadiadi - 3-11-2012 at 21:35

Sorry for posting on an older post. However I would like to give a link showing Fries rearrangement of aspirin using AlCl3 as catalyst. I think it works well.

Random - 13-11-2012 at 21:55

Catechol can be prepared by the demethylation of guaiacol with aluminum chloride and hydriodic acid (from

Composition of a typical beech-tar creosote
Phenol C6H5OH 5.2%
o-cresol (CH3)C6H4(OH) 10.4%
m- and p-cresols (CH3)C6H4(OH) 11.6%
o-ethylphenol C6H4(C2H5)OH 3.6%
Guaiacol C6H4(OH)(OCH3) 25.0%
1,3,4-xylenol C6H3(CH3)2OH 2.0%
1,3,5-xylenol C6H3(CH3)2OH 1.0%
Various phenols C6H5OH— 6.2%
Creosol and homologs C6H3(CH3)(OH)(OCH3)— 35.0%

Creosote can be made from dry distillation of beech wood and the resulting sticky liquid can be used to isolate guiacol. About 25% of guiacol in beech tar creosote.

Then guiacol can be demethylated as described above. I am currently experimenting with creosote and its compounds.

Dronami_inc - 21-3-2013 at 04:12

I think that very interesting way would be replacing the methyl groups in o-xylene with OH-group. Certainly not in one step. More interesting in theory, how to implement it.


IMHO, the first phase - the oxidation to phthalic anhydride or acid

paw_20 - 22-3-2013 at 07:25

hot KMnO4 and then reduction with LAH, not much else reduces carboxylic acids. But it isn't easy to separate o-xylene from it's isomers.

Catechol from salicylaldehyde

phendrol - 19-10-2013 at 03:13

I want to try the preparation of catechol from salicylaldehyde.


To a solution of 122 g. (1 mole) of pure salicylaldehyde (Note 1) in 1000 cc. of normal sodium hydroxide solution at room temperature, is added 1420 g. (1.2 moles) of 3 per cent hydrogen peroxide. The mixture darkens slightly in color and the temperature rises to 45–50°. The solution is allowed to stand for fifteen to twenty hours, whereupon a few drops of acetic acid are added in order to neutralize any excess alkali, and the solution evaporated to complete dryness on the water bath under reduced pressure. The solid residue is finely crushed and warmed nearly to boiling with 500 cc. of toluene; the mixture is then poured into the folded filter paper of an extraction apparatus (p. 375) and extracted with boiling toluene for five hours. The toluene is allowed to cool and is decanted from the catechol, which crystallizes out. The insoluble material is again ground up and extracted in the apparatus with the decanted toluene.

Organic Syntheses, Coll. Vol. 1, p.149 (1941); Vol. 3, p.28 (1923).

The only thing that makes me hesitate is that I don't have a vacuum pump, so I can't evaporate all the water under reduced pressure. I'm afraid that simply boiling of the water under atmospheric pressure will cause loses because a part of the catechol will sublime.

Any thoughts on that anyone? :)

hyfalcon - 19-10-2013 at 04:09

Here's the live link to your paper.

Any reason you can't evaporate at a lower and slower temperature? Possibly over a desiccant?

[Edited on 19-10-2013 by hyfalcon]

CuReUS - 15-5-2015 at 04:28

what about making catechol by oxidising ortho nitrophenol with DMDO or peroxide ?
ortho nitrophenol can be selectively synthesised using clay +nitrating reagent

Chemosynthesis - 15-5-2015 at 11:35

Quote: Originally posted by CuReUS  
what about making catechol by oxidising ortho nitrophenol with DMDO or peroxide ?

Are you still trying to apply Meisenheimer complex chemistry to non-adduct nitrobenzenes? Because that won't work. Unless you have a reference indicating conditions where this has been confirmed, it is important to realize that substituents such as those withdrawing electrons in a specific manner in Meisenheimer complexes can alter reactions and stability in much the same way the Jahn-Teller effect explains anti-aromatic reactivity.

