Preparation of Sudan I
- To 20.0 g (17.9 ml) of aniline was added 26.1 g (22.7 ml) of 30% hydrochloric acid cooled to 0 although -5 ° C and in small portions was added a saturated solution 14.8 g NaNO 2 . A solution benzene diazonium chloride.
- to 31.0 g 2-naphthol solution add 12.1 g KOH and heated until the 2-naphthol dissolved (you can add water). Solution at a temperature of about 80 ° C and stir chladíme to -5 to 0 ° C. So we get a suspension of small crystals.
Final operation is called a coupling reaction (reaction of the diazonium salt and phenol to form an azo compound). After cooling (temperature should not exceed 0 better -5 ° C) přikapáváme cooled solution benzene diazonium chloride to a suspension of 2-naphthol (not reversed). After each addition, check the temperature (not exceed -5 to 0 ° C). After adding all the benzene diazonium chloride mixture stir and let spontaneously warm to room temperature. The resulting azo filter off and dry air at about 35 ° C.