Methyl 5-(2-bromo­acet­yl)-2-propoxybenzoate

The title compound, C13H15BrO4, was synthesized from methyl 5-acetyl-2-hydroxy­benzoate. With the exception of the ester group and some H atoms, the molecule is planar, the average deviation from planarity being 0.086 (5) Å. The dihedral angle between the phenyl ring and the ester group is 41.6 (3)°. Adjacent mol­ecules are inter­connected by C—H⋯O bonds, generating a layered structure

Selective primary alcohol oxidation of lignin streams from butanol-pretreated agricultural waste biomass

We would like to thank the CRITICAT Centre for Doctoral Training for financial support [Ph.D. studentship to IP; Grant code: EP/L016419/1] and BBSRC Global Challenges Research Fund Impact Acceleration Account at St Andrews BB/GCRFIAA/20. CSL thanks the Leverhulme Trust for funding an Early Career Fellowship.Chemically modified lignins are important for the generation of biomass-derived materials and as precursors to renewable aromatic monomers. A butanol-based organosolv pretreatment has been used to convert an abundant agricultural waste product, rice husks, into a cellulose pulp and three additional product streams. One of these streams, a butanol-modified lignin, was oxidized at the γ position to give a carboxylic acid functionalized material. Subsequent coupling of the acid with aniline aided lignin characterization and served as an example of the flexibility of this approach for grafting side chains onto a lignin core structure. The pretreatment was scaled up for use on a multi-kilogram scale, a development that enabled the isolation of an anomeric mixture of butoxylated xylose in high purity. The robust and scalable butanosolv pretreatment has been developed further and demonstrates considerable potential for the processing of rice husks.PostprintPeer reviewe

Conventional and microwave-assisted pyrolysis of biomass under different heating rates

Biomass was subjected to conventional and microwave pyrolysis, to determine the influence of each process on the yield and composition of the derived gas, oil and char products. The influence of pyrolysis temperature and heating rate for the conventional pyrolysis and the microwave power was investigated. Two major stages of gas release were observed during biomass pyrolysis, the first being CO/CO and the second one CH/H. This two-stage gas release was much more obvious for the conventional pyrolysis. While similar yield of liquid was obtained for both cases of conventional and microwave pyrolysis (∼46 wt.%), higher gas yield was produced for the conventional pyrolysis; it is suggested that microwave pyrolysis is much faster. When the heating rate was increased, the peak release of CO and CO was moved to higher reaction temperature for both conventional (500 °C) and microwave pyrolysis (200 °C). The production of CH and H were very low at a conventional pyrolysis temperature of 310 °C and microwave pyrolysis temperature of 200 °C (600 and 900 W). However, at higher heating rate of microwave pyrolysis, clear release of CH was observed. This work tentatively demonstrates possible connections and difference for biomass pyrolysis using two different heating resources (conventional and microwave heating)

CO₂ gasification of bio-char derived from conventional and microwave pyrolysis

Thermal-chemical processing of biomass is expected to provide renewable and clean energy and fuels in the future. Due to the nature of endothermic reactions, microwave and conventional heating have been applied to this technology. However, more studies need to be carried out to clarify the difference between these two heating technologies. In this work, we investigated two bio-char samples produced from conventional pyrolysis of wood biomass (yield of bio-char: 38.48 and 59.70 wt.%, respectively) and one bio-char produced from microwave pyrolysis with a yield of 45.16 wt.% from the same biomass sample at different process conditions. Various methodologies have been used to characterise the bio-chars. CO₂ gasification of bio-char has also been studied using a thermogravimetric analyser (TGA) and a fixed-bed reaction system. The results show that volatile and carbon contents of the bio-char derived from microwave pyrolysis were between the two conventional bio-chars. However, the microwave bio-char is more reactive for CO₂ gasification, as more CO was released during TGA experiments, and the CO release peak was narrower compared with the CO₂ gasification of the conventional bio-chars. It is suggested that the conventional bio-char is less reactive due to the presence of more secondary chars which are produced from secondary reactions of volatiles during the conventional biomass pyrolysis. While the microwave pyrolysis generates more uniform bio-chars with less secondary char, and therefore, has advantages of producing bio-char for downstream char gasification

