2- chloro-5-nitrotoluene-4-sulfonic acid

Toluene-4-sulfonic acid is used as a starting material in the production of 2-chloro-5-aminotoluene-4-sulfonic add (CLT-acid). CLT-acid is manufactured by chlorination of toluene-4-sulfonic add, transformation of 2-chlorotoluene-4-sulfonic add into 2-chloro-5-nitrotoluene-4-sulfonic acid followed by the reduction of the nitro group with iron/HCl. CLT-acid is used, for example, as a raw material in the production of Pigment Red 52 1, Pigment Red 53 1 and other metal complexes. 

---