ChemSusChem

The cover image shows a sustainable biorefinery scheme. Cellulose is a renewable and highly available feedstock that is typically found in wood, straw, grass, municipal solid waste, and crop residues. Its use, as raw material for biofuel production, opens a possibility for sustainable biorefinery schemes that do not compete with the food supply. Tapping into this feedstock for the production of biofuels and chemicals requires, as the first step, its depolymerization or its hydrolysis to intermediates more susceptible to chemical and/or biological transformations. Rinaldi and Schüth from the Max-Planck-Institut für Kohlenforschung describe efficient methods for the conversion of cellulose in their Review found on page 1096.

Myrcene is an interesting natural hydrocarbon with a highly active diene structure that provides a chemistry similar to the unsaturated hydrocarbons already known from oil and gas. This Review is aimed at reviving this industrially available monoterpene as a renewable compound suitable for sustainable chemistry in the areas of vitamins, fragrances, flavors, insect repellents, and polymers.

How to lose cellulose: Hydrolysis of cellulose is experiencing a new research and development cycle, in which this reaction is carried out over solid catalysts and coupled to other reactions for its efficient utilization. This review covers 1) structural features of cellulose, 2) conventional acid-catalyzed processes, 3) mechanism of acid-catalyzed hydrolysis, 4) reaction media, and 5) solid acid catalysts for the transformation of cellulose.

Fuels derived from biobased materials are attracting much attention. In this Minireview, we evaluate the transforming of biobased sources, particularly fatty acids and triglycerides, into fuels. Current technology such as transesterification, micro-emulsion, and cracking, known as the first generation, is covered. Recent novel technology based on deoxygenation reactions producing non-oxygenated biofuels is also discussed.

Esterrific and ketonderful! Mixtures of acids and esters, produced by esterification reactions with alcohols in bio-oils, can be upgraded to larger ketones by ketonization reactions using a ceria–zirconia catalyst, on which acids adsorb more strongly than esters, leading to the preferential ketonization of acids followed by ketonization of esters at higher conversions.

The synthesis of hydrophobic starch is performed under mild conditions through palladium-catalyzed telomerization of butadiene. In a H₂O–dimethylisosorbide mixture at 50 °C and in the presence of Na₂SO₄, a granular texture of native starch is maintained and a turnover number of up to 550 is achieved.

Furfural obtained from biomass is a versatile platform chemical. It is easily transformed into furanones by using sustainable oxidation methods. Amphoteric surfactants are produced from these intermediates by photochemically induced radical addition of fatty amine-derived products.

Cerious chemistry: 5-hydroxymethyl-2-furfural is selectively converted into 2,5-furandicarboxylic acid in water, using air as oxidant, under mild conditions, and with gold nanoparticles supported on nanoparticulate ceria (Au-CeO₂) as catalyst. The catalyst is stable and reusable. Substrate degradation is strongly diminished and catalyst life is increased by performing the reaction in two temperature steps. The catalytic performance of Au-CeO₂ surpasses that of other gold nanoparticle catalysts (e.g., Au-TiO₂, Au-Fe₂O₃).

The use of glycerol as a biorenewable chemical feedstock is of immense importance, because it is a byproduct of the manufacture of biodiesel. Catalysts (1 wt % Au/carbon) are prepared by using a sol-immobilization method, and are shown to oxidize glycerol to glycolate giving yields of ca. 60 %, using hydrogen peroxide as oxidant in an autoclave reactor.

The C factor is suggested as a metric for fast evaluation of the CO₂ burden of chemical processes. The C factor contains information of the total amount of CO₂ emitted in order to produce a product, and thus enables a direct comparison of the CO₂ aspect of different processes. We illustrate how this simple concept can be used to evaluate different resource types and processes.

John Wiley & Sons Ltd., Chichester, 2008. 198 pp., hardcover US$ 90.00—ISBN 978-0-470-05805-3