Abstract: A process for the preparation of the sought-after scent 2,5-dimethyl-4-hydroxy-2,3-dihydrofuran-3-one, and novel intermediates for the preparation of this compound.2,5-Dimethyl-4-hydroxy-2,3-dihydrofuran-3-one is prepared by first epoxidizing hex-3-ene-2,5-diol in the liquid phase with hydrogen peroxide to give the novel compound 3,4-epoxy-hexane-2,5-diol, which at 40.degree.-280.degree. C. is converted, by means of a catalytic amount of an acid, to the novel compound 2,5-dimethyl-3,4-dihydroxy-tetrahydro-furan. The latter is dehydrogenated by means of oxygen over a silver catalyst or copper catalyst to give the nove compound 2,5-dimethyl-4-hydroxy-tetrahydrofuran-3-one, which is oxidized by means of bismuth oxide, in concentrated acetic acid solution, to give the desired compound 2,5-dimethyl-4-hydroxy-2,3-dihydrofuran-3-one.

Abstract: Glyoxal is prepared by oxidizing glycol in the presence of a silver catalyst of a defined particle size and under defined conditions of temperature, residence time and inert gas concentration.The glyoxal obtainable by the process of the invention may be used in wrinkle-resist finishing, as an assistant for increasing the tensile strength and resilience of fibrous materials, a tanning agent, a hardener in the photographic industry, and a starting material for the manufacture of synthetic resins, textile auxiliaries, for example to prevent shrinkage after washing, paper additives, for example for increasing the wet strength, and plastics.

Abstract: Diketones are prepared by oxidizing glycols in the presence of a silver catalyst and/or copper catalyst of a specific particle size, under specific temperature conditions and with a specific composition of the catalyst. The end products are starting materials for the preparation of dyes, drugs, plastics, scents, wrinkle-resist finishes and assistants for increasing the tear strength and resilience of fibrous materials, hardeners for use in the photographic industry, textile assistants for preventing shrinkage after washing, and paper assistants.

Abstract: Aliphatic hydroxycarbonyl compounds etherified with aliphatic groups are prepared by oxidizing hydroxyalcohols in the presence of a metal catalyst which consists of one or more layers, each of a particular weight and each containing particles of a particular size, the catalyst bed also having a particular total thickness, and the catalyst components used being silver and copper, with or without added copper/tin/phosphorus or silver alone. The etherified hydroxyaldehydes and hydroxyketones obtainable by the process of the invention are valuable starting materials for the preparation of dyes, pesticides, plastics and scents.

Abstract: Alkyl pyruvates are prepared by oxidizing alkyl lactates in the presence of a silver catalyst of a defined particle size, at from 450.degree. to 700.degree. C. The products are starting materials for the preparation of drugs, synthetic resins and plastics.

Abstract: Aromatic and araliphatic aldehydes are prepared by oxidizing corresponding alcohols with oxygen in the presence of a silver catalyst of a defined particle size, and under defined temperature conditions. The products are starting materials for the preparation of dyes, pesticides, plastics and scents.

Abstract: 3-Methyl-2-buten-1-al is prepared by isomerizing 3-methyl-3-buten-1-al in the presence of acidic or basic compounds. The product is a starting material for the manufacture of dyes, pesticides, pharmaceuticals, plastics and scents.

Abstract: 3-Alkyl-buten-1-als are prepared by oxidative dehydrogenation of 3-alkyl-buten-1-ols in the presence of a silver catalyst, of a particular total thickness, comprising 2 or more layers each of a particular weight and containing particles of a particular size. The products are starting materials for the manufacture of dyes, pesticides, drugs, plastics, naturally occurring materials and scents.

Abstract: Sulfur-free combustion gases of low soot content are produced by mixing oxygen and an off-gas of a defined composition in a defined weight ratio, passing the final mixture thus obtained through a defined number of slit channels of gas burners into a combustion chamber and combusting it at a defined temperature. Compared to the prior art, the process of the invention gives sulfur-free combustion gases, containing little or no soot (in general containing no detectable soot), more simply and more economically. These gases are used for heating, in particular for raising steam.

Abstract: An improved process for the manufacture of silver catalysts, in which the silver is applied to conventional dimensionally stable and chemically inert carriers, eg. alumina or quartz moldings, preferably by electroless deposition from silver salt solutions onto a great variety of surfaces acting as carriers, by the use of suitable reducing agents. In a particular embodiment, a uniform deposition of silver and a dense and well-adhering silver layer on the surface of the carrier are achieved by adding certain materials to the silver salt solutions.

Abstract: Formaldehyde is manufactured by oxidative dehydrogenation of methanol in the presence of a silver catalyst and of certain amounts of steam and formaldehyde, some formaldehyde and a part of the water being withdrawn from the reaction mixture and recycled. The formaldehyde manufactured by the process may be used as a disinfectant, tanning agent, reducing agent and starting material for the manufacture of synthetic resin, adhesives and plastics.

Abstract: Formaldehyde is prepared by oxidative dehydrogenation of methanol in the presence of a silver catalyst, specific amounts of steam and specific amounts of an off-gas, of a specific composition, taken from the manufacture of formaldehyde. The reaction is started at a lower throughput of methanol and at a lower temperature. The formaldehyde obtainable by the process is a disinfectant, tanning agent and reducing agent, and a starting material for the manufacture of synthetic resins, adhesives and plastics.

Abstract: Stabilized, aqueous formaldehyde solutions and a process for their manufacture by addition of isophthalobis-guanamine and/or terephthalo-bis-guanamine. The formaldehyde solution of the invention is used as a disinfectant, tanning agent or reducing agent, and as a starting material for the manufacture of synthetic resins, adhesives and plastics.

Abstract: A continuous process for the manufacture of cyclohexanol from cyclohexene in two stages involving the addition of sulfuric acid and hydration, the addition of sulfuric acid being carried out in the presence of iron(II) sulfate. In a special embodiment, the addition of sulfuric acid is carried out in the first stage at atmospheric pressure and at the boiling temperature of cyclohexene.

Abstract: Manufacture of phthalo-bis-guanamines by reaction of phthalodinitriles with dicyandiamide in the presence of basic compounds and dialkylsulfoxides. The products are starting materials for the manufacture of synthetic resins, plastics, textile auxiliaries, plant protection agents and dyes.