Abstract

Thiamine, usually meaning the hydrochloride, is a water-soluble salt which as its pyrophosphate ester, plays essential roles in nearly all life forms as a cofactor for metabolic dehydrogenase and transketolase enzymes. Its biosynthesis in microorganisms and plants is tightly limited to very low levels by feedback and repression mechanisms. Animals are dependent on a regular supply in their diets to prevent deficiencies which can progress from mild subjective symptoms of malaise to serious degenerative disorders and death.

Knowledge of the biosynthesis of thiamine is limited and manufacture from biosources is not practical. All world production of thiamine is by chemical synthesis. All three of the major manufacturing groups use variants of one synthesis wherein the thiazole group is built up on the pyrimidine ring. The common intermediate, known as Grewe diamine, is synthesized from malononitrile or acrylonitrile, formate synthons, and acetonitrile. The thiazole ring is derived from carbon disulfide, butyrolactone, and acetate esters by the common intermediate thiolthiamine, which is oxidized to thiamine sulfate and then converted to other salts. Thiamine is sold as the hydrochloride and mononitrate salts which are widely used in foods, feeds, and multivitamin supplements. Thiamine is safe and stable when dry or in acidic solution, but degrades with base, irradiation, and nucleophilic attack.

Essentials of the history, occurrence, biosynthesis, biochemical and physiological functions, chemical transformations, manufacturing chemistry, analytical methods, safety and handling, product forms, derivatives, analogues, and uses of thiamine are discussed.