Sciencemadness Discussion Board - Oxidation of leaf alcohol?

Oxidation of leaf alcohol?

blogfast25 - 18-5-2011 at 12:13

I’m pretty desperate for OTC feedstocks of C5/C6/C7 (preferably linear) materials, anything from 1-ols, 1-halos, 1-aldehydes, 1-carboxylic acids and even 2-ketones. Searching I came across a fairly OTC substance commonly called ‘leaf alcohol’, IUPAC: cis-3-hexen-1-ol.

Could this be easily oxidised to the corresponding carboxylic acid using K2Cr2O7/acid (maybe in acetone, and/or using another oxidising agent) without affecting the double bond, to cis-3-hexenoic acid (CAS 1775-43-5)?

ItalianChemist - 18-5-2011 at 12:56

KMnO4 is stronger than dichromate! I suggest you to use KMnO4 if yo want carboxylic acid and heating until the red color becomes brown.

DJF90 - 18-5-2011 at 13:31

@ItalianChemist: Two things suggest you have no idea what you're talking about - the first is that permanganate is likely to have a greater propensity to "tickle" that alkene; the second is that the colour change you give is incorrect (permanganate is purple, not red. The colour arises from a LMCT band).

@Blogfast: There are oxidisers that will successfully effect the desired transformation. I'd suggest looking at the literature, something is bound to have been mentioned.

[Edited on 18-5-2011 by DJF90]

Magpie - 18-5-2011 at 14:09

Perhaps nitric acid would work. It worked for me making malonic acid. Also my procedure for same in Prepublication lists a reference IIRC.

Where is leaf alcohol OTC? What's its OTC use?

Neil - 18-5-2011 at 15:34

There is a patent for using gold catalysts Oxidative dehydrogenation of alcohols to aldehydes and ketones.

The WiZard is In - 18-5-2011 at 16:17

Quote: Originally posted by Magpie

Perhaps nitric acid would work. It worked for me making malonic acid. Also my procedure for same in Prepublication lists a reference IIRC.

Where is leaf alcohol OTC? What's its OTC use?

Perfume perhaps. The Chemical Week Buyers Guide only
lists one supplier in la US of A.

Google it.

Getting my monies worth out of The Merck Index 14th ed.
It came w/ a CD allowing for online access good for one year,
I have just opened it.

Trivia - What were the first editions of now what is called The
Merck Index labeled?

Monograph Number: 0004700
Title: 3-Hexen-1-ol
CAS Registry Number: 544-12-7
Additional Names: Leaf alcohol
Trademarks: Blätteralkohol
Molecular Formula: C6H12O
Molecular Weight: 100.16
Percent Composition: C 71.95%, H 12.08%, O 15.97%
Line Formula: CH3CH2CH=CHCH2CH2OH
Literature References: Occurs in leaves of odoriferous plants (including shrubs and trees). Isoln from Japanese oil of peppermint: Walbaum J. Prakt. Chem. [2] 96, 245 (1917); Walbaum, Rosenthal, Ber. Schimmel 1929 Jubiläums-Ausg., p 205; from raspberry juice: Bohnsack, Ber. 75, 72 (1942). The natural product has the cis configuration: Crombie, Harper, J. Chem. Soc. 1950, 873; Harper, Smith, ibid. 1955, 1512.
Properties: Liquid. Strong odor resembling that of isoamyl alc, approaching the odor of green leaves when highly dil. d1522 0.846. bp 156-157°; bp9 55-56°. nD20 1.4389.
Boiling point: bp 156-157°; bp9 55-56°
Index of refraction: nD20 1.4389
Density: d1522 0.846

[Edited on 19-5-2011 by The WiZard is In]

The WiZard is In - 18-5-2011 at 16:38

Quote: Originally posted by Magpie

Where is leaf alcohol OTC? What's its OTC use?

Having a moment to kill....

This from Ullmann's 5th. A11:148

Neil - 18-5-2011 at 16:51

You can purchase it from number of suppliers in the flavor/scent/perfume supplies industry. Bloody expensive by my standards...

blogfast25 - 19-5-2011 at 06:24

Quote: Originally posted by Magpie

Perhaps nitric acid would work. It worked for me making malonic acid. Also my procedure for same in Prepublication lists a reference IIRC.

