Hydrometalation of α,β-unsaturated carbonyl compounds provides access to reactive metal enolates, which can then be trapped by a suitable electrophile. The coppercatalysed reductive aldol reaction involves hydrometalation of an α,β-unsaturated carbonyl compound, followed by an inter- or intramolecular aldol reaction. While there have been numerous examples of copper-catalysed reductive aldol reactions reported in the literature, the corresponding reductive Michael reaction has been relatively understudied. Herein, the copper-catalysed reductive Michael cyclisation of substrates containing two α,β-unsaturated carbonyl moieties is described. A range of structurally and electronically diverse substrates were prepared by various different methods. Both α,β-unsaturated ketones and esters underwent cyclisation, in the presence of a copper catalyst, a bisphosphine ligand, and a stoichiometric reductant, to afford 5- and 6- membered carbocyclic and heterocyclic products, with good-to-excellent levels of diastereo- and enantiocontrol. Furthermore, the diastereochemical outcome of these reactions is dependent on the specific reaction conditions used.

Benzenesulfonates, para-substituted with amine, chloride and methyl groups were successfully incorporated into layered double hydroxides of two different compositions, 2:1 Mg-Al LDH and 2:1 Zn-Al LDH. These parent materials were also doped with small amounts of nickel and the differences in the two systems were studied. The hexamethylenetetramine route of layered double hydroxide synthesis was investigated to verify if the mechanism is indeed homogeneous. This included attempting preparation of 2:1 Mg-Al LDH, 2:1 Zn-Al LDH and 2:1 Zn-Cr LDH with two different concentrations of hexamethylenetetramine. The analytical data of the products suggest that the homogeneous precipitation may not be the true mechanism of reaction involved in LDH synthesis by this method.

Master of Science / Department of Chemical Engineering / Larry E. Erickson / Caprolactam (C₆H₁₁NO) is produced in industry primarily as a monomer to be converted to nylon-6 via a polymerization reaction. More demanding purity requirements for nylon-6 have increased the performance requirements of extraction columns in the purification train of caprolactam production. Caprolactam is produced by performing a Beckmann Rearrangement on cyclohexanone oxime followed by a neutralization of the excess oleum post reaction. The resulting side product is ammonium sulfate in water with a residual amount of caprolactam that has to be extracted with benzene from the aqueous ammonium sulfate solution to reduce product losses. The aqueous caprolactam liquor is extracted in another column into benzene which purifies the product from water soluble impurities. The resulting caprolactam dissolved in benzene is back extracted into water where the final purification steps are completed prior to storage. Rotating disk contactor (RDC) extraction columns were invented by Royal Dutch Shell in the early 1950’s. The columns have a rotor in the center that is driven by an electric motor to rotate equally spaced flat disks inside the column. There are equally spaced annulus shaped stators that serve to provide mixing-separation compartments for each of the mounted disks on the rotor. Of the variables to consider for the optimum performance of the extraction in the RDC extraction column is the rotor speed. Rotor speed curves are generated for the 3 RDC extraction columns of the caprolactam purification as well as calculations of the number of theoretical stages for each of the columns based on actual performance data. Benzene is the solvent of choice in this purification process however recent push by environmental groups and agencies as well as tightening regulations have driven a desire to find a more benign alternative to benzene for this process. A review of the research and literature on potential alternative solvents for caprolactam purification is summarized with positives and drawbacks for each possible alternative.

A dissertation submitted to the Faculty of Science for the degree of Master of Science University of the Witwatersrand, Johannesburg / It is well known that chlorinated organic compounds behave as highly toxic substances in the environment. Catalytic hydrodechlorination .... one of the more convenient approaches used to treat chlorinated organic substances with the aim of obtaining compounds with lower or null toxiciy. Further, the selective cleavage of the C-Cl bond plays a key role in processes related to the manufacture of fine chemicals. These reactions can be performed over noble-metal catalysts, either in the gas or liquid phase. (Abbreviation abstract) / Andrew Chakane 2018

