Selection of reaction media and process optimization for the synthesis of cyclopentane-1,2-dicarboximude in pure solid media: Temperature, concentration distribution and multi-factor analysis

The selection of green reaction media with excellent thermal and chemical stability, along with superior heat transfer and dispersion capabilities, is crucial for high-temperature reactions. In this study, various solid powders, including graphite, stainless steel powder, aluminum oxide, and silicon carbide, were evaluated as reaction media for the cyclization-based synthesis of cyclopentane-1,2-dicarboximude at temperatures above 250°C. The relationship between key properties of the solid media—such as thermal conductivity, specific heat capacity, density, and grain size—and their performance in heat transfer and dispersion was systematically investigated. Solid media with high thermal conductivity and specific heat capacity, small grain size, and a density comparable to that of the reactant were found to rapidly bring the system to the target temperature, ensure uniform temperature distribution, and facilitate efficient reactant dispersion, ultimately enhancing the reaction yield and product purity. Based on these findings, graphite with a grain size of 2.6 µm was selected as the optimal reaction medium for the synthesis of cyclopentane-1,2-dicarboximude. The influence of key reaction parameters, such as the reactant-to-media ratio, cyclization temperature, rotational speed and reaction time, was further investigated. Specifically, 4 g of cyclopentane-1,2-dicarboxamide was added to 50 mL of 2.6 µm graphite, and cyclization was conducted at 270°C for 2.5 hours with stirring at 600 rpm. The product was obtained with a 90 % yield and a purity of 99.5 %, which was achievable by simply extracting the product from graphite using room-temperature water. Further recrystallization with acetonitrile can increase the purity of the product to 99.9 %. This study introduces a novel approach to high-temperature reactions and opens new avenues for future research.