Organic carbonates are green compounds with a wide range of applications. They are widely used for the synthesis of important industrial compounds including monomers, polymers, surfactants, plasticizers, and also used as fuel additives. They can be divided into two main classes: cyclic and linear carbonates. Dimethyl carbonate (DMC) and diethyl carbonate (DEC) are the important linear carbonates. Carbonyl and alkyl groups present in DMC and DEC make them reactive and versatile for synthesizing various other important compounds. Ethylene carbonate (EC), glycerol carbonate (GC) and propylene carbonate (PC) are well-known cyclic organic carbonates. Phosgenation of alcohols was widely used for synthesis of organic carbonates; however, toxicity of raw materials restricted use of phosgenation method. A number of new non-phosgene methods including alcoholysis of urea, carbonylation of alcohols using CO₂, oxy-carbonylation of alcohols, and trans-esterfication of alcohols and carbonates have been developed for synthesizing organic carbonates. Carbonylation of alcohols is preferred as it helps in utilization and sequestration of CO₂, however, poor thermodynamics due to high stability of CO₂ is the major obstacle in its large scale commercialization. Oxy-carbonylation of alcohols offers high selectivity but presence of oxygen poisons the catalyst. Recently, alcoholysis of urea has received more attention because of its inexpensive abundant raw materials, favorable thermodynamics, and no water-alcohol azeotrope formation. Also, ammonia evolved in this synthesis route can be recycled back to urea by reacting it with CO₂. In other words, this method is a step towards utilization of CO₂ as well. This article reviews synthesis of DMC, DEC, GC, PC, and EC from urea by critically examining various catalysts used and their performances. Mechanisms have been reviewed in order to give an insight of the synthesis routes. Research challenges along with future perspectives have also been discussed.

有机碳酸盐是绿色化合物，具有广泛的应用范围。它们被广泛用于重要工业化合物的合成，包括单体，聚合物，表面活性剂，增塑剂，还用作燃料添加剂。它们可以分为两大类：环状和线性碳酸盐。碳酸二甲酯（DMC）和碳酸二乙酯（DEC）是重要的线性碳酸酯。DMC和DEC中存在的羰基和烷基使其具有反应性和通用性，可用于合成其他各种重要化合物。碳酸亚乙酯（EC），碳酸甘油酯（GC）和碳酸亚丙酯（PC）是众所周知的环状有机碳酸酯。醇的光气化被广泛用于有机碳酸盐的合成。但是，原料的毒性限制了光气化方法的使用。_{如图2所示}，已经开发了醇的氧羰基化以及醇和碳酸盐的酯交换反应以合成有机碳酸盐。醇的羰基化是优选的，因为其有助于CO _2的利用和隔离，但是由于CO _2的高稳定性而导致的热力学差是其大规模商业化的主要障碍。醇的氧羰基化具有很高的选择性，但是氧的存在会毒化催化剂。近年来，尿素的醇解因其廉价的丰富原料，良好的热力学和不形成水-醇共沸物而受到越来越多的关注。同样，通过该合成路线释放的氨可以通过与CO ₂反应而再循环回尿素。换句话说，该方法也是朝向利用CO ₂的步骤。本文通过严格检查所用的各种催化剂及其性能，回顾了由尿素合成DMC，DEC，GC，PC和EC的方法。为了综述合成途径，对机理进行了综述。还讨论了研究挑战以及未来的观点。