Organic reactions in ionic liquids:A simple and highly regioselective N-substitution of pyrrole

In ionic liquids [Bmim][PF6] or [Bmim][BF4], pyrrole replaced the halogen atom of an alkyl halide to give the corresponding N-substituted pyrrole in excellent yield. Benzenesulfonyl chloride, p-methylbenzenesulfonyl chloride and benzoyl chloride reacted similarly with pyrroles to afford the N-substituted pyrroles in quantitative yield. Michael addition reaction of pyrrole with electrophilic olefins was completed in a highly regioselective manner to afford the N-alkylpyrroles.

Studies in the anionic polymerization of methyl methacrylate

A study has been made of the anionic polymerization of methyl methacrylate using butyllithium and polystyryl lithium as initiators and using aluminium triisobutyl as a cocatalyst. The aspects of the polymerization that were examined were the effect of changing the order of addition of reagents, the temperature at which polymerization takes place and the polarity of the solvent. Trends were assessed in terms of molecular weight, molecular weight distribution and tacticity. In addition, a second monomer addition test was carried out to verify that the polymerization was truly a living one, and a kinetic study was attempted. Studies to investigate the effect of changing the order of addition of reagents showed that polymer with similar polydispersities and tacticities are produced whether the pre-mixing (mixing initiator and cocatalyst before addition of monomer) or the post-mixing (mixing monomer and cocatalyst before addition of initiator) method were used. However, polymerizations using the post-mixing mixing method demonstrated lower initiator efficiencies, possibly indicating a different initiating species. Investigations into the effect of changing the polymerization temperature show the molecular weight distribution to narrow as the temperature decreases, although a small amount of low molecular weight tailing was also observed at low temperature. A clear relationship between tacticity and temperature was observed with syndiotacticity increasing with decreasing temperature. Changes in solvent polarity were achieved by using mixtures of the standard solvent, toluene, with varying amounts of cyclohexane, tetrahydrofuran or dichloromethane. Experiments at low solvent polarity (using toluene/cyclohexane mixtures) showed problems with initiator solubility but produced polymer with lower polydispersity and higher syndiotacticity than in toluene alone. Experiments using toluene/THF mixtures yielded no polymer, thought to be owing to a side reaction between THF and aluminium triisobutyl. Increased solvent polarity, achieved using toluene/dichloromethane mixtures produced polymer with higher polydispersity and at lower yields than the conventional system, but also with higher syndiotacticity. Second monomer addition reactions demonstrated that the polymerization was 'living' since an increase in molecular weight was observed with no increase in polydispersity. Kinetic studies demonstrated the high speed of the polymerization but yielded no useful data.

Free radical reactions in atherosclerosis; An EPR spectrometry study

The copper catalysed oxidation of homocysteine has been studied by electron paramagnetic resonance (EPR) spectroscopy and spin trapping techniques to determine the nature of free radical species formed under varying experimental conditions. Three radicals; thiyl, alkyl and hydroxyl were detected with hydroxyl being predominant. A reaction mechanism is proposed involving Fenton chemistry. Inclusion of catalase to test for intermediate generation of hydrogen peroxide showed a marked reduction in amount of hydroxyl radical generated. In contrast, the addition of superoxide dismutase showed no significant effect on the level of hydroxyl radical formed. Enhanced radical formation was observed at higher levels of oxygen, an effect which has consequences for differential oxygen levels in arterial and venous systems. Implications are drawn for a higher incidence of atherosclerotic plaque formation in arteries versus veins. © 2006 - IOS Press and the authors. All rights reserved.

Facility closure management:the case of Vauxhall Motors Luton

Purpose – The purpose of the paper is to present the findings of a study of factory closure management. It details the sequence and the results of the key strategic manufacturing management decisions made from the time of the announcement of the plant closure to the cessation of operations. The paper also includes an analysis of the human resource management (HRM) actions taken during this same time period and their consequences upon all those involved in the closure management process. Design/methodology/approach – The case study methodology consisted of two initial site visits to monitor closure management effectiveness (adherence to plan and the types and frequency of closure management communications). During these visits, documentary evidence of the impact of the closure decision upon production performance was also collected (manufacturing output and quality performance data). Following plant closure, interviews were held with senior business, production and HRM managers and production personnel. A total of 12 interviews were carried out. Findings – The case study findings have informed the development of a conceptual model of facility closure management. Information obtained from the interviews suggests that the facility closure management process consists of five key management activities. The unexpected announcement of a factory closure can cause behavioural changes similar to those of bereavement, particularly by those employees who are its survivors. In addition, similar reactions to the closure announcement may be displayed by those who choose to remain employed by the factory owner throughout the phased closure of the plant. Originality/value – Facility closure management is an insufficiently researched strategic operations management activity. This paper details a recommended procedure for its management. A conceptual model has also been developed to illustrate the links between the key facility closure management tasks and the range of employee changes of behaviour that can be induced by their execution.

