Decomposition of thiamine in alcohol solution. I.

Characterization of 2-Methyl-4-amino-5-(2-methyl-3-furylthiomethyl)pyrimidine from Thermal Degradation of Thiamin

“…As we previously mentioned, the C-8 in the pyrimidine moiety shifted upfield. The evidence strongly supports the assumption that the pyrimidine unit and 2-methyl-3-furanthiol (7) connected with each other through the methylene bridge. The HMBC spectrum decisively showed a cross-peak between H-8 and C-3′ (Figure 1).…”

“…Consequently, the compound was determined to be 2-methyl-4-amino-5-(2-methyl-3-furylthiomethyl)pyrimidine (MAMP; 1) (Figure 1). The structure suggested for compound 1 was ultimately confirmed by synthesis, which was performed according to modified methods of Shimahara et al (7). The spectral characteristics of compound 1 were identical with those of the compound isolated from synthesis.…”

“…The extract was then purified by column chromatographic methods to obtain compound 1 as described in the purification of compound 1 from thermal reaction of thiamin. This synthetic method was modified from the method of Shimahara et al (7).…”

“…4-Methyl-5-(2-hydroxyethyl)thiazole (6), 4-amino-5-(aminomethyl)-2-methylpyrimidine, and 3-mercaptopropanol, along with hydrogen sulfide, ammonia, acetic acid, formic acid, formaldehyde, and acetaldehyde, have been reported as major compounds from thermally degraded thiamin (1,2). Additionally, many furans and thiophenes, including the character-impact meaty aroma compound 2-methyl-3-furanthiol (7), were identified from thermally degraded thiamin (7) (3). Although numerous volatile thermal degradation compounds have been identified from thiamin, limited information is available on nonvolatile or semivolatile compounds from thermally degraded thiamin.…”

Restricted rotation of the amino group bonded to thiamin and to 2-(1-hydroxyethyl)thiamin and the question of intramolecular amino group catalysis

“…6 Thiamin chloride was liberated from its hydrochloride (Sigma) using triethylamine. 22 Methanol was dried before use; samples contained a few pellets of 3Á molecular sieves to keep them dry. Wet samples slowly underwent degradation, presumably hydrolytic cleavage of the thiazolium ring.…”