The mass spectrum of vitamin B 1 and some model compounds

Vitamin B₁, in chloride ( 1 ) or iodide form, decomposes thermally in the mass spectrometer mainly into 2-methyl-4-amino-5-chloromethyl(iodomethyl)-pyrimidine and 4-methyl-5-β-hydroxyethyl-thiazole, and partly, by loss of HCl (HI) under cyclisation, into the base 2 . The mass spectrum exhibits peaks due to these products and their fragments. The mass spectra of some model compounds are discussed.