The gas-liquid critical temperatures of the ten binary mixtures that can be chosen from nitrogen, carbon monoxide, argon, oxygen, and methane have been measured with a precision of 0.10 K. The critical temperature is almost a linear function of composition for the mixtures. The maximum deviation ranges from 30 K for mixtures of nitrogen and methane, to 0.20 X for argon and nitrogen. A second order theory of solutions applied to these results, is used to make deductions about the three distinct intermolecular potentials which occur in a binary mixture. These deductions are compared with those made by applying the same theories of solution to the excess thermodynamic functions of mixing. The agreement is good when the sizes and energies of the molecules are similar, for example, for mixtures of argon and oxygen, and of nitrogen and carbon monoxide. POT these mixtures it is clear that the energy parameter for the cross interaction is not given by the geometric average of the parameters for the pure components. The theories are unsatisfactory if the, sizes of the pure components differ by more than 10 %. PART II. A Burnett apparatus has been designed for the measurement of the second virial coefficient of the pure substances and mixtures of Part I, at temperatures down to their normal boiling points. Volumes and temperatures are controlled, and a series of pressure ratios are measured. It is shown that the precision of B is sensitive to the numerical value of the ratio of successive pressure measurements, and that it is a maximum when this ratio is in the range 1•4 - 2.2. An accurate manometer has been constructed. It measures pressures in the range 6 - 85 cm. Hg., with an associated standard deviation of about 2 microns.

This thesis describes some work on the thermal decomposition of acetylene and vinylacetylene. The Introduction surveys the earlier work on the pyrolysis of these and related compounds and describes also some of the important properties of carbons formed in both pyrolytic systems and flames. Special attention is paid to the ways in which the properties of pyrolytic carbons depend on the conditions under which carbon formation occurs, and the various mechanisms by which carbon may be formed are discussed. The Experimental Section describes both the static system used for the study of the pyrolysis of acetylene and vinylacetylene, and also the gas chromatographic, electron diffraction and radio-assay techniques employed for the analysis of the reaction products. In the Results Section data are presented on the reactions of pure vinylacetylene and of vinylacetylene/acetylene mixtures. At sub-atmospheric pressures, and temperatures below about 500°C, the pyrolysis of vinylacetylene follows second-order kinetics and results mainly in the formation of polymers, the overall activation energy of the reaction being 28 kcal. mole.-1. At higher temperatures, however, the pyrolysis is complex and results in the formation of large amounts of acetylenes ethylene, hydrogen, methane and soot. Only traces of diacetylene and methylacetylene can be detected among the products. Studies of the pyrolysis of mixtures of vinylacetylene with 14C-acetylene show that vinylacetylene is not an intermediate in the formation of surface carbon from acetylene. The Results Section presents data also on the variation with temperature of the properties of the carbonaceous deposits formed in these reactions. The steady increase with temperature of the atomic carbon:hydrogen ratio contrasts with the more complex dependence of crystallite size on temperature. In the Discussion Section these results are related to previous data, and a critical analysis of the possible reaction steps which may be involved leads to a postulated mechanism which accounts for the principal features of the pyrolysis of both compounds. The variations with temperature of formation of the dimensions of the carbon crystallites are accounted for in terms of the relative rates of carbon deposition and ordering, but it is shown that simple quantitative relationships between the crystallite diameter and the atomic carbon: hydrogen ratio are unlikely to be valid except under very restricted conditions. The importance of these results in relation to the overall mechanism of carbon formation is also discussed and it is concluded that vinylacetylene is not an important intermediate in the formation from acetylene of either diacetylene, methylacetylene or carbon. Finally, suggestions are made for possible lines of future work.

