Abstract: The present invention relates to a method for preparing cyclohexene derivatives of the general formulae I or II by reducing alkyne compounds of the general formulae III or IV with a mixture of zinc and at least one ammonium salt of the formula V as reducing agent, in which the substituents R1 to R8 have independently of one another the meaning specified in the description, wherein the reducing agent comprises from 0.3 to 0.49 mol of at least one ammonium salt of the formula V per mol of zinc.

Abstract: The invention relates to a method for producing compounds of general formula (I), wherein Rt represents an oxocyclohexyl radical which is optionally substituted by a hydroxyl radical, an alkoxy radical, and/or alkyl radicals, or an oxocyclohexenyl radical which is optionally substituted by a hydroxyl radical, an alkoxy radical, and/or alkyl radicals, the oxo groups being in the form of an acetal, a ketone, or an enol ether, and R2 represents a hydroxy group or a protective group which can be transformed into a hydroxy group by means of hydrolysis. A compound of general formula (II) is cathodically reduced in a divided or partially divided electrolysis cell at a pH value of between 2 and 9.

Abstract: A process is provided for the preparation of cyclohexene derivatives of general formula I or II: in which the substituents R1 and R2 independently of one another are defined as follows: R1 is R2 is OH or a protective group convertible to a hydroxyl group by hydrolysis; R3 and R4 are hydrogen or C1-C4-alkyl; and R5 is hydrogen or C1-C4-acyl, by the reduction of alkyne compounds of general formula III or IV: in which the substituents R1 and X are as defined above, wherein the reducing agent used is a mixture of zinc and at least one compound B selected from the group consisting of ammonium salts, copper salts and alkali metal and alkaline earth metal salts.

Abstract: A process is provided for the preparation of cyclohexene derivatives of general formula I or II: in which the substituents R1 and R2 independently of one another are defined as follows: R2 is OH or a protective group convertible to a hydroxyl group by hydrolysis, R3 and R4 are hydrogen or C1-C4-alkyl, and R5 is hydrogen or C1-C4-acyl, by the reduction or alkyne compounds of general formula III or IV: wherein the reducing agent used is at least one salt of hyposulfurous acid or hydroxymethanesulfinic acid or a mixture of at least one salt of hyposulfurous acid and at least one salt of hydroxymethanesulfinic acid.

Abstract: A process is provided for the preparation of cyclohexene derivatives of general formula I or II: 1

Abstract: A process is provided for the preparation of cyclohexene derivatives of general formula I or II: 1

Abstract: A process for the stereoselective preparation of (-)3a,6,6,9a-tetramethylperhydronaphtho[2,1-b]furan of the formula Ia ##STR1## by dehydration and cyclization of decahydro-2-hydroxy- 2,5,5,8-tetramethyl-1-naphthaleneethanol using solid acidic catalysts, wherein the decahydro-2-hydroxy- 2,5,5,8-tetramethyl-1-naphthaleneethanol is heated in the molten state at from 80.degree. to 200.degree. C. in the presence of from 10 to 100% by weight, based on the diol, of an active acidic aluminum oxide commercially supplied for (preparative) column chromatography.

Abstract: A process for preparing spray granules or microgranules, which contain no binder, are non-dusting and free-flowing, from finely divided pure riboflavin, comprises subjecting an aqueous or water-containing suspension of the pure finely divided riboflavin toa) a fluidized bed spray dryingb) a single-nozzle spray drying orc) a disk-type spray dryingin particular a fluidized bed spray drying, without adding binders to the suspension, and the spray granules or microgranules of riboflavin obtainable by this process.

Abstract: A method of purifying ferment-produced riboflavin, wherein the impure riboflavin is suspended in water or dilute aqueous acid, and the suspension is heated at a temperature of from 75.degree. to 130.degree. C. for from 0.3 to 3 hours with stirring, during which time crystal transformation takes place, after which the mixture is cooled and the purified product is isolated in known manner.

Abstract: Riboflavin is removed from fermentation suspensions by them being heated at from 50.degree. to 90.degree. C. for from 1 to 3 hours, than cooled to from 0.degree. to 30.degree. C. over a period of from 1 to 5 hours, and subsequently being centrifuged to give a sediment fraction and liquid fraction in such a way that the sediment fraction contains predominantly riboflavin crystals as solid, and the liquid fraction contains virtually no crystalline riboflavin, and, where appropriate, resuspending the sediment fraction in from 0.5 to 2 parts by volume of water per part by volume of sediment fraction and repeating procedure c.

Abstract: An improved process for preparing riboflavin 5'-phosphate (FMN) or its monosodium salt by reacting riboflavin with excess phosphorus oxychloride in a solvent, hydrolyzing of the resulting reaction mixture and, if desired, partially neutralizing with aqueous sodium hydroxide solution, comprises reacting the riboflavin with from 1.2 to 3 moles of phosphorus oxychloride per mole of riboflavin in a suitable lactone, especially .gamma.-butyrolactone, as solvent. The process is particularly advantageous when the reaction mixture is hydrolyzed at from 80.degree. to 90.degree. C. continuously or batchwise.

Abstract: Riboflavin-4',5'-cyclophosphoric acid chloride of the formula I ##STR1## its preparation by reacting an alkali metal salt of riboflavin, in an aprotic solvent, with phosphorus oxychloride, its use for the preparation of riboflavin-5'-phosphate and of the sodium salt of riboflavin-5'-phosphate, and a process for the preparation of riboflavin-5'-phosphate or its sodium salt via the novel phosphoric acid ester chloride.

