Abstract: 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.

Abstract: A process for the preparation of mixtures of isomeric cresols with a molar ratio of para- to meta-cresol of from 0.6:1 to 10:1 by isomerization of cresol mixtures or ortho- and/or metal-cresol on zeolite catalysts of the pentasil type in the gas phase at from 300.degree. to 600.degree. C. under from 0.01 to 50 bar entails the mean particle size of the zeolite catalyst being at leat 3 .mu.m, and the selectivity in the established test for the disproportionation of ethylbenzene to diethylbenzene isomers being at least 60% for para-diethylbenzene.

Abstract: Cyclic 6-membered to 8-membered 1,2-vinylenedioxy compounds of the general formula I ##STR1## where A is ##STR2## R.sup.1 to R.sup.7 independently of one another are each hydrogen, C.sub.1 -C.sub.8 -alkyl, C.sub.2 -C.sub.16 -alkoxyalkyl, C.sub.2 -C.sub.8 -alkenyl, C.sub.2 -C.sub.8 -alkynyl, C.sub.5 -C.sub.8 -cycloalkyl, aryl, C.sub.7 -C.sub.10 -alkylphenyl, C.sub.7 -C.sub.10 -phenalkyl, C.sub.8 -C.sub.10 -phenalkenyl or a heterocyclic structure, or R.sup.2 and R.sup.3, R.sup.2 and R.sup.4, R.sup.3 and R.sup.4, R.sup.2 and R.sup.6, R.sup.3 and R.sup.6, R.sup.4 and R.sup.5 or R.sup.6 and R.sup.7 together form a cycloaliphatic or heterocyclic ring, and R.sup.1 to R.sup.7 may furthermore carry substituents which are inert under the reaction conditions, and n is 0 or 1, are prepared by a process in which a cyclic 2-oxymethyl-1,3-dioxa compound or one of its derivatives of the general formula II ##STR3## where R.sup.1 to R.sup.7, A and n have the abovementioned meanings, and R.sup.8 is hydrogen or C.sub.1 -C.sub.

Abstract: Compounds of the formula IR.sup.1 --CH.dbd.CH--R.sup.2 Iwhere R.sup.1 is hydrogen or alkyl and R.sup.2 is alkoxy or acylamino, and R.sup.1 and R.sup.2 together may form a heterocyclic ring, are prepared by elimination of the radical R.sup.3 OH from a compound of the formula II ##STR1## where R.sup.1 and R.sup.2 have the above meanings and R.sup.3 is alkyl, by a method in which the elimination is carried out by passing the compound of the formula II in a liquid or gaseous state into a high-boiling mineral oil above the boiling point of compound I being formed, compound I is taken off in gaseous form, and the high-boiling mineral oil enriched with by-products is removed and replaced with fresh mineral oil.

Abstract: 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.

Abstract: Organic halogen compounds in which one or more halogen atoms are covalently bonded to the carbon are subjected to reductive dehalogenation by reaction with a hydrocarbon in the presence of carbon at elevated temperatures with formation of a hydrogen halide, by a process in which the dehalogenation is carried out in the presence of iron powder or an iron compound as a cocatalyst, at from 100.degree. to 450.degree. C.

Abstract: 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.

Abstract: 4-Nitro-5-imidazolyl ethers and thioethers of the formula I ##STR1## where R.sup.1 is alkyl, alkoxyalkyl, cycloalkyl, aryl, aralkyl or alkylaryl, R.sup.2 is hydrogen, alkyl, cycloalkyl, aryl, aralkyl or alkylaryl, R.sup.3 is alkyl, cycloalkyl, aryl, aralkyl, alkylaryl or a heterocyclic or heteroaromatic radical or a counter-ion of the corresponding alcoholate or thiolate or, where X is sulfur, R.sup.3 is hydrogen, and X is oxygen or sulfur, and the stated organic radicals may furthermore carry substituents which are inert under the reaction conditions, are prepared by reacting a dinitroimidazole of the formula II ##STR2## with an alcohol or thiol of the formula IIIR.sup.3 --XH (III)in a solvent or diluent at a pH of the from 4 to 16.

Abstract: Hexaarylbisimidazoles I ##STR1## where Ar.sup.1, Ar.sup.2 and Ar.sup.3 are each aryl, of which Ar.sup.2 and Ar.sup.3 can be linked to form an anellated ring system, are prepared by oxidizing the corresponding triarylimidazoles II in an aqueous/organic two-phase system in the presence of active amounts of an onium salt III.

