Hydroxide Test for Nitro Compounds

Preparation Sign in at www.cengage.com/logln to read the MSDSs for the chemi-cais used or produced in this procedure. 

In a smaii test tube, mix about 20 mg of a soiid or 1 drop of a iiquid unknown with 1.5 mL of freshly prepared 5% ferrous ammonium suifate soiution. Add 1 drop of 3 M sulfuric acid and 1 mL of 2 M potassium hydroxide in methanol. Stopper the tube immediately and shake it. A positive test is indicated by the blue precipitate turning rust-brown within 1 min. A slight darkening or greenish coloration of the blue precipitate is nof considered a positive test. 

Filter the test mixture and flush the filtrates down the drain. Put the filter cake in the container for nonhazardous solids. 

Two different types of derivatives of nitro compounds may be prepared. Aromatic nitro compounds can be di- and trinitrated with nitric acid and sulfuric acid. Discussion of and procedures for nitration are given in Section 25.10. 

The other method for preparation of a derivative may be utilized for both aliphatic and aromatic nitro compounds. This involves the reduction of the nitro compound to the corresponding primary amine (Eq. 25.61), followed by conversion of the amine to a benzamide or benzenesulfonamide, as described in Section 25.14. The reduction is most often carried out with tin and hydrochloric acid. 

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