Magnetized High Velocity Clouds in the Galactic Halo: A New Distance Constraint

High velocity gas that does not conform to Galactic rotation is observed throughout the Galaxy's halo. One component of this gas, H i high velocity clouds (HVCs), have attracted attention since their discovery in the 1960s and remain controversial in terms of their origins, largely due to the lack of reliable distance estimates. The recent discovery of enhanced magnetic fields toward HVCs has encouraged us to explore their connection to cloud evolution, kinematics, and survival as they fall through the magnetized Galactic halo. For a reasonable model of the halo magnetic field, most infalling clouds see transverse rather than radial field lines. We find that significant compression (and thereby amplification) of the ambient magnetic field occurs in front of the cloud and in the tail of material stripped from the cloud. The compressed transverse field attenuates hydrodynamical instabilities. This delays cloud destruction, though not indefinitely. The observed ${\boldsymbol{B}}$ field compression is related to the cloud's distance from the Galactic plane. As a result, the observed rotation measure provides useful distance information on a cloud's location.A.G. and T.T. G. acknowledge financial support from the Australian Research Council (ARC) through an Australian Laureate Fellowship awarded to J.B.H. N.M.G. acknowledges the support of the ARC through Future Fellowship FT150100024

Integrated processing of sugarcane bagasse : arabinoxylan extraction integrated with ethanol production.

The authors gratefully acknowledge the funding for “Project POC02_NOV 14 Campbell” from the Lignocellulosic Biorefinery Network (LBNet), funded by the Biotechnology and Biological Sciences Research Council (BBSRC).A proof-of-concept project compared extraction of arabinoxylans (AX) from sugarcane bagasse and wheat bran via alkaline hydrogen peroxide followed by enzyme-assisted extraction with combinations of feruloyl esterases and a xylanase. Bagasse contains comparable amounts of AX to wheat bran, but with a much lower arabinoxylan substitution on the xylan backbone (A:X ratio of around 0.2 compared with 0.6 for wheat bran), hence offering AX products with distinctive functionality and potential end uses. In the current work, bagasse released its AX more readily than wheat bran, and released a wider range of molecular weights. Use of feruloyl esterase and xylanase enzymes on their own or following alkaline peroxide extraction did not enhance AX release substantially; however, the xylanase appeared to be effective at reducing the size of AX molecules, and there is scope to optimise the effects of enzymes to produce specific AX product fractions. As bagasse frequently arises within the context of bioethanol production, integration of AX extraction with ethanol production could allow economic production of a portfolio of AX products, as has been demonstrated in principle for AX co-production in a wheat ethanol plant.PostprintPeer reviewe

Towards energetically viable asymmetric deprotonations : selectivity at more elevated temperatures with C2-symmetric magnesium bisamides

A novel chiral magnesium bisamide has enabled the development of effective asymmetric deprotonation protocols at substantially more elevated temperatures. This new, structurally simple, C2-symmetric magnesium complex displays excellent levels of asymmetric efficiency and energy reduction in the synthesis of enantioenriched enol silane

PCDDs, PCDFs and PCNs in products of microwave-assisted pyrolysis of woody biomass - Distribution among solid, Liquid and gaseous phases and effects of material composition

Microwave-assisted pyrolysis (MAP) of lignocellulosic biomass is a technique that could potentially be used to produce and upgrade renewable energy carriers. However, there is no available information about the formation of dioxins and other organic pollutants in MAP treatment of woody biomass. In this study, MAP experiments were conducted in lab-scale using virgin softwood, bark, and impregnated wood as feedstocks. The non-condensable gas, liquid (fractionated into aqueous and oil phases), and char fractions generated during pyrolysis were collected and analysed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs). The concentrations of PCDDs, PCDFs and PCNs in the pyrolysis products ranged from 0.52 to 43.7 ng kg-1. All investigated compound groups were most abundant in the oil fraction, accounting for up to 68% (w/w) of the total concentrations. The highest PCDD, PCDF and PCN concentrations were found from the pyrolysis of bark, which has relatively high contents of chlorine and mineral matter, followed by impregnated wood, which contains organic and metal-based preservatives. The homologue profiles of all three compound groups were dominated by the less chlorinated homologues. The homologue abundance decreased as the degree of chlorination increased. This trend was observed for all three feedstocks