Phenylhydrazine-p-sulfonic acid

Order of Elution (1) Phenylhydrazine-p-sulfonic acid (PHSA) (2) sulfanilic acid (SA) (3) l-(4-sulfophenyl)-3-ethylcarboxy-5-hydroxypyrazolone (PY-T) (4) l-(4-sulfo-phenyl)-3-carboxy-5-hydroxypyrazolone (EEPT) (5) 4,4 -(diazoamino)-dibenzenesulfonic acid (DAADBSA). 

Method of manufacture phenylhydrazine p-sulfonic acid is condensed with sodium ethyl oxalacetate the product obtained from this reaction is then coupled with diazotized sulfanilic acid. 

A solution of trifluoroacetic acid in toluene was found to be advantageous for cyclization of pyruvate hydrazoncs having nitro substituents[4], p-Toluene-sulfonic acid or Amberlyst-15 in toluene has also been found to give excellent results in preparation of indole-2-carboxylate esters from pyruvate hydra-zones[5,6J. Acidic zeolite catalysts have been used with xylene as a solvent to convert phenylhydrazines and ketones to indoles both in one-flask procedures and in a flow-through reactor[7]. 

Titrate a separate 10-ml sample of phenylhydrazine solution with 0.5 N p-toluene-sulfonic acid to an endpoint of pH 3.5. 

Uracil-5sodium sulfonate, light brown needles, by salting out the reaction product of phenylhydrazine-/)-sulfonic acid on isodialuric acid, soluble in water, dyes wool orange. 

---