The role of attributions in reactions to job relocation

Job relocation refers to the process of simultaneously moving to a new job and house and this can cause considerable stress for the relocator and his/her family. Based upon an attributional analysis, we predicted that negative psychological reactions would be a function of (1) number of relocation problems, and (2) making pessimistic attributions for relocation problems (that is, the tendency to attribute negative events to internal, stable and global causes). Furthermore, these factors should interact, such that individuals with many relocation problems who also make pessimistic attributions will experience the worst psychological reactions. The results from a cross-sectional survey of 93 relocators supported these predictions. As expected, those relocators who had many relocation problems and made pessimistic attributions reported the worst mental health and relocation-specific stress. In addition, a reanalysis of a longitudinal study of relocators by Martin (1996) also supported the above predictions using attributions of perceived control. Furthermore, the relocators predicted to be most at risk (many problems}/low control) reported the worst changes in mental health during the course of the move.

Reactions of directly related tellurium and selenium heterocycic compunds with triiron dodecacarbonyl

The reactions of directly related tellurium and selenium heterocyclic compounds with triiron dodecacarbonyl are described. The reaction of 2-telluraphthalide, C8H8OTe with [Fe3(CO)12 gave [Fe{C6H4(CH2)Te}(CO)3]2, (1). An iron atom has inserted into the telluracyclic ring, and it is probable that one co-ordinated CO ligand arises from the initially organic carbonyl group. X-ray analysis of compound (1) showed that the compound has a Fe2Te2 core, which is achieved by dimerisation. The reaction of telluraphthalic anhydride, C8H402Te with [Fe3(CO)12] gave a known, but unexpected, organic phthalide product, C8H602, which was confirmed by X-ray crystallography. Selenaphthalic anhydride,  C8H4O2Se gave intractable products on reaction with [Fe3(CO)12], 2-selenaphthalide, C8H6OSe, on reaction with [Fe3(CO)12] gave a major product [Fe2{C6H4(CH2)Se}(CO)6], (2) and a minor product [Fe3{C6H4(CH2)Se}(CO)8], (3) which is an intermediate in the formation of (2). X-ray analysis of (2) shows that compound (2) is very similar to (1) except that the 18 electron rule is satisfied by co-ordination of a Fe(CO)3 moiety, rather than dimerisation. Compound (3), also studied by X-ray crystallography, differs from (2) mainly in the addition of an Fe(CO)2 moiety. Telluraphtbalic anhydride, C8H402Te, and selenaphthalic anhydride, C8H402Se, are both monoclinic and crystallise in space group P21/n. 2-Selenaphthalide, C8H402Se, is also monoclinic, space group P21/C. The reactions of the following compounds (l,3-dihydrobenzo[c]selenophene, 1,3,7,9-tetrahydrobenzo[1,2c; 4,5c'] ditellurophene, dibenzoselenophene, phenoxselenine, 3, 5-naphtho-1-telluracyclohexane and 3,5-naphtho-1-selenacyclohexane) with [Fe3lCO)12] are reported. It is unfortunate that the above compounds do not react under the conditions employed; this may be due to differing degrees of ring strain. 1,8-bis(bromomethyl)naphthalene, C12H10Br2 is monoclinic and crystallises in space group C2/c. 1,1-diiodo-3,5-naphthotelluracyclohexane, C12H10TeI2 and 3,5-naphtho-l-telluracyclohexane, C12H10Te are monoclinic and crystallise in space group P21/c. 3,5-naphtho-l-selenacyclohexane, C12H10Se and 2,2,8,8-tetraiodo-1,3,7,9-tetrahydrobenzo[1,2c;4,5c']ditellurophene are also monoclinic, space group P21/a. The syntheses of intramolecular stabilised organo-tellurium and selenium compounds are reported, having a general formula of REX (where R = phenylazophenyl; E = Se, Te; X = electronegative group, for example C1, Br or I). The crystal structures of R'TeBr, RTeI, RSeCI, RSeCI/I and RSeI (where R = phenylazophenyl) are reported. The tellurium containing X-ray structures are triclinic and have a space group P-1. The selenium containing X-ray structures are monoclinic with space group P21/n. The inclusion of nitrogen in selenium heterocycles provides access to an entirely new area of organometallic chemistry. The reaction of 2-methylbenzoselenazole with [Fe3(CO)12] gave [Fe2{C6H4(NCH2CH3)Se}(CO)6]. The reactions of 2-(methyltelluro)benzanilide or 2-(methylseleno)benzanilide with [Fe3(CO)12] gave reaction products [Fe2(μTeMe)2(CO)6] and [Fe2 (μ-SeMe)2(CO)6] respectively, which were confmned by X-ray crystallography. The use of Mossbauer spectroscopy on the products obtained from the reactions of heterocyclic compounds with [Fe3(CO)12] can give useful information, for example the number of iron sites and the environments of these iron sites within the products.

