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Chromsäureester als Zwischenprodukte bei der Oxydation von Alkoholen. Geschwindigkeits‐limitierende Veresterung eines sterisch Gehinderten Alkohols
Author(s) -
Roček J.,
Westheimer F. H.,
Eschenmoser A.,
Moldoványi L.,
Schreiber J.
Publication year - 1962
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19620450725
Subject(s) - chemistry , chromic acid , steric effects , acetic acid , alcohol , kinetic isotope effect , decomposition , aqueous solution , kinetics , medicinal chemistry , reaction rate constant , organic chemistry , deuterium , physics , quantum mechanics
Abstract The formation of a chromic ester as an intermediate in the chromic acid oxidation of secondary (and by analogy of primary) alcohols is strongly suggested by a study of the kinetics and deuterium isotope effect in the oxidation of an alcohol with a strongly sterically hindered hydroxyl group. For this alcohol (3β,28‐diacetoxy‐6β‐hydroxy‐18β‐12‐oleanene), either the formation of the ester or (in part) its decomposition can be made rate‐limiting. When the reaction is carried out in the presence of mineral acid in solvents of high acetic acid content, the esterification is presumably rate‐limiting, since k H / k D is 1.0; when the reaction occurs in 60% aqueous acetic acid in the presence of sodium acetate, both esterification and the decomposition of the ester contribute to the kinetics, since the isotope effect reaches a value of about 2.