No / Mechanochemistry provides a method to reduce or eliminate the use of solvents by carrying out reactions through the grinding of neat reagents. Until recently a significant drawback of this form of synthesis has been the limited ability to scale up. However, it has been shown that twin screw extrusion (TSE) may overcome this problem as demonstrated in the continuous synthesis of co-crystals, Metal Organic Frameworks (MOFs) and Deep Eutectic Solvents (DES), in multi kg h−1 quantities. TSE has provided a means to carry out mechanochemical synthesis in a continuous, large scale and efficient fashion, which is adaptable to a manufacturing process. Herein, we highlight the potential of this technique for organic synthesis by reporting four condensation reactions, the Knoevenagel condensation, imine formation, aldol reaction and the Michael addition, to produce analytically pure products, most of which did not require any post synthetic purification or isolation. Each reaction was carried out in the absence of solvents and the water byproduct was conveniently removed as water vapour during the extrusion process due to the elevated temperatures used. Furthermore, the Knoevenagel condensation has been studied in detail to gain insight into the mechanism by which these mechanochemical reactions proceed. The results point to effective wetting of one reactant by another as being critical for these reactions to occur under these reaction conditions. / EPSRC EP/L019655/1

Sodium borohydride reduces alkyl halides and their related tosylate derivatives in the order primary > secondary > tertiary, while the relative order of leaving-group ability is Ts⁻ ≥ I⁻ > Br⁻ > > Cl⁻. The yields obtained ranged from 90-100% for most simple, primary and secondary iodides, bromides, and tosylates, to 1-2% for the tertiary compounds. As in the case of the more reactive lithium aluminum hydride, the. reduction is believed to occur by an S_N2 displacement on carbon. The reduction of a series of para-substituted benzyl chlorides revealed that the electronic effects of groups ranging from p-methoxy to p-nitro had a rather small effect on the rate of reduction. Aryl halides arc reduced by sodium borohydride in yields dependent upon the particular halogen involved, the presence of other ortho and para electron-withdrawing substituents, and the reaction temperature, among other factors. The same relative order of dehalogenation displayed by the alkyl halides was found. Polyhalomethanes such as carbon tetrachloride react with sodium borohydride to give the monohydro and dihydro compounds as the major products, the former predominating. The exact mechanism of the reduction is as yet undetermined, as water apparently catalyzes the reaction in some unknown manner. / Master of Science

The expanding role of electronic nose instrumentation, as a quality-monitoring tool for food-packaging materials, is examined and reviewed. The food industry is interested in determining the applicability of using an electronic nose for odor analysis of retained printing solvent levels in packaging. Three electronic nose systems were optimized for this application and their performance assessed. These include the FOX 3000, the Cyranose 320, and the QMB6. Response surface methodology was used to generate 2nd order models of sensor response as a function of system and experimental parameters for the three electronic nose systems. Forty-seven of 50 sensor models generated were found to be significant at an a-level of 0.05. Optimum settings, that allowed adequate signals to be obtained for the full range of examined retained solvents levels, were selected for the remaining work using these models. Performance analyses of these systems, which use three leading sensor technologies, showed that the conducting polymer sensor technology demonstrated the most discriminatory power. All three technologies proved able to discriminate among different levels of retained solvents. Each complete electronic nose system was also able to discriminate between assorted packaging having either conforming or non-conforming levels of retained solvents. Each system correctly identified 100% of unknown samples. Sensor technology had a greater effect on performance than the number of sensors used. Based on discriminatory power and practical features, the FOX 3000 and the Cyranose 320 were superior. The results indicate that electronic nose instrumentation can be used as a complimentary discriminatory tool in quality control. / Master of Science

Microcosms were constructed from aquifer sediment samples taken from an actively degrading chlorinated solvent contaminated site located in Virginia Beach, Virginia. The objective of this study was to determine if and how the addition of cyclodextrin (CD) affects reductive dechlorination of chlorinated ethenes. After chlorinated solvent degradation rates were established in anaerobic and aerobic microcosms, 100 mg/L of CD solution was added for a period of 21 days. CD was then removed after 26 days to simulate the degradation response of the aquifer in a post CD injection environment. Degradation rates were determined by analyzing PCE, TCE, and cis-DCE concentration data over the various phases of the experiment. Results from this study indicated that chlorinated solvent degradation could be either impaired or facilitated by the addition of CD. CD appeared to stimulate one anaerobic microcosm (IY-2c) where daughter production had not previously occurred. The activity of this microcosm was greatly enhanced by the addition of CD (0 uM/day to 13.89 uM/day). However, biotransformation of PCE in another anaerobic microcosm in which reductive dechlorination was occurring, ceased after the addition of CD (IY-1a). In a third group of microcosms the rate and extent of reductive dechlorination was greatly enhanced by the addition of CD. The effect of adding CD was also found to be highly dependent on the redox conditions in the microcosm, specifically if the conditions were strongly reducing. The most active microcosms, found in the Aerobic Group, also had the lowest ferrous iron concentrations (3.57 mg/L for BY-1a, 2.25 mg/L for BY-1b, and 0.41 mg/L for BY-1c). The microcosm (IY-2b) that showed no daughter production had the highest level of ferrous iron (44.22 mg/L). This study presents a qualitative approach to the affect of CD on MNA. / Master of Science

