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Rando1234
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Easy-to-synthesize odor compounds
I'm looking for concise and simple syntheses of odor compounds with a pleasant smell. I don't want to make esters. Do you have any suggestions?
-JacobM
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Texium
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Welcome to the forum! Hate to burst your bubble though: esters are about as easy and simple as it gets, so if you aren't equipped to make those, you
aren't going to have an easy time accessing anything else.
Edit: though, you can always steam distill some plant material and isolate the aroma compounds. Cloves and anise work really well (yielding anethole
and eugenol respectively). All you need for that is clean water and a simple distillation apparatus.
[Edited on 1-8-2022 by Texium]
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Rando1234
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I see, but I have trouble making concentrated sulfuric acid. I have to distill battery acid, and it never gets above ~80-90%. I do have a jar of
polyphosphoric acid, which does work for simpler aliphatic esters, albeit in poor yields (20%).
What's your opinion of cyclopentanone? I've made it before, and I think it smells alright, but it does have a bit of a chemical undertone to the minty
smell.
I've done all sorts of other things that polyphosphoric acid and my weakish sulfuric acid will easily catalyze. Esterifications just seem to be
difficult for me for some reason.
[Edited on 8-1-2022 by JacobM]
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Bedlasky
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Use directly battery acid. Sulfuric acid is used in very small amount anyways, so 0,5 ml of water doesn't hurt reaction much.
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DraconicAcid
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I've had rotten luck with a lot of esters, but one thing I've learned is that you need primary alcohols. Secondary ones don't work very well (they
require very long refluxes, or the use of anhydrides), and tertiary ones don't work at all.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Bedlasky
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Quote: Originally posted by DraconicAcid  | | I've had rotten luck with a lot of esters, but one thing I've learned is that you need primary alcohols. Secondary ones don't work very well (they
require very long refluxes, or the use of anhydrides), and tertiary ones don't work at all. |
Secondary and tertiary alkyl acetates can be made from alcohol and acetic acid using manganese(III) acetate catalyst. Never tried that, but looks
interesting.
https://www.sciencedirect.com/science/article/abs/pii/S13811...
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DraconicAcid
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Yes- I've seen the article, but haven't tried it yet. I wasn't going to mention it until confirmed.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Rando1234
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That looks interesting, but I find that alternative catalysts don't work well for me.
I think the reaction is more water sensitive than you think, Bedlasky. It would probably do for simple esters of primary alcohols, but for aryl
esters, no way.
Tertiary alcohols just dehydrate to alkenes. I am aware of that.
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Tsjerk
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80% sulfuric acid is perfect for a Fischer esterification. Maybe not perfect, but fine at least.
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Rando1234
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Okay. I might have to try it.
To be honest I have had some success with aryl esters. I made methyl benzoate once. It was fine up until I had to distill. I just got a flask of tar
and some liquid with a BP 40 degrees too low. I didn't use vacuum distillation because I thought it would be fine and I have a heating mantle good
enough.
Edit: Battery acid sold by the autozone a few minutes away from my house is only 30-50%.
[Edited on 8-1-2022 by JacobM]
[Edited on 8-1-2022 by JacobM]
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teodor
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| Quote: Originally posted by DraconicAcid | | I've had rotten luck with a lot of esters, but one thing I've learned is that you need primary alcohols. Secondary ones don't work very well (they
require very long refluxes, or the use of anhydrides), and tertiary ones don't work at all. |
But the secondary alcohols give a better, more gentle smell. I have examples: isopropyl and sec-butyl acetates. Yes, the reflux time is longer, but
the yield is good.
If you don't like long-time reactions try to use a Dean-Stark with hexane / benzene / toluene, depending on what you have. This also eliminates the
problem with wet starting components - all the water is collected in the Dean-Stark anyway.
But I think to get the pure aroma from alcohols like sec-butanol you have to purify the alcohol by fractional distillation and selecting fraction with
the most stable boiling temperature, and it usually has the most nice smell. It should not be pungent like in my commercial sec-butanol sample prior
to fractionation.
p-toluenesulfonic acid is a better catalyst than H2SO4 and it is not restricted in EU.
But both don't work for cyclohexanol, HCl is recommended instead. Also, probably, for some secondary alcohols, you have to use HCl.
The best method to saturate the alcohol with HCl is to add some calculated amount of acetyl chloride. Otherwise, gaseous HCl is used. I am curious,
can be 36% HCl be used instead in a Dean-Stark rearrangement (I planned to check it but now I am working on menthyl acetate which has the best smell
of all esters I saw till this moment).
