Phosgene-free carbamoylation of aniline via dimethyl carbonate

Abstract

Abstract:The synthesis of N-phenylcarbamate from aniline and dimethyl carbonate (DMC) in the presence of homogeneous, supported heterogeneous, and heterogeneous catalysts was investigated in batch conditions. First, a selection of homogeneous catalysts was studied and their reactivity in the same reaction conditions was compared to zinc acetate, a catalyst extensively used for this reaction. Then the best homogeneous catalysts were supported on silica or alumina, and the resulting heterogeneous supported catalysts were tested for the carbamoyl ation of aniline.Finally, several heterogeneous catalysts were investigated. Zinc carbonate basic was shown to be the best catalyst, giving quantitative conversion and selectivity for the N-phenylcarbamate. Its catalytic activity was fully investigated taking into account substrate concentration, amount of catalysts, and temperature influence. Zinc carbonate was also shown to be recyclable, once it was recovered from the reaction mixture and calcinated.

Zr-MOF-808@MCM-41 catalyzed phosgene-free synthesis of polyurethane precursors

“…Several homogeneous and heterogeneous catalytic systems have been developed for the N-carbamoylation of aromatic amines with DMC. Homogeneous catalysts are lead compounds, 5,6 zinc derivatives, [7][8][9][10][11][12][13][14][15] Yb(OTf)3 16 and organocatalysts. 17,18 Among these, Zn(OAc)2 often gives the best activity for aromatic dicarbamate synthesis.…”

“…27 Basic zinc carbonate has been used as a heterogenous catalyst in the same reaction yielding the desired carbamoylated product in 94% yield, and it could be further reused with a moderate decrease in the selectivity. 10 This latter system has also allowed to carry out the carbamoylation reaction of aniline in a fixed-bed continuously fed reactor. 28 A nanostarchfuntionalized ionic liquid containing a cobalt chelate anion have been successfully applied in the carbamoylation reaction of anilines and aliphatic amines by the reaction with DMC.…”

5-Membered cyclic ethers via phenonium ion mediated cyclization through carbonate chemistry

“…In fact, DMC acts as methoxycarbonylation agent with harder nucleophiles via a B Ac 2 mechanism at reflux temperature (T = 90 °C) and as methylating agent with softer nucleophiles via a B Al 2 mechanism, at higher temperature (T > 150 °C) [15][16][17][18][19][20][21][22][23] (Fig. 1).…”

1,3-Oxazinan-2-ones via carbonate chemistry: a facile, high yielding synthetic approach

“…DMC is a well known environmentally benign substitute for dimethyl sulfate and methyl halides in methylation reactions, and for phosgene in carboxymethylation reactions. In fact, in the presence of a nucleophile and a catalyst or a base, DMC can act either as methylating agent [13,14] (B Al 2 mechanism) or carboxymethylating agent [15,16] (B Ac 2 mechanism) giving as by-products only methanol and eventually CO 2 . Similarly, commercially available short chain dialkyl carbonates (DACs) have found numerous applications in innovative synthetic pathways and industrial processes [17][18][19].…”