The invention relates to novel sulphur compounds, to the production thereof by a method carried out in an aqueous medium and the use thereof in the form of transfer agents in a method for controlled radical polymerisation of acrylic acid and/or acrylic acid with water-soluble monomers in water. The thus obtained polymers are usable in the form of dispersing agents or grinding aid agents and/or aid agents for combined grinding of mineral materials in an aqueous suspension and in the form of dispersing agents directly incorporated into aqueous formulations containing mineral materials.