Cis-5-norbornene-exo-2,3-dicarboxylic anhydride crystal form and preparation method thereof

[0034] The preparation method of the exo-nadic anhydride crystal form of this embodiment, the exo-nadic anhydride crystal form is the exo-nadic anhydride crystal form of Example 1 of the exo-nadic anhydride crystal form, comprising the following steps:

[0035] Under the condition of 50°C, stir and dissolve 5g of exo-nadic anhydride in 15g of dioxane. After the dissolution is complete, cool the solution to 0°C and keep it for 2h. The precipitated crystals are suction-filtered, washed with alcohol and dried to obtain exo Nadic acid anhydride crystal form.

[0036] The XRD test results of exo-nadic anhydride and exo-nadic anhydride crystal form are shown in the appendix figure 1 The purity of the product obtained by gas chromatography (GC-7900) analysis is 98.94%, and the primary precipitation yield is about 62.32%.

[0038] The preparation method of the exo-nadic acid anhydride crystal form of the present embodiment comprises the following steps:

[0039] At 20°C, stir and dissolve 5g of exo-form Nadic anhydride in 18g of N-methylpyrrolidone (NMP). After the dissolution is complete, cool the solution down to 0°C and keep it for 2h. Suction filter the precipitated crystals and wash them with alcohol. , After drying, the Nadic acid anhydride crystal form is obtained.

[0040] The XRD test results of exo-nadic anhydride and exo-nadic anhydride crystal form are shown in the appendix figure 2 The purity of the product obtained by gas chromatography (GC-7900) analysis is 99.12%, and the primary precipitation yield is about 64.46%.

[0042] The preparation method of the exo-nadic acid anhydride crystal form of the present embodiment comprises the following steps:

[0043] Under the condition of 50°C, stir and dissolve 5g of exo-nadic anhydride in 12g of dimethylformamide (DMF). The crystals were suction filtered, washed with alcohol and dried to obtain the Nadic acid anhydride crystal form.

[0044] The XRD test results of exo-nadic anhydride and exo-nadic anhydride crystal form are shown in the appendix image 3 The purity of the product obtained by gas chromatography (GC-7900) analysis is 99.01%, and the primary precipitation yield is about 58.12%.