Acetates diarylmethanes

In the presence of acetate ion a diarylmethane type of dimer is formed [11]. 

A A -Dialkylarylamines react under classical conditions at C-4 if that position is unsubstituted. For example, A. )V-dimethylaniline reacts with formaldehyde and dimethylamine to afford 4-)V, A -dimethyl-amino-A, Af-dimethylbenzylamine in 82% yield (equation 20). Under acidic conditions fragmentation of the initial product can occur, leading to the formation of diarylmethanes. In the reaction of A A -dimethy-laniline with formaldehyde and pyrrolidine the best yield of the Mannich base (44%) is obtained in the presence of 1.5 mol equiv. of acetic acid with 4.0 mol equiv. the yield is only 7%. The reaction of N-methylenemorpholinium chloride with 4-A -morpholinylmethyl-)V,A -dimethylaniline results in the introduction of a second A -morpholinylmethyl residue at the 2-position, but with other iminium chlorides quaternary salts are formed by reaction with the nitrogen of the 4-dialkylaminomethyl group. There is dso a brief report of the use of the mixed A. Af-dialkylmethyleneiminium salt, A -f-butyl-A -methyl-methyleneiminium perchlorate, with A. Af-dimethylaniline. °... 

---