Benzene and toluene are known groundwater contaminants . Male CD-I mice were continuously exposed to 0, 31, 166, and 790 mg/ L benzene and 0, 17, 80, and 405 mg/L toluene, respectively, in drinking water for four weeks. Benzene caused a reduction of leukocytes, lymphocytes and erythrocytes, and resulted in a macrocytic anemia. Lymphocyte response to both B- and T-cell mitogens, mixed lymphocyte response to alloantigens, and the ability of cytotoxic lymphocytes to lyse tumor cells were enhanced at the lowest dose of benzene and depressed in the higher dosage animals. Benzene at doses of 166 and 790 mg/L decreased the number of sheep red blood cell (SRBC) -specific plaque-forming cells, the level of serum anti-SRBC antibody, and the activity of interleukin-2 (IL -2). Benzene treatment increased endogenous concentrations of the brain biogenic amines norepinephrine (NE), dopamine (DA) and serotonin (5-HT), and concomitantly, elevated the levels of their respective major metabolites vanillymandelic acid (VMA), 3,4-dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA), in several brain regions . In most cases, the changes were dose related; in several instances, maximum effects occurred at the 166 mg/L benzene dose. Toluene did not adversely affect the hematological parameters. Depression of immune function was evident at the highest dose (405 mg/L), except for mitogeneses. Increased neurochemical concentrations caused by toluene displayed a dose-dependent biphasic manner which began at a dose of 17 mg/L, peaked at 80 mg/L, and decreased at 405 mg/L. Toluene treatment had more selective effects on NE, 5-HT ,VMA and 5-HIAA, than DA, DOPAC and HVA. Both compounds, by increasing concentrations of the hypothalamic NE and its major metabolite VMA, stimulated the hypothalamic-pituitary-adrenocortical axis activity, resulting in an elevated plasma adrenocorticotropic hormone and serum corticosterone which had an additive adverse effect on IL-2 synthesis. Toluene, 325 mg/ L, completely inhibited benzene-induced cytopenia and immunosuppression when it was coadministered with benzene (166 mg/L). The low dose of toluene (80 mg/L ) did not antagonize benzene immunotoxicity. Mice given the combined exposures exhibited raised levels of regional neurochemicals when compared to the untreated controls. Increased levels of monoamine metabolites in several brain regions were greater in the combined treatments of benzene and toluene than when either chemical was used alone. The results of the interaction studies support the known metabolic interaction mechanisms of benzene and toluene.

Thesis (Ph. D. in Biochemistry)--Vanderbilt University, May 2007. / Title from title screen. Includes bibliographical references.

ABSTRACT This study investigated the influence of temperature and humidity on the decomposition efficiency of benzene vapor in a packed-bed UV/TiO2 photocatalytical reactor. The packed-bed annular photocatalytical reactor illuminated by a 15-watt ultraviolet lamp was originally designed for this particular study. Pyrex glass beads coated with Degussa P-25 TiO2 (80 % anatase) were packed in the photocatalytical reactor. The operating parameters investigated in this study included reaction temperature (100-260¢J), water vapor concentration (0-1.58¡Ñ104 mg/m3), retention time (3.1-10.3 sec), and inlet benzene concentration (239-478 mg/m3). Experimental results indicated that the decomposition efficiency of benzene increased with reaction temperature whish was lower than 180¢J, for oxygen content of 21 %, water vapor concentration of 4.69¡Ñ103- 1.58¡Ñ104 mg/m3, and reaction temperature lower then 180¢J. However, the decomposition efficiency of benzene could not be further increased for reaction temperature higher than 180¢J. In addition, the decomposition efficiency of benzene increased with water vapor concentration which was lower than 1.16¡Ñ104 mg/m3. For water vapor concentration higher than 1.16¡Ñ104 mg/m3, the decomposition of benzene could not be further enhanced significantly. In this study, up to 100% of benzene decomposition could be achieved at water vapor concentration of 1.58¡Ñ104 mg/m3 and reaction temperature of 180¢J. Moreover, the decomposition efficiency of benzene increased from 57 to 100% as retention time increased from 3.1 to 10.3 seconds, while decreased from 100 to 65% as benzene concentration increased from 239 to 478 mg/m3. Modified Langmiur-Hinshewood kinetic model was applied to simulate the photocatalytic decomposition of benzene in the annular packed-bed photocatalytic reactor. The simulation of experimental results was successfully developed to describe the reaction rate of benzene for various reaction temperatures (160-260¢J) during the UV/TiO2 photocatalytical reaction process. Furthermore, reaction rate constant (KLH) and adsorption equilibrium constant (Kc and Kw) were functions of reaction temperature, where can the described by the Arrihenius Law. The rate controlling steps were either photocatalytic reaction on the surface adsorption of reaction products from the surface photocatalysts.

