Stuck waiting for chemicals and looking for an alternative base (not NaH) for the synthesis of a malonic ester from phenylacetic acid? Any suggestions for possible replacement of NaH that will work?
Dear Jason Hibbard an alternative base would be e.g. lithium diisopropylamide (see attached reference).
Synthesis of malonic ester from phenylacetic acid and diethyl carbonate .
First esterify phenyl acetic acid with ethanol using conc. H2SO4 to get
Phenyl diethyl malonate.Then react this with diethyl carbonate using sodium ethoxide as a base catalyst.
Jason, if you are a beginner, I recommend Madhukar's suggested method. You can use sodium alkoxides which are not as sensitive as LDA. (If you prepare methyl ester, then you can use sodium methoxide. If you use a different alkoxide with your ester moiety, transesterification will give you a mixture of esters, which makes your NMR analysis more difficult.
Frank's suggested method is actually a very good one, but dianion formation using LDA, and even a clean formation of LDA, requires a good synthetic skill. Cheers!
Having actually done this chemistry ... or a variant of it, I would go with Madhukar's answer - sodium ethoxide and the ethyl ester of the acid. Practically speaking, diethyl carbonate is not that reactive however. I used diethyl oxalate - the resulting ester can be pyrolysed to the malonate (it loses CO)
Dear Jason Hibbard I fully agree with Madhukar Baburao Deshmukh, Kohei Torikai and David J R Brook in that sodium ethoxide is also a good choice because it is easier to handle than LDA.
- Badges
- Science method
- Similar topics
- Chemistry, Organic
- Synthesis