A Simple Preparation of Sulfanilic Acid Many laboratory manuals give a preparation for sulfanilic acid in which an excess of sulfuric acid is used. This sulfonation is not only a wrong reproduction of the industrial baking process, but also it takes much time. Most of laboratories have at their disposal a dryingoven, and so it is possible, with less work, to convert the aniline hydrogen sulfate into sulfanilic acid, while the students work on another project. Put in a porcelain dish 4.6 ml aniline and add 5.0 ml 10 M sulfuric acid. Remove the water on a sand bath by heating slowly up to 190°C., until the mass solidifies completely. During heating stir with the thermometer.
274
/
Journal of Chemical Fducofion
Heat the aniline salt for 4 hrs in the drying-oven st 200°C. After cooling, break up the lumps and dissolve them in sufficient 10% sodium carbonate solution (40 ml) by heating. After boiling a few minutes with decolorizing charcoal, filter and acidify with sulfuric acid. Cool in a cold water bath, collect the crystals on s Buchner funnel, wash with a little cold water, and dry in the dryingdven on llO°C. Noel Roeges Hoger Technisch Instituut St. Lieven
Gent, Belgium
