Additional effect of para‐hydroxyl on the reduction potentials of theN‐benzylidenebenzenamines

Abstract

The reduction potential E Red of disubstituted N-benzylidenebenzenamines XArCH NArY (abbreviated as XBAY) is a measure of the electron acceptance ability of the Lowest-energy Unoccupied Molecular Orbital (LUMO) in molecule, which is closely related to the electronic effects of substituents X and Y in molecule. Previous studies on the E Red of XBAY reported by Luo, Wang, and Yuan all did not involve these molecules containing hydroxyl. In this work, 28 samples of disubstituted N-benzylidenebenzenamines containing parahydroxyl, (abbreviated as 4-OHBAY or XBAOH-4 0 ) were synthesized, and their E Red values were measured. Then, 127 compounds were taken as a complicated E Red data set, which involved 28 compounds (4-OHBAY and XBAOH-4 0 ) of this work and 99 compounds XBAY reported by Luo. Based on these data E Red set, through a quantitative regression analysis method and comparison of the factors affecting the E Red , the following results are obtained: (a) Because the phenolic hydroxyl OH can dissociate H + to form phenolic oxygen anion, the change regularity of E Red of compounds 4-OHBAY and XBAOH-4 0 is somewhat different from that of E Red of XBAY compounds without hydroxyl OH. That is, hydroxyl OH has an additional effect on the E Red , which decreases the E Red value. (b) The additional effects of 4-OH on the E Red is different from that of 4 0 -OH. The effect of hydroxyl OH attached to the aldehyde aromatic ring on the E Red is more than that of OH attached to the amine aromatic ring. K E Y W O R D Sadditional effect, para-hydroxyl N-benzylidenebenzenamine, reduction potential, substituent electronic effect