摘要:
A process for the continuous production of 1,3-dioxolan-2-ones such as ethylene carbonate or propylene carbonate by reacting a corresponding oxirane with carbon dioxide in the liquid phase in the presence of a catalyst comprises conducting the reaction in a two-part reactor in whose first part the reaction is taken with backmixing to a conversion of not less than 80% of the oxirane II and in whose second part the reaction is completed under nonbackmixing conditions, and passing the carbon dioxide in countercurrent to the oxirane II in the entire reactor.
摘要:
A process for preparing substituted imidazoles of the formula I ##STR1## R.sup.1, R.sup.2 and R.sup.3 are identical or different and are each hydrogen, halogen, NO.sub.2, CN or a C.sub.1 -C.sub.20 -hydrocarbon radical which is unsubstituted or substituted by one or more halogens or R.sup.1 and R.sup.2 together are members of a 3- to 20-membered hydrocarbon ring which is unsubstituted or substituted by one or more halogens and/or C.sub.1 -C.sub.8 -alkyl groups and which may contain 1, 2 or 3 heteroatoms from the group consisting of nitrogen, oxygen and sulfur, andR.sup.4 is a C.sub.1 -C.sub.20 -hydrocarbon radical which is unsubstituted or substituted by one or more halogens,comprises using an aqueous phase of the imidazoles of the formula II ##STR2## where R.sup.1, R.sup.2 and R.sup.3 are as defined above with compounds of the formula IIIR.sup.4 --O--R.sup.5 IIIwhereR.sup.4 is as defined above andR.sup.5 is hydrogen or R.sup.4, it being possible in the latter case for the two R.sup.4 substituents to be identical or different,and reacting it at from 200.degree. to 550.degree. C. in the presence of a catalyst comprising oxides and/or phosphates of one or more metals of the 2nd, 3rd and 4th main group and the 4th subgroup of the Periodic Table in the presence or absence of phosphoric acid and/or phosphoric esters.
摘要:
In a process for isolating alkylene glycol having a low aldehyde content, in which a mixture comprising alkylene glycol is subjected to a final distillation, formic acid or a formate or a mixture of two or more formates or a mixture of formic acid and one or more formates is present in the mixture comprising alkylene glycol.
摘要:
Alkali metal ions are separated off from alkoxylates containing alkali metal ions by a process comprising: a) dilution of the alkali metal-containing alkoxylate with an inert solvent, b) treatment of the alkali metal-containing solution of the alkoxylate with a cationic exchanger in order to obtain a substantially alkali metal-free solution of the alkoxylate, and c) removal of the solvent from the substantially alkali metal-free solution of the alkoxylate in order to obtain a substantially alkali metal-free and substantially solvent-free alkoxylate.
摘要:
In a process for the continuous preparation of alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid with alkanols having from 1 to 8 carbon atoms in a homogeneous, liquid, solvent-free phase at elevated temperature and in the presence of an acid esterification catalyst, in which the (meth)acrylic acid, the alkanol and the acid catalyst are fed to a reaction zone, the water formed is removed by rectification during a residence time as constituent of a mixture comprising starting alkanol in a rectification unit (III) superposed on the reaction zone, the distillate obtained is separated into an organic phase comprising alkanol and an aqueous phase comprising water, the organic phase is essentially completely returned to the rectification unit (III), the reaction mixture is discharged from the reaction zone and conveyed into a distillative separation zone comprising further rectification units and in the latter the alkyl (meth)acrylate formed is separated off.a) (Meth)acrylic acid and alkanol are reacted in a molar ratio of from 1:0.75 to 1:2, b) part of the aqueous phase obtained at the top of the rectification unit (III) is returned to the rectification unit, c) the reaction mixture discharged from the reaction zone is fed to a further rectification unit (I) and in this the reaction mixture is separated into a product (II) comprising the catalyst and a product (I) comprising the alkyl ester of (meth)acrylic acid, remaining alkanol and remaining (meth)acrylic acid, and d) the product (I) is fed to a further rectification unit (II) and in this the alkyl ester of (meth)acrylic acid is separated from the remaining alkanol and from the remaining (meth)acrylic acid and the remaining alkanol and the remaining (meth)acrylic acid are returned to the reaction zone.
