Derivatives of diesters of 4-methylthiophenyl 1-amine-2-methyl-propanophosphoric acids, process for the preparation of derivatives of diesters of 4-methylthiophenyl 1-amine-2-methyl-propanophosphoric acids and the use of the derivatives of diesters of 4-methylthiophenyl 1-amine-2-methyl-propanophosphoric acids