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Jor
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ester project
For a project at uni I need to make an ester, wich is in the category 'smells' (duh!).
I'm thinking about making diethyl malonate, but it involves cyanide, wich I can not use. Therefore I wanted to ask if one knows an alternative method.
E.g does ethyl iodide or diethylsulfuric acid work? Or other methods?
And does anyone have ideas of an ester with a good or bad smell, wich can be synthtises without use of too toxic chemicals (e.g. proven carcinogens,
HCN, HF, Br2,etc), but is not the easy way (simple Fischer esterification). I can use many acyl chlorides and anhydrides, besides the alcohols and
acids. I can do a Fischer, but I want a special one then, not like a simple ethyl acetate or something.
Oh and yes, forgot almost, I can also use POCl3, to make esters of phosphric acid. That should greatly increase the possibilities.
Ideas?
[Edited on 5-9-2008 by Jor]
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kclo4
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http://en.wikipedia.org/wiki/Butyl_acetate
http://en.wikipedia.org/wiki/Amyl_acetate
http://en.wikipedia.org/wiki/Methyl_salicylate
Check out some of the other alcohols and esters of similiar organic acids, albiet you'd find other smelly ones.
Most of these can be produced via a Fischer esterification which is basically the alcohol, the acid, and a bit of H2SO4 as a catalyst. read more about
it if you want http://en.wikipedia.org/wiki/Fischer_esterification
Oh right also this, almost interesting
http://www.moleculeoftheday.com/2006/07/18/amyl-butyratepent...
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Jor
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First of thank you for the reply.
Im more looking for a bit more 'exotic' ester than just the simple ester made by reacting an simple alkyl alcohol with a simple 'alkonoic acid'. Or
just diethylmalonate, because it's easy to write about it (useful reagent).
Besides we cannot use the C-4 to C-6 aliphatic mono-alcohols, because they stink too much!
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Klute
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You could make ethyl acetoacetate. It's an ester, has a faint but nice fruity smell, and is a pretty important compound (Claisen condensations) in
organic chemistry.
It is made from ethylacetate and sodium, not too hard but your ethyl acetate needs to be pretty pur.
You could also try making allyl hexanoate or allyl heptanoate from allyl halide and the potassium salt of the corresponding acid, not the usual fisher esterification.
Another idea would be making an ester through a Bayer Villiger on a ketone (using peracids). For example, on cyclohexanone to give
ε-caprolactone, which can then be hydrolyzed to adipic acid.
[Edited on 6-9-2008 by Klute]
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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ScienceSquirrel
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Why not make benzyl benzoate via the Tishchenko reaction.
http://en.wikipedia.org/wiki/Tishchenko_reaction
And it is a pleasant smelling and interesting compound.
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Jor
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I think i will make benzyl benzoate.
I am thinking about two different pathways.
One is Tischchenko reaction.
http://www.organic-chemistry.org/abstracts/literature/129.sh...
The reaction starting from benzaldehyde I'm referring to. But the catalyst used is too complex. Can another catalyst be used e.g aluminium
isopropoxide? And if yes, is there still 0,5 mol% needed or more?
The other one is Bayer Villager reaction benzophenone, in trifluoroacetic acid. But I'm not sure if I can use TFA, because AFAIK someone told me that
it can hydrolyse to HF.
Im not sure wich one I will do.
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tapira1
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TFA --> HF
TFA will not hydrolyze to HF as far as I know. What about making methyl salycylate; it smells good and has medicinal properties. Here, Fischer
esterification is the best way
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Klute
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Here is the prep of benzyl benzoate from Org. Synthese (the book):
BENZYL BENZOATE
2 C6H5CHO + C6H5CH2ONa--> C6H5CO2CH2C6H5 + C6H5CH2ONa
Prepared by O. KAMM and W. F. KAMM. Checked by ROGER ADAMS and
R. L. JENKINS.
1. Procedure
THREE grams of metallic sodium are dissolved by warming for half an hour
in 70 g. of pure benzyl alcohol (see notes), and after the mixture
has cooled to room temperature the solution is added gradually,
with thorough mixing, to 454 g. of c. p. benzaldehyde (which must
contain LESS than 1 per cent of benzoic acid). The reaction mixture has
a tendency to become warm, but the temperature should be kept slightly
below 50-60'0 by cooling, if necessary. A pasty gelatinous mass results.
