P-Toluidine hydrochloride

Dissolve 1 g. of the sulphonic acid or its sodium salt in the minimum volume of boiling water and add a saturated aqueous solution of 1 g. of p-toluidine hydrochloride. Cool, Alter off the precipitate of the p-tolu-idine salt, and recrystallise it from hot water or from dilute ethanol. 

Dissolve 36 g. of p-toluidine in 85 ml. of concentrated hydrochloric acid and 85 ml. of water contained in a 750 ml. conical flask or beaker. Cool the mixture to 0° in an ice-salt bath with vigorous stirring or shaking and the addition of a httle crushed ice. The salt, p-toluidine hydrochloride, will separate as a finely-divided crystalline precipitate. Add during 10-15 minutes a solution of 24 g. of sodium nitrite in 50 ml. of water (1) shake or stir the solution well during the diazotisation, and keep the mixture at a temperature of 0-5° by the addition of a httle crushed ice from time to time. The hydrochloride wUl dissolve as the very soluble diazonium salt is formed when ah the nitrite solution has been introduced, the solution should contain a trace of free nitrous acid. Test with potassium iodide - starch paper (see Section IV,60). 

These are prepared by the interaction of the sulphonic acid or its sodium salt with p-toluidine hydrochloride in aqueous solution ... 

Di (m p -tolyl) triazene, It-yel ndls (from petr eth), mp 96—97° mod sol in hot org solvs less sol in cold was prepd from m-toluenediazoniumchloride p-toluidine hydrochloride in the presence of Na acetate or Na dicarbonate (Ref 1, p708)... 

Preparation. p-Toluidine hydrochloride is diazotized, and the solution of the diazonium chloride is brought to pH 6.8-7.2 at 0° with a cold, coned, solution of sodium carbonate. The resulting deep red solution is added slowly to a vigorously... 

Derivation By heating 2,7-dihydroxynaphthalene with p-toluidine and p-toluidine hydrochloride. 

A few drops of sample solution are added into 5 ml of 5% p-toluidine hydrochloride aqueous solution. If a white precipitate appears, there is anionic surfactant in the sample solution. 

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