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.