The reaction of diphenyl carbonate with amines and its application to polymer synthesis

Abstract

SynopsisSelective formation of biscarbamates from diphenyl carbonate (DPC) and diamines and the preparation of polyurethanes from the carbamates and diols under mild conditions were studied. The reaction of DPC and diamines was significantly affected by catalysts, biscarbamates being exclusively prepared in high yields in the presence of %-hydroxypyridine. The polycondensation reaction of the biscarbamates with diols was facilitated by catalysts such as metal salts; among the catalysts examined magnesium chloride in pyridine gave the best results. Metal chlorides in pyridine also promoted the reaction of DPC with aromatic amines to give the corresponding ureas, and the direct synthesis of polyureas was achieved by the polycondensation of DPC with diamines in the presence of the chloride.

Carbonic Esters

“…Carbonic esters react with primary and secondary amines to give urethanes and ureas [7]. At higher temperature and in the presence of catalysts, aliphatic carbonates lose carbon dioxide and act as alkylating agents, e.g., for amines [8] and phenols [9].…”

“…It is therefore necessary to ensure that the equilibrium is achieved as quickly as possible by the use of very active catalysts with high selectivity and Vol. 7 Carbonic Estersthat the equilibrium is quickly shifted by suitable modes of operation. The reaction takes place in three catalytic steps:…”

Bambusurils Bearing Nitro Groups and Their Further Modifications

“…Another reagent, diphenyl carbonate, was also used instead of the expensive and moisture-sensitive N,N′-carbonyldiimidazole to give 4a in a similar yield. [11,12] Attempts to convert 4a into 5a were complicated by the formation of the undesired N,N′-bis (4-nitrobenzyl)hydantoin (11a, Scheme 1). Therefore, we screened various mixtures of organic solvents and aqueous HCl and also different concentrations of aqueous HCl (see the Supporting Information for more details).…”

Synthesis and trans-ureation of N,N’-diphenyl-4,4′-methylenediphenylene biscarbamate with diamines: a non-isocyanate route (NIR) to polyureas

“…Carbonylation of 4,4′-MDA with diphenyl carbonate (Scheme 2) Earlier Yamazaki's study showed a carbonylation reaction of 4,4′-methylenedianiline (4,4′-MDA) with diphenyl carbonate (DPC) yielding 4,4′-DP-MDC in 68% yield with 2-hydroxypyridine as the catalyst [26]. More recently, Harada found that the yields of 4,4′-DP-MDC could be enhanced by treating 4,4′-MDA with a diphenyl carbonate in the presence of carboxylic acids such as pivalic acid or benzoic acid as the catalyst at 90°C.…”

“…In fact, several attempts have tried to use carbamates, or biscarbamates directly as precursors for polyurethane (PU) and polyurea synthesis bypassing isolation of diisocyanate completely [26]. In 2000, ring-opening isomerization of cyclic-urethane [27][28][29] and trans-esterification [30,31] to make PU are notable examples.…”