The wide use of wire-reinforced rubber products such as conveyor belts, hose and radial ply tyres has reawakened interest in the parameters affecting the adhesion of rubber to brass plated steel wire. My research work is an attempt to improve and explain the rubber to metal bonding technology; it is concerned with the effect of rubber compounding ingredients as well as wire surface factors on adhesion. This work pertains to show the role played by two of the recently introduced and widely used bonding systems namely (i) Hexamethylene tetramine-resorcinol system and (ii) the Triazine system (Vulcabond SW)* on the adhesion of the rubber to brass plated steel wire. Different carbon blacks, as well as different accelerators and silica are shown to have a great influence on the amount of rubber adhesion to brass plated steel wire. The state of the wire plating as well as the contamination of its surface affects bonding and these parameters were studied using the scanning electron microscope. XPS techniques are employed to explain the role of some accelerators in the mechanism of bonding rubber to brass plated steel wire. A relationship has been found to exist between bind strength and rubber fracture properties. Because of the widespread use of radial tyres in the automobile industry and in every field in which heavy types of tyres are used, this research considers in detail the phenomena of fatigue and pressure at various temperatures on bond life. Also wire ageing is considered to be very important and to effect the bond between the rubber and the brass plated steel. * Trade name of Vulnax International Ltd.

The substitution of the cobalt atom into the active site of zinc metalloenzymes is becoming a useful and common practice. The zinc atom, in fact, is magnetically and optically silent, whillst the cobalt has a characteristic optical and E.P.R. spectrum, so that it can be followed spectroscopically to obtain structural and functional information on the enzyme. In this thesis a spectroscopic study of the cobalt substituted into two metalloenzymes, namely copper-zinc-Superoxide Dismutase and Zinc- Carbonic Anhydrase, and of some low molecular weight cobalt complexes has been performed. In Superoxide Dismutase the cobalt has been selectively substituted either into the zinc or into the copper site, so that all the possible derivatives [Co-Cu], [Co-...], [Co-Co] and [Zn-Co], have been investigated. The [Co-..]SOD derivative is characterized by an axial E.P.R. spectrum and by an absorption spectrum in the visible region of intermediate intensity e530=315, e560=425, e588= 450 and a near infrared band at 1000 nm (e=90), indicating a tetrahedral coordination with a quite strong crystal field around the Co(II) centre. The [Co-Cu]SOD derivative does not show any E.P.R. signal and a magnetic susceptibility study, carried out between 30-210 K indicates that this is due to the strong antiferromagnetic coupling (2J ? 600 cm-1) occurring between the two metal centres. The [Zn-Co]SOD derivative shows an interesting phosphate buffer spectral dependence. In particular, the electronic spectrum, carried out in the presence of phosphate buffer, has three quite intense bands in the visible region (e540=225, e580=330, e605=330) and a band in the near infrared at 1050 nm (e=40). When the same spectrum is carried out in the absence of phosphate buffer the bands in the visible region are much less intense and the near infrared band is shifted toward lower wavelengths. This behaviour indicates a change in symmetry around the Co(II) centre, from tetrahedral to pentacoordinate in the presence and in the absence of phosphate respectively. The E.P.R. spectra also support this hypothesis. The reaction of cyanide and H2O2 with the [Zn-Co] and [Co-Co] SOD derivatives have also been investigated. The binding of CN- to the cobalt is temperature or freezing dependent. The E.P.R. spectra carried out at 77 K shows, in fact, that the CN- easily binds to the cobalt which is transformed into a low spin form, whilst the electronic room temperature spectra show that a very large CN-:Co ratio is needed to decrease the d-d bands of the unreacted high spin cobalt. The E.P.R. spectrum is rhombic with gz=2.027 and Az=115 x 10-4cm-1, suggesting a distorted pentacoordinate structure around the metal. The reaction with H2O2 shows a decrease of the electronic absorption spectrum of the cobalt and the appearance of a radical at g~2 in the E.P.R. spectrum. Oxidation of the Co (II) to Co (III) can probably be excluded because addition of sodium dithionite does not restore back the original spectrum. A comparative study of the K-absorption edge of several cobalt derivatives has allowed several structural correlations to be done. In particular, the [Co(II)-...] and the [Co(II)-Cu(I)]SOD derivatives have a completely identical K-edge spectrum, which is slightly different from that of the [Co(II)-Cu(II)] derivative, indicating that a conformational change and/or a different charge on the imidazole bridging the two metal sites occurs coincidentally with the change of copper valence. An E.P.R. study on low molecular weight model compounds suggests that the zero field splitting value ? between the two Kramers doublets in a high spin cobalt (II) ion can be used diagnostically to assign the geometry around the metal centre. The zero field splitting value is, in fact, greater in the pentacoordinate case than in the tetrahedral one. By comparison with the model compounds a pentacoordinate structure is assigned to the high pH and the iodide form of the cobalt carbonic anhydrase derivative. The study of the reaction of the native and the copper and cobalt substituted Carbonic Anhydrase shows that Cu(II) is easily extracted from the enzyme, Co(II) with some difficulty and Zn(II) is unaffected in any condition. Before the depletion, a stable pentacoordinate species and two stable and different intermediates in the case of cobalt and copper respectively are observed. A ?-irradiation investigation of the native Carbonic Anhydrase and Superoxide Dismutase has allowed detection of the E.P.R. signal of the Zn+ ion with a configuration 3d10 4s1. In both cases, the electron seems to be in an approximately sp hybrid orbital so explaining the lack of magnetic interaction in the native SOD. In fact, the O hybrid orbital of the zinc is in a wrong symmetry to couple with the ? electron system of the imidazole and with the ground state of the copper.