Laboratory microcosm experiments were conducted to assess the potential for biostimulation and bioaugmentation as source reduction measures in support of a monitored natural attenuation remedial strategy at Naval Amphibious Base (NAB) Little Creek. Previous work with laboratory microcosms conducted under simulated natural (unamended) conditions has demonstrated that indigenous dehalorespirators were capable of partial dechlorination of tetrachloroethene (PCE) to cis-dichloroethene (cis-DCE). This study attempts to achieve complete reductive dechlorination with amendments to static microcosms to test the hypotheses that nutrient-limited or microorganism-limited conditions exist in aquifer sediments obtained from the site. The enhanced bioremediation experiments were comprised of nutrient-amended microcosms receiving additions of electron donors, mineral medium, or anaerobic digester supernatant, and dechlorinating culture-amended microcosms were inoculated with a culture capable of transforming PCE to ethene. Reductive dechlorination in the nutrient-amended microcosms proceeded to cis-DCE over a 260-day study period, at slightly higher rates than in experiments conducted with aquifer sediments from the same location under natural conditions. Inoculation of aquifer sediments with a small amount of dechlorinating culture initiated rapid transformation of PCE to vinyl chloride (VC) by day 18 of the study. Zero-order rates of PCE dechlorination in unamended, propionate-, formate-, mineral medium-, digester supernatant-, and dechlorinating culture-amended microcosms were 0.24, 0.750, 1.30, 0.339, 0.177, and 1.75 µM/day, respectively. The results of this study suggest that an engineered biostimulation approach alone may not be as beneficial for PCE source reduction at NAB Little Creek, than bioaugmentation with competent dehalorespirators, along with the inclusion of supplemental nutrients which would be available to stimulate dechlorination activity of both indigenous and introduced microorganisms. / Master of Science

Monitored natural attenuation (MNA) has been widely used as a remedial strategy, acknowledged by the EPA as the most appropriate technology for cost effective remediation under certain site conditions. Despite the widespread use of MNA, empirical methods are lacking to evaluate the sustainability of MNA at a site. The objective of this thesis is to investigate the natural attenuation capacity (NAC) as a quantitative metric for evaluating the sustainability of MNA for contaminants in groundwater systems. Five DoD sites were selected for this study, where the common thread between the sites is the existence of a mature chlorinated ethene groundwater plume and the use of MNA as the long-term remediation strategy. Constituent specific NAC values were quantified and statistically examined to determine past performance of MNA at the sites. A conceptual decision model was developed to be a framework of the statistical tools demonstrated in this thesis. Analyzing MNA sustainability at a site can be separated into two components; past performance of natural attenuation and evaluation of current MNA parameters. The former is the focus of this thesis where NAC is the screening metric and the temporal trend in the rate of natural attenuation being evaluated. Within the conceptual decision model, the use of NAC as a screening tool in combination with a specific analysis of MNA parameters allows engineers, regulators, and decision makers to clearly determine whether MNA at a site is sustainable and whether site specific remediation goals will be met. / Master of Science

Hydrocarbon solvents are widely used in the production of paints, adhesives, dyes, polymers, plastics, textiles, printing inks, agricultural products and pharmaceuticals. While the neuropathic potential of aliphatic solvents was shown in the 1970s, little is known about the neuropathic potential of aromatic solvents. The present study examines such solvents, 1,2-diethylbenzene (DEB) and its metabolite 1,2-diacetylbenzene (DAB), to determine (a) the neuropathological evidence for peripheral neuropathy in rodents treated with 1,2-DAB, (b) the neurochemical basis for the neurotoxic properties of this compound, and (c) the structural requirements for nerve fiber damage. The properties of 1,2-DAB and 2,5- hexanedione (HD) are also compared. A key finding of this thesis is that 1,2-DAB induces a 2,5-HD-like pattern of nerve damage of motor and sensory axons with focal swellings containing neurofilaments. Whereas nerve damage begins distally in 2,5-HD intoxication, with 1,2-DAB treatment axonal swellings begin intraspinally and in the proximal ventral roots of motor nerve fibers. A second key finding is the reactivity of 1,2-DAB with amino acids, notably lysine, a property that is shared with 2,5-HD. 1,2-DAB and 2,5-HD react with amino acids and proteins to form blue and yellow chromophores, respectively. Relative to 2,5-HD, 1,2-DAB is three orders of magnitude more reactive in forming high-molecular-weight species. 1,2-DAB treatment of spinal cord slices in vitro and intact sciatic nerve in vivo showed that neurofilament proteins react more readily than beta-tubulin. The heavy and medium subunits of neurofilament protein were more reactive than the light subunit. The reactivity of these four axonal proteins was in proportion to their lysine content. These data are consistent with selective accumulation of neurofilaments in giant axonal swellings. In summary, these studies have shown a relationship between the chromogenic and neuropathic properties of two gamma-diketones, one aliphatic (2,5-HD) the other aromatic (1,2-DAB). These studies are relevant to occupational and public health for at least two reasons. First, urinary chromogens generated by neuropathic aliphatic and aromatic hydrocarbons could serve as biological markers of exposure to solvents with neuropathic potential, and second, other chromogenic solvents (such as tetralin) should be considered for neuropathic potential. / Graduation date: 2002

