Small-Scale Preparation of Glyoxylic Acid labelled with Carbon-14

Abstract

DURING the course of a study of glyoxylic acid metabolism in wheat it became desirable to obtain glyoxylate labelled with carbon-14, a compound which does not appear to be available commercially. Oxalic acid, which is available commercially as oxalic acid-¹⁴C, has been used in the synthesis of glyoxylic acid^1–4. Weinhouse and Friedmann⁵ synthesized glyoxylate-¹⁴C from oxalate-¹⁴C by reduction with mercuric chloride and Grignard magnesium. In order to isolate the crystalline bisulphite addition product of glyoxylate it was necessary to dilute the oxalate-¹⁴C (2.25 mgm.) with 900 mgm. of inactive oxalate. Tafel and co-workers^3,4 introduced an electrolytic method for the reduction of oxalate to glyoxylate. These workers used relatively large amounts of oxalate (10 gm.) and obtained very high yields (87 per cent). The reaction was carried out in 10 per cent sulphuric acid at 10° C. with a current of 4 amp. and was complete in 30 min. Mohrschulz² investigated the reaction more thoroughly and showed that it could be carried out in 2 per cent sulphuric acid at a temperature of 15–20° C. The highest yields were obtained using mercury as the cathode (rather than lead, copper or nickel).