7,373 research outputs found

    Designing and managing multiple pipelines

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    There is now a growing recognition that supply chains should be designed from ‘the customer backwards’ rather than from ‘the company outwards’. If such a view is accepted then the implication is that since the organisation will likely be serving multiple markets or segments there will be the need to design and manage multiple ‘pipelines’ to serve those different customers. To assist decision makers in their choice of appropriate supply chain design a framework is proposed based upon multiple criteria. A case study is presented which highlights the benefits of selecting, engineering and operating multiple pipelines tailored to the needs of th

    Eosinophile Leucocyte: its occurrence and significance with special reference to asthma

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    I. There are four main groups of conditions in which eosinophilia is of frequent occurrence:-(a) Convalescence from infectious fevers, and in the course of scarlet fever.(h) Skin diseases.(c) Asthma.(d) Parasitic infestations.II. The eosinophilia is of low grade in conva­lescence and in most skin diseases,except dermatitis herpetiformis and pemphigus.III. A low grade eosinophilia is present in 50 per cent of asthmatic patients.IV. High grade eosinophilia is specially associated with infestations of Bilharzia, Pilaria, Trichina and Ankylostoma; a low grade eosinophilia may occur with any parasitic infestation

    Basic Derivatives of Fluorene and Anthracene, and Isomerisation Reactions with Hydrogen Fluoride

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    Part I. Attempts to prepare the basic esters beta-diethyl-aznino ethyl 1,2,3,4,10,11-hexahydrof luorene-9-carboxylate and beta-diethylaminoethyl 1,2,3,4,9,10,11,12-octahydro-anthracene-9-carboxylate for testing as antispasmodic drugs have been made. These compounds have certain structural features which, in similar compounds, have been found to enhance the antispasmodic properties of these compounds. The reduction of fluorene-9-carboxylic acid has been studied with limited success. Hexahydrofluorene-9-carboxylic acid, an intermediate required in the synthesis of the former ester, has been obtained but only in poor yield. A further acid of unknown structure and several neutral by-products have also been isolated. Other synthetic methods failed due to the reluctance of hexahydro-fluorenone to form a cyanhydrin and the ease with which 9-halogene-hexahydrofluorenes decomposed. trans- as-hexahydroanthrone did not form a cyanhydrin so that trans- as- octahydroanthracene-9-carboxylio acid, an intermediate in the synthesis of the latter ester, was not obtained. The basic ethers, beta-diethylaminoethyl fluorenyl-9-ether. beta-diethylsaminoethyl hexahydrofluorenyl-9-ether and beta-diethylaminoethyl trans-as-octahydroanthranyl-9-ether, also required for testing as antispasmodic drugs, were obtained by condensation of the sodio-derivatives of the alcohols 9-fluorenol, hexahydrofluoren-9-ol and 9-hydroxy-traus-as-octahydroanthracene, respectively, with beta-diethylaminoethyl chloride. Summary, Part II. A study of a new type of isomerisation reaction (68, 69) using hydrogen fluoride as catalyst has been extended to durene (1,2,4,5-tetramethylbenzene) and penta-methylbenzene derivatives. It has been confirmed that migration of methyl groups in this reaction occurs only when accompanied by cyclisation. Durene, durylcarboxylic acid and durylacetic acid were unaffected by treatment with hydrogen fluoride at room temperature . Under similar conditions beta-durylpropionic acid was partially converted to a mixture of 4,5,7-trimethyl-indan-l-one and 4,5,6,7-tetramethylindan-l-one. The latter ketone was also obtained from beta-pentamethylphenylpropionio acid under identical conditions. Similarly 1-durylbutyric acid yielded 5,6,7,8-tetramethyl-1,2,3,4-tetrahydroanphthalen-l-one. l-pentamethylphenylbutyric acid was recovered un- changed on similar treatment. Similarities between this type of reaction and previously described isomerisation reactions have been noted though migration in this new type of isomerisation reaction appears to be much more limited in extent. A possible mechanism for the new type of reaction, based on these similarities, has been evolved. A partial isomerisation in the durene nucleus under the influence of aluminium chloride under mild conditions has been noted and correlated to a similar isomerisation in the s-octahydroanthracene nucleus and to the Jacobsen reaction

    Synthesis, structure and pyrolysis of stabilised phosphonium ylides containing saturated oxygen heterocycles

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    yesA range of twelve stabilised phosphonium ylides containing tetrahydrofuran, tetrahydropyran or 2,2- dimethyl-1,3-dioxolane rings have been prepared and fully characterised, including one X-ray structure determination of each type. The X-ray structures confirm the PvC and CvO functions to be syn and all the compounds undergo thermal extrusion of Ph3PO to give the corresponding alkynes. In some cases there is also competing loss of Ph3P to give different carbene-derived products and evidence has been obtained for the generation of 2-phenyloxete in this way. Raising the pyrolysis temperature leads in several cases to new secondary reactions of the alkyne products involving a sequence of alkyne to vinylidene isomerisation, intramolecular CH insertion, and retro Diels Alder reaction
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