07-03-04 04:43
No 517107
Please could anyone enlighten me on the use of monopotassium phosphate in the decarboxylation of phenylglycidic acid salts from the Darzen condensation of benzaldehydes with chloroacetic/2-chloropropionic acid esters...
Is this advantageous over decarboxylation with acids such as HCl/AcOH, a la Barium?
Is it applicable for phenylacetaldehydes and P2Ps, or just phenylacetaldehydes?
The potassium salt of the phenylglycidic acid was used in all the cases of KH2PO4 decarboxylation i have seen; is there a reason for this (instead of the sodium salt)?
Would KH2PO4 be incompatible for decarboxylation of epoxy acid salts formed from benzaldehydes containing more sensitive functional groups, e.g. iodo, methylenedioxy, etc?
Thankx in advance,
-psyx
(Heavyweight Chempion(eer))
07-03-04 17:35
No 517182
The glycidic ester is hydrolysed with NaOH or KOH to either the sodium or potassium salt of the glycidic acid. What's needed now is just a acid strong enough to liberate the glycidic acid. That's it! KH2PO4 should absolutely fill that criteria since it is a pretty acidic salt. Once the glycidic acid is liberated it is pretty easily decarboxylated.
I used those acids because it said so in the refs I found and I had plenty of them. As the time passed I discovered they are not absolutely needed.
Severe Aztecoholic and President of Sooty's fanclub - Sooty for President!!