Characteristics of methoxycarbonylation of aromatic diamine with dimethyl carbonate to dicarbamate using a zinc acetate catalyst

Full N,N-Methylation of 4,4′-Methylenedianiline with Dimethyl Carbonate: A Feasible Access to 4,4′-Methylene bis(N,N-Dimethylaniline)

“…As described above, the full N-methylation of MDA with DMC occurred predominantly under the catalysis of NaY, while the N-methoxycarbonylation process was greatly restrained, obtaining a yield of the MBDMA as high as 97%. Such result presented a sharp contrast with the reaction of MDA with DMC catalyzed by zinc acetate [1][2][3], in which the N-methoxycarbonylation was the predominant process. Apparently, catalysts played a key role in the reaction of MDA with DMC.…”

“…The reaction of 4,4 -methylenedianiline (MDA) with dimethyl carbonate (DMC) produced 4,4 -methylenedimethyldiphenylcarbamate (MDC) in high yield of 98%, under the catalysis of the zinc acetate, as described in literatures [1,2] and our previous work [3]. Furthermore, the results of our research demonstrated that the three main by-products formed during the N-methoxycarbonylation reaction were all N-methylated derivatives [3].…”

“…Apparently, catalysts played a key role in the reaction of MDA with DMC. The zinc acetate effectively activated the carbonyl group of DMC and thus N-methoxycarbonylation product was easily formed by the direct attack of amino group of MDA on the carbonyl carbon of DMC [3,27].…”

“…However, this cannot guarantee a directional selectivity to a particular product, which was closely related to its particular pore structures. Generally, the N-methylation reactions of aromatic amines with DMC may follow two possible pathways [16,18,27]: (i) the amino group of aromatic amine directly attacks the methoxy group of DMC. (ii) The amino group of aromatic amine firstly attacks the carbonyl group of DMC, producing N-methoxycarbonylation intermediate.…”

Zinc Carboxylate Functionalized Mesoporous SBA-15 Catalyst for Selective Synthesis of Methyl-4,4′-di(phenylcarbamate)

“…To avoid using phosgene, several alternative methods for producing MDI have been proposed [3]. Among these methods, thermal decomposition of methylene-4,4 0 -di(phenylcarbamate) (MDC) to obtain MDI is very attractive [4], because MDC can be efficiently synthesized by non-phosgene methods like reductive carbonylation of aromatic nitro compounds [5], oxidative carbonylation of amines [6], methoxycarboxylation of 4,4 0 -methylenedianiline (MDA) with dimethyl carbonate (DMC) [7,8]. The last method employs environmentally benign materials and mild reaction conditions and then has attracted many attentions in recent years.…”