Sciencemadness Discussion Board - Esters and their Synth

Esters and their Synth

ssdd - 29-5-2007 at 16:42

I am trying to make up some Isoamyl Acetate (Banana Oil) along with some other esters. The issue for this synth is that I can seem to find Isoamyl Alcohol anywhere for a decent price. I checked ebay and came up with nothing, and most suppliers have some crazy prices!

Here is the synth in the manner I would like to try it.

Add 15 ml of Isoamyl Alcohol to a 250ml flask. Then pour in 20 ml of Glacial Acetic acid. Add 4 ml of conc. Sulfuric Acid. Place several boiling chips into this. Slowly biol this flask on a hot plate for about an hour. (A reflux condenser is recommended but I think it can be done without one, at least I hope since I don't have one.)

My question would be is there another way to make isoamyl acetate or where can I find Isoamyl Alcohol for cheap?

Thanks for any info...

**Changed name of topic to make it more general - ssdd

[Edited on 2-6-2007 by ssdd]

bereal511 - 29-5-2007 at 16:57

You'd probably need to at least keep the alcohol from escaping the reaction, so just having a condenser attached to the flask would work.

leu - 29-5-2007 at 20:08

Better directions can be found in the attached file, if this compound is prepared in a room with open windows or outdoors expect some interest from the genus apis

Isoamyl alcohol is a major constituent of fusel and potato-spirit oil, and can be made from butadiene as in US 3020314, and from methylbutenes in JACS 82 1505 (1960)

The fractionation of fusel oil and other processes are discussed in pp 107-114 Industrial Chemicals 2d Ed (1957)

[Edited on 30-5-2007 by leu]

Attachment: bananaoil.zip (40kB)
This file has been downloaded 883 times

ssdd - 30-5-2007 at 01:56

Ahhh thank you this gives a better explanation than where I was looking.

Interesting file format by the way.

I was given a link to some isoamyl yesterday so once I have it I'll give this a run.

molar sieves

Tsjerk - 30-5-2007 at 07:49

I recently got some isoamyl alcohol, but I don't like wasting it because it's not one of the easiest chemicals to get as a amateur. I'm planning to make some isoamyl acetate with it and I was thinking how to get the equilirium more towards the ester side.
Which way would give the highest yield? Using a large excess of acetic acid, or refluxing it over molar sieves and taking the water out?

I was planning to reflux it over a soxhlett-extractor, and placing the sieves in the soxhlett.

ssdd - 30-5-2007 at 11:40

So I went rummaging through my schools flammable cabinet and found a small jar of amyl alcohol, I'm not sure if this is just a isomer of isoamyl so I gave it a try.

The result was amyl acetate with a distinct banana scent. I also made wintergreen oil (Ethyl salicylate) and Ethyl Butyrate (pineapple).

My question is is that amyl acetate the same as isoamyl acetate? They have the same smell and oily properties from what I could tell but if anyone has any further info it would help.

Note: Don't inhale to much banana oil, it'll mess you up.

Pyridinium - 30-5-2007 at 13:06

Quote:

Originally posted by ssdd
My question is is that amyl acetate the same as isoamyl acetate? They have the same smell and oily properties from what I could tell but if anyone has any further info it would help.

Note: Don't inhale to much banana oil, it'll mess you up.

"amyl acetate" and "isoamyl acetate" are used interchangeably many times. However, the acetic ester of n-amyl alcohol is not the same molecule as the acetic ester of iso-amyl alcohol.

You can get the data for n-amyl acetate at http://en.wikipedia.org/wiki/Amyl_acetate

You're right, too much banana oil will definitely mess you up.
In very high concentrations it is indeed toxic.

ssdd - 31-5-2007 at 01:50

Hmmm, yea there seems to be a difference. It seems that even the odors produced from the two seem to be mildly different from one another. Amyl Acetate is just banana, where isoamyl is described as being "fruity" in its smell often being compared to banana. Now something that would be neat to try is to see if amyl acetate still works as a bee pheromone or if this mild difference makes it ineffective.

--------------------

So I'm sitting here looking at this flask with the oil in it. The oil seems to be floating on the remnants of the alcohol and neutralizing solution. I am wondering what the best method to extract this would be with the smallest amount of waste and contamination?

