Cocrystal of Codeine and Cyclopentobarbital

The two-component compound formed by codeine and cyclopentobarbital was produced using grinding techniques and through evaporation from alcoholic solutions. The cocrystal nature of this phase was established unequivocally through single crystal X-ray structure determination. The asymmetric unit contains one formula unit. In the cyclopentobarbital molecule, the cyclopentenyl ring is disordered over two positions related by a rotation of approximately 180° about its C—C bond to the pyrimidine ring. The two NH groups of the cyclopentobarbital molecule form N—H⋯N and N—H⋯O bonds to piperidine and hydroxyl groups, respectively, belonging to different codeine molecules. In addition, the hydroxyl and methoxy groups of neighboring codeine molecules are linked by O—H⋯O interactions, resulting in a H-bonded framework structure of codeine and cyclopentobarbital molecules. The cocrystal was also characterized using thermal analysis, X-ray powder diffraction and IR spectroscopy.