Computational studies of 2-(4-oxo-3-phenylthiazolidin-2-ylidene)malononitrile

Abstract

The molecular structure of the 2-(4-oxo-3-phenylthiazolidin-2-ylidene) malononitrile ( 3 ) is calculated using DFT B3LYP/6-311G(d, p) method. The calculated geometric parameters are in good agreement with the experimental data. The NBO calculations were performed to predict the natural atomic charges at the different atomic sites and study the different intramolecular charge transfer (ICT) interactions occurring in the studied system. The BD(2)C17–C19 → BD*(2)C14–C15, LP(2)O2 → BD*(1)N5–C9 and LP(1)N5 → BD*(2)C10–C11 ICT interactions causing stabilization of the system by 23.30, 30.63 and 52.48 kcal/mol, respectively. The two intense electronic transition bands observed experimentally at 249 nm and 296 nm are predicted using the TD-DFT calculations at 237.9 nm (f = 0.1618) and 276.4 nm (f = 0.3408), respectively. These electronic transitions are due to H-3 → L (94%) and H → L (95%) excitations, respectively. Electronic supplementary material The online version of this article (10.1186/s13065-019-0542-6) contains supplementary material, which is available to authorized users.

Effect of pH and concentration on the chemical stability and reaction kinetics of thiamine mononitrate and thiamine chloride hydrochloride in solution

“…Fractional order reactions are common when degradation products participate in subsequent chemical chain reactions, which is probable in the case of thiamine degradation [ 30 , 37 ]. In weakly acidic to neutral solutions (e.g., pH 6), thiamine is susceptible to hydrolysis in which the methylene bridge is broken, resulting in intact pyrimidine and thiazole moieties [ 18 , 34 , 38 , 39 ]. The resulting intact rings are then likely to undergo subsequent reactions.…”