Application
2-Methyl-1,4-phthalic acid can be used as an intermediate in pharmaceutical and chemical synthesis, such as in the synthesis of dimethyl 2-methyl terephthalate. Dimethyl 2-methyl terephthalate is an important compound in the synthesis of vinyl terephthalic acid-based chitosan liquid crystal polymers. Currently, most methods employ acid-catalyzed synthesis, resulting in low yields of only about 33% and significant raw material losses. Since dimethyl 2-methyl terephthalate is a necessary intermediate in the synthesis of vinyl terephthalic acid-based chitosan liquid crystal polymers, improving its yield is crucial. However, most acid-catalyzed esterification reactions suffer from low conversion rates. In this reaction, methanol serves as both a reagent and a solvent. Due to its low boiling point, a suitable dehydrating agent cannot be found for use in oil-water separators. Therefore, based on existing research, anhydrous copper sulfate powder, which has strong hygroscopic properties, is added. At 80°C, anhydrous copper sulfate can bind three water molecules, thereby improving the esterification conversion rate. The results of infrared IR and nuclear magnetic resonance (NMR) analyses of the obtained products confirm the correctness of the synthesized compound, laying the foundation for the next step of large-scale synthesis of vinyl terephthalic acid-based chitosan-type liquid crystal polymers.
