1,4-Di-methyl-piperazine-2,3-dione.

In the title compound, CHNO, the piperazine-2,3-dione ring adopts a half-chair conformation. In the crystal, the mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming (010) sheets.

(1-Benzo-diazol-2-ylmeth-yl)di-ethyl-amine.

In the crystal of the title compound, CHN, the mol-ecules are linked by N-H⋯N hydrogen bonds, generating a (4) chain extending along the -axis direction. One of the ethyl groups is disordered over two sets of sites with a refined occupancy ratio of 0.582 (15):0.

2-(10-Bromo-anthracen-9-yl)--phenyl-aniline.

In the title compound, CHBrN, the central benzene ring makes dihedral angles with its adjacent anthracene ring system and pendant benzene ring of 87.49 (13) and 62.01 (17)°, respectively.

10-Bromo-,-di-phenyl-anthracen-9-amine.

In the title compound, CHBrN, the dihedral angles between the anthracene ring system and the phenyl rings are 89.51 (14) and 74.03 (15)°.

Synthesis, Characterization, Crystal Structure and Molecular Docking Studies of a S-methyldithiocarbazate Derivative: Bis[2-hydroxy- benzylidenehydrazono) (methylthio)methyl]disulfide.

The title compound bis[2-hydroxybenzylidenehydrazono)(methylthio)methyl]disulfide (1), an S-methyldithiocarbazate derivative with a disulfide bond has been synthesized by the condensation of 2-hydroxybenzaldehyde with S-methyldithiocarbazate. It has been characterized by elemental analyses, 1H, 13C NMR and FT-IR spectroscopy and mass spectrometry. The single crystal X-ray structure shows that the compound exists in a tautomeric thione form with the dithiocarbazate fragment adopting an EE configuration with respect to the C=N bond of the benzylidene moiety.

Identification, isolation and characterization of an unknown impurity of varenicline.

An unknown impurity formed during stability sample analysis by a gradient reversed phase ultra-high pressure liquid chromatography (UHPLC) of varenicline tablets at 0.2% level. A simple isocratic preparative method was developed to isolate the unknown impurity with 20 min run time.

Development and validation of a reversed-phase ultra-performance liquid chromatographic method for assay of lacidipine and related substances.

A simple isocratic, RP-ultra-performance LC method was developed and validated for the determination of lacidipine, three process impurities formed during synthesis, and three degradation products present in drug substance and the drug product. An efficient chromatographic separation was achieved on an Acquity BEH C18 column using pH 4.5 ammonium acetate-acetic acid buffer-methanol (70 + 30, v/v) mobile phase.