[Edited on 31-5-2007 by ssdd]

Comedy - 31-5-2007 at 06:57

Quote:

Originally posted by Tsjerk
I recently got some isoamyl alcohol, but I don't like wasting it because it's not one of the easiest chemicals to get as a amateur. I'm planning to make some isoamyl acetate with it and I was thinking how to get the equilirium more towards the ester side.
Which way would give the highest yield? Using a large excess of acetic acid, or refluxing it over molar sieves and taking the water out?

I was planning to reflux it over a soxhlett-extractor, and placing the sieves in the soxhlett.

I think the second option would give the highest yield

ssdd - 31-5-2007 at 12:52

Any ideas anyone on how to remove the floating banana oil from the neutralizing solution?

There is about 20ml of the oil total on about 160mls of solution. Would a separatory funnel work for this? Or is there a better way with less waste?

UnintentionalChaos - 31-5-2007 at 13:16

I'd use a sep funnel to get the majority of it, then do a liquid-liquid extraction on what is left (assuming you have an appropriate solvent) to get the maximum yield.

Chemophiliac - 1-6-2007 at 18:18

I am curently taking an instrumentation class at school that includes a bit of basic organic chemistry experiments and theory. We just synthesized some flavors (I made Ethyl Butyrate- Pineapple) and did analysis on them to prove exactly what our product was. We performed GC (In Dichloromethane solvent), FTIR, Regular IR, and UV-Vis Spec.

Anyway, the synthesis of ester flavors is simple.

Simply combine the reactants and add just a few drops (3 or 4) of concentrated sulfuric acid as a catalyst. Reflux the reaction in a steam bath, the assembly is simple- just attatch a condenser on top of a reaction vessel, grease the joints and add some boiling chips to prevent bumping. Let the reaction reflux for a day.

THEN, use a sep funnel to do a liquid-liquid extraction. Esters are soluable in Dichloromethane so dissolve them in this, which will separate to the bottom. Add a saturated brine solution to help draw out some water from the organic laer. Separate the organic layer and the add some anhydrous sodium sulfate, which will clump on the bottom. Continue adding the sodium sulfate until it stops clumping and is evenly distributed in the liquid when swirled. Filter the solution through a plug of glass wool. hen, boil off the dichloromethane over a steam bath. add 2 or 3 boiling chips to the product that was gathered.

you see, it's fairly simple, just reflux and separate. Now, here are the reactants for some interesting flavor esters including, but not restricted to isoamyl acetate. All of these use the same procedure I outlined above

Banana (isoamyl acetate)- isoamyl alcohol and acetic acid

Apricot (isoamyl butyrate)- isoamyl alcohol and butyric acid

Apple (methyl butyrate)- methyl alcohol and butyric acid

Grape (methyl anthranilate)- methyl alcohol and 2-aminobenzoic acid (anthranilic acid)

Honey (ethyl phenylacetate)- ethyl alcohol and phenylacetic acid

'Juicy Fruit' (isopentyl acetate)- isopentyl alcohol and acetic acid

Orange (octyl acetate)- n-octyl alcohol and acetic acid

Peach (benzyl acetate)- benzyl alcohol and acetic acid

Pear (n-propyl acetate)- n-propyl alcohol and acetic acid

Pineapple (ethyl butyrate)- ethyl alcohol and butyric acid

Pineapple (isoamyl salicylate)- isoamyl alcohol and salicylic acid

Raspberry (isobutyl formate)- isobutyl alcohol and formic acid

Rum (isobutyl propionate)- isobutyl alcohol and propionic acid

Walnut (ethyl valerate)- ethyl alcohol and valeric acid

Wintergreen (methyl salicylate)- methyl alcohol and salicylic acid

Now, try them out!

12AX7 - 1-6-2007 at 18:39

Is there one for raspberry or cherry?

bereal511 - 1-6-2007 at 20:30

3-(4-hydroxyphenyl)-2-butanone appears to have the smell of raspberries based on this database: http://mc2.cchem.berkeley.edu/Smells/

Not sure about cherry, there's a lot of different cited compounds but I'm not definite on which one is "cherry" as in cherry coke or the lot per say. It does list benzaldehyde as "cherry flavor".

