Catalytic Activity of Supported Rhodium(I) Complex for the Carbonylation of Nitrobenzene: Mechanism for Carbamate Formation

Abstract

The investigation of the catalytic activity of supported rhodium(I) complex [Rh(P-S)(CO)2] (P-S; polymer anchored salicylic acid) toward the reductive carbonylation of nitrobenzene in DMF medium has been reported. Use of basic cocatalysts in the reaction medium enhanced the percentage of more useful phenyl carbamates. Spectroscopic studies indicate that the reaction proceeds through a dimer species [Rh(HS)(CO)(C(O)OCH3)(µ-OCH3)]2 and phenyl isocyanate is formed as an intermediate. A plausible reaction mechanism based on the identification of reactive intermediates from the soluble rhodium variety has been proposed for the carbonylation process.

Non-noble Metallic Fe Catalyst Systems for the Reductive Carbonylation of Nitrobenzene

“…该方法起始原料结构简单, 来源方 便; 经一步反应即可制得目标产物, 合成路线简短; 用 一氧化碳作羰基化试剂, 避免了剧毒光气的使用及腐蚀 性废物的产生. 但该方法所用的催化剂为 Ru [3] , Pd [4] , Rh [5] …”

Polystyrene anchored ruthenium(II) complex catalyzed carbonylation of nitrobenzene and amines for the synthesis of disubstituted ureas

“…Based on earlier reported mechanistic studies of catalytic carbonylations of nitobenzene [20,32], the reaction mechanism of this DPU synthesis is proposed in Scheme 3.…”

“…Among the metal complex catalysts used for this purpose, the complexes of palladium(II), rhodium(I) and ruthenium(II) show very good catalytic activity for the preparation of ureas [17e19]. In homogeneous reactions catalyzed by organometallic compounds, the catalyst gets intimately involved with the reactants to form various intermediates during the course of the reaction [20]. The polymer anchored metal complex catalysts which may be separated easily from the product mixture and reused are expected to have higher chemical and thermal stabilities.…”

Polymers without Petrochemicals: Sustainable Routes to Conventional Monomers

“…There are several routes to diisocyanates that are considered more sustainable than conventional isocyanate synthesis methods. For example, aryl isocyanates such as TDI and MDI can be obtained via the reductive carbonylation of nitroarenes with carbon monoxide. , A range of catalysts based on metals, including Te, Se, S and a range of group 8–10 metals have been successfully used in these reactions, but catalyst residues in products commercialization via this method. , More commonly used is the carbonylation to N -phenyl carbamates, followed by a thermal decomposition to isocyanates, for which many catalysts have been described, including cheap iron-based catalysts. − …”