title: Kinetics and mechanism of the aminolysis of aryl phenyl chlorothiophosphates with anilines.
abstract: Kinetic studies of the reactions of aryl phenyl chlorothiophosphates (1) and aryl 4-chlorophenyl chlorothiophosphates (2) with substituted anilines in acetonitrile at 55.0 degrees C are reported. The negative values of the cross-interaction constant rhoXY (rhoXY = -0.22 and -0.50 for 1 and 2, respectively) between substituents in the nucleophile (X) and substrate (Y) indicate that the reactions proceed by concerted SN2 mechanism. The primary kinetic isotope effects (kH/kD = 1.11-1.13 and 1.10-1.46 for 1 and 2, respectively) involving deuterated aniline nucleophiles are obtained. Front- and back-side nucleophilic attack on the substrates is proposed mainly on the basis of the primary kinetic isotope effects. A hydrogen-bonded, four-center-type transition state is suggested for a front-side attack, while the trigonal bipyramidal pentacoordinate transition state is suggested for a back-side attack. The MO theoretical calculations of the model reactions of dimethyl chlorothiophosphate (1') and dimethyl chlorophosphate (3') with ammonia are carried out. Considering the specific solvation effect, the front-side nucleophilic attack can occur competitively with the back-side attack in the reaction of 1'.
authors.affiliation: Department of Chemistry, Inha University, Incheon 402-751, Korea.
authors.forename: Md Ehtesham Ul
authors.initials: ME
authors.lastname: Hoque
authors.forename: Shuchismita
authors.initials: S
authors.lastname: Dey
authors.forename: Arun Kanti
authors.initials: AK
authors.lastname: Guha
authors.forename: Chan Kyung
authors.initials: CK
authors.lastname: Kim
authors.forename: Bon-Su
authors.initials: BS
authors.lastname: Lee
authors.forename: Hai Whang
authors.initials: HW
authors.lastname: Lee
mesh_terms: D000588:Amines / Q000737:chemistry*; D000814:Aniline Compounds / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D010710:Phosphates / Q000737:chemistry*
chemical_list: D000588:Amines; D000814:Aniline Compounds; D010710:Phosphates; C023650:aniline; C035638:thiophosphoric acid