[Edited on 1-6-2007 by bereal511]

ssdd - 2-6-2007 at 06:07

The wikipedia page on esters has some interesting esters.

http://en.wikipedia.org/wiki/Esters

I ran two more of these yesterday with variable success. I made ethyl benzoate, which had a very pleasant odor to it. According to that link it is the smell of the feijoa fruit.

I also made ethyl lactate. If any odors were produced by this I could not pick them up with my nose. It is supost to smell like butter or coconut. Is it perhaps that the smell is to faint or that I didn't reflux it for long enough?

Nicodem - 3-6-2007 at 12:38

Quote:

Originally posted by ssdd
Any ideas anyone on how to remove the floating banana oil from the neutralizing solution?

There is about 20ml of the oil total on about 160mls of solution. Would a separatory funnel work for this? Or is there a better way with less waste?

For the workup check for similar esterifications in Vogel's or other books on practical chemistry (no need to reinvent the wheel…). Mind that you will have to fractionate your product trough a distillation column to separate the ester from amyl alcohol (while acetic acid removes already with a single NaHCO3 wash, the alcohol sticks to the organic extract).

ssdd - 4-6-2007 at 08:10

So I decided to give some of these oils a taste test today.

I'm not sure how good this is for my health but o well. I isolated the banana oil, wintergreen, pineapple, and ethyl benzoate. Now I tried these and most had a fairly tart taste with really no flavor like what they smalled like. Are there any ideas as to why this came out this way?

Eclectic - 4-6-2007 at 08:13

Taste is only satly, sweet, bitter, sour, umami.

Taste

Everything else is smell.

Fleaker - 4-6-2007 at 16:06

If they were really sour, you didn't remove enough of the acid (the sulfuric used to keep it dry).

ssdd - 5-6-2007 at 01:49

Fleaker, I tried adding more Bicarb to it and it did not show any signs that it was still acidic. I'll give an update later after I test it with litmus.

Upon tasting after it had the bicarb added it was still pretty sour and had a strong basic taste to it. Perhaps it is the area of my mouth that I am touching the wood splint to?

not_important - 5-6-2007 at 05:00

better way to taste is to add a small drop to some water, close the container and let it sit for awhile, then taste a little of the water. Straight ester may be overwhelming, enough should dissolve in the water to be released in the mouth to give the aroma - as already said, taste is limited to 5 or 6 basic tastes, not too related to aromas; there is interaction in that acidic and sweet tastes go with fruity aromas and may may the aroma "more real".

Eclectic - 5-6-2007 at 09:02

You could make up some unflavored "Gatoraide" with sugar, citric acid, and a pinch of salt, and add a drop of the various esters to determine the different taste/odor properties.

These products are essentially the same thing, although a bit heavier on the salts:

Calf Electrolyte Replenisher

ssdd - 5-6-2007 at 14:28

Now that is interesting... Is that really all there is to gatoraide?

If that is all it is they sure over price it.

ssdd

Maybe a silly question

tongqiancao - 5-6-2007 at 17:28

you really taste it ?Even books tell us some substances are just that we meet everyday,I don't dare to taste them in lab.

ssdd - 6-6-2007 at 01:51

Quote:

you really taste it ?Even books tell us some substances are just that we meet everyday,I don't dare to taste them in lab.

I can see where your coming from on this, most of these substances have a fairly low toxicity on their own. (Except the amyl acetate which is fairly toxic, but it's the gases that scare me more.) Also, they are being tested in very small quantities, for the original test I simply dipped the tip of a tooth pick into them, and for some of the stuff just mentioned we are talking about a single drop. So as far as I can read this should be fairly safe. (Someone PLEASE inform me if this is not so.

)

Welcome to Science Madness by the way...

[Edited on 6-6-2007 by ssdd]

Thanks for the first reply I have recieved

tongqiancao - 7-6-2007 at 04:57

I come from the China. I am a university student of the chemistry department. This is the first time for me to visit a foreign disscussion board, so your reply courage me so much.
Thank you indeed.
When I wanted to get a article for my experiment by google someday, I finded this board.Glad to become a member of this board.

