P. Raghavendra Kumar

Synthesis of Pd(0) nanocatalyst using lignin in water for the Mizoroki-Heck reaction under solvent-free conditions.

Palladium(0) nanospheres with an average size of 1-5 nm were synthesized and stabilized by lignin in water without any reducing agent. The lignin supported palladium(0) nanoparticles (lignin@Pd-NPs) were characterized by UV-vis., FT-IR, SEM, TEM, HRICP-AES, EDX and PXRD. Absence of the peak at 430 nm in UV-vis., spectrum confirmed the reduction of Pd(II) to Pd(0). The five characteristic peaks at (111), (200), (220), (311) and (222) corresponding to the 2θ values 40°, 46.7°, 67.9°, 81.9° and 86.9°, respectively, appeared in PXRD spectrum indicated the crystallographic planes of Pd(0) with fcc structure. The Pd(0) loaded on lignin was 0.0467 mmol/g determined by HRICP-AES and 0.89% (w/w) by EDX. The performance of lignin@Pd-NPs catalyst have been investigated for the Mizoroki-Heck CC bond formation reactions between n-butyl propene-2-enoate and halobenzenes and substituted halobenzenes in polar to highly polar solvents as well as under solvent-free conditions in the presence of organic or inorganic bases. The lignin@Pd-NPs was found to be a highly efficient catalyst to yield the desired products of up to 94% under solvent-free conditions in short reaction times. The catalyst was heterogeneous and hence recovered by filtration and reused several times in the subsequent batches of the same reaction.

Crystal structure of 1-benzylsulfonyl-1,2,3,4-tetrahydroquinoline

In the title compound, C16H17NO2S, the heterocyclic ring adopts a half-chair conformation and the bond-angle sum at the N atom is 354.6°. The dihedral angle between the planes of the aromatic rings is 74.15 (10)°. In the crystal, molecules are linked by weak C—H⋯O hydrogen bonds, generating C(8) and C(4) chains propagating along [100] and [010], respectively, which together generate (001) sheets.

Synthesis, characterization and determination of absolute structures of palladium complexes of novel chiral acyclic tellurated Schiff base ligands

Enantiomerically pure chiral hybrid organotellurium ligands (R)-L1H, (S)-L2H and (R)-L3H have been synthesized via condensation of the chiral β-organotellurated amines 2a, 2b and 2c, respectively, with salicylaldehyde. When these chiral acyclic tellurated Schiff base ligands reacted with Na2PdCl4 in a 1 : 1 molar ratio, they afforded the corresponding orange-red asymmetric complexes [Pd(L1–3)Cl] (1–3). All these compounds were characterized by elemental analysis, polarimetry, and 1H, 13C{1H} NMR and FT-IR spectroscopies. The absolute structures of the complexes 1 and 2 were determined by single crystal X-ray diffraction, and the complexes 1 and 2 crystallized in the hexagonal and orthorhombic crystal systems with the space groups P65 and P212121, respectively. The characterisation data showed that the ligands coordinated in the deprotonated tridentate (Te, N, O−) mode and acquired a square planar geometry around the central palladium(II) ion along with a monodentate chloro (Cl−) in 1–3. The Pd–Te, Pd–Cl, Pd–O and Pd–N bond lengths found were 2.5008(9), 2.3286(19), 2.037(6) and 2.009(6) A, respectively, in 1 and 2.497(2)/2.506(3), 2.293(6)/2.326(6), 2.035(15)/2.030(2) and 1.949(17)/2.010(2) A, respectively, in 2. There was intermolecular CH⋯Cl [2.81–2.96 A] and CH⋯O [2.40–2.64 A] hydrogen bonding in 1 and 2, which resulted in supramolecular structures. The Te⋯Cl [3.309–3.710 A] secondary interactions resulted in the helical structure of 1 and dimeric structure of 2 with a short Pd⋯Pd [3.500(1) A] distance. The Flack parameters (x) of 1 [0.02(3)] and 2 [0.024(12)] confirmed their absolute configurations.

Crystal structure of 1-methane­sulfonyl-1,2,3,4-tetra­hydro­quinoline

In the title compound, C10H13NO2S, the heterocyclic ring adopts a half-chair conformation and the bond-angle sum at the N atom is 347.9°. In the crystal, inversion dimers linked by pairs of C—H⋯O hydrogen bonds generate R 2 2(8) loops.

Crystal structure of 1-methanesulfonyl-1,2,3,4-tetrahydroquinoline

In the title compound, C10H13NO2S, the heterocyclic ring adopts a half-chair conformation and the bond-angle sum at the N atom is 347.9°. In the crystal, inversion dimers linked by pairs of C—H⋯O hydrogen bonds generate R 2 2(8) loops.

Crystal structure of (2R)-1-[(methyl­sulfon­yl)­oxy]propan-2-aminium chloride: a chiral mol­ecular salt

In the title chiral molecular salt, C4H12NO3S+·Cl−, the cation is protonated at the N atom, producing [RNH3]+, where R is CH3SO2OCH2C(H)CH3. The N atom in the cation is sp 3-hybridized. In the crystal, cations and anions are connected by strong N—H⋯Cl hydrogen bonds to generate edge-shared 12-membered rings of the form {⋯Cl⋯HNH}3. This pattern of hydrogen bonding gives rise to zigzag supramolecular layers in the ab plane. The layers are connected into a three-dimensional architecture by C—H⋯O hydrogen bonds. The structure was refined as an inversion twin.

Crystal structure of 1-[(6-chloro­pyridin-3-yl)sulfon­yl]-1,2,3,4-tetra­hydro­quinoline

In the crystal structure of 1-[(6-chloropyridin-3-yl)sulfonyl]-1,2,3,4-tetrahydroquinoline, the tetrahydropyridine ring of the quinoline system adopts a half-chair conformation and the bond-angle sum at the N atom is 350.0°.

Crystal structure of (2-chloro­eth­yl)[2-(methyl­sulfan­yl)benz­yl]ammonium chloride

In the cation of the title molecular salt, the N atom is protonated with sp 3-hybridization and has a tetrahedral geometry. In the crystal, the cations are bridged by the Cl− anions via N—H⋯Cl hydrogen bonds, forming four-centred inversion dimers with an (8) ring motif.

Crystal structure of 1-methanesulfonyl-1, 2, 3, 4-tetrahydroquinoline

In the title compound, C10H13NO2S, the heterocyclic ring adopts a half-chair conformation and the bond-angle sum at the N atom is 347.9°. In the crystal, inversion dimers linked by pairs of C—H⋯O hydrogen bonds generate R 2 2(8) loops.