Novel materials for membrane separation processes

The aim of this work was to synthesise a series of hydrophilic derivatives of cis-1,2-dihydroxy-3,5-cyclohexadiene (cis-DHCD) and copolymerise them with 2-hydroxyethyl methacrylate (HEMA), to produce a completely new range of hydrogel materials. It is theorised that hydrogels incorporating such derivatives of cis-DHCD will exhibit good strength and elasticity in addition to good water binding ability. The synthesis of derivatives was attempted by both enzymatic and chemical methods. Enzyme synthesis involved the transesterification of cis-DHCD with a number of trichloro and trifluoroethyl esters using the enzyme lipase porcine pancreas to catalyse the reaction in organic solvent. Cyclohexanol was used in initial studies to assess the viability of enzyme catalysed reactions. Chemical synthesis involved the epoxidation of a number of unsaturated carboxylic acids and the subsequent reaction of these epoxy acids with cis-DHCD in DCC/DMAP catalysed esterifications. The silylation of cis-DHCD using TBDCS and BSA was also studied. The rate of aromatisation of cis-DHCD at room temperature was studied in order to assess its stability and 1H NMR studies were also undertaken to determine the conformations adopted by derivatives of cis-DHCD. The copolymerisation of diepoxybutanoate, diepoxyundecanoate, dibutenoate and silyl protected derivatives of cis-DHCD with HEMA, to produce a new group of hydrogels was investigated. The EWC and mechanical properties of these hydrogels were measured and DSC was used to determine the amount of freezing and non-freezing water in the membranes. The effect on EWC of opening the epoxide rings of the comonomers was also investigated

Lithium-aluminium casting alloys and their associated metal-mould reactions

Aluminium - lithium alloys are specialist alloys used exclusively by the aerospace industry. They have properties that are favourable to the production of modern military aircraft. The addition of approximately 2.5 percent lithium to aluminium increases the strength characteristics of the new alloys by 10 percent. The same addition has the added advantage of decreasing the density of the resulting alloy by a similar percentage. The disadvantages associated with this alloy are primarily price and castability. The addition of 2.5 weight percent lithium to aluminium results in a price increase of 100% explaining the aerospace exclusivity. The processability of the alloys is restricted to ingot casting and wrought treatment but for complex components precision casting is required. Casting the alloys into sand and investment moulds creates a metal - mould reaction, the consequences of which are intolerable in the production of military hardware. The primary object of this project was to investigate and characterise the reactions occurring between the newly poured metal and surface of the mould and to propose a method of counteracting the metal - mould reaction. The constituents of standard sand and investment moulds were pyrolised with lithium metal in order to simplify the complex in-mould reaction and the products were studied by the solid state techniques of powder X-Ray diffraction and magic angle spinning nuclear magnetic resonance spectroscopy. The results of this study showed that the order of reaction was: Organic reagents> > Silicate reagents> Non silicate reagents Alphaset and Betaset were the two organic binders used to prepare the sand moulds throughout this project. Studies were carried out to characterise these resins in order to determine the factors involved in their reaction with lithium. Analysis revealed that during the curing process the phenolic hydroxide groups are not reacted out and that a redox reaction takes place between these hydroxides and the lithium in the molten alloys. Casting experiments carried out to assess the protection afforded by various hydroxide protecting agents showed that modern effective, protecting chemicals such as bis-trimethyl silyl acetamide and hexamethyldisilazane did not inhibit the metal - mould reaction to a sufficiently high standard and that tri-methylchlorosilane was consistently the best performer. Tri-methyl chlorosilane has a simple functionalizing mechanism compared to other hydroxide protecting reagents and this factor is responsible for its superior inhibiting qualities. Comparative studies of 6Li and 7Li N.M.R. spectra (M.A.S. and `off angle') establish that, for solid state (and even solution) analytical purposes 6Li is the preferred nucleus. 6Li M.A.S.N.M.R. spectra were obtained for thermally treated laponite clay. At temperatures below 800oC both dehydrated and rehydrated samples were considered. The data are consistent with mobility of lithium ions from the trioctahedral clay sites at 600oC. The superior resolution achievable in 6Li M.A.S.N.M.R. is demonstrated in the analysis of a microwave prepared lithium exchanged clay where 6Li spectroscopy revelaed two lithium sites in comparison to 7Li M.A.S.N.M.R. which gave only a single lithium resonance.