The first part of this work is an investigation of the reason for the abnormally high barrier to rotation around the N-N bond in certain N-quinolone substituted sulphenamides. Some mechanisms by which diastereoisomers of the above compounds could interconvert are also examined. Extension of this work lead to resolution of N-benzyl-N-(1,2-dihydro-2-oxoquinolin-1-yl) glycine as a result of the N-N chiral axis. The thermal stability of some heterocyclic sulphenamides is also investigated. A study of the reaction of some alkylhydrazines with arylsulphenyl chlorides is described and some mechanisms proposed for the fragmentation of the intermediate sulphenylhydrazides. The trapping of dinitrobenzenesulphenylnitrene with alkenes and other reagents is described as well as a study of the stereospecificity of its addition to cis-l-phenylpropene. The generation and attempted trapping of other sulphenylnitrenes is also investigated.

An investigation has been carried out into the interactions of some cations with the sodium pump of red blood cell membranes. Two mechanisms for this system have been proposed previously: one is a two- step (consecutive) mechanism in which sodium ions are transported in one step and then potassium ions in a separate, second step. An alternative mechanism involves simultaneous attachment and transport of both ions. The experiments presented involve studies of pump activation by either reactant at various concentrations of the other. A requirement for these studies is that products of the reaction be absent. This indicates the use of a cellular system with its inherent asymmetry and the modification of such a system to allow changes in intracellular ionic composition. This has been achieved with human and pig red blood cells modified by a cation loading procedure involving the sulphydryl inhibitor p-chloromercuribenzene sulphonic acid. Pump activity has been measured mainly as the ouabain-sensitive influx of 42K+-labelled potassium and 134Cs+-labelled caesium, which is a congener for potassium. The results presented in the first section of the thesis confirm and extend a previous result showing that the affinity for external potassium or caesium is dependent on the intracellular sodium concentration. The second section of results demonstrates that the reverse trans-membrane influence applies - that is, a dependence of intracellular sodium affinity on the extracellular cation concentration. These results, together with those in a third section which demonstrate an influence of intracellular magnesium levels on external cation binding, are consistent with and explicable in terms of not only simultaneous binding of sodium, potassium or caesium and magnesium to the pump, but also a random order of attachment.