[Edited on 8-1-2022 by teodor]
[Edited on 8-1-2022 by teodor]
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Bedlasky
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From what I know, H2SO4/H3BO3 mixture is used as catalyst for phenyl esters, not just H2SO4 alone. But I am not an organic chemist,maybe just sulfuric
works.
Why do you avoid esters of primary alcohols? And do you really think, that 0,5 ml of water significantely affect reaction? Much more water is formed
by reaction itself. If you do esterification, in which water significantely reduce yield, you must remove water with Dean-Stark anyways, so where is
problem with 0,5 ml of water from battery acid?
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Bedlasky
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| Quote: Originally posted by teodor |
But the secondary alcohols give a better, more gentle smell. I have examples: isopropyl and sec-butyl acetates. Yes, the reflux time is longer, but
the yield is good.
If you don't like long-time reactions try to use a Dean-Stark with hexane / benzene / toluene, depending on what you have. This also eliminates the
problem with wet starting components - all the water is collected in the Dean-Stark anyway.
But I think to get the pure aroma from alcohols like sec-butanol you have to purify the alcohol by fractional distillation and selecting fraction with
the most stable boiling temperature, and it usually has the most nice smell. It should not be pungent like in my commercial sec-butanol sample prior
to fractionation.
[Edited on 8-1-2022 by teodor] |
You read my mind Teodor with that Dean-Stark trap  . If you like esters with
gentle smell, try oxalic acid esters. They have weak and pleasant smell, quite characteristic. I can give you some diethyl oxalate if you want, I have
lots of it.
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teodor
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| Quote: Originally posted by Bedlasky | | Quote: Originally posted by teodor |
But the secondary alcohols give a better, more gentle smell. I have examples: isopropyl and sec-butyl acetates. Yes, the reflux time is longer, but
the yield is good.
If you don't like long-time reactions try to use a Dean-Stark with hexane / benzene / toluene, depending on what you have. This also eliminates the
problem with wet starting components - all the water is collected in the Dean-Stark anyway.
But I think to get the pure aroma from alcohols like sec-butanol you have to purify the alcohol by fractional distillation and selecting fraction with
the most stable boiling temperature, and it usually has the most nice smell. It should not be pungent like in my commercial sec-butanol sample prior
to fractionation.
[Edited on 8-1-2022 by teodor] |
You read my mind Teodor with that Dean-Stark trap . If you like esters with
gentle smell, try oxalic acid esters. They have weak and pleasant smell, quite characteristic. I can give you some diethyl oxalate if you want, I have
lots of it. |
Thanks for the recommendation. I will definitely try to do it by myself. I am in a process of vacuum distillation of menthyl acetate, which I already
mentioned, and while waiting for some equipment (which I need to complete the process) I am playing with making trioxalato complexes. And when I
started to do it I was wondering "how oxalate esters should smell"? I didn't find any info, and now you say they have a gentle smell. So, probably you
also are reading my mind 
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Amos
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One of my favorite aroma compound syntheses was making methyl cinnamate, which smells like strawberry, from cinnamon powder. You steam distill the oil
out of cinnamon, react the oil with chromic acid in a Jones oxidation, get nearly pure cinnamic acid out of that via acid base extraction, and finally
esterify that with methanol.
You can try extracting piperine out of pepper and oxidize it to piperonal, which is nice.
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teodor
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From the book "Perfumery, Practice and Principles, Calkin / Jellinek" (you can download it you know where)
"The following is a list of the 162 natural and synthetic materials that it is suggested students should learn to identify within the first six months
of their studies. It is intended to cover a wide range of odor types. These materials are mainly used in fine perfumery. (Materials marked with an
asterisk form the list of 50 materials to be learned first.) .. "
I will skip the natural ones. The full list is in the book, and I will list here only those marked with asterisks. I am not an expert to fast answer
the question which are easy to make and which are not, probably it could be a topic for the discussion:
Aldehyde C11 undecylenic
Aldehyde C12 MNA
Aldehyde C14 (gamma-undecalactone)
Amyl salicylate
Benzyl acetate
Citronellol
Dihydromyrcenol
Ethyl phenylacetate (I believe Fery posted the synthesis here)
Eugenol
Galaxolide
Geranyl acetate
cis-3-Hexenyl acetate
Hexyl cinnamic aldehyde
Hexyl salicylate
Hivertal
Hydroxycitronellal
Indol
Isobornyl acetate
Iso butyl quinoline
Linalool
Linalyl acetate
Methyl anthranilate
Methyl ionone gamma
Phenylacetaldehyde
Phenylethyl alcohol
Rose oxide
Styrallyl acetate
Terpineol
Vanillin
Vertofix
Also, I could recommend the book "Fenaroli's handbook of Flavor ingredients" (which could be downloaded also). It contains the list of probably all
known compounds which are used for their smell and for many of them there are notes about synthetic methods used.
