The thermal stability of S-nitrosothiols: Experimental studies and ab initio calculations on model compounds

One factor responsible for the enhanced thermal stability of S-nitroso-N-acetylpenicillamine (SNAP), compared with S-nitroso-N-acetylcysteine (SNAC), has been shown, by ab initio calculations on model compounds, to be steric interactions in the dimerisation reaction leading to disulfide formation, Studies using DSC and TGA indicate that the two gem methyl groups in SNAP do not have a substantial effect on the strength of the -S-NO bond.