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Effect of pressure on sterically hindered reactions with late transition states
Author(s) -
Gacem Badra,
Jenner Gérard
Publication year - 2004
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.718
Subject(s) - steric effects , chemistry , transition state , conjugate , isoprene , sn2 reaction , computational chemistry , photochemistry , organic chemistry , catalysis , polymer , mathematical analysis , mathematics , copolymer
The effect of high pressure is examined in two types of sterically congested reactions presenting late transition states: isopolar Diels–Alder cycloadditions of isoprene and quinones of various steric environment and conjugate additions of tert ‐butylamine and acrylic compounds. In the Diels–Alder cycloadditions, pressure has no enhanced kinetic sensitivity in sterically demanding reactions compared with unhindered ones. This is due to the structural closeness of the transition state and product. At variance, in the conjugate addition of amines, the effect of pressure is magnified with increasing steric congestion at the reaction centres. This is ascribed to enhanced electrostriction with removal of steric hindrance to ionization. Copyright © 2004 John Wiley & Sons, Ltd.