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chemrox
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Good chemists taste their products whether they do it by licking their fingers is a matter of personal preference. I don't really mean that for
everything.. only medicinal products..I think a few chemists have died from carelessness with nitrile gloves and weird transition metal salts. One
step from acetone to make which intermediate? thioacetone?
I might be a little "devoted" today..sorry.. long cold rainy day and I can't find the keys to my storage area...my GPS and tile spade are in there and
I have three wetlands to delineate this week. Environmental consulting to support organic chemistry fun.
[Edited on 22-3-2016 by chemrox]
"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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CuReUS
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| Quote: | | One step from acetone to make which intermediate? thioacetone? |
very clever reaction atara.I am impressed
moonfisher ,another idea came to my mind which might avoid the use of LDA
why not react n-propylMgBr with acrylonitrile to get the unsaturated ketone and then add acetic acid across the double bond using michael reaction to
directly get the acetylated OH .Then you can convert the ketone to a thione and then a thiol
| Quote: | | Grignard reagents react with acrylonitrile by 1,2-addition and, after hydrolysis, give a,b-unsaturated ketones |
http://reag.paperplane.io/00000035.htm#18
addition of acetic acid to alkenes - https://books.google.co.in/books?id=mMgvCgAAQBAJ&pg=PA38...
[Edited on 23-3-2016 by CuReUS]
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clearly_not_atara
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IIRC formic acid adds easier than any other; I don't have the paper offhand but it's something like an autoclave at 120C. For acetic acid it's more
like 200 C and 50 atmospheres or something.
On the other hand, benzyl mercaptan adds to alkenes quite easily at room temperature. It's not as odorous as the short-chain thiols but it does stink.
TiO2 is an active photocatalyst:
http://pubs.rsc.org/en/content/articlehtml/2015/cc/c4cc09987...
[Edited on 24-3-2016 by clearly_not_atara]
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CuReUS
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I was thinking about removing a few more steps and one of the ways that can be done is doing a one pot reaction from the ketone to the thiol,similar
to a reductive amination.
the first reducing agent that came to my mind was NaBH3CN, but it cannot be used here because it will react with HCl( from the
HCl+H2S method) to liberate HCN.
sodium triacetoxyborohydride could be used,but I have read that it is unstable.
atara,are you sure about that ? because according to the google book I linked - "the addition of acetic acid to alkenes in acetic acid at reflux is
quite general"
also,won't HCOOH decompose at 120'C ?
| Quote: | | On the other hand, benzyl mercaptan adds to alkenes quite easily at room temperature |
forgive me for asking this,but how is this related to our problem ?
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clearly_not_atara
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I can't read your citation but I initially misread your post and thought you were using acetic acid to add the thiol in the keto-thiol. Anyway, I
tried to look at the book you linked but Google won't let me see it. I found this:
http://pubs.rsc.org/en/content/articlelanding/1981/c3/c39810...
which seems to sort of confirm my suspicions; a specialized montmorillonite catalyst at >100 C probably wouldn't be useful if all you needed was
reflux.
But more importantly, the normal conjugate addition to alkenes gives the Markovnikov product, but we want the anti-Markovnikov product. Therefore you
would need to do hydroboration followed by reaction with acetic acid, or HBr/AiBN in a dry solvent.
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CuReUS
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the book which talks about the addition of acetic acid to alkene is - de klein,W.J in "organic syntheses by oxidation with metal compounds",1986,
chapter 4. Please try the google book link again,using a different browser maybe ?
good find on the montmorillonite method. IIRC,this clay catalyst is not as rare as it sounds,and was used by meth cooks in the synthesis of
b-nitrostyrene from styrene.
| Quote: | | But more importantly, the normal conjugate addition to alkenes gives the Markovnikov product |
atara,with all due respect,I kindly ask you to read up on conjugate addition again
| Quote: | | A nucleophile reacts with a α,β-unsaturated carbonyl compound in the β position |
https://en.wikipedia.org/wiki/Nucleophilic_conjugate_additio...
[Edited on 26-3-2016 by CuReUS]
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zero
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Not sure why no one looked at the literature for this compound, it is well known to be one of the most potent odorants and there is a lot of research
on it.
Incidents:
A freezer was painted with paint thinner that had trace mesityl oxide impurity (0.5%) and caused all meat to smell/taste like cat piss by reacting
with trace H2S in the meat. [1]
Mesityl oxide produced in a factory caused a bakery 20 miles away to make cat piss cakes by absorbing into the cooling cakes and reacting with sulfur
compounds (from the eggs?). [1]
Wilmington, North Carolina smells like cat piss so bad that residents can barely breathe, even indoors. Fortron makes polyphenylene sulfide. Acetone
is used as a solvent and contains trace mesityl oxide. This reacts with the sulfur compounds producing the odor. [2]
Odor:
In low concentration it is the odor of boxwood or cat piss. In high concentrations it smells ketone like [3]. The odor threshold is reported between
1-10 ppt. [2]
Synthesis:
Mesityl oxide can be reacted with H2S in a basic alcohol solution to produce 4-MMP.
The simplest procedures are from [3] and more recently [4].
Translated procedure from [4] below:
| Quote: |
To a 4-L round bottom flask place 490 g of mesityl oxide, 1 1/2 L of 96-proof ethanol and 5 g of solid KOH. Cool the reaction vessel to -15C and
introduce H2S while stirring. After 5 hrs. the reaction is completed.
The work-up is carried out according to the instructions of F. ARNDT: The contents of the flask are poured into water, acidified with hydrochloric
acid, extracted with ether and the ether solution is extracted with 2n NaOH. The B-mercaptoketone I is removed from the ether solution with 2n NaOH.
After separation of the alkaline solution, the mercaptoketone is freed with HCl, separated, dried with Na2SO4 and distilled. I cannot be completely
extracted from the ether solution with sodium hydroxide. The workup of the ether solution yields considerable amounts of I in addition to
bis-diacetone sulfide from 82-83C. The total yield is 277 g (60% of the total, calculated on reacted mesityl oxide).
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Discussion:
I have not attempted yet but do have the reagents to, seems fun like thioacetone. Will try a microscale experiment. At least not water sensitive like
my other experiments. Hopefully will finally have a success. I have attached the relevant part of [3] for reference since it was difficult to locate.
[1] https://doi.org/10.1080/10408399109527534
[2] https://www.wwaytv3.com/fortron-confirms-plans-to-address-pl...
[3] F. Arndt (http://dspace.bcu-iasi.ro/handle/123456789/43983?show=full)
[4] https://doi.org/10.1002/jlac.19576100102
Attachment: revue.pdf (1.6MB)
This file has been downloaded 33 times
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