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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 33, Number 6
BKCSDE 33(6)
June 20, 2012 

Kinetics and Mechanism of the Anilinolysis of Dipropyl Chlorophosphate in Acetonitrile
Md. Ehtesham Ul Hoque, Hai Whang Lee*
Phosphoryl transfer reaction, Anilinolysis, Dipropyl chlorophosphate, Deuterium kinetic isotope effect, Steric effect
The kinetic studies on the reactions of dipropyl chlorophosphate (3O) with substituted anilines (XC6H4NH2) and deuterated anilines (XC6H4ND2) have been carried out in acetonitrile at 55.0 oC. The obtained deuterium kinetic isotope effects (DKIEs; kH/kD) are primary normal (kH/kD = 1.09-1.01) with the strongly basic anilines while secondary inverse (kH/kD = 0.74-0.82) with the weakly basic anilines. The steric effects of the two ligands on the rates are extensively discussed for the anilinolyses of the (R1O)(R2O)P(=O or S)Cl-type chlorophosphates and chlorothiophosphates. A concerted mechanism is proposed with a frontside nucleophilic attack involving a hydrogen-bonded four-center-type transition state for the strongly basic anilines and with a backside attack transition state for the weakly basic anilines on the basis of the DKIEs, primary normal and secondary inverse with the strongly and weakly basic anilines, respectively.
1879 - 1884
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