Where is leaf alcohol OTC? What's its OTC use?

It’s mainly sold as ‘leaf acetate’, the acetic acid ester of said alcohol. It’s basically a flagrance thingy, derived from a menthol plant. An Indian company offers it at reasonable prices although shipping is something else.

Nitric may be the way to go. I remember your exploits with making malonic acid and the runaway you got!

I’d probably have to experiment with some alcohol like n-butanol or amyl alcohol to get the conditions more or less right: oxidation reactions of primary alcohols to acids are seriously exothermic.

KMnO4 would almost certainly crack the double bond.

K2Cr2O7 isn’t suitable for allylic alcohols but a cis-3-alkene may survive if the oxidation of the hydroxyl group is carried out in mild conditions…

blogfast25 - 19-5-2011 at 06:33

Quote: Originally posted by Neil

You can purchase it from number of suppliers in the flavor/scent/perfume supplies industry. Bloody expensive by my standards...

I’ve found that all these C5/C6/C7s (or slightly higher) or precursors to them are all quite expensive.

Days ago I extracted about 40 ml of pelargonic acid (nonanoic acid) from Bayer weed killer: a 3 % solution of some pelargonate soap in water at £6/L!

Food ‘supplement’ stores stock caprylic acid (octanoic acid) tablets: assuming complete recovery of the acid is possible the price of the product thus obtained is roughly £10 for about 50 g.

And interesting stuff like tetrahydro myrcenol (a branched 2-octanol) no one wants to sell to me :mad:

[Edited on 19-5-2011 by blogfast25]

Magpie - 19-5-2011 at 08:09

Quote: Originally posted by blogfast25

Nitric may be the way to go. I remember your exploits with making malonic acid and the runaway you got!

I’d probably have to experiment with some alcohol like n-butanol or amyl alcohol to get the conditions more or less right: oxidation reactions of primary alcohols to acids are seriously exothermic.

Yes, by all means experiment with small quantities. As I remember the secret to taming these reactions of nitric acid/alcohol is to bring one reactant up to temperature, say 60-80C, then add the other reactant dropwise. This keeps the reaction under good control.

I did such a reaction yesterday, adding B2O3 slowly to hot methanol to make methyl borate. I think that scale of the reaction is important here also. The smaller the scale the easier it is to control due to the inverse relationship of the ratio of surface area to volume.

================================

That's an interesting citation form the Merck Index, Wizard. I wonder if it would be worthwhile to extract it from Mulberry leaves with say, ethyl alcohol, using a soxhlet extractor. I used to have a mulberry tree but cut it down -- it was making a real mess, and was in a bad spot.

[Edited on 19-5-2011 by Magpie]

unionised - 19-5-2011 at 10:31

Would C8 help
http://resources.metapress.com/pdf-preview.axd?code=b5284m82...

The WiZard is In - 19-5-2011 at 11:56

Quote: Originally posted by Magpie

That's an interesting citation form the Merck Index, Wizard. I wonder if it would be worthwhile to extract it from Mulberry leaves with say, ethyl alcohol, using a soxhlet extractor. I used to have a mulberry tree but cut it down -- it was making a real mess, and was in a bad spot.

The apparently do it in India, the Devil is in the details! Extracting
natural products is a mess ... unless you have a really specific
solvent. A check of Google.com/books or Google can't hurt.

Byda did you ever eat mulberry fruits? I have seen people on
the street on NYC eat them ... so I tired. They rank right up there
with — cactus pairs - cassava - bread fruit - plantains for having
little/no taste neat. Creative cooking can work wonders.

I remember a salad bar on President Street in Brooklyn they had
the best cassava and plantain it has been luck to eat. Another
take-away on Manhattan's Thomas Street on Wednesday had
tripe that I never missed.

Reminds me of a cooking joke.

How do you cook kidneys?

You cook the piss out of them.
(Most soak them overnight, except veal kidneys
which can be cooked straight out of the frig.)

[Edited on 19-5-2011 by The WiZard is In]

The WiZard is In - 19-5-2011 at 12:11

Quote: Originally posted by Magpie

NB — It's WiZard.

http://tinyurl.com/3lnyx7f

If'n its in the oil - expressing the oil could a good start
to limiting extraneous products.