"dip by tooth pick" ...........I see

ssdd - 7-6-2007 at 05:20

It's no problem, I have found that most everyone on this forum is pretty nice and willing to share their knowledge with people.

Feel free to U2U me or use aim if you can...

(Is the china firewall we hear about really like that?)

ssdd

JohnWW - 7-6-2007 at 10:16

Instead of using www.google.cn in China (to which attempting to log onto www.google.com automatically redirects to), you could either directly access the national Google sites of other countries, e.g. www.google.co.uk, www.google.com.au, www.google.fr, www.google.com.br, www.google.co.nz, www.google.ca, www.google.es, etc.; or else access these, according to their countries, through configuring a browser other than Internet Explorer with a proxy server located in some country outside China. Lists of the IP addresses, port numbers, and countries of proxy servers are given at www.samair.ru and www.proxy4free.com .

LSD25 - 17-6-2008 at 06:59

This has some potential for making the ethyl ester of benzoic acid in good yields in a short time.

This article (actually taken from a textbook) describes the various routes to esters, such as from the anhydride of the acid and the heating of the acid in solution with the alcohol in the presence of an acid:

http://courses.chem.psu.edu/chem36/SynFa06Web/Expt84.pdf

The attached article deals with the existence of a mixed anhydride between benzoic acid and polyphosphoric acid in solution.

Now, if one added ethanol to the mixed anhydride what would be the product? Would it be reasonable to expect that the acid anhydride (even the mixed one) would rapidly combine with the alcohol to give the ester in quick time?

The only problem I foresee is that the strong acid (PPA) might cause saponification of the ester before it can be removed. Of course, the other possibility is that the phosphoric anhydride might itself form an ester with the alcohol to form the alkylating agent.

The sudden interest is derived from a pressing need for benzamide so as to attempt the Hoffman rearrangement of the same to aniline. No real reason.

Any ideas would be greatfully received, I would like to try this out soon as I can get my benzoates.

Attachment: PPA.Benzoic.Anhydride.pdf (354kB)
This file has been downloaded 5984 times

Nicodem - 17-6-2008 at 07:28

Yes, you can use polyphosphoric or pyrophosphoric acid for esterifications, but since it is much more simple and economic to use H2SO4, I doubt you will find much examples in the literature (if at all). The intermediate formation of alkyl phosphates is generally irrelevant as long as you let the reaction reflux long enough since the ester with benzoic acid is the thermodynamic product (similarly as I think I explained at the beginning of the thread for alkyl sulfates). Rather than making esters, the use of polyphosphoric acid or P2O5 is more practical for preparing certain volatile acid anhydrides which are otherwise difficult to prepare. The formation of the mixed anhydride is of advantage since even thermodynamically less favorable acid anhydride products can be distiled out given the unvolatility of P2O5, polyphosphoric acid and the mixed anhydrides (for example even triflic anhydride, bp 82°C, can be prepared this way).

To prepare benzamide you can use benzoic acid directly with urea (there is a thread on this somewhere - some members experimented with this method).

[Edited on 17/6/2008 by Nicodem]

LSD25 - 17-6-2008 at 07:51

Thanks, it is nice to be on the right track for a change

Panache - 17-6-2008 at 17:43

Quote:

Originally posted by Eclectic
Taste is only satly, sweet, bitter, sour, umami.

Taste

Everything else is smell.

Nice to see the world finally starting to acknowledge umani, i knew all those cheap japanese take-outs had an important role for society.

There is taste, there is smell and there is touch. For consuming foods, the palate, which is a less directly measurable, is a combination of these three senses in the mouth and nasal cavity. To a certain extent how an item looks also affects its 'palatability' but in any decent testing regime testing is done blindly.

I have been working on making many of these esters and some aldehydes (cinnamonaldehyde, benaldehyde) palatable, without using sugar synergies for some time and its very difficult. We are wired to detect quickly fats. Fats are the only inherently palatable food even sugars are not and the taste must be acquired, although it is readily acquired. Anything bitter needs to be generally at 1000 times lower the concentration of sugars or fats in the mix to be pleasant. This is explained by the taste bud sensitivity, much much more sensitivity to anything bitter, because bitter=poision.

