The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《The polymorphism of organic compounds》. Authors are Naveau, J..The article about the compound:(1S,3R)-1,2,2-Trimethylcyclopentane-1,3-dicarboxylic acidcas:560-09-8,SMILESS:CC1(C)[C@@H](CC[C@]1(C)C(O)=O)C(O)=O).SDS of cas: 560-09-8. Through the article, more information about this compound (cas:560-09-8) is conveyed.
Observations were made of the polymorphic transformations of organic compounds on the stage of a polarizing microscope. The crystals were cooled to -165° and heated to 200°. Under normal pressure polymorphism could not be proved for several compounds Enantiotropic pseudotransition was exhibited by phenol at -2°, caused by impurities. 1-Methylcyclopentanol, phenol, cyclopentyl cyanide, Me3COH, and CHI3 showed no true polymorphism. MeCN was not enantiotropic. Glutaric acid, lauryl alc., chloral hydrate, Me2C(Et)OH, and succinonitrile were enantiotropic. Hydroquinone, malonitrile, and Me oxalate were dimorphic monotropes. d-Camphoric acid was a true monotrope. 55 references.
There are many compounds similar to this compound(560-09-8)SDS of cas: 560-09-8. if you want to know more, you can check out my other articles. I hope it will help you，maybe you’ll find some useful information.
Reference:
Isothiazole – Wikipedia,
Isothiazole – ScienceDirect.com