Vibrational Spectroscopic Studies of Cocrystals and Salts. 4. Cocrystal Products formed by Benzylamine, α-Methylbenzylamine, and their Chloride Salts

The chloride salts formed by benzylamine and α-methylbenzylamine have been characterized using X-ray powder diffraction, differential scanning calorimetry, and infrared absorption spectroscopy. In addition, X-ray powder diffraction and differential scanning calorimetry have been used to establish formation or lack of formation of the 1:1 stoichiometric salt-cocrystal products containing the chloride salts and their respective free bases. For α-methylbenzylamine (which contains a single dissymmetric center), the chiral identities of the free bases and chloride salts were found to play a determining role as to whether a salt-cocrystal product could or could not be formed. It was found that a salt-cocrystal product could only be formed if the salt and free base were of opposite absolute configurations. For those systems where the existence of cocrystals was demonstrated, assignments were derived for the observed peaks in the infrared absorption spectra of the reactants and their products.