dictated by the desired product composition preferred bases are for example alkali metal e g lithium sodium or potassium hydroxides carbonates or bicarbonates or aliphatic tertiary amines e g triethanolamine or triisopropanolamine where a combination of two or more different bases is used the bases may be added in any order or at the same time where it is necessary to adjust the reaction ph using acid examples of acids that may be used include hydrochloric acid sulphuric acid formic acid and acetic acid aqueous solutions containing one or more compounds of general formula 1 may optionally be desalinated either by membrane filtration or by a sequence of precipitation followed by solution using an appropriate base the preferred membrane filtration process is that of ultrafiltration using e g polysulphone polyvinylidenefluoride cellulose acetate or thin film membranes the following examples shall demonstrate the instant invention in more details if not indicated otherwise u201c parts u201d means u201c parts by weight u201d and u201c u201d means u201c by weight u201d 31 4 parts of aniline 2 5 disulphonic acid monosodium salt are added to 150 parts of water and dissolved with the aid of an approx 30 sodium hydroxide solution at approx 25 u00b0 c and a ph value of approx 8 9 the obtained solution is added over a period of approx 30 minutes to 18 8 parts of cyanuric chloride dispersed in 30 parts of water 70 parts of ice and 0 1 part of an antifoaming agent the temperature is kept below 5 u00b0 c using an ice water bath and if necessary by adding ice into the reaction mixture the ph is maintained at approx 4 5 using an approx.