Apologies for the seeming off-topicness but i saw an opportunity to ask a question of members. Sometimes an off hand piece of knowledge can help immensely. If anyone has any interesting 'tips' on this kind of work (ie getting falvanoids palatable without using simple sugars, fats or sweetners) i'd love it if you could message me, posting here would be off topic.

Thanking you all in advance.

16MillionEyes - 12-4-2009 at 16:55

I've recently tried making isopropyl benzoate by following an analogous reaction to that of methyl benzoate as that outlined in Williamson's Organic Experiments. Well, at least in principle, because when it comes to chemistry reagents and apparatus I'm nearly hopeless. Instead of using the typical roundbottom, condenser etc. I used test tubes instead and instead of highly pure sulfuric acid I had to content myself with drain cleaner (don't you wish you were as privileged as me!?). The isopropyl alcohol and benzoic acid I'm lucky enough to be in fairly pure form, sot that's not really my worry.

Now, here's the deal. I've tried this twice and twice I've failed. I take ~0.5g Benzoic acid with 7.5 times the moles amount of alcohol without any use of solvent, I let the stuff sit under "reflux" (with me next to it making sure to keep the stuff refluxing with an improvised test-tube condenser) for an hour, then I neutrilize it with bicarbonate, dry with anhydrous MgSO4 and then simply drive off the excess alcohol. Result? A big nice juicy precipitate of Benzoic acid.

I can't be sure what it's wrong with my synthesis or my procedure or why it would fail. I'm thinking that perhaps the reflux should be done for a longer time (what a hassle without the appropriate equipment) but also the otherwise gunky useless drain sulfuric acid may be the problem. I've noticed this in the color of the semi-oily solution that forms after reflux, and I know that the ester is supposed to be clear. This does not change after neutralizing and drying. I've tried to look for an official synthesis without much success (the ones I've found in the literature are all new fancy stuff--as usual--nothing practical to the mere household chemist). Does anyone know, or may suggest, what I'm doing wrong (except just about everything) or why it wouldn't work?

DJF90 - 12-4-2009 at 20:00

You didnt mention ADDING your acid catalyst... So did you?

Saerynide - 12-4-2009 at 20:32

Are you sure the drain cleaner was H2SO4? Also, maybe it was too dilute - dilute acid will hydrolyze esters.

I've made esters quite a few times and it has always worked. Though I did have a condenser and I used pure reagents.

Edit:
Also, in the future, if you want to make them on a large scale, reflux for longer. 1 hr isnt anywhere enough when trying to make something like 200 ml.

[Edited on 4/13/2009 by Saerynide]

pantone159 - 12-4-2009 at 20:52

______, my best guess is not enough heating. Secondary alcohols like iPrOH react slower than primary ones. Other than that, I don't see anything particularly wrong with your procedure, test tubes can work for small scale. Also - Are you using 100% iPrOH (rather than the more easily available OTC 91% stuff?) You want to avoid any excess water.

16MillionEyes - 13-4-2009 at 15:22

I dried my IPr before hand, so I know I must be using >99%. The acid is dilute though (not sure how much) so this may be a problem. I also think you are right, pantone159, the reflux may just need more time (2-3hours?). I think, if I have the time, I'll try this again and see if it works out.

Panache - 19-4-2009 at 14:54

Quote: Originally posted by __________

I dried my IPr before hand, so I know I must be using >99%. The acid is dilute though (not sure how much) so this may be a problem. I also think you are right, pantone159, the reflux may just need more time (2-3hours?). I think, if I have the time, I'll try this again and see if it works out.

You are using a solvent, it just happens to be the same as one of your reagents in this case.
This will work if your acid catalyst concentration is around 3% of benzoic acid mass. So if you are using 10g BA use 3% of this mass added as H2SO4.

SOME DRAIN CLEANERS ARE CAUSTIC.

Reflux overnight.

Longer reaction times are needed with esterifications when the alcohol is in excess (as opposed to the acid in excess, benzoic acid that is in this case). If you have some mol. sieves lying around throw them in to reduce the reaction time.

[Edited on 19-4-2009 by Panache]