After about half an hour the temperature of the mixture no longer rises;
it is then warmed on the water bath for about one or two hours,
with occasional shaking.
The cooled reaction product is treated with 200 cc.
of water, the layer of oil separated, washed once with a second
portion of water, and subjected to distillation _in vacuo_.
The first fraction of the distillate contains benzyl alcohol together
with unchanged aldehyde, as well as a small quantity of water.
The temperature then rises rapidly to the boiling-point of
benzyl benzoate, when the receivers are changed. The product
boils at 184-185'0/15 mm., and analysis by saponification shows it
to consist of 99 per cent ester. A yield of 410-420 g. is obtained,
which corresponds to 90-93 per cent of the theoretical amount.
This benzyl benzoate supercools readily, but after solidifying
melts within one degree of the highest recorded value (19.4'0) and
therefore need not be refractionated, unless material of exceptional
grade is required.
2. Notes
In the presence of sodium benzylate two molecules of benzaldehyde
react with the alcoholate to form an addition product.
When the reaction mixture is overheated an important side reaction
may occur, as follows:
/ OCH2C6H5
C6H5C -- OCH2C6H5 --> C6H5CO2Na + C6H5CH2OCH2C6H5
\ ONa
Dibenzyl ether no doubt forms the chief impurity in benzyl benzoate.
Since the boiling-point of the former lies near that of the ester,
it is not removed during the process of purification by distillation.
The causes of variations in yield by the use of the older methods
can now be explained. When benzaldehyde is added TO THE ALCOHOLATE,
and especially when the latter is still warm, local overheating results;
in fact, the temperature may rise far above 100'0 with the result
that benzyl ether is formed. Simultaneously, the sodium benzylate
is converted into sodium benzoate, which is of no value for inducing
the desired reaction, and consequently very little benzyl benzoate
is obtained. The same side reactions explain the failure of this
experiment when the benzyl alcohol used in preparing the catalyst
(sodium benzylate) is contaminated with benzaldehyde.
The benzyl alcohol used in this preparation must be free
from impurities, especially aldehyde. One cc. dissolved in 50 cc.
of water and treated with a freshly prepared clear solution of
phenylhydrazine acetate should give no appreciable precipitate.
If it is not pure, it must first be treated with alkali
as described below.
The benzaldehyde should be titrated in order to determine its acidity.
If it is found to contain sufficient benzoic acid to react
with a considerable proportion of the sodium alcoholate, a poor
yield of ester will be obtained. Less than 1 per cent of benzoic
acid will not interfere seriously with the yields obtained,
but the presence of larger quantities of acid will be found to be
detrimental and must be removed by washing the benzaldehyde with
a sodium carbonate solution and redistilling with the precautions
necessary to prevent too free an access of air to the distillate.
The order of mixing the reagents and the temperature of the ingredients
at the time of mixing are the most important factors in the experiment.
The temperature at which the reaction mixture is maintained
after mixing, provided that it is held below 100'0, is less important
from the standpoint of purity.
The reaction mixture is not treated with acetic acid, as usually
recommended, for the reason that such a procedure yields a final
product contaminated with benzoic acid, unless an alkaline wash
is applied subsequently.
The recovered benzyl alcohol can be used for the preparation
of a second lot of benzyl benzoate only after it has been boiled
with strong sodium hydroxide to remove all traces of benzaldehyde.