Magpie - 19-5-2011 at 12:29

Quote: Originally posted by The WiZard is In

Byda did you ever eat mulberry fruits? I have seen people on
the street on NYC eat them ... so I tired. They rank right up there
with — cactus pairs - cassava - bread fruit - plantains for having
little/no taste neat. Creative cooking can work wonders.

I 'm sure I tried them - but as you say I don't remember any food value. The birds ate them, however.

I've also eaten elderberries. Not much food value there either but much better than mulberries.

unionised - 19-5-2011 at 12:30

I strongly suspect that steam distilling the oil would work a whole lot better and I also suspect that the yield (based on weight of leaves) will be less than 1%.

blogfast25 - 19-5-2011 at 12:33

Quote: Originally posted by unionised

Would C8 help
http://resources.metapress.com/pdf-preview.axd?code=b5284m82...

Yes, it would and 2-octanol would be a valued prize! But that procedure, simple as it might be on semi-industrial scale, would require serious adaptations for my use. But it could be worth trying even for lower yields. Thanks!

Wizzard:

I cook lambs kidneys w/o soaking all the time. Added to beef stews it gives that 'je ne sais pas quoi' difference...

[Edited on 19-5-2011 by blogfast25]

Magpie - 19-5-2011 at 13:15

Would 2-ethyl hexan-1-ol be of any interest? I obtained this as a by-product while making phthalic acid from vinyl glove plasticizer.

If so, see: http://www.sciencemadness.org/talk/viewthread.php?tid=6573&a...

blogfast25 - 19-5-2011 at 13:32

Quote: Originally posted by Magpie

Would 2-ethyl hexan-1-ol be of any interest? I obtained this as a by-product while making phthalic acid from vinyl glove plasticizer.

If so, see: http://www.sciencemadness.org/talk/viewthread.php?tid=6573&a...

Yes, it would. I'll be scrutinising that thread tomorrow. Thanks!

The WiZard is In - 19-5-2011 at 15:02

Quote: Originally posted by Magpie

================================

That's an interesting citation form the Merck Index, Wizard. I wonder if it would be worthwhile to extract it from Mulberry leaves with say, ethyl alcohol, using a soxhlet extractor. I used to have a mulberry tree but cut it down -- it was making a real mess, and was in a bad spot.

Shoxlet? Here is just what you need.

http://www.wilmad-labglass.com/group/1081

The LG-6911-104 one.

Leaf - Leaf alcohol content —

http://tinyurl.com/3rk3r8e

Granted Content and extractable ....!

By da this dobe the problem w/ natural products.

From one of my favorite (albeit expensive) books.

JW Purseglove & et al
Spices
Longman 1981
2 Volumes

blogfast25 - 20-5-2011 at 05:48

Quote: Originally posted by Magpie

Interesting extraction from something very OTC. And the obtained phthalic acid is good too.

How about the following mods? Extract DOP from gloves (or other pPVC product) with alcohol. Evaporate alcohol (or most of it anyway), leaving behind the reasonably pure plasticizer. Saponify more or less stoiciometrically with NaOH or KOH, using only little water. The alcohol should be floating on top, decant off.

Treat phthalic acid soap with stoichiometric amount of HCl to recover phthalic acid. Recrystallise for work up.

Magpie, any particular reason for the choice of IPA? From what I read DOP is supposed to be soluble in most lower alcohols.

[Edited on 20-5-2011 by blogfast25]

Magpie - 20-5-2011 at 08:05

Quote: Originally posted by blogfast25

Magpie, any particular reason for the choice of IPA? From what I read DOP is supposed to be soluble in most lower alcohols.

IIRC other forum members were using IPA, and it is readily and cheaply available in 99% concentration at my local drugstore (pharmacy).

Paddywhacker - 21-5-2011 at 03:20

Here is that book mentioned by Wizz.

Attachment: Common Fragrance & Flavor Materials - 4th edition - Baur, Garbe & Surburg - 2001.pdf (1.7MB)
This file has been downloaded 7844 times

blogfast25 - 21-5-2011 at 05:21

Thanks Paddywhacker, it’s been saved.

As a much cheaper source of OTC DOP, I’d suggest waste electrical wire covers and (most) waste garden hose. Probably lower DOP content than vinyl domestic gloves but totally FOC!

