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Palladium-catalyzed reductive homocoupling of aromatic halides can be performed in alcohol solutions without any auxiliary reducing reagents. Pd(dppf)Cl(2) [dppf = 1,1'-bis(diphenylphosphino)ferrocene] has been shown as the most effective catalyst among the palladium catalysts screened for the model reductive homocoupling of iodobenzene in alcoholic solutions. The reduction of iodobenzene is stoichiometrically coupled with the oxidation of solvent alcohol (3-pentanol). The X-ray photoelectron spectroscopic (XPS) studies clearly indicate that the oxidation of solvent alcohol molecules is involved with the in situ regeneration of the reductive Pd(0)(dppf) active species, indicating that the solvent alcohol also reacts as a reducing reagent for the reductive homocoupling of aromatic halides. Elimination of the external reducing reagents will simplify the product separation and purification. Base is essential for the success of the Pd(dppf)Cl(2)-catalyzed redox reaction as 2 molar equiv of base is needed to neutralize the acid byproduct formed. Biaryls are the predominant products for the Pd(dppf)Cl(2)-catalyzed reductions of the unsubstituted aromatic halides in 3-pentanol solution, whereas the dehalogenation products are predominant for the Pd(dppf)Cl(2)-catalyzed reductions of the substituted aromatic halides. The reaction mechanisms have been discussed for the palladium-mediated concomitant reduction of aromatic halides and oxidation of alcohols without any auxiliary reductants and oxidants.

Chitosan membranes with high porosity and good mechanical properties were prepared by selective dissolution of the blend membranes of chitosan (CS) and polyethylene glycol (PEG). The morphology of the obtained porous membranes was characterized by scanning electron microscopy. The pore size changed from 500 nm to several micrometers, depending on the molecular weight of the PEG used. The water permeability of the porous membrane depends on both the pore size and the porosity, except in the case of PEG2000, in which a higher molecular weight of PEG was used, producing greater water permeability. The tensile strength of the porous membranes obtained by this method was higher in both the wet and the dry state than that of the porous chitosan membranes prepared by using silica particles as porogen.

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