Regrouping cation n-oximethylanilinty in the O-/spl sigma/-complex

Abstract

By means of the MNDO semi-empirical method, possible ways of the regrouping N-oximethylaniliniy cation (rr") in the o-a-complex (0-S) are considered. The results of account testify, that the regrouping can proceed on two alternative mechanisms. Introduction The aniline acts as nucleophil with several reactionary centers in the reaction with formaldehyde. The products of the addition and condensation formaldehyde during synthesis of the diaminodiphenylmetan and anilineformaldehyde resins are obtained both on the aminogroup and on the aromatic ring of aniline [l]. The relative yield of the products reaction depends from following factors: temperature, ratio reactants, PH and catalyst used. The stability and relative reactionary ability of the intermediate played the important role in this case [2]. Earlier [3] we estimated relative stability and reactionary ability of the possible intermediates of the aniline interaction with formaldehyde the under acid catalysis conditions. According to results of calculations, protonated alcohol amine, 0-, mand p-a-complexes are formed through dipole-ionic complex, From low temperatures and kinetic control of reaction, the primary product of addition of the formaldehyde to aniline should be alcohol amine according to the obtained results. From the increasing of the temperature and the process duration oximethylol aniline derivative, mainly pand o-isomerics are obtained. Main part In the present work by means of the MNDO method, possible ways of the regrouping N-oximethylaniliniy cation (T') in o-o-complex (0-S) are considered. The distance between atom of the formaldehyde carbon C15 and atom C2 of aniline as coordinate of reaction was chosen. All other geometrical parameters of the reacting system ( bond length, valence and torsion angles were optimized. formation has effect on insignificant geometrical parameters benzol ring of aniline. The formation of new NI2-CI5 bond leads not only to transfer of pair electrons from donor atom but also to infringement atom nitrogen conjugation of with benzol ring. Increase of the CI-N12 bond length from 1,4232 to 1,4773, increase of the negative charge on CI atom and positive charge on C4,' change population of the atomic orbital CI and C4 atoms, the reduction CI-NI2 bond order testifies to it. It is necessary to note the low order of the bond formed NI2-CI5 (0,7751 u.) and the charge transference from oximethyl-cation to the aniline (0,639 u.). It indicates the high labiality of the oximethyl group in the r'; on its ability to participate in various secondary reactions, including reactions of the regrouping. In view of asymmetry oximethyl groups considered intermediates can exist as several rotary stereoisomers. For is anti-form, and for 0-S is orientation of OH-group to the aminogroup. The The comparison of structure r' with initial reactant structures shows, that the 0-7803-5729-9/99/$10.00