Abstract: The invention relates to a process for preparing 2,7-dimethyl-2,4,6-octatrienal monoacetals of the general formula I 1

Abstract: A process for the preparation of 1,1,4,4-tetramethoxy-2-butene by reacting 2,5-dimethoxydihydrofuran with methanol in the presence of acids comprises carrying out the reaction in the presence of solid catalysts having acidic centers.

Abstract: The invention relates to a process for the preparation of cis-6-hexadecenoic acid of the formula I, 1

Abstract: A process for the preparation of 1,1,4,4-tetramethoxy-2-butene by reacting 2,5-dimethoxydihydrofuran with methanol in the presence of acids comprises carrying out the reaction in the presence of solid catalysts having acidic centers.

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

Abstract: 2-Methyl-4-amino-5-aminomethylpyrimidine of the formula 1 1

Abstract: 2-Methyl-4-amino-5-aminomethylpyrimidine of the formula 1 is prepared by reacting 2-methyl-4-amino-5-alkoxymethylpyrimidine of the formula 2 where R=C1-C6-alkyl, with ammonia in the presence of a catalyst.

Abstract: A process for preparing polyenecarbonyl compounds having a high all-E content and their acetals or ketals by aldol condensation or Horner-Emmons reaction comprises carrying out the reaction, for the purposes of the preferred formation of a double bond of E configuration and in order to maintain the E configuration of the double bonds in the stating compounds as completely as possible, in the presence of oxygen or an oxygen-inert gas mixture or nitric oxide or a nitric oxide-inert gas mixture and/or in the presence of specific stable radicals and/or in the presence of quinones or quinone derivatives.

Abstract: A process for the preparation of alkyl esters of 0,0-dialkyl-4-phosphono-2-methyl-2-butenoic acid containing a high percentage of E isomers, wherein the corresponding alkyl esters of 2-hydroxy-2-methyl-3-butenoic acid are caused to react with PBr.sub.3 or PCl.sub.3 at temperatures ranging from 0.degree. to 80.degree. C. in the absence of pyridine and, if desired, the resulting mixture comprising predominantly alkyl esters of 4-halo-2-methyl-2-butenoic acid is caused to react with trialkyl esters of phosphorous acid at temperatures ranging from 70.degree. to 140.degree. C. The end products are desirable C.sub.5 building blocks for polyene syntheses or preceding stages.

Abstract: Improved process for the preparation of astaxanthin by Wittig reaction of 2 mol of 3-methyl-5-(2,6,6-trimethyl-3-oxo-4-hydroxy-1-cyclohexenyl)-2,4-pentadieny ltriarylphosphonium salts with one mol of 2,7-dimethyl-2,4,6-octatrienedial avoiding the use of halohydrocarbons as solvents.

Abstract: Abstract of the Disclosure: Compounds of the formula I ##STR1## where R.sup.1 is H or C.sub.1 -C.sub.4 -alkyl, R.sup.2 is C.sub.1 -C.sub.4 -alkyl and R.sup.3 is an ether, silyl ether or acetal protective group which can be converted into a hydroxyl group by hydrolysis, in particular one of the radicals ##STR2## and a process for preparing these compounds by reacting an alkenyne of the formula II ##STR3## in an inert solvent in the presence of lithium amide with a cyclohexenone of the formula III ##STR4## and the use of the compounds of the formula I for preparing astaxanthin, are described.

Abstract: Compounds of the formula I ##STR1## where R.sup.1 is H or C.sub.1 -C.sub.4 -alkyl,R.sup.2 is C.sub.1 -C.sub.4 -alkyl and R.sup.3 is an ether, silyl ether or acetal protective group which can be converted into a hydroxyl group by hydrolysis, in particular one of the radicals ##STR2## and a process for preparing these compounds by reacting an alkenyne of the formula II ##STR3## in an inert solvent in the presence of lithium amide with a cyclohexenone of the formula III ##STR4## and the use of the compounds of the formula I for preparing astaxanthin, are described.

