The Chemistry of Dimethyl Carbonate
The Chemistry of Dimethyl Carbonate
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DOI：
10.1002/chin.200249227
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发表时间：
2002-12
期刊：
影响因子：
--
通讯作者：
P. Tundo;M. Selva
中科院分区：
文献类型：
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作者：
P. Tundo;M. Selva
碳酸二甲酯 (DMC) 是一种多功能化合物，是甲基化和羰基化过程中卤代甲烷（或硫酸二甲酯）和光气的一种有吸引力的环保替代品。事实上，DMC 的反应活性是可调的：在 T= 90 °C 时，会发生甲氧基羰基化，而在较高的反应温度下，会观察到各种亲核试剂的甲基化反应。在底物易受多重烷基化影响的特殊情况下（例如 CH2 活性化合物和伯胺），DMC 可为单 C 和单 N 甲基化反应提供前所未有的选择性。如今，DMC 采用清洁工艺生产，具有无毒和可生物降解的特性，使其成为真正的绿色试剂，可用于从源头防止污染的合成。此外，DMC 介导的甲基化是使用安全固体（碱性碳酸盐或沸石）的催化反应，从而避免形成不需要的无机盐副产物。其他碳酸酯的反应活性也有报道：DMC 的高级同系物（即碳酸二乙酯和碳酸二苄酯）是优异的单 C 和单 N 烷基化剂，而不对称甲基烷基碳酸酯（ROCO2Me，其中 R ≥ C3）可进行甲基化过程，化学选择性高达 99%。
Dimethyl carbonate (DMC) is a versatile compound that represents an attractive eco-friendly alternative to both methyl halides (or dimethyl sulfate) and phosgene for methylation and carbonylation processes, respectively. In fact, the reactivity of DMC is tunable: atT= 90 °C, methoxycarbonylations take place, whereas at higher reaction temperatures, methylation reactions are observed with a variety of nucleophiles. In the particular case of substrates susceptible to multiple alkylations (e.g., CH2-active compounds and primary amines), DMC allows unprecedented selectivity toward mono-C-and mono-N-methylation reactions. Nowadays produced by a clean process, DMC possesses properties of nontoxicity and biodegradability which makes it a truegreen reagentto use in syntheses that prevent pollution at the source.Moreover, DMC-mediated methylations are catalytic reactions that use safe solids (alkaline carbonates or zeolites), thereby avoiding the formation of undesirable inorganic salts as byproducts. The reactivity of other carbonates is reported as well: higher homologues of DMC (i.e., diethyl and dibenzyl carbonate), are excellent mono-C- and mono-N-alkylating agents, whereas asymmetrical methyl alkyl carbonates (ROCO2Me with R ≥ C3) undergo methylation processes with a chemoselectivity up to 99%.