The WiZard is In - 21-5-2011 at 16:14

Quote: Originally posted by Paddywhacker

Here is that book mentioned by Wizz.

Natural green top notes

How 'bout — Bottom notes?!

THE SPERM TREES OF LOS ANGELES: THE SEARCH CONTINUES

Dear Cecil [Adams]:

I am writing in regard to the identity of the "semen tree" discussed recently in your
column. May I suggest that what the writer was talking about was the female ginkgo
tree? In the fall it drops many small apricot-colored fruits. When the fruit ripens, it
smells more like vomit than semen. Orientals (I lived in Japan for ten years)
consider the nut within this fruit (the ginkgo nut) to be a delicacy. In the early
morning old people put Baggies over their hands, push the smelly fruit away from
the nut, drop the nuts into a bag, and take them home. They are washed and dried
(during which they lose their smell), cracked open, and the nut meat boiled or
baked. Ginkgo nuts are great, but the fruit is still disgusting. --Elyse A., Evanston,
Illinois

[They smell like well worn gym socks to me. /djh/]

Dear Elyse:

Considering I ran the original letter as an example of a question so stupid that nobody
could possibly be interested in it, the sperm trees of LA have generated an extraordinary
response. In addition to vomit, I have heard about trees that smell like, um, fecal matter.
Another tree supposedly smells like a certain well-known female orifice. A recent
graduate of Vassar College in lovely Poughkeepsie, New York, reports that while on
campus she, too, noticed certain trees that smell like vomit. However, another former
Vassar inmate--believe me, I check this stuff out--says the indicated trees are definitely
not ginkgoes. Knowing the party-hearty predilections of college women these days, I'm
not sure the smell is entirely botanical in origin. Similarly, Cecil's longtime buddy and
spiritual adviser Uncle Pat suggests that the smell of the LA tree may be the result of the
city's notorious deve community having its way with the local plant life. I have taken this
under advisement. Gratz Beehler of Washington, D.C.--a fine fellow despite his dubious
moniker--says there is a tall (50-60 feet) and spindly (six to ten inches in diameter) plant
in Florida known as the "punk tree," which has "very spikelike flowers" (hence the name,
presumably). It blooms in March and October, smells "like rotten stuff" (if not
necessarily semenlike), and is known to grow in LA. Gratz promises to try to rustle up a
sample so we can get a positive ID. Meanwhile, I am still waiting patiently for somebody
to send me a specimen of sperm-tree foliage. C'mon, kids--there's a Nobel Prize in this
somewhere.

MORE OPINIONS

Dear Cecil:

Regarding the "sperm trees" of Los Angeles, I've checked with several people, and
they all agree. California privet (sorry, I don't know the scientific name) is your
culprit. I've seen it in hedge and tree form. I've seen its hairy flowers bloom in
spring and fall; however, it only smells for a few weeks in the spring. That's when
swarm of bees are attracted to it. --C.H., Glendale, California

Dear Cecil:

. . . carob trees. Said trees abound, for example, in the Los Feliz area north of
Franklin near Edgemont. The trees smell like sperm, or Clorox on some days, and
have nothing to do with appearing or acting like sperm. --Frank W., Thousand
Oaks, California

Dear Cecil:

. . . the carob tree. These trees emit this odor only in the fall when they show a
hairlike pollen-tipped fuzz growing from the bark near the tips of narrow branches.
--Tom K., Los Angeles

Dear Cecil:

. . . the carob tree. We had a small one growing in our schoolyard in Arizona. One of
the reasons it may be hard to identify is that it does not always smell. It seems to
have a cycle, but not a yearly one. --M.N., Long Beach, California

Cecil replies:

The mail at this point is running about 2-to-1 carob tree, so I guess we'll declare it the
winner. Unfortunately, the one sample of sperm tree blossom we received had been
dumped into an ordinary envelope (rather than, say, a baggie), giving it time to dry out
and disintegrate before we could get it to an expert for analysis. Let's use our heads out
there, gang.

