摘要:
5-Hydroxymethylthiazole is prepared in an improved manner by reducing 5-formylthiazole using a borane compound. Particularly advantageous in this case is the use of 5-formylthiazole which has been obtained by reaction of a 2-halomalonaldehyde compound with thioformamide in the presence of less than 5% by weight of water (based on the reaction mixture).
摘要:
2-(Arylimino-methyl)-3-dialkylaminoacrylonitriles can be obtained by reaction of .beta.-anilino-acrylonitriles with ortho-formamides. They are suitable as starting substances for the preparation of 4-amino-5-iminiummethylene-2-pyrimidines or 4-amino-5-formyl-2-pyrimidines.
摘要:
In a particularly advantageous process for producing 2-cyanoindan-1-ones from 2-halogenated indan-1-ones by reaction with a cyanide salt, the cyanide salt is dissolved in a dipolar aprotic solvent or in a water-miscible ether and 2-halogenated indan-1-one is metered into this solution.
摘要:
Halogenated aromatic carboxylic acids are decarboxylated by heating them in the presence of water at temperatures of 80.degree. to 180.degree. C. and in the presence of water and other acids at temperatures above 80.degree. C.
摘要:
Hydroxypivalic acid is obtained from aqueous solutions by removal of the water by azeotropic distillation and subsequent crystallization from a solvent mixture which is composed of a polar and a non-polar component. The distillation is carried out under reduced pressure and at a maximum bottom temperature of 90.degree. C., until a residual water content of at least 0.1% of the total weight of the resulting solution is achieved.
摘要:
A process for separating off poorly soluble by-products from reaction mixtures which are produced in the oxidation of p-cresol with oxygen or an oxygen-containing gas in methanol as solvent in the presence of alkali metal hydroxide and in the presence of metal compounds as catalyst, is characterized in that, after the oxidation, excess alkali is neutralized to the extent that a salt precipitate forms and this salt precipitate is separated off together with the poorly soluble by-products.
摘要:
Diphenylamine can be dehydrocyclized on noble metal catalysts in the liquid phase at temperatures of 200.degree. to 340.degree. C. The reaction proceeds with a surprisingly high selectivity.
摘要:
2-Chloro-6-nitrophenyl alkyl sulphides of the formula ##STR1## in which the substituents are as defined in the description, can be prepared by reacting 2,3-dichloro-nitrobenzenes of the formula ##STR2## with mercaptans of the formulaHS-R.sup.1 (III)in the presence of 1-1.2 equivalents of a base per mole of mercaptan and in the presence of a phase transfer catalyst, at a temperature of 0.degree.-100.degree. C., in an aqueous or aqueous-organic medium. The majority of the 2-chloro- 6-nitrophenyl alkyl sulphides obtainable in this way are novel.
摘要:
In the preparation of m-chloroaromatics by isomerizing corresponding o- and/or p-chloroaromatics in the liquid phase over zeolites, the activity of the zeolites remains at a high level for a particularly long time if the process is carried out in the presence of from 1 to 30 mol % of hydrogen, based on the chloroaromatics used.
摘要:
2,4- or 2,6-dihalogeno-aniline can be prepared by reacting an amino-benzoic acid ester of the formula ##STR1## in which R.sup.1, R.sup.2 and R.sup.3 have the meanings indicated in the description, with 2-2.5 moles of a chlorinating or brominating agent in an inert reaction medium at a temperature of 40.degree.-160.degree. C. and subsequently hydrolyzing and decarboxylating the dihalogenated amino-benzoic acid ester.