Catalytic performance of carbonaceous materials in the esterification of succinic acid

Mesoporous carbonaceous materials have outstanding potential in many different applications such as adsorption, medicine and catalysis. We have recently reported the synthesis of a new form of mesoporous carbon, named Starbon((R)), obtained after low temperature carbonization of expanded starch. Such starch-derived mesoporous materials have several tunable properties including surface energies (ranging from hydrophilic to hydrophobic surfaces), which can be easily controlled by the degree of carbonization (from 200 to 700 degrees C). Due to the diversity of surface functional groups, Starbons((R)) can be easily chemically modified. Treatment of Starbon((R)) materials with sulfuric acid gave a solid acid that has promising properties as heterogeneous catalyst. Comparative catalytic studies with some other similar commercial carbonaceous materials such as DARCO((R)) and NORIT (R), as well as phosphorous-containing microporous carbons, are reported. (c) 2008 Elsevier B.V. All rights reserved

Synthesis of unsaturated polyester resins from various bio-derived platform molecules

Utilisation of bio-derived platform molecules in polymer synthesis has advantages which are, broadly, twofold; to digress from crude oil dependence of the polymer industry and secondly to reduce the environmental impact of the polymer synthesis through the inherent functionality of the bio-derived platform molecules. Bulk polymerisation of bio-derived unsaturated di-acids has been employed to produce unsaturated polyester (UPEs) which have been analysed by GPC, TGA, DSC and NMR spectroscopy, advancing on the analysis previously reported. UPEs from the diesters of itaconic, succinic, and fumaric acids were successfully synthesised with various diols and polyols to afford resins of MN 480-477,000 and Tg of -30.1 to -16.6 °C with solubilities differing based on starting monomers. This range of properties allows for many applications and importantly due to the surviving Michael acceptor moieties, solubility and cross-linking can be specifically tailored, post polymerisation, to the desired function. An improved synthesis of itaconate and succinate co-polymers, via the initial formation of an itaconate bis-diol, is also demonstrated for the first time, resulting in significantly improved itaconate incorporation

Facile and rapid decarboxylation of glutamic acid to γ-aminobutyric acid via microwave-assisted reaction : towards valorisation of waste gluten

The growing trend towards the utilisation of biomass to produce fuels and chemicals has the potential to produce large quantities of protein-rich wastes that may be unsuitable for use as a feed. This protein waste could instead serve as a sustainable feedstock for the production of useful nitrogen-containing bio-based chemicals. We report herein the production of γ-aminobutyric acid from glutamic acid via a microwave-assisted decarboxylation reaction using isophorone as an inducer reagent. High yields of 63% can be achieved with only short reaction times (7 min) required. The influences of inducer loading, reaction time and hydrochloric acid concentration used for hydrolysis step of the work up were investigated at different scales. As a proof of concept, glutamic acid was facilely isolated from waste gluten, via microwave assisted hydrolysis, and subsequently decarboxylated with success. To the best of our knowledge this is the first organocatalytic route to γ-aminobutyric acid using glutamic acid as a reagent, and represents an alternative cleaner route to a valuable precursor for bio-based solvents, polymers and pharmaceuticals

P-cymenesulphonyl chloride : A bio-based activating group and protecting group for greener organic synthesis

A bio-derived protecting/activating group has been synthesized by introducing a sulphonyl chloride group to the aromatic ring of p-cymene derived from citrus peel waste. The resulting p-cymenesulphonyl chloride was evaluated as an activating group by reacting with 1-octanol, 2-octanol, phenol and piperidine, and further reactions of the activated alcohols. The comparison to tosyl chloride demonstrates that the bio-based alternative can be effectively utilized as a direct replacement for the current fossil derived equivalent

Laminaria digitata and palmaria palmata seaweeds as natural source of catalysts for the cycloaddition of CO2 to Epoxides

Seaweed powder has been found to act as an effective catalyst for the fixation of CO2 into epoxides to generate cyclic carbonates under solvent free conditions. Model background reactions were performed using metal halides and amino acids typically found in common seaweeds which showed potassium iodide (KI) to be the most active. The efficacy of the seaweed catalysts kelp (Laminaria digitata) and dulse (Palmaria palmata) was probed based on particle size, showing that kelp possessed greater catalytic ability, achieving a maximum conversion and selectivity of 63.7% to styrene carbonate using a kelp loading of 80% by weight with respect to epoxide, 40 bar of CO2, 120◦C for 3 h. Maximizing selectivity was difficult due to the generation of diol side product from residual H2O found in kelp, along with a chlorinated by-product thought to form due to a high quantity of chloride salts in the seaweeds. Data showed there was loss of organic matter upon use of the kelp catalyst, likely due to the breakdown of organic compounds and their subsequent removal during product extraction. This was highlighted as the likely cause of loss of catalytic activity upon reuse of the Kelp catalyst

