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Thermodynamic and Kinetic Data for the Base‐On/Base‐Off Equilibration of Alkylcobalamins
Author(s) -
Hamza Mohamed S. A.,
Zou Xiang,
Brown Kenneth L.,
Eldik Rudi van
Publication year - 2003
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200390036
Subject(s) - chemistry , base (topology) , protonation , acid–base reaction , kinetic energy , thermodynamics , kinetics , function (biology) , spectroscopy , computational chemistry , organic chemistry , ion , mathematical analysis , physics , mathematics , quantum mechanics , evolutionary biology , biology
The base‐on/base‐off equilibration of a series of alkylcobalamins (XCbl) was studied as a function of the electronic properties of X. A square scheme was developed to incorporate all species that participate in this equilibration. The equilibrium between five‐ and six‐coordinate species was studied for several alkylcobalamins (protonated base‐off) and alkylcobinamides as a function of pressure by using UV/Vis spectroscopy. In addition, the kinetics of the acid‐induced base‐on/base‐off equilibration of β‐NCCH 2 Cbl, β‐CF 3 Cbl and CNCbl were studied; the data obtained reveal evidence for an acid‐catalysed reaction path. The results of this study and the observed correlations are discussed in reference to those reported in the past, and enable the formulation of an overall equilibration scheme. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)