3. Other Methods of Preparation
Benzyl benzoate has been identified in certain natural plant
products.[1] In the laboratory it has been prepared by the action of
(_a_) benzoyl chloride upon benzyl alcohol,[2] (_b_) benzyl chloride
upon sodium benzoate, and (_c_) alcoholates upon benzaldehyde.[3]
Recently, Gomberg and Buchler[4] have shown that reaction (_b_) may
be conducted even with aqueous solutions of sodium benzoate.
[1] Ann. 152, 131 (1869).
[2] Gmelin's Handbuch der Organ. Chem. 3, 40.
[3] Ber. 20, 649 (1887). Cf. also J. Chem. Soc. 75, 1155 (1899).
[4] J. Am Chem. Soc. 42, 2059 (1920).
The Claisen method (_c_) furnishes the most convenient and practical
procedure for the preparation of this ester. The materials are cheap,
the experimental procedure simple, and the product obtained is free
from objectionable traces of benzyl chloride. Unfortunately the
method has been found to be extremely erratic in regard to yield
(10-95 per cent), as well as in regard to purity of the product
(87-97 per cent ester).[1] As a result of the present study,[2]
causes for variations are fully accounted for and the procedure
has been converted into a satisfactory method of preparation.
[1] C. A. 14, 3500 (1920).
[2] J. Am. Pharm. Assoc. 11, 599 (1922).
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Bayer villiger oxidations cna be done with performic acid (formic and H2O2 on the spot), peracetic acid (prepared a week before, or by adding sodium
perborate to GAA), and persulfuric acid (peroxodisulfate in H2SO4). I have few procedure with persulfate is you want, and experience with the other
oxidants.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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ScienceSquirrel
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Scale it down by about 10 - 20 fold and it looks like an OK experiment.
Nice preparation though and I reckon it would give good yields with a bit of care.
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chemrox
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This is a different kind of ester but it could help keep your TA awake and on his toes. The nitrite of isoamyl alcohol or n-butanol ....
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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panziandi
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How about demonstrating not all esters smell nice and fruity... You could make ethyl chloroacetate or bromoacetate. Perhaps too volatile, maybe a
higher ester would be less volatile and nasty, n-hexyl chloroacetate? Certainly a little twist to the topic!
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Jor
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Klute thank you very much for the detailed preparation. that's probably the one I will perform. i want to make benzyl benzoate, but not yet sure if I
want to do a Beyer Villager anyway. What the procedure with persulphate?
No nitrite esters, we have to make either a normal ester or a phosphoric acid ester.
Ethyl bromoacetate? How would you like me to demonstrate the smell? 
That stuff is highly toxic and a lachrymator.
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panziandi
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Well just holding an unopen bottle of ethyl bromoacetate near me makes my eyes begin to itch! That's what I was hinting at, the fact that they are not
pleasant like the normal esters just by inserting a halogen! I'd be tempted to try hexyl or octyl chloroacetate. Benzyl benzoate is a bit nicer I'd
imagine! Although don't make it with benzoyl chloride or you'll be dealing with another lachrymator!
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Klute
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I have a few papers on the bayer villiger oxidation of chalcones and aliphatic ketones, but most of them use soemwhat concentrated sulfuric acid
solution, and obtain the hydrolysis products of the formed esters....
JOC; 35, 3080 (1970)
But, using Oxone, or peroxodisulfate with stoichiometric amounts of H2SO4, you can stop at the ester withgreat yields. One of the most important
reactions is the oxydation of cyclohexanone to it's lactone (cyclic ester), e-caprolactone.
Here is an extract from the experimental of a related article:
| Quote: |
e-caprolactone. in aqueous solution (400 nil.) of the
KHSOS-KHSOa-K2S04 mixture (150 g.) was added slowly
to a cold (0-5') mixture of cyclohexanone (19 g.) and
water (250 ml.). The resulting mixture was stirred for 30
min., then neutralized with an aqueous solution of potassium
carbonate. The aqueous layer nas extracted with three
100-ml. portions of ether. The ether extracts were combined,
dried over anhydrous sodium sulfate and filtered.