LATE NEWS ON THE SPERM TREES OF LOS ANGELES (01-Nov-1996)
Longtime readers will recall the heated debate in this space some years ago over the
identity of a tree, originally spotted in Los Angeles, that at certain times of the year
smelled like, uh, sperm. (To be precise, like semen. But you know what we mean.)
It wasn't our idea to get into this repulsive topic. It did, however, capture the imagination
of the Teeming Millions. Not that the Teeming Millions were much help getting to the
bottom of it. Despite repeated pleas, no one ever sent us an identifiable sample, and we
never settled the matter.

The controversy flared anew on our America Online message board last summer. But this
time our call for samples got results. In fact, we got two samples--one from Robert
Williams, the other from Brian Maffitt.

Just one little problem. They weren't the same tree. What's more, neither of them was one
of the trees suggested in our previous go-round on this subject.

I quote from a letter from the experts at the plant clinic at the Morton Arboretum near
Chicago, to whom I sent the above-mentioned samples.

The two specimens you sent us arrived in, well, somewhat poor shape.
[Hey, so I delayed a little sending them out. I'm a busy guy.]

Although you mentioned semen as the putative odor given off by the trees,
and one of the specimens had degraded to what looked like a baggie full of
the bodily fluid, we found the odor much more offensive than an innocent
penis could possibly produce.

However, one brave soul examined the samples long enough to determine
their identity.

The Williams sample is a chestnut (Castanea sp.), known to produce
flowers with an offensive odor (offensive to humans but revered by
pollinating insects). It is likely a Chinese chestnut or hybrid chestnut since
our American chestnut was pretty much wiped out by a fungal disease
introduced to the U.S. around 1906, and there are very few American
chestnuts that reach flowering age.

The Maffitt sample is undoubtedly a tree of heaven (Ailanthus altissima),
although, in honesty, we lacked the courage to pull a leaf out of the
'semen-filled' bag. Tree of heaven is said to stink to high heaven as its
flowers produce a decidedly disagreeable stench.

Interestingly, it is the male flowers that produce the stench, while the
female flowers are aroma-free (there are separate male and female trees
for this species). So perhaps the connection your reader made with male-
produced semen is not too far off.

Very good, except that previously the consensus was that the sperm tree was the carob
tree, with one radical holding out for the California privet. Now we've got three or four
possible sperm trees out there.

So there you have it. The truth ain't pretty. But I feel you need to know.

blogfast25 - 24-5-2011 at 11:44

I extracted some DOP from 111 g of vinyl flooring, by chopping it up and refluxing it with methylated spirits at BP. The solvent was then distilled off until about 11 ml was left, presumably mainly DOP and some residual solvent.

The DOP was treated with a stoichiometric amount of 50 w% KOH and heated to BP. An oily liquid collected at the top and upon solidification of the dipotassium phthalate solution/melt the oily phase was decanted off. It's presumed to be 2-ethyl hexan-1-ol.

It was washed twice with saturated CaCl2 solution and separated with a separating funnel, obtaining about 3.5 g of crude alcohol. It smells positively weird and not like what some sources claim it should smell like.

The dipotassium phthalate was diluted with some water, heated until it melted/dissolved and strong HCl was added to it: quite a bit of white precipitate formed: phthalic acid and evidence the extracted product is at least a phthalate.

But it’s not the alcohol I’m interested in but rather the methyl ester of the corresponding acid (2-ethyl hexanoic acid). So an attempt was made to oxidise the alcohol by means of K2Cr2O7. 100 ml of about 0.2 M K2Cr2O7 (in 1 M H2SO4) was made up and the hot solution added gradually to the alcohol. Reaction started immediately but gave an unexpected result: a dark brown/blackish sludge with an unpleasant smell resulted. I’ve oxidised both MeOH and EtOH w/o problems using dichromate in the past.

Some more DOP has now been extracted, this time from 66 g of chopped up vinyl domestic gloves and methylated spirits for another test…

[Edited on 24-5-2011 by blogfast25]

Magpie - 24-5-2011 at 12:04

Quote: Originally posted by blogfast25

Some more DOP has now been extracted, this time from 66 g of chopped up vinyl domestic gloves and methylated spirits for another test…

I'm predicting you'll have better success with the vinyl gloves. I bought a shower curtain to use as a source of DOP but was rather disappointed in the low yield.

Sedit - 24-5-2011 at 12:20

Quote: Originally posted by blogfast25

Nitric may be the way to go. I remember your exploits with making malonic acid and the runaway you got!

