Additional effect of para-hydroxyl on the reduction potentials of the N-benzylidenebenzenamines

摘要

The reduction potential E-Red of disubstituted N-benzylidenebenzenamines XArCH(sic)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 para-hydroxyl, (abbreviated as 4-OHBAY or XBAOH-4 ') 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 ') 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 ' 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 '-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.