Expected and unexpected products of reactions of 2-hydrazinylbenzothiazole with 3-nitrobenzenesulfonyl chloride in different solvents

Acknowledgements We thank the EPSRC National Crystallography Service (University of Southampton) for the X-ray data collections. Funding information MVNdS and JLW thank CNPq (Brazil) for financial support.Peer reviewedPublisher PD

Validation of a capillary zone electrophoresis method for the determination of ciprofloxacin, gatifloxacin, moxifloxacin and ofloxacin in pharmaceutical formulations

An alternative capillary zone electrophoresis (CZE) method for the determination of ciprofloxacin (CPFLX), gatifloxacin (GTFLX), moxifloxacin (MFLX) and ofloxacin (OFLX) through a simple aqueous electrolyte system consisting of 25 mmol L-1 of TRIS/ hydrochloride and 15 mmol L-1 of sodium tetraborate buffer mixture (pH 8.87) using direct UV detection at 282 nm within 3 min was validated. The analytical parameters of validation evaluated were: linearity (r > 0.998), selectivity (comparison between slope of the calibration curve of external standard and calibration curve of standard addition), repeatability in area for sample (RSD%: < 3.94% for CPFLX, < 3.87% for GTFLX, 1.30% for MFLX and < 1.88% for OFLX), intermediate precision in area for sample (RSD%: < 3.59% for CPFLX, < 3.09% for GTFLX, 2.67% for MFLX and < 2.25% for OFLX), accuracy (mean of recovery range: 101.2% for CPFLX, 101.0% for GTFLX, 101.3% for MFLX and 99.9% for OFLX), limit of detection (mg L-1: 2.72 for CPFLX, 1.92 for GTFLX, 0.795 for MFLX and 1.05 for OFLX), limit of quantification (mg L-1: 9.06 for CPFLX, 6.40 for GTFLX, 2.65 for MFLX and 3.50 for OFLX) and robustness. Due to its simplicity, selectivity, precision, accuracy and rapidity, the methodology can be an interesting alternative for quality assurance in the pharmaceutical industry of these drugs

Reações de Ortometalacão em Piridinas

In this paper we describe a powerful methodology for the regiospecific construction of polysubstituted aromatic and heteroaromatic compounds. The DoM reaction (direct ortho-metalation) comprises the deprotonation in position ortho of a aromatic or heteroaromatic containing DMG (directed metalation group) by strong bases, normally an alkyllithium reagent, leading to an ortho-lithiated species. These species, upon treatment with electrophilic reagents, gives 1,2 disubstituted products.

Different hydrogen-bonded chains in the crystal structures of three alkyl N-[(E )-1-(2-benzylidene-1-methylhydrazinyl)-3- hydroxy-1-oxopropan-2-yl]carbamates

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Crystal Structure of the Chiral Azomethine Imine, (Z)-(S)-4-(tert-Butylcarbonylamino)-2-(2-methoxybenzylidene)-5-oxopyrazolidin-2-ium-1-ide, Obtained by the Cyclization of tert-Butyl (S)-2-[2-(methoxybenzylidene)hydrazine]-1-(hydroxymethyl)-2-oxocarbamate

Open Access via Springer Compact Agreement. The use of the NCS crystallographic service at Southampton and the valuable assistance of the staff there are gratefully acknowledged. JLW thanks FAPERJ and CNPq, Brazil for support.Peer reviewedPublisher PD

4-[(2-Chloro­ethyl)amino]quinolinium chloride monohydrate

In the title salt hydrate, C11H12ClN2 +·Cl−·H2O, the quinolin­ium core is essentially planar (r.m.s. deviation = 0.027 Å) with the chloro­ethyl side chain being almost orthogonal to the core [C—N—C—C torsion angle = −80.0 (3)°]. In the crystal packing, the water mol­ecule bridges three species, forming donor inter­actions to two chloride anions and accepting a hydrogen bond from the quinolinium H atom. The chloride anion accepts a hydrogen bond from the amine N atom with the result that a two-dimensional supra­molecular array is formed in the ac plane. A C—H⋯Cl interaction also occurs

7-Chloro-4-(2-hydroxyethylamino)quinolin-1-ium chloride

The use of the EPSRC X-ray crystallographic service at the University of Southampton, England [Coles, S. J. & Gale, P. A. (2012). Chem. Sci. 3, 683-689.]), and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil). Structural studies are supported by the Ministry of Higher Education (Malaysia) and the University of Malaya through the High-Impact Research scheme (UM·C/HIR/MOHE/SC/3).Peer reviewedPublisher PD

4-[(E)-2-(2,4-Dichloro­benzyl­idene)hydrazin-1-yl]quinolin-1-ium chloride monohydrate

In the title hydrated salt, C16H12Cl2N3 +·Cl−·H2O, there is a small twist in the cation as seen in the torsion angle linking the benzene ring to the rest of the mol­ecule [171.96 (17)°]. In the crystal, the quinolinium H atom forms a hydrogen bond to the lattice water mol­ecule, which also forms hydrogen bonds to two Cl− anions. Each Cl− ion also accepts a hydrogen bond from the hydrazine H atom. The three-dimensional architecture is also stabilized by π–π inter­actions between centrosymmetrically related quinoline residues [centroid–centroid distance = 3.5574 (11) Å]

N-(4-Bromo­phen­yl)pyrazine-2-carbox­amide

The mol­ecule of the title compound, C11H8BrN3O, is close to planar (r.m.s. deviation of all 16 non-H atoms = 0.103 Å), a conformation stabilized by an intra­molecular N—H⋯N hydrogen bond, which generates an S(5) ring. In the crystal structure, supra­molecular chains mediated by C—H⋯O contacts (along a) are linked into a double layer via N⋯Br halogen bonds [3.207 (5) Å] and C—Br⋯π inter­actions [Br⋯ring centroid(pyrazine) = 3.446 (3) Å]. The layers stack along the b axis via weak π–π inter­actions [ring centroid(pyrazine)⋯ring centroid(benzene) distance = 3.803 (4) Å]

Different packing motifs of isomeric (E)-N1-(halophenylmethylidene)-N-methyl-2-(thiophen-2-yl)-acetohydrazides controlled by C—HO interactions

We thank the EPSRC National Crystallography Service (University of Southampton) for the X-ray data collectionsPeer reviewedPublisher PD