Application
Cis-5-norbornene-exo-2,3-dicarboxylic anhydride is an important curing agent for epoxy resins. During the curing process, the anhydride groups react with the epoxy groups to form a cross-linked network structure. Using this compound as a curing agent can significantly improve the heat resistance, mechanical strength, and electrical insulation properties of epoxy resins. Therefore, it is widely used in the manufacture of high-performance coatings, adhesives, composite materials, and packaging materials for electronic components.
Synthesis
A method for preparing high-purity cis-5-norbornene-exo-2,3-dicarboxylic anhydride by microwave reaction is disclosed. The method comprises the following steps: using cis-5-norbornene-endo-2,3-dicarboxylic anhydride as a raw material, as follows:(1) In a 1L reaction flask, 200g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride and 600mL of toluene were added, stirred and mixed, and transferred to a microwave autoclave. The reaction system was warmed up to 200 °C and heated under microwave radiation at 100-200 GHz for 8 min; (2) After the reaction, the reactor was cooled to 110 °C and stirred continuously in an oil bath for 30 min to promote crystallization. Subsequent cooling to room temperature, filtration and drying were performed to obtain the target product cis-5-norbornene-exo-2,3-dicarboxylic anhydride 160.2 g; the yield was 80.1%; the purity was 98.2%; and the content of oxidized impurities was 0.06%.
References
[1] Organic Letters, 2016, vol. 18, # 8, p. 1808 - 1811
[2] Chemistry Letters, 1991, # 7, p. 1173 - 1176
[3] Chemistry Letters, 1991, # 7, p. 1173 - 1176
[4] Patent: CN104130228, 2016, B. Location in patent: Paragraph 0038-0040
[5] Journal of Organic Chemistry, 1982, vol. 47, # 20, p. 3953 - 3959