Abstract: Riboflavin produced by a microbial method is prepared in the form of free-flowing, non-dusting, spray-dried granules or microgranules as a feed additive by removing water from the mixture discharged from microbial fermentation for the preparation of riboflavin, wherein the mixture is subjected to(a) a fluidized-bed spray-drying process(b) a one-material spray-drying process or(c) a disk spray-drying process without significant amounts of binders being added to the discharged fermentation mixture.

Abstract: Riboflavin of the formula I ##STR1## is prepared by an improved process by condensing a 4,5-dimethyl-N-(D)-ribityl-2-phenylazoaniline of the formula II ##STR2## where R is H, --CL, --NO.sub.2, --CH.sub.3 or --OCH.sub.3 in the o- or p-position, with barbituric acid of the formula III ##STR3## in the presence of an acid as a condensing agent, by a process in which the acidic condensing agent used is an aliphatic secondary carboxylic acid of the general formula IV ##STR4## where R.sup.1 is methyl or ethyl and R.sup.2 is alkyl of 3 or 4 carbon atoms.

Abstract: Very pure riboflavin (I) is obtained by a process in which the riboflavin is dissolved in dilute aqueous alkali metal hydroxide solution, if necessary the alkaline solution is purified by treatment with active carbon or with a solvent which is insoluble or only slightly soluble in water, the resulting alkaline solution of I is introduced into water which is at 90.degree.-100.degree. C. and to which an acid has been added in an amount such that the reaction mixture is brought to a pH of from 6.5 to 0.8, the temperature being maintained at from 40.degree. to 100.degree. C., the reaction mixture is kept at from 90.degree. to 100.degree. C. for from 10 to 80 minutes and cooled, and I is then isolated.

Abstract: Riboflavin of the formula I ##STR1## is prepared by condensation of a 4,5-dimethyl-N-(D)-ribityl-2-phenylazoaniline of the formula II ##STR2## where X is H, --Cl, --NO.sub.2 or --CH.sub.3 in the o- or p-position, with barbituric acid of the formula III ##STR3## in the presence of an acidic condensing agent in an inert organic solvent by an improved process in which the reaction is carried out in an aliphatic diol or triol derivative of the general formula IV ##STR4## where R.sup.1 is H or CH.sub.3, R.sup.2 is H or CH.sub.3 -- or, when n is 0, is CH.sub.3 --CO--O--CH.sub.2 --, R.sup.3 is CH.sub.3 --, C.sub.2 H.sub.5 -- or CH.sub.3 --, R.sup.4 is CH.sub.3 --CO--, or is H when R.sup.3 is CH.sub.3 -- or C.sub.2 H.sub.5 --, and n is 0 or 2, preferably 0, having a boiling point of 80.degree.-180.degree. C., or in a mixture of these as a solvent. In this process, the riboflavin is obtained in particularly pure form and in very good yields.

Abstract: An improved process for the purification of crude riboflavin which has been prepared by condensation of an N-(D)-ribityl-2-arylazo-4,5-dimethylaniline and barbituric acid or another N-(D)-ribityl-4,5-dimethyl-aniline derivative with a barbituric acid derivative, by dissolving the crude riboflavin in sulfuric acid or phosphoric acid which has been diluted with water and oxidizing the impurities by treating the solution with hydrogen peroxide, or by dissolving the riboflavin in dilute nitric acid at elevated temperature and then isolating the pure riboflavin by precipitation with water, wherein the mineral acid solution of the riboflavin and the oxidizing agent or the solution of the riboflavin in 20 to 70% strength by weight nitric acid is heated extremely rapidly to a temperature at which the solution clearly changes color from greenish to yellow-orange, the solution is kept at this temperature for from 1 to 50, seconds and the oxidation reaction is then interrupted by addition of water.

Abstract: Anthranilic acid amides are prepared by mixing phthalamic acid with a caustic alkali solution, a catalyst and a hypohalite, allowing the mixture to stand for from 1 to 1,000 seconds, then introducing the amine and thereafter addig acid until the pH of the mixture is from 6 to 8.The anthranilic acid amides obtainable by the process of the invention are valuable starting materials for the preparation of dyes, scents and pesticides.

Abstract: A process for the continuous preparation of phthalimide by reacting phthalic anhydride with ammonia in about the stoichiometric ratio, in a mixing apparatus and subsequently in a reaction tube at a particular flow velocity and a particular temperature.The phthalimide obtainable by the process of the invention is a valuable starting material for the preparation of dyes, pesticides and pigments, especially copper phthalocyanines.

Abstract: A process for the continuous preparation of isatoic anhydrides by two-stage reaction of an alkali metal phthalamate and/or alkali metal phthalimidate with an alkali metal hypohalite, the first stage being carried out substantially adiabatically and both stages being carried out at high flow rates, wherein phthalimide and/or phthalamic acid is first dissolved in a certain amount of an alkali metal hydroxide solution, the resulting solution is mixed with a hypohalite and reacted at a particular temperature, acid is then added and the reaction is completed at a particular temperature. The compounds obtainable by the process of the invention are valuable starting materials for the preparation of dyes, crop protection agents and scents.