A step towards hydroformylation under sustainable conditions: platinum-catalysed enantioselective hydroformylation of styrene in gamma-valerolactone

Platinum-catalysed enantioselective hydroformylation of styrene was performed in γ-valerolactone (GVL) as a proposed environmentally benign reaction medium. Optically active bidentate ligands, possessing various types of chirality elements e.g. central (BDPP), axial (BINAP, SEGPHOS, DM-SEGPHOS, DTBM-SEGPHOS) and planar/central (JOSIPHOS) elements, were applied in in situ generated Pt-diphosphine-tin(II)chloride catalyst systems. In general, slightly higher activities and regioselectivities towards a branched aldehyde (2-phenylpropanal) were obtained in toluene as a reference conventional solvent. However, higher chemoselectivities towards aldehydes (up to 98%) in GVL were obtained at lower temperatures. The application of GVL proved to be also advantageous regarding enantioselectivity: although moderate enantioselectivities were obtained in both solvents, in most cases higher ee values were detected in GVL. From the mechanistic point of view, the formation of different catalytic intermediates and/or different kinetics can be envisaged from the different temperature dependences of ee in GVL and toluene. The 31P-NMR characterization of catalyst species in GVL was also provided

Isoreticular Metalation of Metal-Organic Frameworks

Sequential covalent transformation and metalation were performed on (Zn(4)O)(3)(BDC-NH(2))(3)(BTB)(4) with maintenance of crystallinity and porosity. Reaction of (Zn(4)O)(3)(BDC-NH(2))(3)(BTB)(4) with 2-pyridinecarboxaldehyde in toluene at room temperature for 5 days resulted in the formation of the extended crystalline structure (Zn(4)O)(3)(BDC-C(6)H(5)N(2))(3)(BTB)(4), which possesses iminopyridine moieties covalently bound to the organic links of the framework. Subsequent reaction with PdCl(2)(CH(3)CN)(2) in CH(2)Cl(2) at room temperature for 12 h yielded the metalated metal-organic framework (Zn(4)O)(3)(BDC-C(6)H(5)N(2)PdCl(2))(3)(BTB)(4). Both functionalized materials retained high crystallinity and were permanently porous with high surface areas [3200 and 1700 m(2) g(-1) for (Zn(4)O)(3)(BDC-C(6)H(5)N(2))(3)(BTB)(4) and (Zn(4)O)(3)(BDC-C(6)H(5)N(2)PdCl(2))(3)(BTB)(4), respectively.].Christian J. Doonan, William Morris, Hiroyasu Furukawa, and Omar M. Yagh

COLLECTIVE ACTION IN SMALLHOLDER ORGANIC FARMING: A STUDY OF THE EZEMVELO FARMERS' ORGANIZATION IN KWAZULU-NATAL

This study analyses the Ezemvelo Farmers' Organisation (EFO), a certified organic smallholder group in KwaZulu-Natal province (South Africa), as an institution to improve smallholder access to a niche market by reducing unit production and transaction costs in the supply chain. Using a multinomial logit model, results suggest that EFO is more likely to survive if it continues to secure fully subsidised information, transport, fencing, and certification services for its members, and if it improves the benefits of participating by synchronising harvest and delivery dates, negotiating price discounts for organic inputs, and by maintaining an office with telephone, fax and postal services. Copyright (c) 2006 The Authors. Journal compilation (c) 2006 Economic Society of South Africa.