This thesis describes an investigation into the thermal and oxidative degradation of polyethylene and into the influence on these reactions of the presence of bromine-containing additives in the atmosphere surrounding the polymer. The thermal degradation reaction was studied at both 400 and 430°C and the oxidation reaction was studied at 430°C In the Introduction a survey is made of previous studies of the thermal and oxidative degradation of polyethylene and other organic polymers. Work on the influence of bromine-containing additives on the flammability of organic polymers is also discussed together with relevant work on the combustion of volatile hydrocarbons. The techniques and apparatus used are described in the Experimental Section. A static system was used which incorporated a reaction vessel designed specifically for the introduction of solid polyethylene samples into the system. The reactions were followed by pressure change and loss of weight measurements and by analysis of the volatile products of the reactions. The Results Section gives details of the kinetic and analytical results obtained. Hydrogen bromide reduces the rate of loss of weight of polyethylene during thermal degradation at both 400 and 430°C whereas this additive increases the rate of breakdown in the gas phase of the volatile products formed from the polymer. The rate of degradation of polyethylene was also found to be reduced by those organic bromides which decomposed to yield hydrogen bromide under the experimental conditions used. Hydrogen bromide reduced the rate of loss of weight of polyethylene during oxidation whereas the rate of oxidation of the volatile products formed from the oxidising polymer was increased by this additive. The experimental results are critically examined in the Discussion. The reduced loss of weight of the polymer during both thermal and oxidative degradation in the presence of hydrogen bromide is discussed in the light of the possible physical and chemical effects of this additive. On the basis of a proposed chain mechanism for the thermal degradation of polyethylene, the influence of hydrogen bromide is attributed to an increased rate of chain termination in the presence of this additive. It is suggested that a similar effect may also contribute to the observed reduction of the rate of loss of weight during oxidation of the polymer. Finally the relevance of this work to the influence of additives on the flammability of polyethylene is discussed.

In the introduction some of the mere important aspects of cancer chemotherapy are reviewed, special emphasis being placed on the chemistry and design of drugs derived from nitrogen mustards and from ∝ -halo-ketones. Some enol carbamates, representing a class of compound not described in the literature so far, have been synthesised from 2-chloro-2-phenylacetophenone, via the enol dhloroformate. Such enol carbamates, derived from ∝ -halo-ketones, are expected to undergo enzymic cleavage in vivo, to yield two cytotoxic units. Syntheses are described of a range of compounds containing a carbamate bridge, linking the amino group of N,N-di-(2-dhloroethyl)-p-pbenylenediamine (or the m-isomer) to the hydroxyl function in the following types of compounds: (i) alcohols, (ii) phenols, (iii) hydroxyaromatic acids and esters, (iv) hydroxy-amino-acids (sorine, threonine, tyrosine) and their derivatives. Several model compounds analogous to these nitrogen mustard derivatives have been synthesised for possible use as "enzymic potentiators". Some other derivatives of N,N-di-(2-chloroethyl)-p-phenylenediamine (and of its m-analogue), containing an amido or an imido linkage, have been synthesised by acylation of the amino group with a variety of acyl chlorides.

Polylactide (PLA) as a biodegradable and biocompatible polymer has had a lot of interest as an alternative to petrochemical-based polymers. PLA is synthesised from bio-renewable resources by the ring-opening polymerisation (ROP) of cyclic monomer lactide (LA). A variety of polymers can be synthesised with variations of microstructure and molecular weight. Initiators currently utilized in industry exhibit little stereocontrol, allowing a high demand for active stereoselective initiators. This thesis will discuss the synthesis of initiators, as well as investigations into co-polymerisations with other monomer. Chapter 1 initially introduces the synthesis of PLA, with a detailed discussion of possible polymer architectures along with previously reported initiators will be discussed and their influences on the polymeric physical properties. To date, the formation of lactide co-polymers and investigations into the morphology and microstructures of the resulting co-polymers. Chapter 2 describes a series of Group 4 isopropoxide complexes using inexpensive, commercially available ligands. Interesting coordination chemistry of such complexes will be discussed and their potential as initiators in the ROP of PLA will be investigated with kinetic studies to probe the control of architecture and molecular weights. Chapter 3 concerns the formation of lactide co-polymers using inexpensive, commercially available co-monomers. The study of block co-polymers by either one-pot or sequential polymerisations will be assessed and subsequent thermal properties analysed. Chapter 4 initially details the synthesis of cyclic monomers for lactide co-polymerisations. The ability to synthesise random or alternating lactide co-polymers in a one-pot synthesis will be probed with a variety of different cyclic monomers with varying stoichiometries and their properties examined. Chapter 5 reports the overall conclusions of the thesis and what work should be carried forward. Chapter 6 provides details analytical techniques, procedures and characterisations used throughout this thesis.

