Dibutyl carbonate

Dibutyl carbonate is a by-product of the Ube dibutyl oxalate process, and conditions that lead to a higher oxalate carbonate ratio include lower reaction temperatures, lower concentrations of butanol, and higher CO pressure. A reaction mechanism for dibutyl oxalate and carbonate formation has been proposed based on the observed trends for selectivity and kinetic studies (Scheme 8.4) [18, 20]. Pd° species are believed to favor oxalate formation, while Pd species favor carbonate formation (step la/2a). Oxalate formation starts with facile oxidative addition of "BuONO to Pd" (step lb) and is followed by the rate-limiting CO insertion (step Ic). 

Synthesis involves the formation of apoly(alkylene carbonate) prepolymer formed from intermediates of organic carbonate moieties by reaction of a diol and organic carbonate monomer at elevated temperatures in the presence of a catalyst such as stannous octoate. Diols include 1,6-hexanediol, 1,4-butanediol and 1,8-octanediol, wi hile carbonates include diphenyl carbonate and dibutyl carbonate. p-Dioxanone is then added to form the poly(p-dioxanone-co-alkylene carbonate) copolymer. 

An example of a nonphosgene route to IPDI is the reaction of 17 with urea and -butanol in the presence of dibutyl carbonate at 210-220°C. Thermolysis of the biscarbamate at 270-280°C at 30 mbar affords 18 (26). IPDI is a mixture of 72% cis isomers and 28% trans isomers (27). 

In addition to 2c, a small amount of dibutyl carbonate 3c and carbon dioxide were obtained as by-products. Ratio of the products 2c and 3c was largely influenced by the reaction temperature, the concentration of butanol, and CO pressure. The selectivity for oxalate 2c increased (i) at the lower reaction temperature, (ii) at lower concentration of butanol, and (iii) under the higher CO pressure. ... 

Feng X, Wang Q, Wang G, Qiu F. Preparation of Nano-TiOj by ethanol-thermal method and its catalytic performance for synthesis of dibutyl carbonate by transesterification. Chin J Catal 2006 27(3) 195-196. 

Note 1,2-BC 1,2-dunethylethylene carbonate 1,3-DOL 1 -dioxolane AC acetonitrile A.N. acceptor number BC butylene carbonate BEC butyl ethyl carbonate BMC butyl methyl carbonate CF3-EC trifluoromethyl ethylene carbonate QEC chloroethylene carbonate DBC dibutyl carbonate DEC diethyl carbonate DEE 1,2-diethoxyethane DGM diethyleneglycol dimethyl ether DIPC di-isopropyl carbonate DMC dimethyl carbonate DME 1,2-dimethoxyethane DMSO dimethyl sulfoxide D.N. donor number DPC di-n-propyl carbonate EC ethylene carbonate EIPC ethyl isopropyl carbonate EMC ethyl methyl carbonate EPC ethyl propyl carbonate MeTHF 2-methyl tetrahydrofuran MIPC methyl isopropyl carbonate MFC methyl propyl carbonate PC propylene carbonate TEGM tetraethylene glycol dimethyl ether TGM triethylene glycol dimethyl ether TFIF tetrahydrofuran. 

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