ChemInform Abstract: Determination of Reactivity by MO Theory. Part 51. Theoretical Studies of Solvent Effects on Gas‐Phase Reactions of Methoxide Ion with Substituted Ethylenes.

Abstract

ChemInform Abstract Calculations on the gas-phase reaction of the ethylenes (I) with bare or monosolvated methoxide ion are carried out by the AM1 method. In all reactions the methoxide approaches in plane but in addition reactions subsequently rotates out of plane to form tetrahedral complexes. All reactions of bare methoxide, mainly the β-addition, are exothermic. In the case of the β-addition the excess energy is carried by the adduct and renders it unstable. The α-H+ abstraction by a monosolvated methoxide is endothermic for (Ia).

Reactions of nitrophenide and halonitrophenide ions with acrylonitrile and alkyl acrylates in the gas phase: addition to the carbonyl group versus Michael addition

“…Quantum chemical calculations of reactions of the free methoxide ion with acrylonitrile, acrolein, and nitroethylene support the results obtained by Bartmess and by Bowie. AM1 calculations described by Lee et al . showed that the reactions leading to β‐adduct formation in the gas phase are highly exothermic (Δ H acrylonitrile = −37.3 kcal/mol, Δ H acrolein = −39.6 kcal/mol, Δ H nitroethylene = −63.2 kcal/mol).…”

Negative ion gas‐phase chemistry of arenes

“…Carbanions react with Michael acceptors (a,b-unsaturated compounds possessing electron-withdrawing groups) by forming b-adducts. This is the principal mode of reaction in condensed phase, whereas in the gas phase, the observation of such b-adducts is difficult due to the high exothermicity of the addition, which leads to rapid dissociation (Bartmess, 1980;Lee, Lee, & Won, 1987). The increased intrinsic stability of the b-adduct can be realized by introducing a solvent molecule, which is released during the formation of the adduct to remove an excess of its energy (Bartmess, 1980).…”