Abstract: Indanes are prepared by reacting substituted or unsubstituted benzyl halides with olefins in the presence of a Lewis acid as catalyst by reacting benzyl halides I ##STR1## (where R.sup.1 and R.sup.2 =hydrogen, alkyl, alkoxy, cycloalkyl, aryl, aryloxy, aralkylR.sup.3 =R.sup.1, halogen or an ortho-fused ring systemX=halogen)with olefins II ##STR2## (where R.sup.4 to R.sup.7 =hydrogen or alkyl unbranched at alpha) in the presence of catalytic amounts of titanium tetrachloride.

Abstract: .beta.-Dicarbonyl, .beta.-cyanocarbonyl and .beta.-dicyano compounds I ##STR1## where R.sup.1 is an organic radical, X and Y are COOR.sup.2, --CO--R.sup.2 or --CN and R.sup.2 is an organic radical, are prepared from R.sup.1 --CHO (II) and X--CH.sub.2 --Y (III) by reaction in the presence of a condensation catalyst, hydrogen and a hydrogenation catalyst, using an oxide or phosphate of Mg, Al, Ti, Zn or a rare earth metal as the condensation catalyst.

Abstract: 3-Formyl-5,6-dihydro-2H-pyran is prepared by conversion of acrolein in the presence of water, acids and halohydrocarbons of 1 to 6 carbon atoms and 1 to 6 halogen atoms as solvents at from 60.degree. to 150.degree. C. The 3-formyl-5,6-dihydro-2H-pyran obtained by the novel process is a valuable starting material for the preparation of dyes and crop protection agents.

Abstract: A pyridine or a pyrrole is obtained in a one-stage process directly from an .alpha.,.omega.-dinitrile of appropriate carbon skeleton when the dinitrile is reacted in the gas phase with hydrogen, over a hydrogenation catalyst.

Abstract: Novel malondialdehyde tetraalkylacetals and the preparation of malondialdehyde tetraalkylacetals by reacting alkyl formates, oxiranes and alkyl vinyl ethers in the presence of a halide of boron, antimony(V), iron(III), tin(II or IV) and/or zinc.The malondialdehyde tetraalkylacetals obtainable by the process of the invention are valuable starting materials for the preparation of dyes, pest control agents and pharmaceuticals.

Abstract: A process for the continuous preparation of glyoxal by oxidation of ethylene glycol, in which the ethylene glycol, oxygen and an inert gas are passed, at from 450.degree. to 800.degree. C., over a catalyst consisting of one or more layers of copper crystals and one or more layers of silver crystals, the copper and silver crystals having a particle size of from 0.1 to 2.5 mm.

Abstract: A process for the continuous preparation of 3-alkyl-buten-1-als by oxidative dehydrogenation of 3-alkyl-buten-1-ols at from 320.degree. to 650.degree. C. with oxygen over a catalyst containing copper and/or silver, wherein, within one second after contact with the catalyst, the vaporous reaction mixture, which is at from 320.degree. to 650.degree. C., is brought into contact with a liquid comprising water and/or the condensed reaction mixture at from -20.degree. to 50.degree. C., and the 3-alkyl-buten-1-als are separated off from the resulting condensate.

Abstract: A process for the preparation of .alpha.-methylsubstituted ketones by reacting the corresponding non-methylsubstituted ketones with formaldehyde under hydrogenating conditions. The reaction proceeds easily and with good yields if a catalyst containing metallic palladium deposited on a zirconium, hafnium, titanium or tin phosphate is used. The products are valuable intermediates for the preparation of dyes, crop protection agents or drugs.

Abstract: Preparation of 5-(2,2-dihalovinyl)-4,4-dialkyl-tetrahydro-furan-2-ones of the formula I ##STR1## where R.sup.1 and R.sup.2 are each alkyl of 1 to 4 carbon atoms and X is halogen, by reacting a carboxylic acid amide of the formula II ##STR2## where R.sup.3 and R.sup.4 are each alkyl of 1 to 4 carbon atoms, aralkyl of 7 to 9 carbon atoms or aryl of 6 to 10 carbon atoms, or together with the nitrogen form a 5-membered or 6-membered saturated ring which may contain a second hetero-atom, with a carbon tetrahalide of the formula IIICX.sub.4 (III)to give an iminium salt of the formula IV ##STR3## and then hydrolyzing the iminium salt; and novel iminium salts of the formula IV.

Abstract: Preparation of 5-(2,2,2-trihaloethyl)-4,4-dialkyl-tetrahydro-furan-2-ones of the formula I ##STR1## where R.sup.1 and R.sup.2 are each alkyl of 1 to 4 carbon atoms and X is halogen, by reacting a carboxylic acid amide of the formula II ##STR2## where R.sup.3 and R.sup.4 are each alkyl of 1 to 4 carbon atoms, aralkyl of 7 to 9 carbon atoms or aryl of 6 to 10 carbon atoms or together with the nitrogen on which they are present as substituents form a 5-membered or 6-membered saturated ring which may contain a second hetero-atom, with a carbon tetrahalide of the formula IIICX.sub.4 (III)to give an iminium salt of the formula IV ##STR3## and subsequently hydrolyzing this iminium salt; and novel iminium salts of the formula IV.

Abstract: A process for the preparation of 3,3-dimethyl-pent-3-enoic acid amides of the formula I ##STR1## where R.sup.1 and R.sup.2 may be identical or different and each is alkyl of 1 to 4 carbon atoms, or R.sup.1 and R.sup.2 together with the nitrogen on which they are present as substituents form a 5-membered or 6-membered saturated ring which may contain a further hetero-atom,wherein an acetamido-acetal or ketene-acetal-aminal is reacted with 3-methyl-but-2-en-1-ol at from 80.degree. to 220.degree. C., in the presence or absence of an inert organic solvent. The products are valuable intermediates for the preparation of insecticidal cyclopropanecarboxylic acid esters.

Abstract: This invention relates to a process of making flame-retardant polystyrene foams by an extrusion process in which a stabilizer of a dialkyl-tin carboxylate or a mixture of a dialkyl tin carboxylate and a barium and/or cadmium carboxylate is added to the extrusion melt.

Abstract: 4-Methyl-5-chloromethyl-imidazole is prepared in the form of its hydrochloride by direct chloromethylation of 4-methyl-imidazole, thus becoming readily available industrially as an intermediate.

Abstract: 4-Methyl-5-[(2-aminoethyl)-thiomethyl]-imidazole dihydrochloride is prepared in a single-step process by thiomethylating 4-methylimidazole. The product is an intermediate for other imidazole derivatives, especially the drug cimetidine.

Abstract: Process for the manufacture of .alpha.-naphthol by hydrolyzing .alpha.-naphthyl esters of aliphatic carboxylic acids in a distillation column by means of steam in counter-current at a particular temperature, and in a certain ratio, in the presence of naphtholsulfonic acids and/or sulfonic acids of naphthyl esters. The .alpha.-naphthol obtainable by the process of the invention is a valuable starting material for the manufacture of dyes, drugs and insecticides, e.g. .alpha.-naphthyl N-methylcarbamate.