Xylidines
Xylidines
aminoxylenes, (CH3)2C6H3NH2. All six isomers are known (see Table 1).
| Table 1. Some properties of xylidines | ||||
|---|---|---|---|---|
| Xylidine | Position of groups in benzene ring | Boiling point (°C) | Density, g/cm3(att) | |
| CH3 | NH2 | |||
| *Melting point, 51 C † ‡At 739 mm Hg (1 mm Hg − 133.322 newtons per m2 | ||||
| ‡At 728 mm Hg §Melting point, 15.5°C | ||||
| Ordinary o-x........ | 1.2 | 3 | 221 | 0.9910 (15°C) |
| Asymmetrical o-x*.... | 1.2 | 4 | 226 | 1.0755 (17.5°C) |
| Ordinary m-x...... | 1.3 | 2 | 214† | 0.9796 (20°C) |
| Asymmetrical m-x..... | 1.3 | 4 | 216‡ | 0.9783 (19.6°C) |
| Symmetrical m-x..... | 1.3 | 5 | 220 | 0.9935 (0°C) |
| ρ-x§ ........... | 1.4 | 2 | 213.4 | 0.9790 (21.3°C) |
All xylidines are colorless substances with an odor of aniline; they darken rapidly on exposure to air. They are readily soluble in organic solvents, and poorly soluble in water. Xylidines form highly explosive vapor-air mixtures. They exhibit a toxic effect on blood and damage the liver. They are bases and readily form salts and undergo diazotization. Xylidines are obtained by nitration of xylenes and subsequent reduction of nitro compounds. The isomers are separated by the fractional crystallization of their salts. Xylidines serve as antioxidants and frothing agents in flotation processes. They are also used in the preparation of azo dyes.