Metal binding to transferrin and immune reactions in Parkinson's disease

The binding of iron (59Fe) and gallium (67Ga) to the plasma protein transferrin (Tf) was investigated by G75 gel filtration chromatography in control patients and treated and untreated patients with Parkinson's disease (PD). Fe-Tf binding was 100% in all controls and PD patients suggesting that a defect in Fe-Tf binding was not involved in the aetiology of PD. Ga-Tf binding was significantly reduced in both untreated and treated PD patients compared to controls. In addition, treated PD patients had significantly higher Ga-Tf binding than untreated patients. A reduction in metal binding to Tf could result in the increase of a low molecular weight species which may more readily enter the CNS. Alternatively, it could lead to a decrease in the transport of essential metals into the brain via the Tf receptor system. A significant elevation in neopterin was demonstrated within the plasma of untreated PD patients compared to controls suggesting the activation of a cellular immune response. Furthermore, plasma neopterin was lower in treated compared to untreated PD patients, although the difference was not significant. There was no evidence for the activation of the humoral immune response in untreated or treated PD patients as measured by circulating immune complex (CIC) levels within the plasma. An inverse relationship between Ga-Tf binding and neopterin was observed in untreated PD patients. The addition of oxidants in the form of potassium permanganate and activated manganese dioxide reduced Ga-Tf binding in control plasma. However, relatively little response was observed using monocyte preparations. The results suggest that oxidants produced by activation of the cellular immune system could damage the Tf molecule thereby reducing its ability to bind metals.

Expatriate managers adjustment and its impact on subordinates reactions: a cross cultural leadership study of Kenya and Ethiopia

Research on culture, leadership and adjustment shows that societal culture influences leadership in such a way that it can impact on expatriate managers' effectiveness and adjustment in a new culture. In previous research, cultural background, personality, motives or behaviour of expatriate managers and their followers' reactions to them have been investigated in Europe, America and Asia. However, little attention has been paid on research on expatriate managers in African cultures especially in Eastern Africa. The present study represents an attempt to address the gap by examining how societal culture, leadership and adjustment success are interrelated for expatriate managers in Kenya and Ethiopia. Questionnaire data were obtained from a) local middle managers (N=160) for studying societal culture and leadership in Kenya and Ethiopia, b) expatriate managers in non-governmental organizations - NGOs (N=28) for studying expatriate managers' personality, motives and adjustment success and c) their immediate subordinates (N=125) for studying the expatriate managers' behaviours and their subordinates' reactions to them. Additionally, expatriate managers were interviewed and responses were coded for implicit motives, experiences and adjustment. SPSS was used to analyse data from questionnaires to obtain cultural and leadership dimensions, leader behaviour and subordinate reactions. The NVIVO computer based disclosure analysis package was used to analyse interview data. Findings indicate that societal culture influences leadership behaviours and leadership perceptions while the expatriate managers' motives, behaviours, personality and the cross cultural training they received prior to their assignment impact on the expatriates' adjustment success and on subordinates' reactions to them. The cultural fit between expatriate managers' home country (19 countries) and the target country (Kenya or Ethiopia) had no significant association with adjustment success but was positively related to expatriate behaviour and negatively associated with subordinates reactions. However, some particular societal practices - obviously adopted by expatriates and transferred to their target country - did predict subordinates' commitment, motivation and job satisfaction. Furthermore, expatriates' responsibility motivation was positively related to their adjustment success. Regarding leadership behaviours and effectiveness, expatriate' supportive behaviours predicted subordinates' job satisfaction most strongly. Expatriate managers expressing their management philosophies and experience shed light on the various aspects of adjustment and management of NGOs. In addition, review of Kenyan and Ethiopian cultures and the NGO context in these countries offers valuable information for expatriate managers. This study's general imphcation for Cross Cultural Management and lnternational Human Resources Management is that the combination of culture general and culture specific knowledge and reflections on Eastern Africa countries can inform senior management and international HR staff about the critical issue of what to include in training, coaching, and actual experience in a particular host country in order to ensure effective leadership. Furthennore, this knowledge is expected to influence expatriate managers' behaviour modification to enhance positive subordinate reactions. Questions about how to prepare expatriate managers and subordinates to work more competently and sensitively across cultures are addressed. Further theoretical implications, limitations of the study and directions for future research are also addressed.

