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The kinetics and mechanism(S) of nucleophilic attack by catecholate anion on epibromohydrin‐ d 2
Author(s) -
Cawley John J.,
Onat Ediz
Publication year - 1994
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610070802
Subject(s) - chemistry , nucleophile , mechanism (biology) , kinetics , ion , medicinal chemistry , computational chemistry , stereochemistry , organic chemistry , catalysis , physics , quantum mechanics , philosophy , epistemology
The reaction which forms hydroxymethylbenzodioxane from epibromohydrin and catecholate anion was examined by ultraviolet spectroscopy for the kinetics and by proton nuclear magnetic resonance spectroscopy to follow the fate of CD 2 from reactant to product. Over the practical temperature range it was found that both CH 2 positions in the epihalohydrin are attacked by catecholate anion to give product. Therefore, the difference in energy for the two pathways was small. The individual rate constants were obtained from the total rate constants. Further, the individual Δ H ‡ and Δ S ‡ values were calculated. It was found that the pathway of higher Δ H ‡ had the less negative Δ S ‡, which explains the subtlety of two mechanisms being operative over the available temperature range. Interestingly, it proved impossible to prepare epibromohydrin with two deuteriums at only one position in what appeared to be a relatively straightforward synthesis.