Collect. Czech. Chem. Commun. 1980, 45, 1072-1078

Velocity of rearrangement of ortho-substituted 3-(X-benzal)phthalides into 2-(X-phenyl)-1,3-indanediones and study of ortho-effect

Ľudovít Krasnec, Jr.a, Pavol Hrnčiara and Anton Gáplovskýb

a Department of Organic Chemistry
b Chemical Institute, Comenius University, 816 31 Bratislava


Velocity of the second order rearrangement of ortho-substituted 3-(X-benzal)phthalides into respective 2-(X-phenyl)-1,3-indanediones by action of methanolic sodium methoxide has been studied spectrophotometrically. The values of logarithm of the rate constant obtained by extrapolation of the concentration dependences to zero concentration of methoxide have been correlated with σ, σ0, σ+, F, R, and Es constants of the substituents and with the Charton ν constant for the ortho-substituted derivatives. The obtained dependences log k vs the mentioned constants have been compared with the corresponding dependences of the rearrangement of the meta- and para-substituted 3-(X-benzal)phthalides into the respective 3-(X-phenyl)-1,3-indanediones. Transmission of the substituent effect on the reaction centre is almost the same from ortho and from para position. Possible ortho-effect and steric hindrance of the substituents have been followed.