Asymmetric reactions of organosilicon compounds and properties of novel optically active organosilanes

Partial reduction of racemic methoxysilanes by 1:1 complexes of lithium aluminium hydride with optically active cinchona and ephedra alkaloids give optically active silanes and methoxysilanes. Optical yields depend on the groups attached to silicon and the alkaloid used but in some cases approach 50%, The method has been used to prepare novel optically active organosilanes, possessing an asymmetric silicon centre, which are either inaccessible by any of the other available routes or would require a time consuming preparation. Such compounds are of use in the study of the mechanism of substitutions at silicon. Attempts have been made to rationalize the results of the asymmetric reductions in terms of differences in sterio and electronic interactions in diastereoisomeric transition states. Circular dichroism and optical rotatory dispersion spectra have been obtained for the optically active products in an attempt to elucidate the absolute configurations of the novel asymmetric organosilanes. The results from these studies provide a useful addition to the data so far accumulated for asymmetrically perturbed aromatic chromophores. Nuclear magnetic resonanoe studies of diastereoisomaric (-)-menthoxysilanes show that these compounds possess resonances extremely useful in the determination of optical purities for asymmetric organosilanes which possess an aromatic group. The effect of variable temperature on the spectra has revealed evidence for the conformational preferences in these compounds. Other diastereoisomeric alkoxysilanes have been prepared and their n.m.r.spectra studied in the hope of establishing trends. Exploratory studies for other asymmetric reactions proceeding at silicon have proved unfruitful.

Pyrolysis study of halogen-containing aromatics reflecting reactions with polypropylene in a posttreatment decontamination process

Halogen-containing aromatics, mainly bromine-containing phenols, are harmful compounds contaminating pyrolysis oil from electronic boards containing halogenated flame retardants. In addition, theirformation increases the potential for evolution of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs) at relatively low temperature (up to 500 °C). As a model compound, 2,4-dibromophenol (DBP) was pyrolyzed at 290-450 °C. While its pyrolysis in a nitrogen flow reactor or in encapsulated ampules yields bromine-containing phenols, phenoxyphenols, PBDDs, and PBDFs, pyrolysis of DBP in a hydrogen-donating medium of polypropylene (PP) at 290-350 °C mainly results in the formation of phenol and HBr, indicating the occurrence of a facile hydrodebromination of DBP. The hydrodebromination efficiency depends on temperature, pressure, and the ratio of the initial components. This thermal behavior of DBP is compared to that of 2,4-dichlorophenol and decabromodiphenyl ether. A treatment of halogen-containing aromatics with PP offers a new perspective on the development of low-environmental-impact disposal processes for electronic scrap. © 2005 American Chemical Society.

Coupling of Heck and hydrogenation reactions in a continuous compact reactor

A continuous multi-step synthesis of 1,2-diphenylethane was performed sequentially in a structured compact reactor. This process involved a Heck C-C coupling reaction followed by the addition of hydrogen to perform reduction of the intermediate obtained in the first step. Both of the reactions were catalysed by microspherical carbon-supported Pd catalysts. Due to the integration of the micro-heat exchanger, the static mixer and the mesoscale packed-bed reaction channel, the compact reactor was proven to be an intensified tool for promoting the reactions. In comparison with the batch reactor, this flow process in the compact reactor was more efficient as: (i) the reaction time was significantly reduced (ca. 7 min versus several hours), (ii) no additional ligands were used and (iii) the reaction was run at lower operational pressure and temperature. Pd leached in the Heck reaction step was shown to be effectively recovered in the following hydrogenation reaction section and the catalytic activity of the system can be mostly retained by reverse flow operation. © 2009 Elsevier Inc. All rights reserved.