Distillation of the extracts, first at atmospheric pressure,
then underr reduced pressure, gave 26 g. crude e-caprolactone(
2, b 1 ) . 97-llUo/14 mm,
The procedure used for the preparation of 8-valerolactone was similar to the above, except that the solvent used was a
mixture of water, ethanol and sulfuric acid. |
Oxydation of Organic Substances by Potassium peroxymonosulfate
R.J Kennedy, A.M. Stock
(unknown journal); 25, 1901-1906 (1960)
(Can upload if anyone is interested)
I have succesfully conducted such reaction in acetic acid (dissolves the organic ketones, no biphasic system), adding a solution of the oxidant to the
stirred substrate at 5-10°C and stirring for a few hours (4-6H, can surely be diminished).
Now, another approach, which combines a Bayer Villiger and a Fishcer esterification, is esterifying the acid obtained by hydrolysis of a lactone
formed by BV oxydation of a cyclic ketone:
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Ethyl 7-Hydroxyheptoate,-Potassium persulphate (50 g.) was gradually added to a well stirred
mixture of sulphuric acid (71 c.c., d 1.84) and water (24 c.c.) maintained below 15";
alcohol (100 c.c.) was then introduced, also below 15". The temperature being kept at 15', a
mixture of suberone (10 g.) and alcohol (30 c.c.) was added during 1 hour, and stirring was continued
for a further 1 1/2 hours. The mixture was diluted to 1 litre, filtered, saturated with
ammonium sulphate, and thoroughly extracted with ether. After removal of the solvent from the
dried extract, the residue was mixed with alcohol (15 c.c.) and sulphuric acid (1 c.c.) and heated
(bath at 110") for 6 hours. The product was isolated by means of ether and distilled, b. p.
140-146"/12 mm. (nearly all at 142") (7.5 g.), with a clear brown oily residue, b. p. 193"/0.5 mm.
(Found : C, 64-3; H, 10.4. C,,H,,O, requires C, 63.6; II, 9.9%). This substance appears to
be a di-ester of the formula OH-[CH,],CO*OfCH,] ,CO,Et, since it furnished the hydrazide
described below.
The main fraction, ethyl 7-hydroxyheptoate, afforded a phenylurethane, glistening white
plates from light petroleum, m. p. 64-65' (Found : N, 4.9. C,,H,,O,N requires N, 4.8%), and
a hydrazide, which crystallised from ethyl acetate as silky white needles, m. p. 121-123" (Found :
N, 17.6. In some experiments, under other conditions, the
odour of pineapples was very pronounced, and in such cases the yield was diminished. The substance
responsible for the odour is a volatile solid which we have not examined because our
object was to avoid its formation. Taking into consideration the work of Natta, Hill, and
Carothers (J. Amer. Chern. Soc., 1934, 56, 455) on the 14-membered ring dilactone related to
6-hydroxyhexoic acid, and of Ruzicka and Stoll (Helv. Chim. Acta, 1928,11, 1159) on the relation
between odour and number of ring-members in large-ring lactones, it seems certain that this
volatile odoriferous solid is the 16-membered ring dilactone related to 7-hydroxyheptoic
acid.
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The Oxidation of cycloHexanone and Suberone by means qf
Caro's Acid.
R. Robinson and L. H. Smith.
I can also upload this article if people are interested.
If you want to try the persulfuric acid in GAA, I can go get my notes and send you them.
Lets us know how your project goes!
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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Jor
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Because we are not allowed to do to too complex procedures, I will just make Oil of wintergreen (methyl salicylate). Sorry Klute, thanks anyway for
all your references. Might use em later in my own lab 
However, in Vogel it is stated that there is an possibility that an emulsion will form when washing the reaction mixture. Add 10ml carbon
tetrachloride. OOPS! Not allowed too!