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Tsjerk
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Boil it down until it is produces heavy fumes, be careful because the fumes are very acidic. This should be around 80% sulfuric.
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Texium
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Since you have
AutoZone I’m going to assume you’re in the US, and if that’s the case, you likely also have an Ace Hardware near you (they’re in all 50
states) and I know for a fact that they sell 98% sulfuric acid by the gallon as drain cleaner.
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Rando1234
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Tsjerk, that's what I did. I guess it was the distillation after all?
Thanks for all of the suggestions, I think that I'll either make a simple ester (butyl acetate seems niceish) or 1-phenylethanol (it will take some
effort to obtain acetophenone). I have done the dry distillation of calcium acetate and benzoate, and I got a terrible smelling liquid. It had the BP
of acetophenone though....are there any methods to make acetophenone?
I'm interested in making acetophenone for the purpose of exploring its chemistry even though I can buy it. Borohydride is available to me with
difficulty. I really want to avoid carcinogens like benzene, and because I'm in the US, acetyl chloride is a controlled substance and difficult to
acquire, not to mention the HCl it fumes.
Edit: What are your favorite esters? I might make an ester instead.
[Edited on 8-1-2022 by JacobM]
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Texium
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Um, no. Acetyl chloride is most definitely
not a "controlled substance." It isn't even a listed chemical. It isn't the easiest thing to acquire, that's true, nor is it the most pleasant thing
to work with, but I want to nip that misinformation in the bud because there isn't anything illegal about owning acetyl chloride in the US.
Also, to repeat myself now that you've confirmed you're in the US: I can almost guarantee that you can find concentrated sulfuric acid OTC near you
and you don't need to waste your time and money on battery acid. You can also order it from Duda Diesel for a really good price.
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Rando1234
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Texium,
Well shows how much I know about US drug law. I thought it would be controlled because it can be used to make heroin but apparently not.
I can buy sulfuric acid at the Ace Hardware near me. I'll use that when I do make an ester sometime soon.
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Rando1234
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Terpineol is also an option, however I haven't had the best luck with it. I've purchased 1/2 litre of alpha-pinene and attempted the reaction of some
of it with acetic acid and polyphosphoric acid. After 2 hours reflux and a simple basic workup, I just got a yellow oil that smelled horrid in an
indescribable way. If that was terpinyl acetate, I wouldn't know of it.
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myr
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http://libgen.rs/book/index.php?md5=34B65FF56EE3EFE564EB5423...
Really out of date but it's a good range of many fragrance and flavor chemicals in industry c 1965.
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Rando1234
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Thanks, that might help.
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Texium
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| Quote: Originally posted by JacobM | Texium,
Well shows how much I know about US drug law. I thought it would be controlled because it can be used to make heroin but apparently not.
I can buy sulfuric acid at the Ace Hardware near me. I'll use that when I do make an ester sometime soon. |
Yeah, it is honestly kind of weird that acetic anhydride is listed while acetyl chloride is not, even though they can accomplish the
same things. Just goes to show how arbitrary some of these laws are. To be clear though, List I and List II chemicals are not controlled substances.
They are not illegal to own, and the legal requirements fall on companies that import, manufacture, or distribute them, not on individuals who
purchase them. Take a look here: https://en.m.wikipedia.org/wiki/DEA_list_of_chemicals You can see here that for List II chemicals (which includes acetic anhydride along with such
OTC staples as acetone, toluene, and sulfuric acid) the only requirement that could potentially affect an end user is that “unusual” purchases be
reported to the DEA. For List I chemicals, sellers have to report mail-order purchases (I suppose online purchases count?) as well if they are to
non-registered buyers like us. But even then, unless you order large amounts of red phosphorus and iodine and recently purchased a lot of Sudafed, I
don’t think you have to worry about the DEA coming knocking over a List I chemical… and once again, owning them is not illegal unless you secretly
imported them from another country.
While you’re at Ace, look for toluene if you don’t already have some. I never see it at the larger hardware stores, but I’ve seen it there
before.
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