Thiamin, also known as Vitamin B₁ has the chemical formula (when isolated in the chloride form):

C₁₂H₁₇ClN₄OS·HCl

It is colourless, soluble in water, and insoluble in alcohol. It decomposes if heated too much.

The mononitrate looks like this:

Thiamin pyrophosphate is a coenzyme of pyruvate dehydrogenase[?], α-ketoglutaran dehydrogenase[?], and transketolase[?]. Because the first two of these enzymes are important in the metabolism of carbohydrates, thiamin deficiency causes problems with it. Thiamin deficiency also causes the diseases Wernicke-Korsakoff syndrome[?] and beriberi.

Commonly also spelled "thiamine".