Author Topic: Tetra-alkyl-ammonium Hydroxide Alkaloid Hydrolysis  (Read 2784 times)

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Bubbleplate

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Tetra-alkyl-ammonium Hydroxide Alkaloid Hydrolysis
« on: October 09, 2003, 05:59:00 PM »
Standard procedure calls for alkaline hydrolysis of Lysergic Acid amides (ergotamine, LSA, etc.) with a Methanolic solution of Potassium hydroxide to obtain Lysergic Acid.
However,

Patent US6242603

describes a method of preparing Lysergic Acid by isomerizing Paspalic Acid with a Tetra-alkylammonium hydroxide solution, such as Tetra-butylammonium hydroxide, with excellent yields (80%).

My question is, couldn't a Tetra-alkyl-ammonium Hydroxide also be used in the alkaline hydrolysis of lysergic amides in place of Potassium hydroxide, and with better yields?

Offline Vesp

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Re: Tetra-alkyl-ammonium Hydroxide Alkaloid Hydrolysis
« Reply #1 on: February 14, 2015, 05:06:42 PM »
This question though 12 years old seems like it would still be of interest to some members. 

I really don't understand the mechanism of this reaction so I can't really comment on why it wouldn't or would work for the amide hydrolysis. 

It is apparently a fairly strong base, which seems a bit counter intuitive to me.  Is it actually strong enough induce amide hydrolysis?

I wonder if something could be done with the readily available choline? Choline hydroxide seems to have similar uses and is also considered a strong base.
« Last Edit: February 14, 2015, 05:12:59 PM by Vesp »
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Offline fishinabottle

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Re: Tetra-alkyl-ammonium Hydroxide Alkaloid Hydrolysis
« Reply #2 on: February 14, 2015, 08:58:33 PM »
The patent describes an isomerisation and the other reactions are a hydrolysis. So thats a different shoe to wear.

But strong base being strong base and as this good candidates for catalyzing a hydrolysis I had a look and it seems no. Won't work well.
Adding some KOH or NaOH though could change the picture.

Or LiOH alone or in combination with anything named above.
I have no idea why but LiOH seems just right to me.
A shot in the dark, nothing else.

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