| abstract |
Xanthogen disulphides of the following formula: <IMAGE> wherein R and R1 independently represent hydrogen, C1-C6 alkyl, C5-C8-cycloalkyl or an oxygen-containing heterocyclic ring system having from 5 to 8 ring members and optionally mono- or tri-substituted by C1-C4-alkyl, and wherein R and R1 may also be connected together to complete a hetero cyclic ring having from 3 to 6 carbon atoms and from 1 to 3 oxygen ring members, and the ring may be substituted by from 1 to 3 C1-C4-alkyl groups, with a content of elemental sulphur of less than 1.7% by weight, a process for their production by the reaction of a xanthic acid-O-ester-alkali metal salt of the following formula: <IMAGE> wherein R and R1 are as defined in claims 1 and 3, and M represents an alkali metal, with aqueous chlorine bleach liquor, characterized in that aqueous chlorine bleach liquor having a concentration of less than 0.9 mol NaOCl/kg is used, and oxidation is carried out at a temperature of from 10 DEG to 20 DEG C. and at a pH of from 8 to 12, only until from 0.1 to 5.0 mol % of the xanthic acid-O-ester-alkali metal salt, based on the quantity used, is still present at the end of the reaction, as well as their use as molecular weight regulators in the polymerization of chloroprene. |