Double-Bond-Stabilizing Abilities of Dimethylamino, Alkylsulfonyl, and Acetyl Substituents

Article abstract of DOI:10.1021/jo01302a014

Equilibrium constants have been determined for the isomerization of trans-XCH2CH=CHY to trans-XCH=CHCH2Y for three combinations of X and Y.The values obtained were 40+/-15 for X = dimethylamino and Y = phenyl, 40+/-15 for X = methyl and Y = n-butylsulfonyl, and 4,8+/-0,5 for X = acetyl and Y = methyl.These data give D values (double-bond-stabilizing parameters) of 8,2, -0,1, and 3,36 kcal/mol for dimethylamino, n-butylsulfonyl, and acetyl substituents, respectively.The dimethylamino substituent is thus by far the best double-bond-stabilizing substituent that has been studied.The equilibrium constant for isomerization of n-butyl trans-1-butenyl sulfone is about eight times as large as that reported by other workers and it yields a D value for the n-butylsulfonyl group that is much nearer the value for the methylsulfonyl group.The D value for acetyl is near that found earlier for carbomethoxy.