摘要:
N-substituted-pyrazoles of the formula ##STR1## wherein R.sup.1 is C.sub.1 -C.sub.12 -alkyl or C.sub.7 -C.sub.20 -alkyl, and R.sup.2, R.sup.3 and R.sup.4 independently denote hydrogen, C.sub.1 -C.sub.12 -alkyl, phenyl, C.sub.7 -C.sub.20 -alkylphenyl and C.sub.7 -C.sub.20 -phenylalkyl, are prepared by reacting a pyrazole of the formula ##STR2## wherein R.sup.2, R.sup.3 and R.sup.4 have the meanings above, with an alcohol or ether of the formulaR.sup.1 --O--R.sup.5 III,wherein R.sup.5 is hydrogen or R.sup.1, at a temperature of from 200.degree. to 550.degree. C. and a pressure of from 0.001 to 50 bar in the presence of a heterogeneous catalyst, preferably one which contains acid centers such as the oxides of aluminum, silicon, titanium and/or zirconium, optionally doped with phosphoric acid.
摘要:
4,5-Disubstituted imidazole-2-carboxylic acids are prepared by reacting 4,5-disubstituted imidazoles with carbon dioxide under superatmospheric pressure at from 150.degree. to 300.degree. C. in the presence of a base.
摘要:
Ketones of the general formula (I) ##STR1## where R.sup.1 and R.sup.2 independently of one another are each alkyl, cycyloalkyl, arylalkyl, aryl or hetaryl, and one or more of the radicals R.sup.1 and R.sup.2 carry one or more hydrogen atoms on the .alpha.-carbon atom, are prepared by reacting two carboxylic acids of the general formulae (IIa/IIb), R.sup.1 --COOH (IIa) and R.sup.2 --COOH (IIb) or by reacting a carboxylic acid R.sup.1 --COOH (IIa) and a ketone ##STR2## or by reacting a mixture of IIa, IIb and Ib, in the gas phase in the presence of a catalyst, by a process in which a catalyst is used whose active material contains at least 50% by weight of titanium dioxide having a specific surface area greater than 10 m.sup.2 /g.0.
摘要:
Acylated imidazoles of the formula ##STR1## where R.sup.1 and R.sup.3 are each H, alkyl of from 1 to 12 carbon atoms, alkenyl of from 1 to 12 carbon atoms, aryl, aralkyl or alkylaryl, R.sup.4 is H, alkyl of from 1 to 12 carbon atoms, alkenyl of from 1 to 12 carbon atoms, aryl, aralkyl or alkylaryl, and R.sup.5 is alkyl of from 1 to 12 carbon atoms, alkenyl of from 1 to 12 carbon atoms, aryl, aralkyl, alkylaryl or carboxyl, are prepared by reacting imidazoles of the formula ##STR2## where R.sup.1, R.sup.2 and R.sup.3 are each alkyl of from 1 to 12 carbon atoms, alkenyl of from 1 to 12 carbon atoms, aryl, aralkyl or alkylaryl, at least one of the radicals R.sup.1, R.sup.2 and R.sup.3 being hydrogen, and R.sup.4 is H, alkyl of from 1 to 12 carbon atoms, alkenyl of from 1 to 12 carbon atoms, aryl, aralkyl or alkylaryl, with widely used acylating agents of the formula ##STR3## where R.sup.5 is as defined above and Y is halide, alkoxy, acyloxy or hydroxyl, in the presence of acidic metal oxides and/or phosphates, preferably in the gas phase.
摘要:
Aliphatic, cycloaliphatic, aromatic or araliphatic halogen compounds are reductively dehalogenated by reaction with hydrocarbons in the presence of carbon in the liquid phase at from 100.degree. to 450.degree. C. with formation of hydrogen halides.