Study On Synthesis Of N-(4-hydroxyphenyl) Maleimide And Related Physical Properties

Maleimide(BMI) is an important monomer for heat-resistant polymers which can be copolymerized with vinly monomer to prepare polymer materials with excellent thermal resistance. N-(4-hydroxyphenyl) maleimide (4-HPM) which plays a crucial role in the development of insulation materials and heat-resistant polymer materials, is one of functional monomer with both rigid malmeimide heterocycle and active terminal hydroxyl group and most of the copolymers produced have good electromechanical characteristics and excellent heat resistance. As a result,4-HPM plays an important role in the development of insulation materials and heat-resistant polymer materials.In this work, maleic anhydride(MA) and p-aminophenol(4-AP) are adopted as raw materials, acidic ion-exchange resin as catalyst, DMF as solvent, and toluene as water-carrying agent to prepare 4-HPM through two-step reaction. In order to obtain a higher yield, both single-factor and orthogonal experimental designs have been introduced to optimize the process, and the result is as follows: The catalyst content is 12% of total weight of raw materials, n(MA):n(4-AP)=1.1:1, VToluene:VDMF=3:1, TStep 2= 9 hours. The yield of crude product is 78% and its purity is up to 97%. Furthermore, the structure of final product is confirmed by FT-IR, NMR, etc.Acidic ion-exchange resin can be used 3 times without activation, and it has the same activity as fresh resin after activation which costs little. The catalyst has high selectivity, causes little equipment corrosion, and can be easily seperated from the reaction system, which lowers the standards towards equipments. Meanwhile, the resin is not only environmentally friendly, but also convenient to be stored and metered. Generally speaking, the properties of this catalyst are in accordance with the developing trend.A set of apparatus used for determining the data of solid-liquid equilibrium with equilibrium method at atmospheric pressure, in which HPLC and laser monitoring were involved, was carried out. The solubilities of N-(4-hydroxyphenyl) maleimide in ethanol, isopropanol, ethanol+50%water and isopropanol+50%water were measured. Two parameter and three parameter equation were used to correlated the experimental data and the fitting result of three parameter equation was better. In addition, the data about solubilities in isopropanol of N-(4-hydroxyphenyl) maleimide has been obtained which is quite necessary in the purification of crude N-(4-hydroxyphenyl) maleimide.Densities and viscosities of the binary mixtures of N-(4-hydroxyphenyl) maleimide with ethanol, isopropanol, dimethylformamide and the ternary mixtures of N-(4-hydroxyphenyl) maleimide with ethanol+50%water, isopropanol+50%water were determined by using Ostwald-Sprengel-type pycnometers and Ubbelohbe capillary viscometer under atmospheric pressure. The temperature was range from (293.15 to 318.15) K. Densities of solutions were used to calculate apparent molar volumes and the limiting partial molar volumes respectively. Densities and viscosities were fitted by VTF equation respectively. The total average standard deviations between the measured and fitted values were less than 2.5%, which reveals that VTF equation can be used to correlate those systems.