Abstract: A process for the production of high molecular weight .alpha., .beta.-unsaturated aldehydes by alkylation of the .gamma.-carbon atom of a lower molecular weight .alpha., .beta.-unsaturated aldehyde with a substituted allyl alcohol which has a chain branching in the 3-position carbon atom or a phenyl radical in the 3-position or of a corresponding allyl alcohol carboxylic ester at elevated temperature in the liquid phase.The products are valuable intermediates for the production of natural substances and odorants.

Abstract: A process for the recovery of pure 2-methyl-2-hydroxyheptanone-6 by conversion of impure 2-methyl-2-hydroxyheptanone-6 into 2,2,6-trimethyl 2,3-hydro-4-H-pyran by treatment with an acid which is not volatile under the reaction conditions at a temperature of from 30.degree. to 150.degree.C, purification of the 2,2,6-trimethyl-2,3-hydro-4-H-pyran thus obtained by distillation, reaction of the purified 2,2,6-trimethyl-2,3-hydro-4-H-pyran with water in the presence of an acid ion exchanger and removal of the excess water from the aqueous solution of 2-methyl-2-hydroxyheptanone-6 thus obtained by distillation. 2-methyl-2-hydroxyheptanone-6 is suitable for the production of 2-methyl-2-hydroxy-6-aminoheptane which is effective as a pharmaceutical for conditions of the heart and circulation.

Abstract: A process for the production of high molecular weight unsaturated ketones by alkylation of low molecular weight .alpha.,.beta.-unsaturated ketones with an allyl alcohol at elevated temperature in the presence of an acid catalyst. The products are intermediates for the production of various natural substances and perfumes such as the damascenones, damascones or natural dyes such as zeaxanthin, rhodoxanthin or xanthophyll.

Abstract: A process for the production of 2-methyl-4-halobut-2-en-1-als by reacting 2-methylbut-3-en-1-al-2-ol or an acetal or acylate thereof at a temperature of from -10.degree.C to +100.degree.C in the presence of copper or a copper salt with the appropriate hydrogen halides.

Abstract: Manufacture of high molecular weight unsaturated ketones by reacting allyl alcohols with 1-substituted butadiene-1-alkyl ethers or with 1-substituted butadiene-1-alkyl esters or with substances capable of forming said compounds under the conditions of the reaction, in the presence of acid catalysts at elevated temperatures and in the liquid phase. The resulting unsaturated ketones are precursors or intermediates in the manufacture of a variety of natural dyes such as zeaxanthin, rhodoxanthin and xanthophyll or of odorants such as damascones and damascenones.