6839-23-2Relevant articles and documents
Bimolecular nucleophilic displacement at tertiary carbon centers: Aminolyses of 2-cyano-2-propyl and 1-cyanocyclooctyl arenesulfonates
Oh, Hyuck Keun,Kwon, Young Bong,Chung, Dong Soo,Lee, Ikchoon
, p. 683 - 688 (2007/10/03)
Kinetic studies were carried out on the reactions of anilines with 2-cyano-2-propyl and 1-cyanocyclooctyl arenesulfonates in acetonitrile at 50·0°C. The second-order rate constants for the former are in general greater than those for the latter but the rates of the two become comparable for a strong nucleofuge. The cross-interaction constants, ρXZ (and βXZ), are considerably smaller (ca -0·04) than those for the primary (ca 0·33) and secondary (ca 0·12) compounds. The negative sign and small magnitude are consistent with a dissociative SN2 mechanism with a loose transition state structure. The ab initio MO theoretical results for Cl- + RCl?ClR + Cl- at the MP2 level (MP2/6-31 + G*//MP2/6-31 + G*) confirm the looseness of the transition state for the tertiary (R) alkyl compounds. The average r*(Cl...Cl) value is 4·88 ± 0·03 A, which is larger than those for the reactions at primary (4·68± 0·02 A) and secondary (4·80 ± 0·02 A) carbon centers. Thus a looser transition state with a smaller magnitude of ρXZ for the tertiary carbon centers has a larger theoretical r*(Cl-Cl) value.
