Search

Molybdenum oxides (MoO3 − x, x = 1, 2, and 3) with three types of morphologies were prepared and applied to the reaction of benzyl alcohol with dimethylformamide (DMF) for synthesis of tertiary amines. The MoO3 − 1 catalyst prepared by direct calcination exhibited high activity and tertiary amines selectivity in the N,N‐dimethylamination of benzyl alcohol under the reaction conditions at 150°C for 12 h using DMF as a methylating agent and solvent, as compared to MoO3 − 2 and MoO3 − 3 catalysts. This feature was ascribed to the high proportion of surface chemisorbed oxygen for MoO3 − 1 sample, which can promote the adsorbed benzyl alcohol transformation into benzaldehyde. The MoO3 − 1 catalyst was also found to be reusable in five consecutive runs without a significant decrease in catalytic activity. In addition, control experiments showed two parallel reaction routes in this catalytic system. One route is the reaction of benzaldehyde intermediate and DMF to form tertiary amines (Route I); the other route is that benzyl formate intermediate reacted with DMF (Route II), which has not been reported before and specifically involves the esterification of benzyl alcohol with formic acid from DMF decomposition to form benzyl formate. [ABSTRACT FROM AUTHOR]

Biaryl skeletons were directly constructed via palladium-catalyzed ortho-arylation of N, N-dimethyl benzylamine with aryl boronic acids with high efficiency and high regioselectivity under open-flask conditions. The N,N-dimethylaminomethyl group was first applied as a directing group in such an oxidative coupling. Various substrates proved to be efficient coupling partners, furnishing the corresponding ortho-monoarylated or -diarylated arenes in moderate to good yields under mild conditions. [ABSTRACT FROM AUTHOR]

Reaction of {[Pd(dmba)(μ-Cl)]2} (dmba = (CH3)2NCH2C6H4) with an in situ generated N-heterocyclic carbene (NHC = 1,3-dimesitylimidazolidin-2-ylidene) afforded crystals containing [chloro-(1,3-dimesitylimidazolidin-2-ylidene)(N,N-dimethylaminobenzyl-C1,N)palladium(II)] (VII). Molecular and crystal structures of the title compound have been determined by single crystal X-ray diffraction technique. Complex VII crystallizes in space group P 1, with a = 13.685(3) Å, b = 13.590(2) Å, c = 16.229(3) Å, α = 87.162(13)°, β = 70.514(15)°, γ = 84.153(16)°, Z = 4, DCalcd = 1.367 g cm-3. There are two independent molecules in the asymmetric unit. [ABSTRACT FROM AUTHOR]

The X-ray crystal structures of cyclopalladated complexes are reported. Reaction of {[Pd(dmba)(μ-Cl)]2}, (1), (dmba=N(CH3)2CH2C6H5) with triphenylphosphine gave crystals containing {chloro–(triphenylphosphino)-bis[N,N-dimethylaminobenzyl-C1,N]palladium(II)} (2a) and {trans-bis(triphenylphosphino)-chloro-[N,N-dimethylaminozyl-C]palladium(II)} (2b). Complex (1) crystallises in the space group P2(1)/c with a=7.849(1) A˚, b=15.635(3) A˚, c=8.352(1) A˚, β=109.29°, and Dcalc=1.895 g cm −3 for Z=2. Complexes (2a) and (2b) crystallize together in the space group P2(1)/n with a=9.964(2) A˚, b=34.228(5) A˚, c=18.127(3) A˚, β=91.91 °, and Dcalc=1.439 g cm−3. [Copyright &y& Elsevier]

Dimethylbenzylamine (DMBA) is used in the production of epoxy resins. The aims of this study were to assess occupational exposure to DMBA and evaluate the usefulness of monitoring the urinary excretion of DMBA and DMBA metabolites as indicators of exposure to DMBA. A sensitive gas chromatographic method for analysis of DMBA in air and in urine has been developed. The detection limit for DMBA in air for a 60-l air sample collected in 10 ml absorption solution was 2 μg/m and in charcoal tubes, 0.3 μg/m. The detection limit for DMBA in urine was 0.02 mg/l. Ten male workers manufacturing epoxy resin were monitored during a full shift in the working environment and urine samples were collected at the end of exposure. The mean exposure and the highest DMBA concentration observed in air were 18 μg/m (time-weighted average; range 3-48 μg/m) and 91 μg/m, respectively. The DMBA concentrations in the urine samples were below the detection limit. After reduction of the urine samples the DMBA concentrations in the urine samples were below the detection limit. After reduction of the urine samples the DMBA concentrations (U-SumDMBA) ranged from 0.02 to 0.22 mg/l. There was significant correlation between the exposure to DMBA and the U-SumDMBA. This observation suggests that the U-SumDMBA in urine samples collected at the end of a shift is a useful indicators of occupational exposure to DMBA. [ABSTRACT FROM AUTHOR]