Abstract: Process for the preparation of 1-alkylimidazoles of the general formula (I) ##STR1## where R.sup.1 is alkyl, R.sup.2 and R.sup.3 are hydrogen, alkyl, aryl, arylalkyl, or alkylaryl, R.sup.4 is carboxy, alkoxycarbonyl R.sup.5 OCC--, carbamoyl, or cyano, and R.sup.5 is an alkyl of from 1 to 8 carbon atoms--by the reaction of imidazoles of the general formula (II) ##STR2## with dialkyl sulfates of the general formula (III)(R.sup.1 O).sub.2 SO.sub.2 (III)at elevated temperatures in the presence of a carboxylic acid or anhydride or of both acid and anhydride.

Abstract: 3,4-dihydro-2H-pyrans I ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each H or C.sub.1 -C.sub.6 -alkyl and R.sup.3 is not C.sub.2 -C.sub.4 -alkyl when A is COOR.sup.5 and A is COOR.sup.5, .dbd.CHOR.sup.5, in which R.sup.5 is C.sub.1 -C.sub.4 -alkyl, or CH.sub.2 OR.sup.6, in which R.sup.6 is C.sub.1 -C.sub.4 -alkyl or is benzyl which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl, alkoxy or halogen, or is formyl, C.sub.2 -C.sub.4 -alkylcarbonyl or benzoyl which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl, alkoxy or halogen, are prepared by eliminating an alcohol from a 2-alkoxytetrahydropyran II ##STR2## where R.sup.7 is C.sub.1 -C.sub.18 -alkyl and A' is COOR.sup.5, CH(OR.sup.5).sub.2 or CH.sub.2 OR.sup.6, in which R.sup.5 and R.sup.

Abstract: 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.

Abstract: Organic sulfur compounds, such as sulfonic acids, sulfonyl halides, sulfonates, sulfonamides, sulfonic acid anhydrides, sulfones, sulfoxides and/or disulfanes, are reduced by a method in which the sulfur compound in the liquid or gas phase is reacted with a hydrocarbon in the presence of carbon at from 100.degree. to 500.degree. C.

Abstract: 4(5)-nitroimidazole-5(4)-carboxylic acids are prepared by reacting an imidazole-4(5)-carboxylic acid with a mixture of sulfuric acid and nitric acid at not less than 80.degree. C., the water content of the reaction mixture at the beginning of the reaction being no higher than 5% by weight, based on the reaction mixture.

Abstract: In an improved process for preparing caprolactam by heating 6-aminocaproic acid, an ester or amide or mixture thereof in the presence of an inert reaction medium which is liquid under the reaction conditions and has a boiling point above that of caprolactam, the improvement comprises using as the reaction medium a hydrocarbon, maintaining a temperature of from 150.degree. to 350.degree. C., charging the 6-aminocaproic acid, ester, amide or mixture thereof at a rate commensurate with their rate of conversion, and separating caprolactam from the reaction mixture at a rate commensurate with its rate of formation.

Abstract: Tertiary phosphine oxides, phosphine sulfides and/or phosphine dihalides are reduced to tertiary phosphines by reaction with a hydrocarbon in the presence of carbon at elevated temperatures.

Abstract: Imidazole-4(5)-monocarboxylic acids and their salts or betaines are prepared by reacting an imidazole with carbon dioxide and an alkali metal carbonate, an alkali metal bicarbonate and/or an alkali metal hydroxide at from 140.degree. to 230.degree. C. and under from 2 to 350 bar and, if desired, then reacting the product with an acid.The imidazole-4(5)-monocarboxylic acids which can be prepared by the process of the invention are useful starting materials for the preparation of dyes, crop protection agents and drugs.

Abstract: 5,6-Dihydro-2H-thiopyran-3-carboxaldehydes of the formula ##STR1## where R denotes hydrogen or methyl, are prepared by a method in which acrolein or crotonaldehyde is reacted with hydrogen sulfide in a mineral oil whose boiling point is higher than those of the starting materials and of the end product, and the 5,6-dihydro-2H-thiopyran-3-carboxaldehyde is obtained by distillation. These aldehydes are important intermediates for the preparation of some crop protection agents.

Abstract: 2-Alkyl-4,5-dihydroxymethyl-imidazoles of the formula ##STR1## where R is alkyl, are prepared by a process in which an imidazole of the formula ##STR2## is reacted with not less than 2 moles of formaldehyde in the presence of a base.

Abstract: Quinoline and substituted quinolines are prepared by reacting aniline or a substituted aniline with an .alpha., .beta.-monounsaturated aldehyde in a high-boiling mineral oil by a method in which the high-boiling mineral oil is replaced when it becomes enriched with by-products, and the said mineral oil enriched with by-products is removed.