Graphene Oxide Supported Molybdenum Cluster: First Heterogenized Homogeneous Catalyst for the Synthesis of Dimethylcarbonate from CO2 and Methanol

The octahedral molybdenum cluster‐based compound, Cs₂Mo₆Brⁱ₈Br^a₆ was immobilized on graphene oxide (GO) by using a facile approach. High resolution transmission electron microscopy results revealed that molybdenum clusters were uniformly distributed on the GO nanosheets. Cs₂Mo₆Brⁱ₈Br^a₆ was attached to the GO support via chemical interaction between apical ligands of Mo₆Brⁱ₈Br^a₆ cluster units and oxygen functionalities of GO, as revealed by XPS studies. The developed material was used for the synthesis of dimethyl carbonate by reduction of carbon dioxide. The synthesized catalyst, that is, GO–Cs₂Mo₆Brⁱ₈Br^a_x, exhibited higher catalytic efficiency than its homogeneous analogue without using dehydrating agent. The catalyst was found to be efficiently recyclable without significant loss of catalytic activity.     

Recent resurgence toward the oxidation of heteroatoms using dimethyldioxirane as an exquisite oxidant

This review covers the literature from 2005 to till date. Oxidation chemistry is a dynamic field of organic synthesis as it keeps evolving with the passage of time. There is a recent surge in that area to switch over from inorganic oxidants to organic oxidants. The oxidation of heteroatom is an intriguing task for the synthetic chemists, as it requires mild oxidant with no harmful side products. Dimethyldioxirane serves as a super-effective oxidant as it shows high functional group tolerance and possess acetone as byproducts which is also eco-friendly. This review summarizes the heteroatom oxidation of sulfur, nitrogen, iodine, selenium, phosphorous, and platinum atoms using DMDO as an oxidant.     

Suzuki-Miyaura reactions of N-protected tribromopyrazoles. Efficient and site-selective synthesis of 3,4,5-triaryl-pyrazoles, 3,5-diaryl-4-bromopyrazoles and 5-aryl-3,4-dibromopyrazoles

Suzuki-Miyaura reactions of N-protected tribromopyrazoles were studied. The reactions proceed with excellent site-selectivity. The first attack occurs at position 5, while the second and third attack occur at positions 3 and 4, respectively. A variety of 3,4,5-triaryl-pyrazoles, 3,5-diaryl-4-bromopyrazoles, and 5-aryl-3,4-dibromopyrazoles were efficiently prepared. The products are not readily available by other methods.     

Static permittivity and molecular interactions in binary mixtures of ethanolamine with alcohols and amides

The relative static permittivity at 1 MHz and high frequency limit permittivity at wavelength of sodium-D line of the binary mixtures of ethanolamine (2-aminoethanol) with alcohols (ethyl alcohol, ethylene glycol and glycerol) and amides (formamide, N,N-dimethylformamide and N,N-dimethylacetamide) have been investigated over the entire concentration range at 30 °C. The excess permittivity and Kirkwood correlation factor of the binary mixtures were determined to explore the hydrogen-bonded hetero-molecular interactions and their dependence on the number of hydroxyl groups of alcohols molecules and the extent of substitution in amides molecules. Results confirm that ethanolamine form weak H-bond interactions with alcohols, N,N-dimethylformamide and N,N-dimethylacetamide, but the dipolar alignments in these mixtures vary with number of hydroxyl group of alcohols and their molecular size. Comparatively strong H-bond interactions were found between ethanolamine and formamide molecules with reduce in number of parallel aligned effective dipoles.     

Synthesis,Characterization and Crystal Structure of 2-Nitro-<Emphasis Type="Italic">N</Emphasis>-[2,4-dichlorophenyl]-<Emphasis Type="Italic">N</Emphasis>-(2-methylbenzoyl)benzamide

Abstract  

The title benzamide was synthesized in two steps by refluxing N-(2,4-dichlorophenyl)-2-nitrobenzamide with thionyl chloride in dry toluene to afford 2,4-dichloro-N-[chloro(2-nitrophenyl]methylene)benzenamine intermediate followed by treatment with 2-methyl benzoic acid in presence of triethyl amine. The structure was confirmed by spectroscopic and elemental analysis. The crystal structure was determined from single crystal X-ray diffraction data. It crystallizes in the monoclinic space group P 21/c with unit cell dimensions a = 10.4122(7), b = 12.9613(7) and c = 15.5518(10) ?. The dihedral angle between the two aromatic rings is 82.32(4)°. The N2 and N3 nitro groups are oriented with respect to their attached phenyl rings at dihedral angles of 1.97(3)° and 15.73(3)°, respectively.     

Chemical images of marine bio-active compounds by surface enhanced Raman spectroscopy and transposed orthogonal partial least squares (T-OPLS)

Surface enhanced Raman spectroscopy combined with transposed Orthogonal Partial Least Squares (T-OPLS) was shown to produce chemical images of the natural antibacterial surface-active compound 1,1,3,3-tetrabromo-2-heptanone (TBH) on Bonnemaisonia hamifera. The use of gold colloids functionalised with the internal standard 4-mercapto-benzonitrile (MBN) made it possible to create images of the relative concentration of TBH over the surfaces. A gradient of TBH could be mapped over and in the close vicinity of the B. hamifera algal vesicles at the attomol/pixel level.