Molecular Cocrystals of Carboxylic Acids. XV. Preparation and Characterization of Heterocyclic Base Adducts With a Series of Carboxylic Acids, and the Crystal Structures of the Adducts of 2-Aminopyrimidine With 2,6-Dihydroxybenzoic Acid, 4-Aminobenzoic Acid, Phenoxyacetic Acid, (2,4-Dichlorophenoxy)acetic Acid, (3,4-Dichlorophenoxy)-acetic Acid and Salicylic Acid, and 2-Aminopyridine With 2,6-Dihydroxybenzoic Acid

Abstract

The molecular adducts of the heterocyclic base 2-aminopyrimidine with the aromatic and aromatic aliphatic carboxylic acids salicylic acid, 2,6-dihydroxybenzoic acid and 4-aminobenzoic acid, phenoxyacetic acid, (2,4-dichlorophenoxy)acetic acid, and (3,4-dichlorophenoxy)acetic acid have been prepared, and their interactive modes characterized by single-crystal X-ray diffraction methods. In addition, the complexes with (4-chlorophenoxy)acetic acid, (2,3-dichlorophenoxy)acetic acid, (4-chloro-2-methylphenoxy)acetic acid and (2,4,5- trichlorophenoxy)acetic acid have been characterized by analytical methods, including infrared spectroscopy. Except for the phenoxyacetic acid adduct (2:1), all form 1:1 molecular associations in which the carboxylic acid shows a variable tendency to protonate the hetero nitrogen of the base. The 1:1 complex of 2-aminopyridine with 2,6-dihydroxybenzoic acid has also been characterized by single-crystal X-ray diffraction.