I too suggest using HNO3 to perform the oxidation. This is the only reagent I have tried that gave me good results oxidising EtOH and MeOH to there respective carboxylic acids without resorting to high PH condition. The runaway can be eliminated by using red nitric acid since the cause of the runaway is the fact that pure Nitric must decompose and the NO2 is what catalyses the reaction. By the time its hot enough to decompose and start the reaction its already to hot to control. I found I got some of my best results by forming very concentrated HNO3 using NaNO3 and 97% H2SO4. The heat generated forming the nitric made sure it was red from the start and then it was a matter of slowly dripping the EtOH into the oxidant. NOx was formed on a massive scale.

I am still curious about this reaction because the alcohol kept reacting even after equalmolar amounts where used. It seems very easy for HNO3 to oxidise much more then one mol of substate and im not fully sure why.

Magpie - 24-5-2011 at 15:33

Quote: Originally posted by blogfast25

It's presumed to be 2-ethyl hexan-1-ol.

It was washed twice with saturated CaCl2 solution and separated with a separating funnel, obtaining about 3.5 g of crude alcohol. It smells positively weird and not like what some sources claim it should smell like.

I smelled my 2-ethyl hexan-1-ol. It smells like vinyl gloves.

PHILOU Zrealone - 25-5-2011 at 04:35

Quote: Originally posted by Sedit

I am still curious about this reaction because the alcohol kept reacting even after equalmolar amounts where used. It seems very easy for HNO3 to oxidise much more then one mol of substate and im not fully sure why.

That's an easy one

CH3-CH2OH + HNO3 --> CH3-CO2H + NO + NO2
NO + 1/2 O2 --> NO2
H2O + 3 NO2 --> 2 HNO3 + NO
So most of your NxOy are regenerated again as HNO3 for a second, a third, ....rounds again and again.
This would be infinite if there was no escape of NxOy and full supply of O2 from air...

blogfast25 - 25-5-2011 at 07:26

So 66 g of chopped vinyl gloves were refluxed for 2 h with 300 ml of methylated spirits at BP, at high reflux ratio (some solvent was allowed to come over).

The obtained liquid (171 g) was slightly yellowish and slightly turbid but filtered (No 1 filter) well to a clear solution.

The solvent was distilled off in about 1h15 minutes, at oil bath 130 - 140 C, distillate consistently coming over at 78 - 79 C. After that time, no more distillate came over and boiling had all but stopped.

20 g of bottom fraction were recovered. Assuming it’s mainly DOP that would be a yield of about 30 %. Magpie’s right (but somewhat predictably so). The glove material is now quite hard and brittle, a clear indication that plasticizer had been removed.

The product has been washed twice with sat. CaCl2 solution and is yellow/amber in colour and milky in appearance. I’m taking it a bit slower with this crop so it’ll be left to stand overnight, hopefully it’ll clear some more. I might ‘salt’ it tonight.

@Sedit:

Part of the problem with the oxidation of primary alcohols to acids is the high value of the reaction enthalpy, for EtOH estimated on three occasions by me as about - 350 to - 400 kJ/mol. That’s a whopppper: about 7 times the heat of neutralisation (OH- + H3O+)! Enough heat to get severe boil-overs, especially with low boiling alcohols...

If I can isolate the alcohol (2-ethyl hexan-1-ol), I’ll try oxidising it with nitric acid but I’ve only got 38 %. But 38 % nitric actually worked even for the oxidation of sucrose to oxalic acid (albeit a bit sluggish).

If you have a suggested recipe, I’d be interested in hearing it.

‘In theory’ the redox reactions are:

R-CH2-OH + H2O === > R-COOH + 4 H+ + 4 e

HNO3 + 3 H+ + 3 e === > NO + 2 H2O

So:

3 R-CH2-OH + 4 HNO3 === > 3 R-COOH + 4 NO + 5 H2O

So the molar ration of acid to alcohol is ‘theoretically’ 4/3.

@PHILOU:

You’re nuts.

