Abstract
In 1922, in cooperation with Dr. Casimir Funk, we attempted the synthesis of the gentisic alanine by the Sasaki 1 and Hirai 2 , 3 methods, namely condensation of dimethoxy gentisic aldehyde with glycine anhydride in presence of anhydrous sodium acetate and acetic anhydride, and subsequent splitting of the diketo piperazine compound by means of prolonged heating with strong hydriodic acid and red phosphorus.
We failed to obtain the desired compound at that time and, due to pressure of other work, temporarily dropped the problem. Early in 1927, we again resumed this work and succeeded in preparing a crystalline substance which gave all the reactions of the desired compound. A Kjeldahl nitrogen determination gave the correct analysis for nitrogen, but due to the small amount of material available, we were unable to do a complete combustion at that time and were therefore loathe to publish our results.
As K. Hirai 4 has lately reported the synthesis of this amino acid, and as our compound appears to be identical with Hirai's in all respects, we feel justified in reporting our work.
Splitting of the 2.5-dimethoxy benzal glycine anhydride to racemic 2, 5-dihydroxy phenyl alanine.
1.1 gm. of 2.5-dimcthoxy benzal glycine anhydride were mixed with 10 cc. hydriodic acid (s.g. 1.7) and 0.8 gm. red phosphorus and the mixture refluxed in an oil bath at 110° C. for 7 hours. The mixture, on cooling, was diluted with water, filtered and the filtrate acidified with glacial acetic acid. ZQ% lead acetate solution was added to complete precipitation. The precipitates of lead iodide and lead phosphate were filtered and to the clear colorless filtrate, ammonia was added until a Precipitate was no longer formed. This casein-like precipitate which is the lead salt of the amino acid was filtered and washed well with water.
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