Solid-liquid phase-transfer-catalysed methoxylation of chloronitrobenzenesto nitroanisoles

Nitroanisoles are important precursors in the organic process industry and are made from chloronitrobenzenes by using sodium hydroxide and methanol un der liquid-liquid phase-transfer catalysis, which requires higher temperatu res, leading to loss in selectivity. Synthesis of p-nitroanisole was carrie d out from p-chloronitrobenzene (PCNB) and solid sodium methdoxide by using tetrabutylammonium bromide as a catalyst under solid-liquid phase-transfer catalysis (S-L PTC) as opposed to the standard liquid-liquid (L-L) PTC sys tem. The advantages of the S-L PTC are that the reaction is conducted at ro om temperature with 100% conversion and 100% selectivity, The kinetics and mechanism are also established for this reaction. The methoxylation of o-ch loronitrobenzene (OCNB) was also studied. The rate of methoxylation of PCNB was much greater than that of OCNB at 30 degrees C. m-Chloronitrobenzene d oes not react with sodium methoxide under otherwise similar conditions, For the reaction of PCNB with sodium methoxide, the diffusional resistance was found to be unimportant, The rate of the reaction was found to be of first order with respect to both the concentration of catalyst and the substrate .