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Selectivity of Stabilized Benzhydrylium Ions
Author(s) -
Denegri Bernard,
Matić Mirela,
Kronja Olga
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200901327
Subject(s) - chemistry , solvolysis , carbocation , solvation , selectivity , hydrolysis , solvent , aqueous solution , ion , solvent effects , medicinal chemistry , reaction rate constant , inorganic chemistry , computational chemistry , organic chemistry , kinetics , catalysis , physics , quantum mechanics
Methyl carbonates ( 1 – 4 –OCO 2 Me) and phenyl carbonates ( 2 – 4 –OCO 2 Ph) were subjected to solvolysis in the series of aqueous ethanol, the product ratios were determined and the selectivities ( k E / k W ) of the corresponding stabilized benzhydrylium ions 1 – 4 were calculated. The individual rate constants for ethanolysis ( k E ) and hydrolysis ( k W ) have been calculated. Ethanolysis proceeds via earlier more carbocation‐like transition state than hydrolysis. Due to more important solvation, k E decreases slower than k W if the fraction of the water in the binary solvent increases, which net effect is pronounced dependence of the selectivity on the solvent polarity. The selectivities of less stable carbocations 5 – 8 are reduced and influenced by the leaving group because of pairing and bending of the log k vs. E plot.