Simon W. Breeden

The preparation of high-grade bio-oils through the controlled, low temperature microwave activation of wheat straw

The low temperature microwave activation of biomass has been investigated as a novel, energy efficient route to bio-oils. The properties of the bio-oil produced were considered in terms of fuel suitability. Water content, elemental composition and calorific value have all been found to be comparable to and in many cases better than conventional pyrolysis oils. Compositional analysis shows further differences with conventional pyrolysis oils including simpler chemical mixtures, which have potential as fuel and chemical intermediates. The use of simple additives, e.g. HCl, H(2)SO(4) and NH(3), affects the process product distribution, along with changes in the chemical composition of the oils. Clearly the use of our low temperature technology gives significant advantages in terms of preparing a product that is much closer to that which is required for transport fuel applications.

Direct Microwave-Assisted Hydrothermal Depolymerization of Cellulose

A systematic investigation of the interaction of microwave irradiation with microcrystalline cellulose has been carried out, covering a broad temperature range (150 → 270 °C). A variety of analytical techniques (e.g., HPLC, (13)C NMR, FTIR, CHN analysis, hydrogen-deuterium exchange) allowed for the analysis of the obtained liquid and solid products. Based on these results a mechanism of cellulose interaction with microwaves is proposed. Thereby the degree of freedom of the cellulose enclosed CH2OH groups was found to be crucial. This mechanism allows for the explanation of the different experimental observations such as high efficiency of microwave treatment; the dependence of the selectivity/yield of glucose on the applied microwave density; the observed high glucose to HMF ratio; and the influence of the degree of cellulose crystallinity on the results of the hydrolysis process. The highest selectivity toward glucose was found to be ~75% while the highest glucose yield obtained was 21%.

Use of green chemical technologies in an integrated biorefinery

A new concept is demonstrated for an integrated close to zero waste wheat straw biorefinery combining two novel green technologies, CO2 extraction and low temperature microwave pyrolysis, to produce a variety of products, including energy and CO2 which can be internally recycled to sustain the processes. CO2 adds value to the process by extracting secondary metabolites including fatty acids, wax esters and fatty alcohols. Low temperature microwave pyrolysis (<200 °C) is shown to use less energy and produce higher quality oils and chars than conventional pyrolysis. The oils can be fractionated to produce either transport fuels or platform chemicals such as levoglucosan and levoglucosenone. The chars are appropriate for co-firing. The quality of the chars was improved by washing to remove the majority of the potassium and chlorine present, lowering their fouling potential. The economic feasibility of a wheat straw biorefinery is enhanced by intergrating these technologies.

Microwave-mediated pyrolysis of macro-algae

Macro-algae (seaweed) is an abundant and, for the most part, under-utilised resource. This study has shown that microwave (MW)-mediated pyrolysis of seaweed occurs at extremely low temperatures and produces chemical rich bio-oils which are rich in aromatics, sugars and other high value chemicals.

Microwave heating for rapid conversion of sugars and polysaccharides to 5-chloromethyl furfural

A range of carbohydrates has been rapidly and selectively converted to 5-chloromethyl furfural using microwave heating in a biphasic reaction system with a range of organic solvents. Fructose and inulin were especially effective for production of this valuable bio-platform molecule, with yields of >70% obtained in 15 minutes under microwave heating. Yields from cellulose were dramatically increased with ball mill pre-treatment, this being associated with a reduction in polysaccharide crystallinity.

Expanding the potential for waste polyvinyl-alcohol

Expanded polyvinyl-alcohol (PVA) was successfully prepared using a similar process to that of starch expansion. The addition of an iodine solution was necessary to facilitate expansion and led to surface areas of up to 143.1 m2 g−1. The use of recycled material from LCD screens required no additional iodine and produced an expanded material with high surface areas (95.0 m2 g−1) and total pore volumes (0.56 cm3 g−1). The PVA–iodine complexes were found to better mimic the interactions between amylose and amylopectin in starch expansion.

6-O-Demethylation of the thevinols with lithium aluminium hydride: Selective demethylation of a tertiary alkyl methyl ether in the presence of an aryl methyl ether

In the pursuit of ring-constrained analogues of buprenorphine, we wished to prepare 6-O-demethylated analogues of the thevinols and orvinols. Previously it had been disclosed that lithium aluminum hydride (LAH) in THF containing a chlorinated solvent could achieve this transformation. Here we report the results of our work with LAH in the non-coordinating solvent toluene. In refluxing toluene, the selective 6-O-demethylation of thevinols could be achieved with no 3-O-demethylation being observed. It appears that a C(20)−OH or C(20)−NH2 group is needed on the substrate for this hydrogenolysis to proceed.

Ring constrained analogues of the orvinols : The furanomorphides

A series of furanomorphides were synthesised as ring-constrained analogues of buprenorphine and related orvinols. Evaluation in binding and functional assays has shown that the furanomorphides have reduced efficacy at the mu opioid receptor compared to the orvinols.

Acid catalysed rearrangements of the thevinols: The mechanism of furanocodide formation

Abstract The acid catalysed rearrangement of thevinols has been shown to proceed with retention of configuration at C-7 and therefore not via a sp2 hybridised centre at C-7 as had been proposed previously. Additionally a single diastereomer possessing the 20[ R ] configuration is formed in the rearrangements of the two diastereomeric i -propyl alcohols.

Green(er) Pharmacy

Although the issue of pharmaceuticals in the environment has been known for many years in some quarters, it has recently come to the attention of the general public in a much more substantive way. This has led to a growing body of research on environmental risk assessment and the environmental classification of drugs, as well as on the stewardship of drugs post-manufacturing (Kummerer 2007). As with any chemical-containing article it is important that we understand, control, avoid or minimise the impact of the drugs entering the environment, and the deliberately high biological activity of active pharmaceutical ingredients (APIs) makes this especially important. There are many authoritative publications on the impact of pharmaceuticals on the environment post consumer use, and so these issues will not be addressed in any significant way in this chapter, but very little work has been carried out on determining the environmental impact of pharmaceuticals prior to administration to the patient.