This thesis is concerned with exploring novel applications of N-oxides as organocatalysts. Specifically, aromatic N-oxides have been successfully implemented as catalysts within the Baeyer-Villiger oxidation of α,β-unsaturated ketones and electrophilic aromatic bromination reactions. Chapter 1 provides a review of the current applications of N-oxides, highlighting their use as organic oxidants, neutral ligands and in particular organocatalysts. These roles exploit several key features of the N-oxide, including the intrinsic weakness and polarity of the N→O bond, their Lewis basicity and ability to function as hydrogen bond acceptors. As organocatalysts, these species have predominantly been utilised as nucleophilic catalysts, however their potential to act as hydrogen bond catalysts represents an emerging area of interest. Chapter 2 describes the development of an organocatalysed Baeyer-Villiger oxidation, for which N-oxides and carboxylates have been identified as suitable catalysts. The optimised protocol, which employs DMAP as the pre-catalyst, was applied to a wide range of saturated and more specifically α,β-unsaturated ketones, with enhanced reaction rates and/or chemoselectivities achieved in the majority of cases. From extensive mechanistic studies, it is proposed that the N-oxide functions as a hydrogen bond acceptor; facilitating concerted proton transfer within the addition step. The unique role of the catalyst allowed for predictions to be made about the rate determining step of the oxidations performed. A series of by-products obtained from the over oxidation of (E)-4-phenyl-3-buten-2-one were characterised and the mechanistic pathway for their formation has been fully elucidated. Development of the reaction conditions for the selective formation of many of these species is also provided. Additionally, the novel reactions of 3-(4-methoxyphenyl)but-3-en-2-one are examined. Chapter 3 details investigations into the applicability of the novel, relatively bench stable formate ester, (formyloxy)(phenyl)methyl acetate, as a formylating reagent. A high yielding and operationally simple procedure for the synthesis of this formate ester from commercially available, inexpensive (E)-4-phenyl-3-buten-2-one is described in Chapter 2. A solvent and catalyst free protocol has been developed for the N-formylation of various amino species including primary and secondary (aliphatic and aromatic) amines and an amino acid ester as well as the O-formylation of alcohols. Demonstrating its synthetic utility, the developed methodology was applied to the one-pot synthesis of an isocyanide from the corresponding amine as well as the N-formylation of an unprotected amino acid under aqueous conditions. Chapter 4 outlines preliminary studies into the application of N-oxides as nucleophilic catalysts for electrophilic aromatic bromination reactions with elemental bromine. The development of novel methodology for the 4-picoline N-oxide catalysed regioselective monobromination of tert-butylbenzene is discussed, for which a reactive N-oxide bromine complex is thought to be generated in situ. Conditions have also been established for a KI promoted system, with IBr proposed as the catalytic species. Both methodologies allow for selective electrophilic aromatic bromination of toluene in the light without competitive benzylic bromination. Chapter 5 contains experimental procedures and compound characterisation data for Chapters 2-4 inclusive.

