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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 34, Number 6
BKCSDE 34(6)
June 20, 2013 

Kinetics and Mechanism of the Anilinolysis of Aryl Ethyl Isothiocyanophosphates in Acetonitrile
Hasi Rani Barai, Keshab Kumar Adhikary, Hai Whang Lee*
Phosphoryl transfer reaction, Anilinolysis, Y-Aryl ethyl isothiocyanophosphate, Deuterium kinetic isotope effect, Cross-interaction constant
The nucleophilic substitution reactions of Y-aryl ethyl isothiocyanophosphates with substituted X-anilines and deuterated X-anilines were investigated kinetically in acetonitrile at 75.0 oC. The free energy relationships with X in the nucleophiles exhibited biphasic concave downwards with a break point at X = H. A stepwise mechanism with rate-limiting bond formation for strongly basic anilines and with rate-limiting bond breaking for weakly basic anilines is proposed based on the negative and positive ρXY values, respectively. The deuterium kinetic isotope effects (DKIEs; kH/kD) changed gradually from primary normal with strongly basic anilines, via primary normal and secondary inverse with aniline, to secondary inverse with weakly basic anilines. The primary normal and secondary inverse DKIEs were rationalized by frontside attack involving hydrogen bonded, four-center-type TSf and backside attack involving in-line-type TSb, respectively.
1829 - 1834
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