Abstract: The present invention relates to processes for making 1,4-butanediol, 1,4-butenediol, or a mixture thereof by processing 1,4-butynediol in a dynamic mixing apparatus in an inert gas atmosphere at from 25 to 150° C. at a shear rate in the radial gap between rotor and stator of the mixing apparatus of more than 100 000 sec?1; phase separating the processed 1,4-butynediol at a temperature of from 25 to 150° C.; removing a bottom phase to obtain purified 1,4-butynediol; and reacting the purified 1,4-butynediol with hydrogen in the presence of a catalyst.

Abstract: The present invention relates to a process for purifying 1,4-butynediol, which comprises compressing 1,4-butynediol to from 50 to 1500 bar, depressurizing it, waiting for phase separation to occur after depressurization and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.

Abstract: The present invention relates to a process for purifying 1,4-butynediol, which comprises processing 1,4-butynediol in a dynamic mixing apparatus in an inert gas atmosphere at from 25 to 150° C. at a shear rate in the radial gap between rotor and stator of the mixing apparatus of more than 100 000 sec?1, awaiting phase separation at temperatures of from 25 to 150° C. and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.

Abstract: A process for catalytically hydrogenating methylolalkanals of the general formula in which R1 and R2 are each independently a further methylol group or an alkyl group having from 1 to 22 carbon atoms or an aryl or aralkyl group having from 6 to 33 carbon atoms, in the liquid phase over a hydrogenation catalyst, which comprises setting a pH of from 7.0 to 9.0 in the hydrogenation effluent by adding at least one tertiary amine, an inorganic base or an inorganic or organic acid to the hydrogenation feed.

Abstract: The invention relates to a process for preparing polymethylol compounds of the formula (I) where the radicals R are each, independently of one another, a further methylol group or an alkyl group having from 1 to 22 carbon atoms or an aryl or aralkyl group having from 6 to 22 carbon atoms, by condensation of aldehydes having from 2 to 24 carbon atoms with formaldehyde in an aldol reaction using tertiary amines as catalyst to form alkanals of the formula (II) where the radicals R each independently have one of the abovementioned meanings, and subsequent hydrogenation of the latter. The particular inventive feature of this process is that the aldol reaction is carried out using an aqueous formaldehyde solution having a formic acid content of <150 ppm and preferably <100 ppm. In this way of carrying out the process, the formation of by-products can advantageously be prevented in a targeted manner and the yield of the desired polymethylol compound can thereby be increased.

Abstract: The present invention relates to a process for purifying 1,4-butynediol, which comprises processing 1,4-butynediol in a dynamic mixing apparatus in an inert gas atmosphere at from 25 to 150° C. at a shear rate in the radial gap between rotor and stator of the mixing apparatus of more than 100 000 sec?1, awaiting phase separation at temperatures of from 25 to 150° C. and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.

Abstract: The present invention relates to a process for purifying 1,4-butynediol, which comprises compressing 1,4-butynediol to from 50 to 1500 bar, depressurizing it, waiting for phase separation to occur after depressurization and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.

Abstract: The invention relates to a process for separating off maleic anhydride from a gas stream comprising maleic anhydride, in which a) the gas stream comprising maleic anhydride is brought into contact with a liquid absorbent phase comprising at least one high-boiling inert absorption medium for maleic anhydride and b) maleic anhydride is separated off from the resulting liquid absorbate phase by stripping with a hydrogen-comprising gas as stripping medium in a column, wherein the stripping medium is fed in at two points on the column which are at least one theoretical plate apart.