Addition of 1,3,4,5 tetramethylimidazol 2 ylidene (IMe4) to Ru(PPh3)3HCl (in the presence of H2) or Ru(PPh3)4H2 gave the all trans isomer of Ru(IMe4)2(PPh3)2H2, whereas 1,3 diethyl 4,5 dimethylimidazol 2 ylidene (IEt2Me2) reacted with Ru(PPh3)4H2 to form cis, cis, trans Ru(IEt2Me2)2(PPh3)2H2. The previously reported trans dihydride complex, Ru(IMe4)4H2, was synthesized by a new method involving the reduction of Ru(IMe4)4Cl2 with KC8/H2. CO reacted with Ru(IMe4)2(PPh3)2H2 to give a mixture of Ru(IMe4)2(PPh3)(CO)H2, Ru(IMe4)(PPh3)2(CO)H2 and Ru(IMe4)2(CO)3; Ru(IEt2Me2)2(PPh3)2H2 reacted in a similar manner, although more slowly, allowing isolation of the monocarbonyl species Ru(IEt2Me2)2(PPh3)(CO)H2. Insertion of CO2 into one of the Ru H bonds of Ru(NHC)2(PPh3)H2 (NHC = IMe4, IEt2Me2) generated mixtures of major and minor isomers of the κ2 formate complexes Ru(IMe4)2(PPh3)(OCHO)H and Ru(IEt2Me2)2(PPh3)(OCHO)H. The hydridic nature of Ru(NHC)2(PPh3)2H2 (NHC = IMe4, IEt2Me2) was apparent by their reactivity toward MeI, which gave [Ru(IMe4)2(PPh3)2H]I, Ru(IEt2Me2)2(PPh3)HI, [Ru(IEt2Me2)2(PPh3)2H]I, and Ru(IEt2Me2)(PPh3)2HI. H/D exchange of Ru(IMe4)2(PPh3)2H2 with C6D6 (elevated temperature) or D2 (room temperature) gave Ru(IMe4)2(PPh3)2HD and Ru(IMe4)2(PPh3)2D2. Addition of P(C6D5)3 to a solution of the dihydride precursor resulted in the rapid substitution of the PPh3 ligands. Addition of D2 to Ru(IMe4)4H2 gave Ru(IMe4)4HD and Ru(IMe4)4D2. The dihydride complex activated benzene and toluene at room temperature and could catalyse H/D exchange between the two solvents. The catalytic activity of Ru(NHC)2(PPh3)2H2 (NHC = IMe4, IEt2Me2) for the reduction of CO2 by pinacolborane has been contrasted with that of the all NHC analogue Ru(IMe4)4H2. Despite the latter being substitutionally inert, it affords a far more active catalyst and yields a wider array of reduction products. These findings suggest that access to vacant coordination sites on the metal centre may not be a prerequisite for catalytic activity in the reduction of CO2 and that, in this case, the presence of a highly nucleophilic hydride ligand may be of greater relevance. The dihydridoborate hydride complexes Ru(IMe4)2(PPh3)(H2Bpin)H and Ru(IEt2Me2)2(PPh3)(H2Bpin)H were isolated by reaction of pinacolborane with Ru(NHC)2(PPh3)2H2 (NHC = IMe4, IEt2Me2) and were structurally characterized.

This thesis describes the synthesis and stoichiometric/catalytic reactivity of Ru and Rh N-alkyl substituted N-heterocyclic carbene complexes. In an effort to make new Ru(NHC)x (x = 1-4) complexes, a range of Ru halide precursors, including Ru(DMSO)4Cl2 and Ru(PPh3)3Cl2, were combined with N-alkyl substituted carbenes. Treatment of Ru(PPh3)3Cl2 with IiPr2Me2 or ItBu resulted in C-H activation of the NHCs to form Ru(IiPr2Me2)2(IiPr2Me2’)Cl and Ru(ItBu’)(PPh3)2Cl respectively. C-H activation also took place with Ru(DMSO)4Cl2 and IEt2Me2 to give Ru(IEt2Me2’)(DMSO)3Cl. This underwent substitution with 13CO to afford the tricarbonyl complex Ru(IEt2Me2’)(CO)3Cl, and with PPh3 to give the bis-phosphine species Ru(IEt2Me2’)(PPh3)2Cl. Attempts to generate Ru(IEt2Me2’)(PPh3)2Cl by an alternative reaction of IEt2Me2 with Ru(PPh3)3Cl2 proved successful with two equiv. of carbene, although with four equiv. of NHC, the dichloride complex Ru(IEt2Me2)4Cl2 was produced. Upon turning to Ru(PPh3)3HCl, our group observed that the non-metallated tetrakiscarbene species [Ru(NHC)4H]+ are formed instead where alkyl = Me, Et and iPr. The reactivity of these species towards a range of amine boranes were investigated. [Ru(IMe4)4H]+ was able to catalyse the dehydrogenation of H3B.NMe2H to form the dimeric species [H2B-NMe2]2 and also catalytically hydrogenate a series of organic substrates such as ketones, nitriles, alkynes and alkenes at 323 K. Treatment of Rh(PPh3)4H with the six-membered ring NHCs 6-Me and 6-Et afforded the rhodium mono-carbene hydride complexes Rh(6-NHC)(PPh3)2H, in each case as a mixture of cis- and trans-phosphine isomers. Treatment of Rh(PPh3)3(CO)H with 6-Et did not afford a hydride complex but instead gave the CO bridged dimer Rh(PPh3)2(CO)2Rh(PPh3)(6-Et). Reaction of Rh(6-Me)(PPh3)2H with Et3N.3HF gave only the trans-isomer of the bifluoride complex Rh(6-Me)(PPh3)2(FHF), whereas the 6-Et hydride precursor gave Rh(6-Et)(PPh3)2(FHF) as a mixture of cis- and trans-phosphine isomers. 19F NMR Magnetization transfer and chemical exchange experiments revealed intra- and intermolecular F exchange in both of these bifluoride compounds. Treatment of 6-Rh(NHC)(PPh3)2H (NHC= 6-Me, 6-Et, 6-iPr) with CF3CF=CF2 gave the corresponding fluoride complexes Rh(6-NHC)(PPh3)2F. The 6-iPr derivative reacted slowly with H2 to partially reform Rh(6-iPr)(PPh3)2H, but rapidly with CO to give Rh(6-iPr)(PPh3)(CO)F and Rh(PPh3)2(CO)F, and also with Me3SiCF3 to form Rh(6-iPr)(PPh3)2(CF3).

