39274-83-4Relevant academic research and scientific papers
Kinetics and mechanism of the anilinolysis of dicyclohexyl phosphinic chloride in acetonitrile
Ul Hoque, Md. Ehtesham,Lee, Hai Whang
, p. 1997 - 2002 (2012/02/01)
The nucleophilic substitution reactions of dicyclohexyl phosphinic chloride [3; cHex2P(=O)Cl] with substituted anilines (XC6H 4NH2) and deuterated anilines (XC6H 4ND2) are investigated kinetically in acetonitrile at 60.0 °C. The anilinolysis rate is too slow to be rationalized by the stereoelectronic effects. The rate is contrary to expectations for the electronic influence of the two ligands and exhibits exceptionally great negative deviation from the Taft's eq. The deuterium kinetic isotope effects (DKIEs) involving deuterated anilines invariably change from primary normal (kH/kD > 1; max kH/kDt = 1.10 with X = 4-MeO) with the strongly basic anilines (X = 4-MeO, 4-Me, 3-Me) to secondary inverse (kH/kDt H/k Dt = 0.673 with X = 3-Cl) with the weakly basic anilines (X = H, 4-F, 4-Cl, 3-Cl). A concerted SN2 mechanism is proposed on the basis of both secondary inverse and primary normal DKIEs. The obtained DKIEs imply that the fraction of a frontside attack increases as the aniline becomes more basic. A hydrogen-bonded, four-center-type transition state is suggested for a frontside attack, while the trigonal bipyramidal pentacoordinate transition state is suggested for a backside attack.
Kinetics and mechanism of the aminolysis of dimethyl and methyl phenyl phosphinic chlorides with anilines
Dey, Nilay Kumar,Hoque, Md. Ehtesham Ul,Kim, Chan Kyung,Lee, Bon-Su,Lee, Hai Whang
experimental part, p. 425 - 430 (2010/04/30)
The reactions of dimethyl phosphinic chloride (1) and methyl phenyl phosphinic chloride (2) with X-anilines have been studied kinetically in acetonitrile at 15.0 and 55.0 °C, respectively. The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC 6H4ND2) are also reported for the same reactions. The obtained KIEs for 1 are secondary inverse (kH/k D=0.703-0.899H/kD=1.62-2.10> 1). A concerted mechanism involving predominantly backside nucleophilic attack is proposed for the anilinolysis of 1. A concerted mechanism involving predominantly frontside attack via a hydrogen-bonded four-center-type transition state is proposed for the anilinolysis of 2. The degree of steric hindrance is the major factor that determines both the reactivity of the phosphinates and the direction of the nucleophilic attack on the phosphinates. Copyright