A series of spirophosphoranes was prepared in order to study different aspects of nucleophilic substitution at five-co-ordinate phosphorus. The phosphoranes were treated with nucleophiles under temperature controlled conditions and the reactions were monitored by 19F and 31P NMR spectroscopy. The half-lives of the resulting phosphorides could be extended by increasing the electron withdrawing properties of the ligands and by introducing ligands with low lying empty orbitals. Wherever possible nucleophilic attack was assisted by the greatest number of antiperiplanar lone pair interactions from the donor atoms (stereoelectronic effects). This led to the kinetically controlled formation of the trans-isomer of some six-co-ordinate bis (bidentate) phosphorus anions, which under thermodynamic conditions produced the more stable cis-isomer (s). In some cases the trans-cis isomerisation proceeded via a dissociative mechanism, this involving a unidentate ligand. Some cis-phosphorides underwent intramolecular isomerisation processes, possibly via trigonal prismatic intermediates. Six-co-ordinate phosphorus anions containing a phosphor-inane ring or non-equivalent bidentate/unidentate ligand donor atoms were short-lived. Increasing steric hindrance by introduction of substituents onto a donor atom disfavoured the formation of phosphorides. Only one equilibrium between a phosphorane and a phosphoride became rapid on the NMR timescale on increasing the temperature; all other equilibria were slow on the NMR timescale. Introduction of an oxazaphospholane ring into a phosphorane decreased the half-life of the generated phosphoride and introduced in some cases a rigidity at the nitrogen centre. A review of 19F and 31P NMR data of chemical shifts and coupling constants of phosphorides anions is given.

Methanol was initially reviewed and examined in the fundamental and overtone stretching regions of the infrared spectrum as a solute in inert solvents to produce a basis for studies into its role as a solvent. Interactions of methanol monomers with bifunctional secondary amines as cosolutes were then briefly studied. As a bulk solvent, the interactions of methanol with aprotic organic bases as cosolvents were studied at some length, firstly in the OH stretching region and then in the COH bending region. Spectra of the bulk solvent at low temperatures showed some trifunctionality of methanol, and data obtained from methanol/base systems were in good agreement with those from terniary inert solvent systems. Examination of the bending mode showed agreement with other results but was altogether fairly uninformative. COH bend region studies of MeOH-C10-4 and -I- solutions showed evidence of weak hydrogen bonds to the perchlorate ion as well as to the iodide ion, and the existence of solvent-shared ion-pairs. Examination of the HOH bending mode of water highlighted the 1:1 H2O / Base complexes --- difficult to observe using the OH stretching modes of water --- as well as the scavenging by the base of (OH)free groups present in bulk water. The monitoring of solely the frequency shifts from HOH bend spectra of H2O / salt solutions was uninstructive but, coupled with dissymmetry data, produced support for the results obtained from the OH stretching region. Evidence towards the possibility of doubly-bonded 1:1 water / perchlorate species was also suggested. Finally, the infrared bending mode for water / methanol mixtures produced results inconsistent with data obtained from the following aquomethanolic salt-solution studies and previous N.M.R. results concerning relative acidic and basic properties of water and methanol, but in agreement with results obtained from other techniques.