This thesis details the current methods for meta-selective C-H functionalisation and contains three chapters relating to the area of ruthenium catalysed meta selective functionalisation by σ-activation. The first of which contains a published manuscript entitled “Catalytic meta-selective C-H functionalization to construct quaternary carbon centres” and describes a meta selective tertiary alkylation procedure on 2-phenylpyridine substrates. Key findings from this work provide good evidence for a radical based mechanism and proposes a catalytic cycle involving two distinct roles for the ruthenium catalyst; both in the activation of the substrate molecule and in the formation of a tertiary radical coupling partner. The second chapter contains another published manuscript entitled “Mechanistic insight into ruthenium catalysed meta-sulfonation of 2-phenylpyridine” and provides mechanistic analysis for the meta selective sulfonation of 2-phenylpyridine. Key findings from this work show through stoichiometric experiments that sulfonation occurs at the position para to the C-Ru bond formed following cyclometalation with a radical addition being implied. The work also shows that the catalytic species involved do not require an arene ligand and deuterium labelling studies identified a likely rate limiting radical sulfonation step. The final chapter contains additional work relating to the use of α-halo carbonyl coupling reagents to enable meta selective primary, secondary and tertiary alkylations. The use of a triphenylphosphine ligand source was necessary for the coupling of primary α-halo carbonyl coupling partners at the meta position. Crucially, this transformation was not possible with simple, straight-chain alkyl halides, highlighting the privileged reactivity of α-halo carbonyl coupling reagents. This work also contains experimental and computational mechanistic analysis which reveals additional support for a dual activation pathway.

This thesis presents research into the development of a novel conjugate-addition/cyclisation methodology for the synthesis of isoindole derived nitrones. To begin, a review of the principle methods for synthesising nitrones is reported, followed by a discussion of the current uses of nitrones and the requirement for straightforward syntheses of nitrones contained within an isoindole scaffold. The synthesis of an aryl cyclisation substrate possessing the key ortho- relationship between an alpha,beta-unsaturated ester and formyl group is then described. The planned conjugate-addition/cyclisation reaction using hydroxylamine was carried to afford a different nitrone structure to that expected, which was later confirmed by X-ray crystallography. A full discussion of the work undertaken to elucidate the compound structure and to probe the reaction mechanism is reported. A monocyclic nitrone reported in the literature was thought to have been synthesised according to a 1,3-azaprotio cyclotransfer mechanism. Application of the newly discovered conjugate-addition/cyclisation protocol to a linear substrate successfully afforded this monocyclic nitrone, leading us to propose our mechanism as a plausible alternative. Exploration of the scope and limitation of the nitrone forming reaction afforded total of fourteen isoindole derived nitrones. Applying the protocol to modified cyclisation substrates afforded five dihydroisoquinoline derived nitrones and a bicyclic hydroxamic acid also. Research into the reactivity of isoindole derived nitrones is then presented. Varying degrees of success were obtained, largely due to the fact that the substrate does not react as a nitrone, but as its isoindole tautomer. An attempted 1,3-dipolar cycloaddition reaction with tert-butyl acrylate instead afforded a bridged hydroxylamine product, synthesised by a [4+2] Diels-Alder cycloaddition reaction. The final part of this thesis reports the application of the [4+2] cycloaddition reaction between nitrone and an alkyne as a novel route for the synthesis of substituted naphthalenes.