The invention relates to a method for producing butadiene that is fed with a butanediol feedstock, with said method comprising at least: a) An esterification step comprising: A reaction section; A separation section producing a butanediol diester effluent, a water effluent, and a carboxylic acid effluent; b) An esterification pyrolysis step; c) A separation step comprising at least: A cooling section producing a liquid pyrolysis effluent and a vapor pyrolysis effluent; A gas-liquid washing section that is fed at the top with a fraction of the carboxylic acid effluent that is obtained from the separation section of step a) and at the bottom with said vapor pyrolysis effluent and producing at the top a butadiene effluent and at the bottom a washing effluent; in which a carboxylic-acid-rich stream comprising at least a portion of the liquid pyrolysis effluent is recycled to step a); d) A separation step.

The invention relates to a method for producing butadiene that is fed with a butanediol feedstock, with said method comprising at least: a) An esterification step comprising: A reaction section; A separation section producing a butanediol diester effluent, a water effluent, and a carboxylic acid effluent; b) An esterification pyrolysis step; c) A separation step comprising at least: A cooling section producing a liquid pyrolysis effluent and a vapor pyrolysis effluent; A gas-liquid washing section that is fed at the top with a fraction of the carboxylic acid effluent that is obtained from the separation section of step a) and at the bottom with said vapor pyrolysis effluent and producing at the top a butadiene effluent and at the bottom a washing effluent; in which a carboxylic-acid-rich stream comprising at least a portion of the liquid pyrolysis effluent is recycled to step a); d) A separation step.

The invention relates to a conversion method that is fed with a diol feedstock that comprises at least 90% by weight of diol and a carboxylic acid feedstock that comprises at least 80% by weight of carboxylic acid. The method comprising at least: An esterification step which is fed with at least the diol feedstock and at least the carboxylic acid feedstock, wherein the carboxylic acid/diol molar ratio at the inlet of the esterification step is between 2 and 6, the esterification step comprises at least one reactive distillation column that has a mixed reaction/separation zone located between two separation zones; and A water elimination step that is fed with distillate from the esterification step that comprises water and producing at least one water effluent.

The invention relates to a conversion method that is fed with a diol feedstock that comprises at least 90% by weight of diol and a carboxylic acid feedstock that comprises at least 80% by weight of carboxylic acid. The method comprising at least: An esterification step which is fed with at least the diol feedstock and at least the carboxylic acid feedstock, wherein the carboxylic acid/diol molar ratio at the inlet of the esterification step is between 2 and 6, the esterification step comprises at least one reactive distillation column that has a mixed reaction/separation zone located between two separation zones; and A water elimination step that is fed with distillate from the esterification step that comprises water and producing at least one water effluent.

The invention relates to a conversion method that is fed with a diol feedstock that comprises at least 90% by weight of diol and a carboxylic acid feedstock that comprises at least 80% by weight of carboxylic acid. The method comprising at least: An esterification step which is fed with at least the diol feedstock and at least the carboxylic acid feedstock, wherein the carboxylic acid/diol molar ratio at the inlet of the esterification step is between 2 and 6, the esterification step comprises at least one reactive distillation column that has a mixed reaction/separation zone located between two separation zones; and A water elimination step that is fed with distillate from the esterification step that comprises water and producing at least one water effluent.

A compound represented by General Formula (I), A.sup.1 to A.sup.4 each independently represent a non-aromatic ring group, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group, which may have a substituent, Z represents O, S, CHRCHR, OCHR, CHRO, CO, SO, SO.sub.2, COO, OCO, COS, SCO, OCOO, SCHR, CHRS, SOCHR, CHRSO, SO.sub.2CHR, CHRSO.sub.2, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, OCHRCHRO, SCHRCHRS, SOCHRCHRSO, SO.sub.2CHRCHRSO.sub.2, CH?CHCOO, CH?CHOCO, COOCH?CH, OCOCH?CH, COOCHRCHR, OCOCHRCHR, CHRCHRCOO, CHRCHROCO, COOCHR, OCOCHR, CHRCOO, CHROCO, CR?CR, CR?N, N?CR, N?N, CR?NN?CR, CF?CF, C?C, or a single bond, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and m1 represents an integer of 2 to 7.

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Provided herein are compounds and methods of using the compounds for determining levels of, for example, para-hydroquinones in a sample.

The present invention relates to a biphenyl derivative and use thereof, and the biphenyl derivative has a structure represented by the formula (I) as defined in the specification. The use refers the use of the biphenyl derivative or a pharmaceutically acceptable salt or solvate thereof, or a pharmaceutical composition comprising the biphenyl derivative or a pharmaceutically acceptable salt or solvate thereof in the preparation of a medicament for the treatment and/or prevention of ischemic stroke.

The present invention relates to a biphenyl derivative and use thereof, and the biphenyl derivative has a structure represented by the formula (I) as defined in the specification. The use refers the use of the biphenyl derivative or a pharmaceutically acceptable salt or solvate thereof, or a pharmaceutical composition comprising the biphenyl derivative or a pharmaceutically acceptable salt or solvate thereof in the preparation of a medicament for the treatment and/or prevention of ischemic stroke.

A method for producing 1,3-butadiene from a 1,4-butanediol feedstock: One step for esterification of 1,4-butanediol, One step for pyrolysis of 1,4-butanediol diester, producing butadiene.