Hoechst Aktiengesellschaft

Konrad Baessler

Gert Volkwein

Hans H Schubert

Siegfried Planker

Kurt C Habig

Otto Fuchs

Klaus Warning

Hubert Schonowsky

Lothar Schulz

Hans Wolfram

Heinz Schutte

Norbert Szczepanski

Helmut Muller

Process for the continuous preparation of 3,3'-dichloro-benzidine

The invention provides a process for the preparation of p-nitrophenetole with high yields and in an especially pure form from p-chloronitrobenzene and ethanol by heating to a temperature of from 60.degree. to 80.degree. C. with addition of alkali metal hydroxide and a phase transfer catalyst.

Process for the preparation of p-nitrophenetole

Crude 3,4,3',4'-tetraaminodiphenyl (TAD) prepared by ammonolysis of 3,3'-dichlorobenzidine in the presence of mainly Cu catalysts is purified by a process in which

Process for the purification of crude 3,4,3',4'-tetraaminodiphenyl

Process for the preparation of 4-phenoxyphenols of the formula ##STR1## in which R.sup.1 through R.sup.5 are hydrogen, halogen or alkyl, by diazotization of amines of the formula ##STR2## in a hydrochloric acid medium, and boiling in aqueous sulfuric acid at 110.degree. to 150.degree. C.

Process for the preparation of 4-phenoxyphenols

Nitrosation agent(s), contained as by-products in nitrated aromatic compounds after nitration with nitric acid or nitration acid, are removed by a water treatment, wherein the water is distilled off at least partially in vapor form, advantageously under reduced pressure. In the further reaction of the nitrocompounds treated in this manner undesired nitrosamines are practically not formed. The process is especially suitable for the manufacture of 4-di-n-propylamino-3,5-dinitrobenzotrifluoride (Trifluralin), a valuable herbicide, substantially free from nitrosamine(s).

Method for removing nitrosation agent(s) from a nitrated aromatic

A process for preparing 5-chloro-2-nitrophenol from 2,4-dichloronitrobenzene and excess alkali metal hydroxide in the presence of aprotic polar solvents at 20.degree. to 150.degree. C.

Process for preparing 5-chloro-2-nitrophenol

1,3,5-trichlorobenzene is manufactured by treating 5-chloro-1,3-dinitrobenzene and/or 3,5-dichloronitrobenzene with chlorine, at a temperature from about 200.degree. to 270.degree. C., preferably from about 230.degree. to 250.degree. C. The resulting process product is an intermediate, for example in plant protection.

Process for the manufacture of 1,3,5-trichlorobenzene

The catalytic hydrogenation of o-nitro-chlorobenzene in aqueous alkali metal hydroxide solution with addition of an aromatic non-watermiscible solvent at an elevated temperature and under pressure using a noble metal catalyst and a polycyclic quinone as a co-catalyst leads to high and well-reproducible yields of 2,2'-dichloro-hydrazobenzene when the quinone is a derivative of anthraquinone, especially a hydroxy-anthraquinone. The product is obtained in so high a quality that it can be transformed without isolation or purification into 3,3'-dichlorobenzidine.

Process for the preparation of 2,2'-dichloro-hydrazobenzene

2,4-DINITROANILINE IS OBTAINED IN HIGH YIELD AND QUALITY IN A SAFE REACTION BY INTRODUCING 4-CHLORO-1,3-DINITROBENZENE INTO AT LEAST THREE-FOLD STOICHIOMETRIC AMOUNT OF AQUEOUS AMMONIA OF A CONCENTRATION OF 15 TO 40% BY WEIGHT AT A TEMPERATURE OF 60.degree. TO 90.degree. C.

Process for the preparation of 2,4-dinitroaniline

Preparation of chlorohydroquinone by adding hydrogen chloride to p-benzoquinone, wherein a 1 to 20 % by weight solution of p-benzoquinone in benzene is treated discontinuously or continuously with hydrogen chloride at a hydrogen chloride pressure of from 1 to 6 atmospheres gauge, at a temperature of from 40.degree. to 80.degree.C, the residence time being from 1 to 4 hours and the chlorohydroquinone is isolated in known manner.

Process for preparing chlorohydroquinone

Preparation and isolation in substance of ortho-aminothiphenols by the reduction of ortho-chloronitrobenzenes with hydrogensulfides or sulfides, subsequent neutralization in the presence of sulfites, hydrogensulfites or disulfites, separation and following purification of the crude products. The ortho-aminothiophenols are obtained in very good yields and with a high degree of purity. Oxydation to the disulfide compound is avoided by the processes of the invention.

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Frankfurt am Main, Germany

Konrad Baessler