Primary and secondary kinetic deuterium isotope effects and transition-state structures for benzylic chlorination and bromination of toluene

Journal Article · Wed Aug 05 04:00:00 EDT 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00250a028· OSTI ID:6290088

Hanzlik, R P; Schaefer, A R; Moon, J B; Judson, C M

As a chemical model for benzylic hydroxylation effects by cytochrome P-450 enzymes, the chlorination of PhCH/sub 3/, PhCH/sub 2/D, PhCHD/sub 2/, and PhCD/sub 3/ in a two-phase system of hypochlorite/CH/sub 2/Cl/sub 2/ with a phase-transfer catalyst has been investigated. On the basis of the deuterium content of the product benzyl chlorides, relative rate constants were deduced for all possible H- and D-abstractions with these substrates. From this the primary (P) and secondary (S) KDIEs were found to be 5.90 +/- 0.41 and 1.03 +/- 0.02, respectively, and the rule of the geometric mean was found to be closely obeyed. For the analogous bromination of toluene by N-bromosuccinimide in CCl/sub 4/, P and S were 6.37 +/- 0.43 and 1.05 +/- 0.01. The transition states of these processes must therefore involve extensive C-H bond breaking but relatively little rehybridization toward planarity at the reacting carbon.

• Research Organization: Univ. of Kansas, Lawrence
• OSTI ID: 6290088
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:16; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALKYLATED AROMATICS
AROMATICS
BROMINATION
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHLORINATION
CYTOCHROMES
DATA
DEUTERIUM
DEUTERIUM COMPOUNDS
ENERGY-LEVEL TRANSITIONS
EXPERIMENTAL DATA
HALOGENATION
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
HYDROXYLATION
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
MATHEMATICAL MODELS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PIGMENTS
PROTEINS
REACTION KINETICS
STABLE ISOTOPES
TOLUENE