Unexpected cleavage of C–S bond in the hydrazination of 2-((3,5-di-tert-butyl-4-hydroxybenzyl)thio) nicotinate: synthesis and mechanistic studies by kinetic and computational approaches
2016
Nordin, Nurdiana | Ariffin, Azhar | Daud, Mohammad Noh | Sim, Yoke-Leng
Methyl 2-((3,5-di-tert-butyl-4-hydroxybenzyl)thio) nicotinate was successfully synthesized from 2-mercaptonicotinic acid and 2,6-di-tert-butyl-4-hydroxy-benzylalcohol. Hydrazination of the esters is a conventional method for preparing acyl hydrazides, 2-(3,5-di-tert-butyl-4-hydroxy-benzylsulfanyl)-nicotinic acid hydrazide. However, an attempt to synthesize the starting material in alcoholic solution by hydrazine hydrate did not lead to the expected products. Unexpected C–S bond cleavage was observed that produced two compounds, 2-thioxo-1,2-dihydro-pyridine-3-carboxylic acid hydrazide, and 2,6-di-tert-butyl-4-hydrazinomethylphenol. A kinetic and a computational DFT studies were carried out in order to propose a rational mechanism.
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