Zur Synthese sulfonierter Derivate von 2‐Amino‐ p ‐xylol

Synthese of sulfonated derivatives of 2‐amino‐ p ‐xylene Sulfonation of 2‐amino‐ p ‐xylene (2) gave 2‐amino‐ p ‐xylene‐5‐sulfonic acid (1) . The 2‐amino‐ p ‐xylene‐6‐sulfonic acid (3) was prepared via three routes: (1) sulfonation of 2‐amino‐5‐chloro‐ p ‐xylene (19) to 5‐amino‐2‐chloro‐ p ‐xylene‐3‐sulfonic acid (20) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2‐amino‐6‐nitro‐ p ‐xylene (21) to 2‐nitro‐ p ‐xylene‐6‐sulfonyl chloride (11) followed by hydrolysis to 2‐nitro‐ p ‐xylene‐6‐sulfonic acid (4) and Béchamp reduction; (3) Béchamp reduction of 2‐chloro‐3‐nitro‐ p ‐xylene‐5‐sulfonic acid (13) to 3‐amino‐2‐chloro‐ p ‐xylene‐5‐sulfonic acid (16) and subsequent hydrogenolysis. Catalytic reduction of 13 in aqueous sodium carbonate solution gave mixtures of 3 and 16 . 2‐Amino‐ p ‐xylene‐3‐sulfonic acid (27) was synthesized via two routes: (1) reaction of 19 with sulfamic acid to 2‐amino‐5‐chloro‐ p ‐xylene‐3‐sulfonic acid (26) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2‐amino‐3‐nitro‐ p ‐xylene (28) to 2‐nitro‐ p ‐xylene‐3‐sulfonyl chloride (12) , hydrolysis to 2‐nitro‐ p ‐xylene‐3‐sulfonic acid (7) and Béchamp reduction.