Abstract: The invention relates to a process for preparing polymethylol compounds of the formula (I) (HOCH2)2—C—R2 ??(I) where the radicals R are each, independently of one another, a further methylol group or an alkyl group having from 1 to 22 carbon atoms or an aryl or aralkyl group having from 6 to 22 carbon atoms, by condensation of aldehydes having from 2 to 24 carbon atoms with formaldehyde in an aldol reaction using tertiary amines as catalyst to form alkanals of the formula (II) where the radicals R each independently have one of the abovementioned meanings, and subsequent hydrogenation of the latter. The particular inventive feature of this process is that the aldol reaction is carried out using an aqueous formaldehyde solution having a formic acid content of <150 ppm and preferably <100 ppm. In this way of carrying out the process, the formation of by-products can advantageously be prevented in a targeted manner and the yield of the desired polymethylol compound can thereby be increased.

Abstract: Process for the catalytic hydrogenation of methylolalkanals of the general formula where R1 and R2 are each, independently of one another, a further methylol group or an alkyl group having from 1 to 22 carbon atoms or an aryl or aralkyl group having from 6 to 33 carbon atoms, in the liquid phase by means of hydrogen over a hydrogenation catalyst, wherein hydrogen is used in a molar ratio to methylolalkanal of greater than 1.

Abstract: The present invention provides a process for distillatively purifying tetrahydrofuran in the presence of a polar solvent.

Abstract: A process is provided for the preparation of polymethylol compounds of formula (I): (HOCH2)2—C—(R)2 , ??(I) in which the radicals R independently of one another are each a further methylol group, an alkyl group having from 1 to 22 C atoms or an aryl or aralkyl group having from 6 to 22 C atoms, by (a) condensing aldehydes having from 2 to 24 C atoms with formaldehyde in an aldol reaction using tertiary amines as a catalyst to give alkanals of formula (II): in which the radicals R independently of one another are each as defined above, (b) then separating, by distillation, the reaction mixture obtained into a bottom product comprising predominantly the compounds of formula II and a low-boiling stream consisting of unconverted or partially converted starting materials, and (c) hydrogenating the distillation bottom, wherein the aldol reaction is carried out with an aqueous formaldehyde solution having a methanol content of 0.35 to 0.

Abstract: Process for the catalytic hydrogenation of methylolalkanals of the general formula where R1 and R2 are each, independently of one another, a further methylol group or an alkyl group having from 1 to 22 carbon atoms or an aryl or aralkyl group having from 6 to 33 carbon atoms, in the liquid phase by means of hydrogen over a hydrogenation catalyst, wherein hydrogen is used in a molar ratio to methylolalkanal of greater than 1.

Abstract: Aqueous glyoxal solutions which contain organic acids are purified by means of a membrane cell comprising two or more compartments by passing the glyoxal solution through at least one of the cell compartments separated from the neighboring compartment(s) by anion exchange membranes and by passing the aqueous solution of a base through at least one of the neighboring compartments.

Abstract: Hydroxycarboxylic esters of the general formula ##STR1## where n is an integer from 0 to 10, R.sup.1 and R.sup.2 are each hydrogen, hydroxyl, alkoxy or an aliphatic or olefinic, straight-chain, branched or cyclic hydrocarbon radical, and R.sup.1 and R.sup.2 together may furthermore form an alkylene radical, and the hydrocarbon radicals may furthermore be substituted by halogen, hydroxyl, epoxy or nitrile, and R.sup.3 is a low molecular weight alkyl radical, are prepared by electrochemical oxidation of a hydroxyaldehyde of the general formula ##STR2## in the presence of an alcohol of the formula R.sup.3 OH and of an ionic bromide or chloride in an undivided electrolysis cell.

Abstract: Pyrazoles of the general formula ##STR1## where R.sup.1, R.sup.2 and R.sup.3 are each hydrogen, alkyl, cycloalkyl or aryl, are prepared by electrochemical oxidation of 2-pyrazolines of the general formula ##STR2## in the presence of an ionic halide.

Abstract: Carbamic acid esters (I)R.sup.1 NHCOOR.sup.2 (I)wherein R.sup.1 is H, alkyl, cycloalkyl or alkylaryl and R.sup.2 is alkyl, are prepared by electro-oxidation of a formamide (II)R.sup.1 NHCHO (II)in the presence of an alcohol R.sup.2 OH and of an ionic halide.