6276-76-2Relevant academic research and scientific papers
Kinetics and mechanism of the anilinolysis of o-ethyl phenyl phosphonochloridothioate in acetonitrile
Ul Hoque, Md. Ehtesham,Lee, Hai Whang
, p. 2707 - 2710 (2012/10/29)
The nucleophilic substitution reactions of O-ethyl phenyl phosphonochloridothioate with substituted anilines (XC6H 4NH2) and deuterated anilines (XC6H 4ND2) are kinetically investigated in acetonitrile at 55.0 °C. The deuterium kinetic isotope effects (DKIEs) invariably increase from a secondary inverse DKIE (kH/kD = 0.93) to a primary normal DKIE (kH/kD = 1.28) as the substituent of nucleophile (X) changes from electron-donating to electron-withdrawing. These can be rationalized by the gradual transition state (TS) variation from a backside to frontside attack. A concerted SN2 mechanism is proposed. A trigonal bipyramidal TS is proposed for a backside attack while a hydrogen-bonded, four-center-type TS is proposed for a frontside attack.
Transition state variation in the anilinolysis of O-aryl phenyl phosphonochloridothioates in acetonitrile
Adhikary, Keshab Kumar,Lumbiny, Bilkis Jahan,Dey, Shuchismita,Lee, Hai Whang
experimental part, p. 2628 - 2632 (2012/02/02)
The nucleophilic substitution reactions of Y-O-aryl phenyl phosphonochloridothioates with substituted anilines (XC6H 4NH2) and deuterated anilines (XC6H 4ND2) are kinetically investigated in acetonitrile at 55.0 oC. The deuterium kinetic isotope effects (DKIEs) invariably increase from an extremely large secondary inverse (kH/kD = 0.439; min) to a primary normal (kH/kD = 1.34; max) as both substituents of nucleophile (X) and substrate (Y) change from electron-donating to electron-withdrawing. These results are opposite to the DKIEs on Y-O-aryl methyl phosphonochloridothioates, and can be rationalized by the gradual transition state (TS) variation from backside to frontside attack. The trigonal bipyramidal pentacoordinate TS is proposed for a backside attack, while the hydrogen-bonded, four-center-type TS is proposed for a frontside attack. The negative values of the cross-interaction constants (nXY(H) = .0.38 for XC6H4NH2 and nXY(D) = .0.29 for XC 6H4ND2) indicate that the reactions proceed by a concerted SN2 mechanism.
