Hoechst Aktiengesellschaft

Manfred Schmidt

Karlheinz Miltenberger

Hans-Jerg Kleiner

Arno Holst

Gunter Roscher

Dennis Miller

Walter Rupp

Harald Berger

Dirk Bottger

Hans-Wolfram Flemming

Sigmar-Peter Von Halasz

Gerhart Schneider

Walter Freyer

Rainer Uhmann

Manfred Rukwied

Karl Petz

Eva M Kohn

In the esterification of aliphatic C.sub.2 -C.sub.6 -carboxylic acids with aliphatic C.sub.1 -C.sub.4 -alcohols, the ester formed is removed by azeotropic distillation together with the water of reaction. After the water of reaction has been separated in a separating condenser, the ester phase is freed, by washing with water, from acid carried over, and water and alcohol are then removed by distilling off a small fraction of the ester. In this way no salt-containing effluents are produced. The ester is obtained in a very good yield, free from acid and alcohol.

Process for the continuous preparation of esters of lower aliphatic

Process for the preparation of pure propanephosphonic anhydride, which comprises distilling crude, impure propanephosphonic anhydride having an average degree of polymerization of 20 to 200 and containing less than 0.5% by weight of water by heating to 230 to 300.degree. C. under a pressure of 0.1 to 100 mbar, pure propanephosphonic anhydride having an average degree of polymerization of 20 to 60 being obtained.

Process for the preparation of pure propanephosphonic anhydride

A process for the preparation of tripeptides of the general formula I

Process for the preparation of tripeptides

In the conversion of trichloroethene and tetrachloroethene into dichloroacetyl chloride (DAC) or trichloroacetyl chloride (TAC) by means of oxygen, the reaction mixture is passed several times as a thin film through the reaction zone. The reaction time for achieving a certain conversion is in this way reduced. In the preparation of DAC, a constant content of acid chloride is established in the reaction mixture by removing some of the mixture and working this up by distillation, while the circulating reaction mixture is simultaneously topped up with fresh trichloroethene.

Process for the preparation of dichloro- or trichloroacetyl chloride

Surfactant mixtures made from 5 to 80% by weight of an ether sulfonate, 5 to 80% by weight of an alkyl or alkylphenol polyglycol ether and 10 to 80% by weight of an alkanesulfonate, petroleumsulfonate or alkylbenzenesulfonate. This combination of surfactants produces stable, aqueous solutions or dispersions which are highly suitable for surfactant flooding in tertiary oil recovery since these aqueous surfactant solutions or dispersions form microemulsions with the oil even at high salinities.

Aqueous surfactant mixtures, and the use thereof in the recovery of

Styrylaryloxy ether sulfonates of the formula ##STR1## in which either R.sub.1 denotes styryl and simultaneously R.sub.2 and R.sub.3 are identical or different and denote hydrogen or styryl, or R.sub.1 and R.sub.2 are nonidentical and each denote methyl or styryl and simultaneously R.sub.3 denotes hydrogen or styryl, x denotes a number from 2 to 20, and M denotes an ammonium or alkali metal cation. These compounds are suitable as surfactant auxiliaries in oil recovery.

Styrylaryloxy ether sulfonates, a process for their preparation and

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Kelkheim, Germany

Manfred Schmidt