Acid-catalysed reactions of amines with dimethyl carbonate

Abstract

Highly effective acid catalysed reactions of amines with dimethyl carbonate (DMC) have been conducted, with significant yields and selectivity towards carboxymethylation or methylation products. Lewis acids (FeCl3, ZnCl2, and AlCl3.6H2O),...

A novel approach to amino acid synthesis: acid-assisted reactions with dimethyl carbonate for efficient O-methylated, N,O-methylated and N-formylated derivatives

“…This is in contrast with previous results for the methylation and carboxymethylation of amines, which provided positive results with these heterogeneous acids. 79 The 1 H NMR spectra of the DMC reactions of amino acids involving AlCl 3 , H 2 SO 4 –SiO 2 , and HClO 4 –SiO 2 as acid indicate the presence of unidentified products, whereas FeCl 3 results in a significantly low conversion (Fig. S56–S59†).…”

“…78 Previous research has shown that under acid-catalysed conditions, DMC is able to perform highly efficient carboxymethylation and methylation of amines. 79 Ji et al 80 reported the use of DMC to O -methylate a few examples of N -Boc amino acids under basic conditions with moderate to high yields. Until now, no publication has studied amino acid modification with DMC under acidic conditions.…”

Facile Sustainable Synthesis of Polyester-Polycarbonate and Effects of the Carbonate on Thermal, Mechanical, and Transparency Properties

“…The 13 C NMR spectrum was used to analyze the sequence distribution of PCCTs, as shown in Figure 2c. The characteristic peaks appearing from 130 to 170 ppm are assigned to terephthalate and carbonate, respectively.…”

“…DMC production, starting with CO 2 , its nontoxicity, and its sustainability, makes DMC an ideal vehicle for preparing sustainable materials. − As a well-recognized green organic synthesis intermediate, DMC is widely used in the synthesis of polycarbonate and polyester-based materials through transesterification, especially aliphatic polycarbonates (APCs) and their copolyesters with aliphatic diols, such as polybutylene carbonate, polypentamethylene carbonate, and poly hexamethylene carbonate. − Nevertheless, the inherently fragile heat resistance and mechanical properties of APCs make them difficult for further application, which are usually improved by copolymerizing aromatic or aliphatic units . Various copolyesters have been prepared by stepwise esterification, such as poly­(butylene carbonate- co -butylene furandicarboxylate), poly­(butylene carbonate- co -butylene cycloadipate ester), poly­(butylene carbonate- co -isophthalate), and poly­(butylene carbonate- co -succinate. − Although the mechanical and thermal properties of these copolyesters have been kept balanced, their glass transition temperature is lower than that of commercial polyethylene terephthalate (PETG), which hinders their further applications, especially in the flexible or soft packaging field.…”

Reaction Pathways in Carbonates and Esters

“…However, in the presence of zeolites, the reaction of aromatic amines and DMC led almost quantitatively to the corresponding mono-N-methyl derivatives through a not well-understood reaction mechanism supposedly via A Al 2 (A h + A N D N + D h mechanism): no appreciable amount of N-methylurethanes and dimethylamines were detected. [104] A remarkable result was achieved when o-and p-aminophenol reacted with DMC under alkali-metal exchanged faujasite NaY catalysis. These reagents were converted to Nmethyl-2-aminophenol (95 % yield) and N-methyl-4-aminophenol (99 % yield), respectively; no O-methylation products were detected (Figure 10b).…”