This work seeks to develop new solvents for environmentally benign chemical synthesis. Switchable solvents are a new class of compounds that change properties upon the application of some stimulus such as heat, UV light, or pH. We have developed the use of a new solvent, thiirane oxide, that has chemical properties similar to DMSO. Thiirane oxide, however, undergoes facile decomposition to two gases at temperatures above 100 C, which is much lower than the temperature required for removing DMSO. Thus we have a solvent with excellent solvation properties, but with a built-in switch for easier removal. However, thiirane oxide leaves behind sulfurous products which make the reverse reaction to reform the solvent unfeasible. We are also developing the use of another solvent, piperylene sulfone, which is expected to have good solvent properties, yet with decomposition products that can be reacted to reform the solvent. This thesis also details the work to date on piperylene sulfone. Gas-expanded liquids (GXLs) also show promise as a new reaction medium. In order to design solvent systems that take full advantage of this medium, we desire to understand the microstructure of these fluids. To that end, we are using cage reactions to probe solute-solvent and solvent-solvent interactions at the molecular level. This thesis discusses the current research on using cage reactions to probe the structure of GXLs.

Developing greener, more efficient, and less energy-intensive processes will lead the chemical industry into a more sustainable future. Gas-expanded liquids (GXLs) form a unique class of environmentally benign and tunable solvents that can be used in a variety of applications. Through the series of studies presented in this thesis, we have investigated both the properties and applications of GXLs. We have developed a more complete understanding of the interactions between the gas, the organic liquid, and solutes at the molecular level through kinetic and solvatochromic experiments. We have examined a Diels-Alder reaction and an SN2 reaction and have described the kinetic results in terms of intermolecular interactions and local composition enhancement. We have also demonstrated the use of Organic-Aqueous Tunable Solvents, a special case of GXLs, to recycle homogeneous hydroformylation catalysts. The results of this research can be used to guide future applications of GXLs as green reaction solvents.

Dissolved and Colloidal substances (DSC) and metals are released from woodduring thermomechanical pulp (TMP) production. These components have atendency to accumulate in process waters, as the water circulation systems inintegrated paper mills are closed. Disturbances such as pitch depositions in thepaper machine (pitch problems), specks in the paper, decreased wet and drystrength, interference with cationic process chemicals, and impaired sheetbrightness and friction properties appear when DSC are present. Transition metalions such as manganese results in higher consumption of bleaching chemicals(hydrogen peroxide) and lowers the optical quality of the final product, andaddition of complexing agents, such as EDTA or DTPA, to prevent this is needed.The never ending trends to decrease water consumption and increase processefficiency in pulp and paper production emphasizes that it is very important bothto know the effects of wood substances on pulping and papermaking and to beable to remove them in an efficient way. From a biorefinery point of view, DSCcomponents can be promising renewable raw materials for biofuels, bio‐basedchemicals and materials.In this thesis, a new approach using induced air flotation (IAF) without a cationicpolyelectrolyte addition for the removal of pitch and metal ions from mechanicalpulp mill process waters is presented. The induced air flotation of different processwaters is facilitated by the addition of a chelating surfactant and different foamingagents. The influence of the pH value, temperature and foaming agentconcentration on the flotation efficiency has been investigated. The investigations presented show that the disturbing components can be removed from TMP presswater to a high extent. A 90% decrease in turbidity and a 91% removal of lipophilicextractives (i.e. resin and fatty acids, triglycerides, sterols and steryl esters) fromunbleached and bleached TMP process water can be obtained by addition of acationic surfactant as foaming agent during flotation. Lower amount of foamingagent is needed to purify efficiently bleached TMP process water, than unbleached.Additionally, fibres located in TMP press water are not removed with the foamfraction but purified. A retained concentration of hydrophilic extractives (i.e.hemicelluloses and lignans) in the process water indicates that the flotation isselective. Moreover, by introduction of a new recoverable surface activecomplexing agent, a chelating surfactant, manganese ions in the form of chelatescan be successfully removed from the pulp fibres and separated from the processwater in the same flotation process. Furthermore, from the purified unbleachedTMP process water a 90% recovery of dissolved hemicelluloses by anti‐solventprecipitation was obtained.The findings presented above indicate new possibilities for the internal watercleaning stage to decrease DSC emissions to recipient and for recovery of valuableraw materials from purified process water if flotation technology is applied in anintegrated mechanical pulp mill. / FORE