CuReUS - 16-5-2015 at 00:07

one of the resonance structures of para nitrophenol has a similar structure like that meisenhiemer complex,so I wondered maybe ortho nitro phenol could also exist in that form,because nicodem had said that ortho and para amino phenol had similar quinoid structures.

meisenhiemer.jpg.bmp - 693kB

Chemosynthesis - 16-5-2015 at 01:50

Interesting idea, but I see quite a distinction between a minor resonance contributor (see the unfavorable charge separation on the nitrogen and both oxygens?) with a stable (isolated even) adduct.

Edit: Also, do note you technically did not draw a resonance structure as one figure is protonated at the phenol and the other assumes deprotonation. Resonance structures are between either structures of the acid itself with arrow pushing, or of the phenoxide with arrow pushing, but not between an acid and its conjugate base, which require an equilibrium arrow by convention rather than resonance notation. Consider where the cation or solvation shells would best fit.

[Edited on 16-5-2015 by Chemosynthesis]

byko3y - 16-5-2015 at 04:23

CuReUS, i think you are right about resonance structure (althoug you will need a base to obtain it), but I see no way to substitute the nitro group, because you can't do Nef reaction on nitroalkene - you need to reduce it first. Maybe you see some other known mechanism that will allow you to substitute the nitro group?

CuReUS - 16-5-2015 at 22:17

I realised later that there was a huge flaw in my idea.Even if nef reaction could be done on the nitronate,it would not tautomerise to a phenol as there is no Hydrogen

clearly_not_atara - 24-5-2015 at 14:24

Other idea:

1. Esterify acetylsalicylic acid with -anything- to get, say, O-acetylsalicylic acid ethyl ester. Use some sort of non-nucleophilic base or dehydrating conditions so you don't cleave the acetate.

2. Use NaNH2/LiNH2/NaOiPr to catalyze an intramolecular Claisen condensation: the acetyl group deprotonates and is attacked by the ortho- carboxyl group to give 2,4-dioxobenzopyran. Sodium/lithium amide should work fine here; it's not as nucleophilic as it looks. KOH/DMSO might work, actually. Aprotic solvents are ideal.

3. A Dakin reaction produces catechol and malonic acid. Malonic acid can be extracted from the rxn by precipitation with Ca2+ since it's kind of interesting too. If you're clever and lucky and perform the rxn in ethanol you could generate diethyl malonate directly.

[Edited on 24-5-2015 by clearly_not_atara]

Chemosynthesis - 24-5-2015 at 21:03

Quote: Originally posted by CuReUS  
I realised later that there was a huge flaw in my idea.Even if nef reaction could be done on the nitronate,it would not tautomerise to a phenol as there is no Hydrogen

Not a tautomer if it's short a hydrogen.

Magpie - 25-6-2015 at 11:56

I tried this synthesis using the 5.1g of salicylaldehyde that I had recently synthesized.

Using a scale factor of 0.05 I added 3% H202 and 1M NaOH to a 250mL beaker. Then I added the salicylaldehyde and stirred with a magnetic stirrer. The solution went from yellow to dark red. Temperature rose to 50°C as indicated in the OrgSyn procedure.

After setting overnight I added a few drops of acetic acid to bring to neutral. I overshot a bit resulting in a pH of 6.

I placed the beaker in a water bath and heated it all day long. Then I changed to a silicone bath controlled to 100°C. Finally it dried to a dark, viscous tar having the smell of phenol..

Today I added 28 ml of toluene, warmed to near boiling, and stirred. There was no color change of the toluene, indicating to me, no dissolution.

This synthesis appears to be a failure. Most likely what I have made is just a tar composed of polymerized catechol.

aga - 25-6-2015 at 13:06

Quote: Originally posted by Magpie  
what I have made is just a tar

Wooohoo !

I am sooo happy that my own tarry products are not totally abnormal.