Exposure to benzene, a ubiquitous environmental pollutant, has been linked to leukemogenesis, although the mechanism of benzene initiated carcinogenesis remains unclear. It has been proposed that benzene can be bioactivated to toxic metabolites such as 1,4 benzoquinone (BQ), which can alter signalling pathways and affect chromosomal integrity. BQ has been shown to increase the activity of c-Myb, which is an important transcription factor involved in hematopoiesis, cell proliferation, and cell differentiation. The c-Myb protein also increases topoisomerase IIα (topo IIα) promoter activity specifically in cell lines with hematopoietic origin. Topo II is a critical nuclear enzyme that removes torsional strain by cleaving, untangling and religating double-stranded DNA. Since topo II mediates DNA strand breaks, aberrant topo II activity or increased protein levels may increase the formation of DNA strand breaks, leaving the cell susceptible to mutational events. I hypothesize that BQ increases c-Myb activity, which in turn increases topo IIα promoter activity resulting in increased DNA strand breaks. Using luciferase reporter assays in K-562 cells (human chronic myeloid leukemic cells) I confirmed that BQ exposure (25 and 37 µM) caused an increase in c-Myb activity after 24 hours. Contradictory to previous findings, overexpression of exogenous c-Myb or a polypeptide consisting of c-Myb’s DNA binding domain (DBD), which competitively inhibits the binding of endogenous c-Myb to DNA, did not affect topo IIα promoter activity. However, BQ exposure (37 µM for 24 hours) caused a significant increase in topo IIα promoter activity, which could be blocked by the overexpression of the DBD polypeptide. Western immunoblotting analysis did not show any significant increases in topo IIα protein levels in cells exposed to 37 µM BQ for 24 hours. Overall, this study suggests that BQ exposure increases topo IIα promoter activity through the c-Myb signalling pathway and furthers our understanding of BQ-mediated toxicity. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2008-01-02 14:09:00.011

No description available.

The studies described herein relate to the co-ordination chemistry of l,3,5-tris(trifluoromethyl)benzene, Ar(^F)H. The unique combination of steric bulk and a highly electron-withdrawing nature found in the a- bound Ar(^F) ligand has already been exploited to stabilise a variety of unusual main group compounds including the surprisingly air- and moisture-stable diphosphene Ar(^F)P=Par(^F). Other examples are discussed in the introductory chapter, as is the increasingly active area of diphosphene research. Chapter 2 describes the synthesis and structural characterisation of six early σ-Ar(^F) transition metal complexes, Mo(N(^t)Bu)(_2)(Ar(^F))2, Cr(NAd)(_2)(Ar(^F))(_2), [Mo(NAr)(_2)(Ar(^F))Cl-LiCl(dme)](_2), V(Ar(^F))(_2)Cl(thf), V(Ar(^F))(_3)-O -Li(thf)(_3) and Cr(Ar(^F))(_2)(PMe(_3))(_2). The first five of these compounds exhibit the rare phenomenon of weak metal-fluorine interactions, which is discussed in terms of several structural factors such as tilting of the aryl ring towards the direction of the M-F interaction The co-ordination chemistry of the diphosphenes Ar(^F)p=PArF, Ar*P=PAr* and Ar*P=PArF (Ar* = 2,4,6-(^t)BuC6H3) is reported in chapter 3. Ar(^F)p=Par(^F) is shown to displace olefins from a bis(imido)molybdenum centre to generate complexes such as Mo(NR)(_2)(PMe)(_3)(Ti2-ArFp=PArF) (R = tBu, 2,6-iPr2C6H3). The crystal structure of Mo(NtBu)2(PMe)3(Ti2- ArFp=PArF) has been elucidated. Related investigations have focused on the co-ordination mode of the diphosphenes Ar*P=PAr* and Ar*P=PArFwith [Pt(PEt3)Cl2]2/ and a variety of Til-complexes has been spectroscopically observed. The development of phosphorus based analogue of the industrially important olefin metathesis reaction is detailed in chapter 4. The reaction of ArPCl2, [Ar = Ar(^F), Ar* and 2,6-(CF3)2-C6H3 (Ar(^f1)] with the halide abstractor W(PMe3)6 leads to the generation of ArP=PAr via a postulated [W]=PAr phosphinidene intermediate. The unsymmetrical diphosphene ArFp=PAr* has been synthesised analogously from a mixture of ArFPCl2 and Ar*PCl2 with W(PMe3)6- When Ar is small (2,4,6-iPr3C6H2, 2,4,6- Me3C6H2), ArPCl2 reacts with W(PMe3)6 to give three-membered tricyclophosphanes, [ArP](_3) π-bound complexes of the Ar(^F)H ligand have been synthesised via metal vapour synthesis experiments, carried out in collaboration with Prof. F.G.N. Cloke at Sussex University. Chapter 5 describes the preparation of the bis-arene complexes M(T|6-ArFH)2 (M=Cr, V, Nb) and Ru(Ti6-ArFH)(Ti4-ArFH).Full experimental details and characterising data for chapters 2-5 are collected in chapter 6.