see de a 2 531 238 however the alcohol can also be used as the solvent 2 to 4 mol of alcohol of the formula iii per mol of compound of the formula ii are preferably employed the process according to the invention can be carried out for example by initially introducing the alcohol of the formula iii at 0 u00b0 c metering in the dichloride at this temperature and under normal pressure subsequently stirring and then allowing to come to room temperature the isolation of the product can be carried out by customary methods depending on the alcohol and additional solvent optionally used some methods will be particularly suitable in the case of n butanol as the alcohol of the formula iii excess alcohol and hcl can easily be removed from the product mixture under reduced pressure and warming to 50 u00b0 c before the isolation of the product for example by distillation using a thin layer evaporator another possibility of the procedure is to initially introduce the alcohol of the formula iii under reduced pressure and to meter in the dichloride in this case the pressure is preferably adjusted in the range from 1013 to 5 mbar depending on the reaction temperature in.