Addition of anions to carbonyl compounds: an ab initio study.
Energies for the addition of anionic nucleophiles, Z(-), to carbonyl compounds, XYCO, are calculated at the G2(MP2) level of theory. The substituents X, Y, and Z are taken from the set {H, CH3, NH2, OH, F, CF3, CHCH2, CHO, CCH, and CN}. The basicity and, to a lesser extent, ionization potential of Z(-) were found to correlate with the enthalpy of addition of Z(-) to H2CO. The enthalpy of addition of Z(-) to XYCO relative to H2CO is largely independent of Z. The ordering of the enthalpies of addition for the series of XYCO's is rationalized. By using a thermodynamic cycle, the independence of this ordering from Z is attributed to the additivity of the inductive stabilization of XYZCO(-) by X and Y versus H2ZCO(-). A method for estimating the enthalpy of addition for nucleophile/carbonyl combinations not studied above is described and shown to give good results on a model system.
Rosenberg
Robert Evan
RE
Transylvania University, Department of Chemistry, 300 North Broadway, Lexington, Kentucky 40508, USA. rrosenberg@transy.edu
D000447:Aldehydes / Q000737:chemistry*; D000465:Algorithms; D000838:Anions / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D013816:Thermodynamics
D000447:Aldehydes; D000838:Anions; D007659:Ketones