The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Improved synthesis of cis-Δ4-tetrahydrophthalic anhydride and cis-hexahydrophthalic acid》. Authors are Jenkins, Edward F.; Costello, Edward J..The article about the compound:cis-Cyclohexane-1,2-dicarboxylic acidcas:610-09-3,SMILESS:O=C([C@H]1[C@@H](C(O)=O)CCCC1)O).COA of Formula: C8H12O4. Through the article, more information about this compound (cas:610-09-3) is conveyed.
Maleic anhydride (1 mole) in 150 ml. C6H6, cooled to 5°, 54 g. liquid (CH2:CH)2 added, and the mixture heated to 115° (within 15 min. the temperature rises to 145° and the pressure to 11 atm.) and allowed to stand overnight, gives 90% cis-Δ4-tetrahydrophthalic anhydride (I), m. 103-4°. I (30.4 g.) in 150 ml. AcOH, hydrogenated 0.5 hr. over 200 mg. Pt oxide at room temperature and 4.5 atm., and the mixture boiled with H2O, gives 90% cis-hexahydrophthalic acid, m. 190-1°.
Compounds in my other articles are similar to this one(cis-Cyclohexane-1,2-dicarboxylic acid)COA of Formula: C8H12O4, you can compare them to see their pros and cons in some ways,such as convenient, effective and so on.
Reference:
Benzisoxazole – Wikipedia,
Benzisoxazole – an overview | ScienceDirect Topics