[Edited on 25-5-2011 by blogfast25]

Jor - 25-5-2011 at 07:34

If you have the methyl ester of 2-ethyl hexanoic acid, why don't you try to do a Grignard on this one with MeI or EtBr? This should give a long chain t-alcohol, wich is you goal right?

blogfast25 - 25-5-2011 at 07:37

Quote: Originally posted by Jor

If you have the methyl ester of 2-ethyl hexanoic acid, why don't you try to do a Grignard on this one with MeI or EtBr? This should give a long chain t-alcohol, wich is you goal right?

That's the goal of synthing the methyl 2-ethyl hexanoate, Jor. Correct. To obtain 2-methyl-3-ethyl-heptan-2-ol.

[Edited on 25-5-2011 by blogfast25]

Jor - 25-5-2011 at 08:20

Quote: Originally posted by blogfast25

Quote: Originally posted by Jor

If you have the methyl ester of 2-ethyl hexanoic acid, why don't you try to do a Grignard on this one with MeI or EtBr? This should give a long chain t-alcohol, wich is you goal right?

That's the goal of synthing the methyl 2-ethyl hexanoate, Jor. Correct. To obtain 2-methyl-3-ethyl-heptan-2-ol.

[Edited on 25-5-2011 by blogfast25]

Sorry I read again way too quickly. I read that you obtained the ester instead of the alcohol you were interested in. Wich is impossible if I would have read your post more carefully

This is the second time now in 2 days

Magpie - 25-5-2011 at 09:01

Quote: Originally posted by blogfast25

If I can isolate the alcohol (2-ethyl hexan-1-ol), I’ll try oxidising it with nitric acid but I’ve only got 38 %. But 38 % nitric actually worked even for the oxidation of sucrose to oxalic acid (albeit a bit sluggish).

38% nitric is 7.44M. I used 6M for the oxidation of 1,3-propane diol to malonic acid.

Quote: Originally posted by blogfast25

If you have a suggested recipe, I’d be interested in hearing it.

Check the reference I provided in the malonic acid synthesis in Prepublication.

blogfast25 - 25-5-2011 at 09:31

Thanks Magpie. Got it. Looks very useful indeed, nice write up!

I'll probably want to give the alcohol some work up...

[Edited on 25-5-2011 by blogfast25]

blogfast25 - 26-5-2011 at 08:34

Well, I tried the oxidation of ethanol with nitric acid, using Magpie’s method but adjusted for a mono alcohol and I’m totally sold in it. 20 ml of 38 % HNO3 were measured up, along with 2.5 ml of EtOH (acid/alcohol ratio = 8/3, twice the stoichio ratio). 10 drops of the alcohol were added to the cold nitric and no reaction took place but on gentle heating NO2 starts to come off. I then added the rest of the alcohol in 10 drop aliquots w/o further external heating, just riding on the heat the reaction gives off. Works a treat. After some more simmering to get rid of the NO/NO2 the smell of acetic acid was unmistakable.

The now clear but crude DOP (19 g) was then hydrolysed with 6.0 KOH flakes dissolved in 7 ml of water. The mixture was heated until reaction was over and the oily alcohol was floating on top of some water and precipitated dipotassium phthalate. It was separated and will now be worked up to at least being able to do a micro (capillary) BP. It’s quite turbid (bits of dipotassium phthalate and some water, I imagine) so it may need distilling. This crop smelled much more agreeable and I agree with Magpie that the smell is indeed reminiscent of vinyl gloves.

The dipotassium phthalate was dissolved in hot, strong HCl (phthalic acid is quite soluble in hot water but practically insoluble in cold water) and should crystallise out later.

Update:

I decided to try to oxidise the crude alcohol (it was fairly clear by then) with nitric acid rather than do further prior work up.

35 ml of 38 w% HNO3 were measured out, to correspond to 13 ml of the alcohol (a 8/3 molar ratio acid/alcohol, twice stoichiom.)

10 drops of the alcohol were added to the acid, which was then covered and heated on an electrical hot plate. No discernable reaction took place, so I added another 10 drops, a bit later another 10, until the first humble signs of reaction took place: a slight whiff of NO2 and slight discolouring of the acid.

Clearly this wasn’t going to cause runaways and was decidedly sluggish. Possible reasons are:

1. reagent mix is heterogeneous: the alcohol doesn’t dissolve in the acid,
2. steric hindrance of the ethyl group so close to the hydroxyl group.

