Abstract:
Butanol and dibutyl ether are separated from a mixture containing water, dibutyl ether and n-butanol, 2-butanol and/or isobutanol by a process in whicha) the mixture is introduced into a first distillation column, essentially butanol is separated off at the bottom of this distillation column and the mixture taken off at the top of the distillation columnb) is introduced into a second distillation column and essentially dibutyl ether is separated off at the bottom of this second distillation column and the mixture formed at the top of the second distillation column is removed,c) the second distillation column being operated at a higher pressure than the first distillation column and at least one of the two mixtures taken off via the top of the distillation columns being subjected to phase separation, only the organic phase separated off being fed to the second distillation column in the case of phase separation downstream of the first distillation column, and separation into an aqueous and an organic phase also being effected in the case of phase separation downstream of the second distillation column, a part stream being recycled from the top or rectification section of the second distillation column to the first distillation column.
Abstract:
A method of devulcanizing crosslinked rubber uses a planetary roller extruder with a central spindle, planetary spindles, a housing, and a feed part. The method includes feeding vulcanized rubber through the feed part into the housing, rotating the central spindle about its rotational axis and thereby causing the planetary spindles to rotate about their rotational axes and revolve about the central spindle. This generates mechanical and thermal stress on the vulcanized rubber by kneading and/or crushing of the vulcanized rubber, breaking or destroying the molecular chains or bonds of the vulcanized rubber. The method further includes at least one of (A) adding particles of the vulcanized rubber eccentrically to the center of the planetary roller extruder module between the planetary spindles and (B) mechanically pressing particles of the vulcanized rubber between the planetary spindles with a crammer feeder.
Abstract:
The present invention relates to a process for purifying a composition (I) at least comprising cyclododecanone. The process according to the invention for purifying a composition (I) at least comprising cyclododecanone comprises at least step (i) (i) irradiation of the composition (I).
Abstract:
The present invention relates to a process for continuously preparing 5-alkoxy-substituted oxazoles, in particular for continuously preparing 4-methyl-5-alkoxy-substituted oxazoles and also a process for preparing pyridoxine derivatives.
Abstract:
A process for preparing 1,6-hexanediol from a carboxylic acid mixture comprising adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols which is obtained as by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol after water extraction of the reaction mixture followed by extraction with aqueous sodium hydroxide solution, by esterification of the acids and hydrogenation comprises a) liberating the carboxylic acids from the alkaline extract by addition of a mineral acid, b) fractionating the organic phase comprising carboxylic acids to give a distillate comprising the low molecular weight monocarboxylic acids and a residue comprising adipic acid and 6-hydroxycaproic acid, c) reacting the monocarboxylic an dicarboxylic acids present in the aqueous dicarboxylic acid mixture with a low molecular weight alcohol to give the corresponding carboxylic esters, d) freeing the esterification mixture obtained of excess alcohol and low boilers in a first distillation step, e) fractionating the bottom product in a second distillation step to give an ester fraction essentially free of 1,4-cyclohexanediols and a fraction comprising at least the major part of the 1,4-cyclohexanediols, f) catalytically hydrogenating the ester fraction which is essentially free of 1,4-cyclohexanediols and g) isolating 1,6-hexanediol from the hydrogenation product in a manner known per se in a final distillation step.
Abstract:
1,6-hexanediol and .epsilon.-caprolactone are prepared from a carboxylic acid mixture comprising adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols which is obtained as a by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol using oxygen or oxygen-containing gases by water extraction of the reaction mixture, by esterifying and hydrogenating a substream to give hexanediol and cyclizing 6-hydroxycaproic esters to give caprolactone.
Abstract:
N-Vinyllactams of the general formula I ##STR1## where n is from 1 to 3, are prepared by a process which comprises reaction of a lactam of the general formula II ##STR2## where n is from 1 to 3, with from 10 to 90 percent by weight of an aqueous alkali metal hydroxide solution with distillation at from 50.degree. to 250.degree. C. and from 1 to 100 mbar and with a residence time of from 0.1 to 5 hours and subsequent reaction with acetylene at from 60.degree. to 250.degree. C. and from 1 to 100 bar.
Abstract:
A process for purifying esters of tetrahydropyran-4-carboxylic acid of the formula I ##STR1## where R.sup.1 to R.sup.3 are each C.sub.1 -C.sub.4 -alkyl, and R.sup.2 and R.sup.3 are each additionally hydrogen, from mixtures produced in the reaction of butyrolactones of the formula II ##STR2## where R.sup.2 and R.sup.3 have the abovementioned meanings, and R.sup.4 is hydrogen, alkyl of 1-6 carbons or acyl of the formula --CO--R.sup.2, with alcohols of the formula R.sup.1 OH in the presence of oxide catalysts, by distillation, which entailsa) removing overhead, in a first column with 5-25 theoretical plates with a distillate pressure of 700-1100 mbar and a distillate temperature of 50.degree.-80.degree. C., an alcohol and up to 10% of the water,b) transferring the bottom product from the first column into a second column with 18-40 theoretical plates, into which a water entrainer is metered between plates 15 and 30, and is circulated, and which operates with a distillate pressure of 35-350 mbar and a distillate temperature of 18.degree.-70.degree. C., with the esters of tetrahydropyran-4-carboxylic acid being removed between plates 8 and 18 at 90.degree.-150.degree. C., and, where appropriate,c) feeding the bottom product from the second column into a third column with 5-25 theoretical plates, and returning the overhead products at a distillate pressure of 1-100 mbar and a distillate temperature of 90.degree.-140.degree. C. to the synthesis of the esters of tetrahydropyran-4-carboxylic acid.
Abstract:
A planetary roller extruder includes a housing with an internal housing toothing. A central spindle is disposed in the housing and has an external central spindle toothing. A plurality of planetary spindles are disposed about the central spindle and in the housing. Each of the planetary spindles has an external planetary spindle toothing configured to mesh with the internal housing toothing and the external central spindle toothing. A drive is configured to rotate the central spindle. The drive includes a drive journal connected to the central spindle to permit transmission of a driving force from the drive to the central spindle. The drive journal includes a bore. The bore has internal projections configured to engage with the external central spindle toothing to secure the central spindle to the drive journal by a screw-type connection.
Abstract:
A process for the extrusion of plastics, such as plastics that tend to adhere or stick to parts of an extruder, using a planetary roller extruder in the feed part.