Abstract: Allyl alcohols are isomerized in aqueous solution in the presence of protonic acids, with the pH of the reaction mixture being adjusted to the range from 2 to 5 with an acid concentration below 0.16 mol per liter of the reaction mixture or with a buffer which comprises the protonic acid.

Abstract: The preparation of 3-alkoxycarbonyl propenals and 3-dialkoxymethyl propenals of the general formulae Ia and Ib respectively: ##STR1## (R.sup.1 =C.sub.1 -C.sub.3 -alkyl group; R.sup.2 and R.sup.3 =hydrogen, methyl, or ethyl; and R.sup.4 and R.sup.5 =C.sub.1 -C.sub.4 -alkyl groups, which may be joined to form a 5-membered or 6-membered ring), is effected by reacting a corresponding alcohol of the general formula IIa or IIb ##STR2## with oxygen or an oxygen-containing gas in the gas phase in the presence of a metal from Group IB of the Periodic Table or a compound of one such metal acting as catalyst.The target products serve as intermediates for the synthesis of carotenoids.

Abstract: In a tube bundle reactor for carrying out catalytic organic reactions in the gas phase, comprising reaction tubes (A) arranged between tubesheets (B), the reaction tubes have an inside diameter ranging from 0.5 to 3 cm, the ratio of reaction tube length to inside diameter ranges from 2 to 10, and the reaction tubes (A) are surrounded by a fluid heat transport medium flowing in the crosswise direction; said tube bundle reactor is useful in particular in exothermic organic reactions.

Abstract: Distillative separation of liquid mixtures of one or more water-insoluble substances which have boiling points higher than that of water and one or more substances which have boiling points lower than that of water or which form azeotropes having boiling points lower than that of water, wherein the mixture to be distilled is mixed with a quantity of water such that the boiling point of the water under the pressure applied limits the bottom temperature of the mixture of substances to be separated.

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: Citral (I) ##STR1## is prepared by heating an acetal (IIa) or (IIb) ##STR2## in the presence of an acid catalyst while continuously distilling from the reaction mixture the 3-methylbut-2-en-1-ol (III, prenol) eliminated during the reaction.

Abstract: Substituted phenylpropanals and a process for their manufacture by reaction of the corresponding phenylethenes with carbon monoxide and hydrogen at temperatures of from 50.degree. to 180.degree. C and pressures of from 20 to 1,500 atmospheres gauge, in the presence of rhodium carbonyl complexes. The phenylpropanals according to the invention have pleasant scents. 3-(4-Isopropyl-phenyl)-butanal-1 and 3-(4-tert.-butyl-phenyl)-butanal-1, in particular, have suitable scents for the preparation of flower oil. They are also valuable starting materials for synthesizing drugs, plant protection agents and dyes.

Abstract: The production of 3-methylpentane-1,5-diol by hydroformylation of 2-methylbut-1-en-4-ol with carbon monoxide and hydrogen at elevated temperature and superatmospheric pressure in the presence of a rhodium carbonyl complex which has been modified by a tertiary organic phosphine followed by hydrogenation of the 2-hydroxy-4-methyltetrahydropyran at elevated temperature and superatmospheric pressure in the presence of a hydrogenation catalyst.