I thought i was just stupid.

Pumukli - 26-6-2015 at 11:59

Quote: Originally posted by Magpie  

Today I added 28 ml of toluene, warmed to near boiling, and stirred. There was no color change of the toluene, indicating to me, no dissolution.

This synthesis appears to be a failure. Most likely what I have made is just a tar composed of polymerized catechol.

Hey, Magpie, maybe you are just one step away from success!
The original article says that the solid residue must be extracted with toluene, then repeatedle extracted again, for several hours, etc.
So you got to the solid residue (although tarry) and extracted it with toluene.
Then you complain about "no color change". Why?
I think catechol is colorless, at least it should be!

Then you wrote what you extracted smelled phenol-like. Woo-hoo! Isn't catechol expected to have at least a faint phenol-like odour? :-)

Why not evaporate (distill off) the toluene to see if you really got something dissolved in it? Maybe you got it, even if the yield is probably not astronomical, but I would not care less at this stage. You made a nice (and tedious) salicylaldehyde synthesis, please don't let it go just like this! I'm curious about the final step - and I'm fairly sure some SM members feel the same!

[Edited on 26-6-2015 by Pumukli]

Magpie - 26-6-2015 at 12:37

Pumukli, I agree. I just lost patience when I saw the tar. I let it sit outside until the toluene evaporated. Then this morning I removed most of the tar with a spatula. Then I added some NaOH and a little water just to clean out the beaker.

[Edited on 27-6-2015 by Magpie]

stoichiometric_steve - 27-6-2015 at 03:20

i have some catechol for sale, if that's what you're after?

Magpie - 28-6-2015 at 06:28

Quote: Originally posted by Magpie  

This synthesis appears to be a failure. Most likely what I have made is just a tar composed of polymerized catechol.

Here's what the product looked like. I meant to post this in the original post but forgot.

catechol reaction product - dried.jpg - 80kB

S.C. Wack - 28-6-2015 at 08:53

Quote: Originally posted by Magpie  
Then I added some NaOH and a little water just to clean out the beaker.

That NaOH should be worked on. Perhaps the toluene was unable to access anything it could dissolve.

zed - 29-6-2015 at 17:39

Lots of faked results out there. But, Organic Synthesis procedures....Well, thus far, every one I have tried has worked.


Magpie - 8-1-2018 at 19:24

I remember reading on this forum about making catechol using calcium bromide. This was 1-2 months ago (I think). But I can't find anything on this. I even bought 25g of Ca(Br)2 with which to make it.

Does anybody remember this synthesis?

PirateDocBrown - 8-1-2018 at 22:00

From phenol?

Magpie - 8-1-2018 at 22:05

yes, I believe it was! It might have been in a referenced paper.

PirateDocBrown - 8-1-2018 at 22:24

It's entirely possible to transform phenol into catechol using hydrogen peroxide. I don't know what catalyst is typically used, but it could be a halide.

yobbo II - 9-1-2018 at 07:56

One up from the bottom

Magpie - 9-1-2018 at 14:57

Thanks so much yobbo II. I have a 400w source of h√ so will give this a try.

Magpie - 9-1-2018 at 19:55

I think I have found 2 better syntheses for catechol:

One starts with guaiacol and uses 48% HBr. This is a 1941 synthesis by Taylor & Clark published in OrgSyn.

The other starts with salicylaldehyde and uses HOOH as reagent. By-product is the formate ion. This is by Dakin and is also published in OrgSyn (1941).

Assured Fish - 9-1-2018 at 20:49

I would advise strongly against the Dakin reaction, the yields tend to suck balls, also you would first have to either prepare of get your hands on salicylaldehyde.
I have however prepared 2-aminophenol by hoffman rearangement of salicylamide followed by hydrolosis of the resulting benzoxazolone.
Unfortunately i still haven't gotten round to performing the sandmeyer reaction as getting my hands on sodium nitrite in NZ is an absolute pain in the buttox.
I followed the following prep and got close to 80% yield starting from salycilic acid, if i recall major loss was during the hoffman rearrangement.
I had an issue doing a large scale batch however (30g), during hydrolysis of the benzoxazolone i foolishly used too high of a concentration of HCl which lead to it not working at all.
A second attempt with dilute HCl worked however it was very slow. I do not know why this requires dilute HCl, if someone could enlighten me it would be much appreciated.

