Societe Nationale Elf Aquitaine (Production)

Elf Atochem S.a.

Societe Nationale Elf Aquitaine

Atofina

Elf Acquitaine Exploration Production

Produits Chimiques Du Bearn

Yves Labat

Jean-Pierre Muller

Yannick Vallee

Guy Desgrandchamps

Georges Fremy

Aristide Boy

Bernard Monguillon

Jean-Marie Poirier

Jean-Francedillaois Devaux

Daniel Litvine

Piet Luyendijk

Catherine Vottero

Process for the manufacture of mercaptocarboxylic acids from unsaturated carboxylic acids

Synthesis of esters of mercaptocarboxylic acids

A process for stabilizing and deodorizing a raw organic polysulfide by treating it with an alkylene carbonate in the presence of a basic catalyst and, optionally, a sulfur donor.

Production of stabilized and deodorized organic polysulphides

Process for purifying a thiophene contaminated by mercaptans comprising selectively oxidizing the mercaptans to form polysulphides, then distilling the thiophene in this way.

Purification of thiopene

To avoid the degradation of thioacetic acid on storage, from 0.005 to 0.5% of a chloroacetic acid, preferably dichloroacetic acid, is added thereto.

Stabilization of thioacetic acid

Process for the preparation of a carboxyalkylthiosuccinic acid of formula ##STR1## in which n=1 to 3 and R.dbd.H or CH.sub.3, a mercapto ester of formula HS--(CH.sub.2).sub.n --COOR' in which R' is a C.sub.1 to C.sub.4 alkyl radical, is reacted, in aqueous medium and without a catalyst, with maleic acid, citraconic acid or their anhydride. The invention is more particularly directed towards the preparation of carboxyethylthiosuccinic acid (CETSA).

Synthesis of carboxyalkylthiosuccinic acids

The invention relates to the preparation of alkylthiophenols by reaction of a dialkyl disulphide with a phenol. In the process according to the invention, the reaction is carried out in the presence of aluminum chloride or of ferric chloride in a solvent of the alkylbenzene type or, soley in the case of methylthiolation, in an excess of dimethyl disulphide. This process makes it possible, in particular to obtain, with a selectivity and in a yield which are excellent, 2-alkylthiophenols which may then be converted into 4-acyl-2-alkylthiophenols by means of a reaction at a temperature ranging from 40.degree. to 100.degree. C. with a complex BF.sub.3 :2RCOOH where R denotes an alkyl or propenyl radical, in a proportion of 10 to 15 moles of complex per mole of 2-alkylthiophenol.

Process for phenol alkylthiolation and its application to the synthesis

The invention relates to production of esters of mercaptocarboxylic acids and alcohols forming an azeotrope with water. The esterification is carried out continuously in the presence of an excess of alcohol and the water formed is removed by entraining azeotropically under vacuum at a temperature such that the residual water concentration in the reaction mixture remains constantly below 0.5% by weight. The process according to the invention applies more particularly to the synthesis of octyl esters of thioglycolic acid.

Continuous synthesis of mercaptocarboxylic acid esters

The invention relates to the manufacture of vicinal alkanedithiols from the corresponding alkylene trithiocarbonates. The method according to the invention consists in treating alkylene trithiocarbonate with an alkaline sulfide, followed by acidification of the reaction medium. The method is particularly well-suited for the synthesis of ethanedithiol from ethylene trithiocarbonate.

Synthesis of vicinal alkanedithiols

This invention relates to the preparation of benzyl mercaptan by reacting benzyl chloride and ammonium sulfhydrate. In the process according to the invention, the reaction is carried out under autogenous pressure in a closed reactor in two steps. The first comprises adding the benzyl chloride to an aqueous solution of ammonium sulfhydrate at a temperature below 80.degree. C. The second comprises heating the reaction mixture to a temperature in the range 80.degree. to 100.degree. C.

Synthesis of benzyl mercaptan

The invention relates to the production of organic polysulphides by the action of sulphur on a mercaptan. According to the invention, the process is carried out in the presence of a thioxanthate formed separately or in situ by combination of carbon disulphide with a mercaptide.

Synthesis of organic polysulphides

New unsaturated alcohol-thioether, in which a double bond is located in the beta position to the S atom, in an aliphatic chain which can repeat. The compounds are generally of the formula ##STR1## In this formula, A is a branched or unbranched aliphatic chain which may be substituted or unsubstituted, and preferably contains from 2-6 carbon atoms; R.sup.1, R.sup.3 and R.sup.4 may be the same or different, and are aliphatic groups and/or hydrogen atoms; R.sup.2 is an aliphatic group, hydrogen, alkylene, or a bond and p gives the degree of polymerization of the beta-unsaturated aliphatic chain. These compounds may be prepared by the reaction of a mercapto-alcohol with a conjugated diene in the presence of a free radical catalyst.

New hydroxy-thia-alkenes, and processes for their preparation and use

The polysulphide is heated with a substance capable of dissolving elemental sulphur. After cooling, the polysulphide reduced to a lower numbver of S atoms is separated from the substance, which can be recovered. An important use consists in converting the polysulphide to the form of dimethyl disulphide, the solvent used for the dissolution of sulphur deposited in conduits, particularly those used for natural gas.

Process of degradation of alkyl polysulphides into polysulphides having

Polymer or copolymer having a chain carrying terminal and/or side-chain groups: ##STR1## in which R is an H or a C.sub.2 to C.sub.12 alkyl, m is 0 to 6, n is 1 to 10 and p is 1 to 10, one, some or all of the p double bonds being saturatable by an active group.

Growing community of inventors

Pau, France

Yves Labat