Fast microwave-assisted acidolysis, a new biorefinery approach for a zero-waste utilisation of lignocellulosic biomass to produce high quality lignin and fermentable saccharides

Generally biorefineries convert lignocellulosic biomass into a range of biofuels and further value added chemicals. However, conventional biorefinery processes focus mainly on the cellulose and hemicellulose fractions and therefore produce only low quality lignin, which is commonly burnt to provide process heat. To make full use of the biomass, more attention needs to be focussed on novel separation techniques, where the lignin can be isolated in a high quality suitable for further valorisation into aromatic chemicals and fuel components. In this paper, three types of lignocellulosic biomass (softwood, hardwood and herbaceous biomass) were processed by microwave-assisted acidolysis, to produce high quality lignin. The lignin from the softwood was isolated largely intact in the solid residue after acidolysis. For example, a 10 min treatment, microwave-assisted acidolysis produced a lignin with a purity of 93% and yield of 82%, superior to other conventional separation methods reported. Furthermore, the py-GC/MS analysis proved that the isolated lignin retained the original structure as native lignin in the feedstock without severe chemical modification. This is a large advantage, and the purified lignin is suitable for further chemical processing. To assess the suitability of this methodology as part of a biorefinery system, the aqueous phase, produced after acidolysis of the softwood, was characterised and assessed for its suitability for fermentation. The broth contained some mono- and disaccharides but mainly organic acids, oligosaccharides and furans. While this is unsuitable for S. cerevisiae and other common ethanol producing yeasts, two oleaginous yeasts with known inhibitor tolerances were selected; Cryptococcus curvatus and Metschnikowia pulcherrima. Both yeasts could grow on the broth, demonstrating suitable catabolism of the oligosaccharides and inhibitors over 7 days. In addition, both yeasts were shown to be able to produce an oil with a similar composition to palm oil. This preliminary work demonstrates new protocols of microwave-assisted acidolysis and therefore offers an effective approach to produce high purity lignin and fermentable chemicals, a key step towards a zero-waste lignocellulosic biorefinery

Synthesis of Biobased Diethyl Terephthalate via Diels-Alder Addition of Ethylene to 2,5-Furandicarboxylic Acid Diethyl Ester: An Alternative Route to 100% Biobased Poly(ethylene terephthalate)

Poly(ethylene terephthalate) (PET) is a ubiquitous thermoplastic currently produced from nonrenewable fossil resources; as such, sustainable biobased routes to the key terephthalate monomer are being widely pursued. Herein is demonstrated a greener solventless route to biobased diethyl terephthalate via a one-pot heterogeneous Lewis acid catalyzed Diels-Alder addition and dehydration of 2,5-furandicarboxylic acid diethyl ester with ethylene, giving yields of terephthalate up to 59% for the key Diels-Alder addition step. A metrics-based comparison against alternative published biobased routes (available from sugars, cellulose and hemicellulose) shows that the clean synthetic pathway developed herein gives a practical atom economy, overall yield and selectivity, making it a viable alternative to routes currently under development

Geminal Diol of Dihydrolevoglucosenone as a Switchable Hydrotrope : A Continuum of Green Nanostructured Solvents

The addition of water to dihydrolevoglucosenone (Cyrene) creates a solvent mixture with highly unusual properties and the ability to specifically and efficiently solubilize a wide range of organic compounds, notably, aspirin, ibuprofen, salicylic acid, ferulic acid, caffeine, and mandelic acid. The observed solubility enhancement (up to 100-fold) can be explained only by the existence of microenvironments mainly centered on Cyrene's geminal diol. Surprisingly, the latter acts as a reversible hydrotrope and regulates the polarity of the created complex mixture. The possibility to tune the polarity of the solvent mixture through the addition of water, and the subsequent generation of variable amounts of Cyrene's geminal diol, creates a continuum of green solvents with controllable solubilization properties. The effective presence of microheterogenieties in the Cyrene/water mixture was adequately proven by (1) Fourier transform infrared/density functional theory showing Cyrene dimerization, (2) electrospray mass-spectrometry demonstrating the existence of dimers of Cyrene's geminal diol, and (3) the variable presence of single or multiple tetramethylsilane peaks in the 1 H NMR spectra of a range of Cyrene/water mixtures. The Cyrene-water solvent mixture is importantly not mutagenic, barely ecotoxic, bioderived, and endowed with tunable hydrophilic/hydrophobic properties