Abstract: A mercaptocarboxylic acid of formula (I) is prepared by reacting an unsaturated carboxylic acid of formula (II) with a hydrosulphide of formula ASH, A being an alkali metal cation or a cation NR3R4R5R6+, R3 to R6 each representing H or a hydrocarbon radical, or of formula Q(SH)2, Q being an alkaline-earth metal cation, by acidifying the resulting reaction medium in order to obtain the desired compound (I). According to the present invention, the reaction is carried out with a supply of H2S other than that supplied by the neutralization of the acid (II). In particular, H2S is introduced into the medium by a direct external supply. H2S can also be produced in situ by reacting the hydrosulphide with at least one acid introduced into the medium. The compound (I) is obtained with a very good selectivity.

Abstract: Esters of formula: HS—X—COOR in which X denotes a C1-C4 alkylene radical and R a C1-C18 alkyl radical, are prepared by reaction of a hydrosulphide with the corresponding halocarboxylic ester: Y—X—COOR where Y denotes a chlorine or bromine atom. The reaction is performed under a hydrogen sulphide pressure of at least 10 bars absolute, and preferably in an anhydrous or substantially anhydrous alcoholic medium.

Abstract: 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.

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

Abstract: 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.

Abstract: 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).

Abstract: Esters of formula:HS--X--COORin which X denotes a C.sub.1 -C.sub.4 alkylene radical and R a C.sub.1 -C.sub.18 alkyl radical, are prepared by reaction of a hydrosulphide with the corresponding halocarboxylic ester:Y--X--COORwhere Y denotes a chlorine or bromine atom. The reaction is performed under a hydrogen sulphide pressure of at least 10 bars absolute, and preferably in an anhydrous or substantially anhydrous alcoholic medium.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A solvent for sulfur consisting of a dialkyl disulfide which is free of any basic substance. It is obtained from a commercial dialkyl disulfide by treatment with a reagent capable of eliminating or blocking the basic substances, particularly amines, which are customarily present in such a product. This reagent may be an acid.The use of the product, after treatment in this manner, for dissolving sulfur which has deposited in the casings of natural gas wells permits the reuse several times of the dialkyl disulfide employed.

Abstract: In a process for preparing alpha-amino-gamma-methylmercaptobutyronitrile by aminating, by means of ammonia, alpha-hydroxy-gamma-methylmercaptobutyronitrile at a temperature of 50.degree. C to 100.degree. C, the ammonia is accompanied by an amount of water corresponding to at least 1 mole per mole of ammonia.The molar NH.sub.3 /cyanhydrine ratio in the reaction medium is 2 to 10, and preferably 4 to 7, the H.sub.2 O/cyanhydrine ratio in the reaction medium is 4 to 20, and preferably 5 to 16, while H.sub.2 O/NH.sub.3 ratio is 1 to 3, and preferably 1.3 to 2. Advantageously the reaction medium is introduced into a piston-type tubular reactor which is maintained at a constant temperature, the dwelling time of the mixture in the heated zone being 1 to 30 minutes, and preferably 2 to 25 minutes, and the reaction medium is maintained under a pressure of 1 to 10 bars, and preferably a 4 to 8 bars.