ORGLIST: barium malonate ppt

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From: M7419 (M7419$##$
Date: Tue Jan 27 1998 - 16:58:05 EST

I followed the procedure of Heisig and Stodola(Org Syntheses) to synthesize
1,1-cyclobutanedicarboxylic acid by reacting NaOEt with 1,3-dibromopropane and
diethyl malonate and then hydrolyzing the diester. After hydrolyzing the
ester with KOH I added conc HCl and boiled the solution a few minutes to
remove CO2 and then made it basic to litmus with NH3(aq). I then added BaCl2
solution to ppt excess malonate. When I added the BaCl2 solution a large
amount of light tan ppt formed. It seemed to me that since the solution was
basic the malonate and the cyclic diacid would both be in ionic form and that
both would be ppt'd by the Ba(2+). Would this be the case? If I interpreted
the NMR spectra I took it indicated there was only a small amount of malonate
in the solution; however, since this is the first time I have gone through
this reaction I figured I had better follow all the steps. Is there a better
way to remove any excess malonate? I thought perhaps one reason the yield of
the diacid was so low was that some of it formed a ppt with the BaCl2, since
in the procedure they added BaCl2 until barium malonate stopped precipitating.

Any help would be appreciated.

Thanks a bunch.

Michael Lynch

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