Abstract: A process for preparing canthaxanthin (Ia) and astaxanthin (Ib) of the formula I ##STR1##where R is H (a) or OH (b), comprises reacting a tertiary alcohol of the formula II ##STR2##where R is H (a) or OH (b), with trifluoroacetic acid, reacting the resulting novel trifluoroacetate of the formula III ##STR3##with triphenylphosphine, and reacting the resulting novel triphenylphosphonium trifluoroacetate of the formula IV ##STR4##with 2,7-dimethyl-2,4,6-octatriene-1,8-dial under the conditions of a Wittig synthesis. The present invention also relates to the novel trifluoroacetates of the formula III and the corresponding triphenylphosphonium trifluoroacetates of the formula IV.

Abstract: 5,9-Dimethylpentadecane (I) and 5,9-dimethylhexadecane (II) and their use in agents for the control of the white coffee-leaf miner, Perileucoptera coffeella, particularly by the confusion technique.

Abstract: Alkyl .gamma.-halotiglates of the general formula I ##STR1## where X is Cl or Br and R.sup.2 is alkyl of 1 to 3 carbon atoms, having a high E isomer content, are prepared by a process in which(a) the corresponding 2-methyl-but-3-enoate of the general formula II ##STR2## is reacted with chlorine or bromine in the absence of a solvent and (b) the resulting 2-methyl-3,4-dihalobutyrate of the general formula III ##STR3## is dehydrohalogenated by reaction with a solution of an alkali metal hydroxide in an alcohol R.sup.2 OH, where R.sup.2 has the stated meaning, or in a mixture of water and an alcohol R.sup.2 OH, and the products are further processed to give O,O-dialkyl-.gamma.-phosphonotiglates of the general formula IV ##STR4## where R.sup.1 is alkyl of 1 to 4 carbon atoms and R.sup.2 is alkyl of 1 to 3 carbon atoms, preferably ethyl, by reaction with a trialkyl phosphite and thermal isomerization. The process gives C.sub.

Abstract: In an improved process for the preparation of 2-n-propyl-4-amino-5-methoxymethyl-pyrimidine of the formula I ##STR1## by reacting butyramidine II ##STR2## with .alpha.-methoxymethyl-.beta.-methoxyacrylonitrile III ##STR3## the butyramidine II is reacted with a 0.4-5 molar excess of .alpha.-methoxymethyl-.beta.-methoxyacrylonitrile III at from -10.degree. to +20.degree. C.

Abstract: N-(D)-ribitylxylidine (I) is prepared by reacting (D)-ribose (II) with 3,4-dimethylaniline (III) or 3,4-dimethyl-1-nitrobenzene (IV) in aqueous or aqueous/organic solution or in solution in a water-soluble organic solvent under an elevated hydrogen pressure and in the presence of a hydrogenation catalyst and of a boric acid compound,(a) using the boric acid compound in a catalytic amount of from about 6 to 35 mmol, preferably from 6 to 20 mmol, per mol of ribose,(b) carrying out the reaction under a hydrogen pressure of from 1 to 20, preferably from 2 to 9, bar and(c) carrying out the hydrogenation at from 40.degree. to 80.degree. C. over Raney nickel as hydrogenation catalyst.

Abstract: Pentoses and hexoses are epimerized by heating sugar dissolved in a solvent in the presence of a molybdenum(VI) compound, by an improved process in which, for the preparation of a sugar having cis OH groups in the 2- or 3-position, of the formula Ia or Ib ##STR1## where R is one of the radicals ##STR2## a homogeneous solution of the corresponding sugar of the formula IIa or IIb ##STR3## is heated to 75.degree.-100.degree. C. in the presence of from 30 to 200 mol %, based on sugar used, of a metal salt of the formula (III)MeX.sub.2 (III)where Me is Mg, Ca, Sr, Ba or Zn and X is Cl or Br, which may or may not contain water of crystallization, and in the presence of from 2 to 20 mol %, based on the sugar used, of a molybdenum(VI) compound.The process is particularly important for the preparation of D-ribose, which is required as an intermediate for vitamin B.sub.2.

Abstract: .alpha.-(o-Chlorophenyl)-aminomethylene-.beta.-formylaminopropionitrile, process for its preparation by reacting a metal salt of .alpha.-formyl-.beta.-formylaminopropionitrile with a salt of o-chloroaniline in an aqueous medium, and use of the product to prepare the compound of the formula ##STR1## by reaction with acetamidine. The pyrimidine thus obtained is an intermediate for the preparation of vitamin B.sub.1.

Abstract: Novel phenylalkylcycloamines, their preparation, agents containing these compounds, and methods for regulating plant growth.