Magpie - 9-1-2018 at 21:17

OK thank you.

DJF90 - 10-1-2018 at 08:01

Magpie, its hard to go wrong with an OrgSyn procedure. I'd say pick whichever one is most accessible to you.

Swinfi2 - 19-2-2018 at 04:22

Synthesis of catechol recently came up in my BSc research project, i found the Dakin oxidation and another method starting with Phenol that may be of interest for making substituted catechols depending reagent availability.

[Edited on 19-2-2018 by Swinfi2]

Magpie - 19-2-2018 at 08:40

I have on hand 50mL of guaiacol with which I plan to make catechol according to the OrgSyn procedure at 1/10 scale.

I began setting up the apparatus 3 days ago trying to assemble a workable assembly from an assortment of RBFs, condensers, etc. I then gave up and decided to order the appropriate glassware. For one, I will use a 500mL vertical 3-neck RBF, 24/40, from eBay.

The separator was the main problem. I tried to use my Dean-Stark but it was a mess. So, I have designed my own separator and am now taking bids on its construction from two glassblowers.

Fortunately, I have a 600mm Hempel column, 19/22. This should do nicely for the requirement of at least a 400mm column.

I apologize for the drawing being upside down. Toggle it; it will right itself.

separator for catechol2.jpg - 188kB

[Edited on 19-2-2018 by Magpie]

Loptr - 19-2-2018 at 19:47

Hydroxylation and decarboxylation of hydroxybenzoic acids by

Halvor Aarnes, Department of Biology, University of Oslo, POB 1066, Blindern, N-0316 Oslo,
NORWAY; E-mail: halvor.aarnes[at]
Unpublished research paper based on experiments done in 1998-1999.


Hydroxylation and decarboxylation of hydroxybenzoic acids occurs rapidly at pH 3 to 6.5 in a system
con 4 2 taining FeSO and Na EDTA. EDTA could be replaced by citric acid. In this in vitro system 4-
hydroxybenzoic acid is hydroxylated to 3,4-dihydroxybenzoic acid (protocatechuic acid) and
decarboxylated to hydroquinone. In an analogous reaction 2-hydroxybenzoic acid (salicylic acid) is
hydroxylated to 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid (gentisic acid) and
decarboxylated to catechol. Surprisingly the reactions showed Micahelis-Menten saturation kinetics for
the products, and this paper is the first description of these reactions. From these data it is also
cautioned to use hydroxylation of hydroxybenzoic acids as an indicator of oxidative stress and hydroxyl
radicals in biological systems without proper controls.

Attachment: Hydroxylation and Decarboxylation of hydroxybenzoic acids by Fe2+-chelates.pdf (884kB)
This file has been downloaded 405 times

Texium - 20-2-2018 at 06:57

An interesting paper, though it leaves some questions unanswered. Is the iron catalytic, or does it need to be used stoichiometrically? If the reaction is allowed to run longer, will it eventually fully decarboxylate all of the benzoic acids present? In the paper, they say they only got 13% yield of catechol from salicylic acid, with 50% 2,5-dihydroxybenzoic acid and 37% 2,3-dihydroxybenzoic acid. Sure it would be easy to separate the catechol from the acids by neutralizing the acids with a weak base and extracting, but it would be nice if you could just convert everything into catechol.

