Furboffle
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Fischer speier esterification
I've attempted the Fischer-speier reaction involving indole-acetic acid and methanole to convert IAA to its methyl ester. Initially I did this with
350mL of methanol, 5g IAA and 10 drops 98% sulfuric acid. The solution turned reddish and I ended up with a reddish brown oil. Intended product should
be a tan crystal. Upon reattempting this reaction I used 35mL methanol, 500mg IAA, and 6 drops h2so4. This time the solution ended as a golden color
and left me with the tan crystal I expected. I assume the issue was not enough acid catalyst to drive the reaction in the right direction. Being as I
don't have access to ms/gc, ir, or NMR at home I don't have a means of identifying the first attempt product: the red brown oil. I'm wondering what
mechanism could be possibly expected between a carboxylic acid and an alcohol if the acid catalyst wasn't present in large enough quantities to
intitiate esterification?
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Paddywhacker
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I would expect the indole ring to be a bit sensitive to concentrated acid. Maybe you can use a milder catalyst, such as toluene sulphonic acid or an
acid ion-exchange resin, and/or absorb the water with a molecular sieve in a Soxhlet.
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kristofvagyok
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Solution of ccH2SO4 with methanol in presence of oxygen is used for the indentification of in indolic compounds.
I also used it and it is an awesome reagent. Just add some ccH2SO4 to a little methanol, heat it up, place the indole in it and wait a bit, or bubble
some O2 through it. Colorination will occour.
This is why indole chemistry is a bit harder, it react the way didn't hope.
P.S.: I know that the IAA esters are really nice fluorescent stuffs, but you won't do any 'bad' with them, right?
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Furboffle
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I knows it easy from here to get to certain compounds... But I'm actually looking to make beta-Carbolines. (Which its fluoresence is what im actually
wanting)Get from here to tryptamine. Perform an eschweiler-Clarke methylation, which with tryptamines causes ring closure rather than methylation..
Melatonin(5-meo-n-acetyl-tryptamine) would probably be a better starting point which Ill probably do, hydrolysis of melatonin should give
5-meo-tryptamine followed by eschweiler to yield that..
Definitely, I don't why that didn't phase me before. Gambling with this working or destroying the indole isn't exactly a good starting point. I'm
curious though how the molecular sieve would be important? Does aqueous acids such as sulfuric hinder the reaction at all? Is dry alcoholic acid
conditions better? Maybe I'm not getting the right reasoning but if I'm right water is generated by Fischer-speier so it would be present anyway.
Could you elaborate on that?
Edit: then again using a Soxhlet would continuously remove generated h2o.... This is interesting the more I think about it
[Edited on 19-10-2012 by Furboffle]
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kristofvagyok
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Quote: Originally posted by Furboffle  | | Edit: then again using a Soxhlet would continuously remove generated h2o.... This is interesting the more I think about it[Edited on 19-10-2012 by
Furboffle] |
Just today I made an ester synthesis of a lactic acid like thing. The main problem was that with mineral acids the OH and the COOH was also
methylated. I just opened Vogel and looked up esterifications.
The one that I have chosen used a acidic resin as a catalyst and the generated water was removed by benzene from the reaction (I used cyclohexane
instead of it). It worked awesome! The generated water just distilled over, I used a dean stark trap to collect the generated water and the workup is
also easy, just filter out the resin (could be reused) and just simply distill of the excess solvents.
So you don't need to use H2SO4, HCl or any stong acid, just think a bit and read a few article, I'm sure that you will find a better recipe for this(:
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