Laurence Bagnell

The use of catalytically active pervaporation membranes in esterification reactions to simultaneously increase product yield, membrane permselectivity and flux

Abstract Nafion tubes that function both as a reaction catalyst and a pervaporation membrane have been used to increase the yield in the esterification of acetic acid with methanol and n -butanol by selectively removing products, mainly water, from the reaction mixture. The experiments were performed at room temperature in a batchwise reactor using acidic protons in Nafion pellets and the Nafion membrane as the reaction catalyst. In some experiments the acidic protons in the membrane were partially or fully exchanged with caesium ions, which increased the intrinsic selectivity of the membrane for water but lowered its permeability. In the methanol reaction, the yield of methyl acetate was increased from the usual equilibrium value of 73% to a maximum of 77%. In the n -butanol reaction, the yield of n -butyl acetate increased from 70% to a maximum of 95%. The effect of the membranes catalytic activity on its permselectivity was investigated. The catalytically active membranes showed significantly higher permselectivities for water at the same or higher flux, compared to when no reaction was taking place within the membrane phase.

Supercritical gas extraction of Victorian brown coals: The effect of coal properties

Abstract A selection of fifteen Victorian brown coals, which varied in lithotype but only slightly in rank, were subjected to supercritical gas extraction with toluene. Seven of these coals were also extracted with 5% tetralin/toluene under the same conditions of temperature and pressure (400 °C and 10 MPa). The overall conversion, the extract yield and the yield of toluene solubles (oil and asphaltene) were correlated with more easily obtained coal properties using simple linear regression analysis. Good correlations were obtained between the total conversions and the volatile matter content of the coals, and for the toluene extractions between both the extract yield and the yield of toluene solubles and the H/C atomic ratio. For the toluene solubles from the toluene extractions, the aromaticity decreased and the molecular weight increased as the H/C atomic ratio of the coal increased. Inorganic constituents of the coals did not appear to have a marked effect on total conversion and liquid yields. Removal of the cations from two coals increased conversion and liquid yields in one case and decreased these in the other, but in both instances the changes were not large.

Extraction of brown coals with supercritical fluid mixtures: Implications for coal structure

Abstract Supercritical fluid extractions of brown coals with mixtures of hydrocarbon and polar solvents showed that aliphatic alcohols and amines are beneficial in the extraction of these coals. Conversions of > 90% were obtained for extraction with benzene-amine mixtures (80:20 w/w) at 300 °C. The results are consistent with the view that ester bond cleavage is an important step in dissolution of low-rank coals.

Nickel-catalysed conjugate addition of trimethylaluminium to 3-Oxo-Δ4-steroids

Nickel-catalysed addition of trimethylaluminium to 3-oxo-Δ4-steroids (cholest-4-en-3-one, testosterone propionate and progesterone) in ether gives the corresponding 5β-methyl saturated ketones in moderate yields. Lithium dimethylcuprate gives similar results.

Pd-catalysed arylation of propan-1-ol and derivatives: oxidative role of the arylating agent

With excess PhI under Pd catalysis, 1-PrOH was converted to a mixture of 3,3-diphenylpropenal and trans-2,3-diphenylpropenal by a concerted, oxidative sequence that involved two arylative couplings and an olefinic aldehyde that was generated in situ.

Uncatalysed hydrogen-transfer reductions of aldehydes and ketones

Aldehydes and ketones are reduced to the corresponding alcohols by transfer hydrogenation at high temperature with EtOH, PrnOH or PriOH as hydrogen donors in the absence of catalysts and base.

The effect of the solvent in stannous chloride catalysed hydrogenation of coal

Abstract Hydrogenation of the same coal in an autoclave using stannous chloride as the catalyst was carried out with donor and non-donor solvents and without solvent at 400° and 450°C. The conversion, product distribution and chemical nature of the oil and asphaltene were very similar with donor and non-donor solvents. However, in the absence of solvent the conversion and the liquid yield were lower, the gas yield higher and the liquid product was more aromatic. At 450°C the gas yield was higher, the asphaltene yield lower and both the oil and asphaltene were more aromatic than at 400°C, both with and without solvent. A possible explanation for the effect of solvent is given.

A CATALYTIC SYMMETRICAL ETHERIFICATION

A novel, catalytic, thermal etherification produces minimal waste and can be carried out under almost neutral conditions.