I'm filing this in the "stuff I'd like to try when I actually have lab time" folder :P

Edit: Merged three catechol preparation threads into one big happy catechol thread

[Edited on 2-20-2018 by Texium (zts16)]

clearly_not_atara - 20-2-2018 at 08:51

I would advise strongly against the Dakin reaction, the yields tend to suck balls
While I agree with your complaint about salicylaldehyde, this is not supported by your link, in which the highest yield of catechol is 89%. It appears that the key is to use reagents at a very low concentration. This accords with the famous Orgsyn procedure in which the yields are decent and 3% off-the-shelf peroxide is used:

[Edited on 20-2-2018 by clearly_not_atara]

S.C. Wack - 20-2-2018 at 15:27

Why not protocatechuic acid from alkali fusion of vanillin or eugenol, and distillation?

UC235 - 20-2-2018 at 15:42

If you're going to use a demethylation of guaiacol, why not start from the considerably more available guaifenesin, readily purified from OTC expectorants.

To reduce the consumption of HBr, I'm under the impression that treatment of guaifenesin with permaganate produces (2-methoxy-phenoxy)acetic acid.

Swinfi2 - 26-2-2018 at 15:23

Quote: Originally posted by Texium (zts16)  
An interesting paper, though it leaves some questions unanswered. Is the iron catalytic...

I've been creating catechol complexes in my uni lab. So far I've found oxygen seems to oxidise/cleave the catechol ligands of complexes but it only seems to occur in solution, the things aren't super sensitive (except the chrome complex which is very sensitive) but i think its worth knowing if you leave a solution instead of a dry product it might not be what you want when you come back to it.

Hope this is helpful guys :)

Texium - 26-2-2018 at 16:19

Quote: Originally posted by UC235  
If you're going to use a demethylation of guaiacol, why not start from the considerably more available guaifenesin, readily purified from OTC expectorants.

To reduce the consumption of HBr, I'm under the impression that treatment of guaifenesin with permaganate produces (2-methoxy-phenoxy)acetic acid.
I've looked into using OTC guaifenesin as a building block and it's very expensive for the amounts you can recover from the tablets, even assuming 100% recovery. You'd be better off buying catechol online.

zed - 26-2-2018 at 16:35


Thirty-odd dollars per pound, is too expensive?

Never hurts to check around.

Magpie - 26-2-2018 at 16:39

The point is to make reagents not buy them, at least the first time. This way you learn some chemistry.

zed - 26-2-2018 at 17:23

Mea Culpa!

I'm good with making reagents, if they are very expensive, or can't be bought easily.

And, these days, most things are very expensive, or can't be bought easily.

So..... When I see something that isn't outlandishly priced, and I CAN buy it easily, I am sorely tempted.

Texium - 26-2-2018 at 17:51

Quote: Originally posted by zed  

Thirty-odd dollars per pound, is too expensive?

Never hurts to check around.
OTC guaifenasin. As in, Mucinex. Which comes in tablets, which must be purified, and is much more expensive by mass. Besides, I've seen catechol at $46/pound which when you factor in the lower molecular weight of catechol, is a much better deal:

I understand you want to make it yourself for the experience, Magpie. I'm mainly posting this info in case anyone is just interested in trying to source catechol in bulk for other reactions. Also, I'm curious: where did you get your guaiacol? It seems to be more expensive and less available than catechol, so I find it odd that you'd be going in that direction, rather than the other way around.

Magpie - 26-2-2018 at 20:16

I paid $15.95 for 50 mL of USP guaiacol. Source:

[Edited on 27-2-2018 by Magpie]

Magpie - 26-2-2018 at 20:26

Quote: Originally posted by Magpie  

The separator was the main problem. I tried to use my Dean-Stark but it was a mess. So, I have designed my own separator and am now taking bids on its construction from two glassblowers.

My 1st choice glassblower (National Scientific) was too busy to give me a bid, so he recommended HS Martin, a vendor with decades of experience who has a good reputation. But my 2nd choice was Eagle Laboratory Glassblowing. HSMartin's bid was $250, Eagle's was $75. Eagle gets the job.

[Edited on 27-2-2018 by Magpie]

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