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Kinetics and mechanism for oxime formation from 4‐dimethylaminobenzaldehyde and 4‐trimethylammoniobenzaldehyde iodide
Author(s) -
Malpica A.,
Calzadilla M.,
Cordova T. C.,
Torres S.,
Saulny G. H.
Publication year - 1999
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1999)31:5<387::aid-kin8>3.0.co;2-v
Subject(s) - chemistry , iodide , kinetics , oxime , catalysis , dehydration , substrate (aquarium) , reaction rate , medicinal chemistry , inorganic chemistry , organic chemistry , biochemistry , physics , oceanography , quantum mechanics , geology
The following lines of evidence establish that oxime formation from 4‐dimethylaminobenzaldehyde and 4‐trimethylammoniobenzaldehyde iodide occurs with a simple two‐step mechanism. The pH‐rate profile for the reaction of 4‐trimethylammoniobenzaldehyde iodide exhibits, in order of decreasing pH, a negative deviation at pH near 2.0, corresponding to a transition from rate‐determining step carbinolamine dehydration with acid catalysis to the uncatalyzed carbinolamine formation. In the case of the reaction of 4‐dimethylaminobenzaldehyde, the pH‐profile exhibits, in order of decreasing pH, a positive deviation at pH near 3.5 and then a negative deviation at pH near 2.0. These deviations have been interpreted in terms of i) transition of the rate‐determining step, and ii) protolytic equilibrium of the substrate. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 387–392, 1999