See for prep, Vogel p. 782/783.
Does anyone has an alternative? The emulsion forms, because methyl salicylate is almost as dense as the other layer. Carbon tetrachloride dissolves
the ester and is very dense.
Can DCM or chloroform be used instead? And diethyl ether, just like it can be used with methyl benzoate (see page 781 Vogel, note (2).).
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panziandi
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I don't see why you can't extract the ester into DCM and then distil that off. So long as the methyl salicylate isn't shaken vigorously it shouldn't
form an emulsion. Shame carbon tetrachloride is banned it's so handy!
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Klute
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Use ether (or AcOEt), and saturate the aqueous with NaCl: the organic will become less dense, and the aqueous more dense. This trick always works
nicely when extracting oils with a density close to 1.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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Jor
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Indeed CCl4 can not be used. So it's either ether or DCM. Wonder what's best for extracting the ester. Is the ester soluble in ether? It seems more
polar (extra OH-group) than methyl benzoate.
I can not try them both. I will have to take the decision today.
So just a single extraction with either ether or DCM, and salt out? Or 2 or 3 extractions?
Oh and how much diethylether should be used for 28g of salicylic acid as starting material? Are 50ml portions enough, or should it be more (Vogel uses
50ml portions for methylbenzoate). And if DCM is the better alternative, how much of that should be used? I have a synthesis wich uses 30ml (2
portions of 15ml, without salting out the water layer, so maybe one is enough if I salt out?) for 4,7g salicylic acid. So is about 1 portion of 80ml,
and salting out enough?
Thank for the replies
[Edited on 16-9-2008 by Jor]
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Klute
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It's always better to fractionnate your extraction in 3 or more times!
As a rough rule, I usually use 3 times 15% of the volume of the aqueous in solvent, like AcOEt, DCM etc, and 4-5 times for toluene.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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tapira1
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extracting...
Just make sure your aqueous phase is saturated brine or something equivalent
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DJF90
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The lab prep in my a-level textbook uses ethyl ethanoate as the extraction solvent. If wanted I will post the whole procedure here. I have performed
the procedure myself, and it is a fairly simple yet enjoyable synthesis.
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Klute
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DJF90, which preparation are you talking about?
Jor, I don't knwo why this didn't cross my mind before, but you could make gamma-nonlactone as an ester, one of the coconut aromas: the reagents
needed are not too toxic (nothing a decent school doesn't have), and the whole procedure (2 steps) can be done in less than 6h.
The ester smells very nice, and is obtained quite pur.
Synthesis of gamma-nonlactone (Coconu aroma)
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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DJF90
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Sorry the methyl salicylate. I think it smells really nice and, if washed properly (and probably re-distilled), would be a nice thing to have in the
medicine cabinet as it has analgesic properties when rubbed into the skin. IIRC this is one of the main components in "deep heat", an ointment ( I
think this is the right word) for muscle aches.
If the preparation is wanted then I can type it up for you all.
[Edited on 21-9-2008 by DJF90]
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Jor
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I'm really not sure if DCM or AcOEt is better for extracting the methyl salicylate. You guys have any idea?
I didnt know it had analgesic properties DJF90! I thought it was too toxic to use as medicine in pure form. Learned something new 
Ah Klute, that indeed a very nice ester, and I would have chosen that If I could still change, however I cannot. Was nice to read the writeup anyway,
shame you have no pictures
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kclo4
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Well, from what? Methanol, Water, a combination of the two with dilute H2SO4?
I'd say it depends on the use for it, If you want to use it for its analgesic properties, or something similar I'd say go with the Ethyl Acetate.
If you want yield, then I don't really know. But to increase yield I think you could also try to salt it out along with the solvent extraction, or
something like that. - that is, if you are trying to extract it from water, which i think it is only slightly soluble in.
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