A description of the absorption of light by organic molecules and the ways by which the energy gained can be lost by the excited compounds has been presented. The Stern-Volmer equation has also been described. Free radical photoinitiation of polymerisation has been reviewed. An investigation has been carried out of ketone / amine photoinitiation of polymerisation of thin film and bulk polmerisations of acrylate esters. The photoreduction and photooxygenation of the amines used in the polymerisations, dimorpholinoalkanes N,N,N,N-tetraethyldiaminoalkanes and others have been carried out in an attempt to rationalise the observations made in the polymerisation experiments. The dehalogenation of aryl halides has been described. The photolysis of [special character omitted]-(4-halophenoxy)alkyl bromides and [special character omitted]-phenoxyalkyl halides has been carried out and evidence presented for the nature of the excited state responsible for reaction. Criteria for the intervention of radical ions in the photoreactions of aromatic halides with triethylamine have been given and where appropriate evidence for the intermediacy of such species has been presented. The photo-Claisen rearrangement has been studied and the effect of hydrogen bromide on the reaction investigated. The photoinitiation of cationic polymerisation by sulphonium and iodonium salts has been reviewed and a study carried out of thin film polymerisations in printing inks. The photochemistry of triaryl-sulphonium, thioxanthylium and diaryliodonium salts in methanol have been examined and a mechanism proposed for the decomposition. The photosensitization of photoinitiated cationic polymerisation has been investigated and Stern-Volmer plots recorded of the quenching of their fluorescence by cationic photoinitiators carried out.

A differential pulse polarographic method has been developed for the determination of ascorbic acid and food colours in the same solution. Aniline, sulphanilic acid and naphthionic acid were shown to be formed from particular food colours: visible spectrophotometric methods involving diazotization and coupling with N-l-naphthylethylenediamine dihydrochloride.were developed for monitoring their formation. The method is not subject to interference from the other amines formed from the cleavage of the azo bonds. Ammonia was shown to be present in the degraded solution and an indophenol method was developed for following its formation. These methods have been used to monitor permitted food colouring matters and ascorbic acid during interaction in accelerated light and heat degradation studies in the presence and absence of EOTA. Heat degradation studies were also carried out in the absence of ascorbic acid. EOTA was found not only to stabilise ascorbic acid but also to stabilise food colouring matters in the presence of ascorbic acid. Full yields of ammonia were obtained from the degradation of azo groups via sulphanilic acid and naphthionic acid during the light degradation studies. Interaction of food colours and ascorbic acid has also been shown to occur at room temperature in the dark and to yield ammonia and simple amines. In the heat degradation studies (130°C) relatively low yields of amines and ammonia were obtained despite complete visible degradation of food colours. This indicated the formation of more complex nitrogen containing compounds. EOTA was shown to stabilise acetamido groups from photolytic hydrolysis in several drug compounds as well as in the food colouring matters Red 2G and Black PN. A rapid differential pulse polarographic method for the determination of food colours in boiled sweets directly without prior separation or extraction procedures has been developed. A detector cell designed and constructed in our workshops and previously used with a glassy carbon electrode has been adapted very successfully for use with a sessile mercury drop electrode. The use of the system in flow injection analysis has been demonstrated by determining food colours in the reductive and oxidative modes. Ascorbic acid, sulphite and other species have also been determined. In the determination of ascorbic acid deoxygenation is not necessary.

No description available.

An introduction to phosphoranes is presented. Phosphoranes were synthesized to obtain data on the relative thermodynamic apicophilicities of ligands and to compare these data with known data on the relative kinetic apicophilicities of ligands. The relative thermodynamic apicophilicity of phenoxy and p-fluorophenoxy was found to be larger than expected and the relative thermodynamic apicophilicity of oxygen and sulphur was found to be too large to be observed suggesting that relative thermodynamic apicophilicities of ligands are greater than the corresponding relative kinetic apicophilicities. A range of P-2-furylphosphoranes was synthesized to gain data on the relative kinetic apicophilicity of the 2-fury1 group. The apicophilicity of 2-fury1 varied with other P-substituents' over quite a large range. A series of P-phenylselenophosphoranes was synthesized and data on the relative kinetic apicophilicity of phenylseleno were obtained. It was found that phenylseleno has a similar apicophilicity to phenylthio and phenoxy. Phosphoranes containing prochiral centres were synthesized and from their variable temperature n.m.r. spectra it was concluded that prochiral centres could be used as probes in pseudorotations.