I then added all of the remaining alcohol and slowly NO2 started to develop. After about 15 min it started showing signs of bumpiness which I attribute to too much heat being developed, so I took it off the hot plate. Reaction continued for quite some time but eventually died and I carried on for at least another hour by heating on and off. Every time I thought reaction was now over, more NO2 developed. Eventually it more or less subsided and I added some twenty ml of DIW and poured everything into a separating funnel:

The organic phase is a pale yellow/green liquid, almost perfectly clear and quite viscous. It smells different than the alcohol, much fainter for one. The volume obtained is roughly the same as the alcohol starting volume.

Assuming the oxidation to 2-ethylhexanoic acid was indeed successful then this is far from an ideal procedure. Possible stronger acid or reaction in solution (acetone? ether?) would be preferable.

[Edited on 27-5-2011 by blogfast25]

blogfast25 - 4-6-2011 at 08:46

Another attempt at oxidising vinyl-gloves-extracted 2-ethyl hexan-1-ol. Literature cites oxidation of 1-octanol (to octanoic acid) with CrO3 using acetone as a solvent/diluent. So I prepared a solution of 1 g 2-ethyl hexan-1-ol and 1 g of acetone (perfectly clear mixture), and separately 1.5 g of K2Cr2O7 in 30 ml of 1 M H2SO4 (the stoichiometric amount to oxidise the alcohol).

I set up a burette to be able to add the oxidiser very gradually. The alcohol/acetone mixture was heated gently on a hot plate. But the dichromate chews up the compound almost immediately: after 1 ml of dichromate solution added, the reagent mix starts getting brown, after another ml the whole thing is a stinky dark mess.

Sedit - 4-6-2011 at 10:04

Glad to see your having some success using HNO3 blogfast, Since NO2 is the initiator in the nitric acid oxidation perhaps adding a small amount of NaNO2 to the alcohol which is running sluggish will aid in speeding up the reaction a bit and carrying it further to completion. Given that they are not mixing well it might be a lot harder to form the first trace amounts of NO2 to really get this to take off.

blogfast25 - 4-6-2011 at 11:35

Quote: Originally posted by Sedit

Glad to see your having some success using HNO3 blogfast, Since NO2 is the initiator in the nitric acid oxidation perhaps adding a small amount of NaNO2 to the alcohol which is running sluggish will aid in speeding up the reaction a bit and carrying it further to completion. Given that they are not mixing well it might be a lot harder to form the first trace amounts of NO2 to really get this to take off.

The problem, Sedit, is that it wasn't that succesful. The reaction product was very viscous, much more so than I would expect from an isomer of nonanoic acid. The reaction also just never seemed really over, with more NO2 being generated each time a added a bit of heat. I suspect the reaction product was either oligomerised or perhaps some esterification took place with yet unreacted alcohol.

Sedit - 4-6-2011 at 12:04

Yeh I know thats why I suggested the use of a NaNO2 initiator to aid the reaction a bit. Is there any possibility of an inertsolvent perhaps that could thin it allowing it to proceed better.

Also when I oxidise EtOH with it I use much more concentrated acid then you have so maybe you will get lucky if you up the concentration of it. No matter what though make sure there is NO2 there. Look in the reference request thread Nicodem posted me some papers that speak about the oxidation using HNO3 a bit. There goal was to make the aldahyde but Im sure you may find some kind of useful information in there.

GL
~Sedit

m1tanker78 - 4-6-2011 at 12:06

Not sure if this thread has any relevance. It touches on the interactions of H2SO4 and acetone; may be worth a look.

Quote:

A similar experience I had with adding conc. H2SO4 to pure acetone. Immediately after adding the acid and swirling well, the liquid is colorless, but it slowly turns yellow, orange, red, red/brown and finally almost black. The liquid also turned more viscous. This reaction takes many hours. Again, I think that acetone molecules are broken down somewhat and some polymeric species is formed and with increasing molecular size the color of this species intensified.

Tank

blogfast25 - 5-6-2011 at 08:48

Thanks guys but I won’t be pursuing this any longer. The time and effort to extract the alcohol are just a little too high, combined with the difficulty of reliably oxidising the alcohol without IR ‘quality control’.

Instead I’ll be concentrating on extracting the C8/C10 fatty acids from fractionated coconut oil, for further synthesis into 2-methyl alkan-2-ols…