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Communication | Regular issue | Vol 26, No. 1, 1987, pp.13-17
Published online, 1st January, 1970
DOI: 10.3987/R-1987-01-0013
Chemical Behavior of Isolated Thiamin Ylide in Neutral Aqueous Solutiion — A New Mechanism of Interconversion of Thiamin and Thiamin Thiolate

Hirihiko Sugimoto and Kentaro Hirai

*Shionogi Research Laboratories, Shionogi & Co. Ltd., Fukushima-ku, Osaka 553-0002, Japan


The isolated thiamin ylide (TY) was found to he converted into thiamin thiolate (TH+TS-, 3) in neutral aqueous solution. The formation of the ion-pair can best be explained by the disproportionation of the ylide into the yellow form (TH+YF-, 4) followed by ring-opening by the attack of water to pyrimido[4,5-d]pyrimidine ring of the yellow form. These results suggested a new mechanism for the interconversion between thiamin (TH+CI-) and thiamin thiolate (Na+TS-).