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any of three amino derivatives of toluene.

Ortho, meta, and para isomers of toluidines are known (see Table 1). Toluidines are readily soluble in organic solvents but poorly soluble in water; they may be steam-distilled, and they darken (oxidize) upon storage in light in the presence of air.

Toluidines are obtained industrially by the reduction of nitro-toluenes using iron and hydrochloric acid. They are similar to aniline in their chemical properties. They form salts with acids and

Table 1. Selected properties of toluidines
 Melting point (°C)Boiling point (°C)Density at 20°C (g/cm3)
Ortho-toluidine(1,2-). . . . . . . . . .–24,4 (unstable)200.30.9984
Ortho-toluidine (1,6-). . . . . . . . . .–16.25 (stable)200.30.9984
Mete-toluidine(1,3-or 1,5-). . . . . . . . . .–30.4203.40.9891
Para-toluidine (1,4-). . . . . . . . . .44.5–45,0200.551.046

undergo diazotization, acylation, halogenation, sulfonation, and alkylation. Toluidines are used in the manufacture of various dyes.


References in periodicals archive ?
Following analysis of the tests performed on stains on paper, we found that false negatives were detected using tetramethylbenzidine with low-concentration blood samples (1:400000), whereas o-tolidine and leucomalachite green produced the same with samples that were slightly more concentrated (1:200000) and phenolphthalein gave false negatives in samples concentrated at 1:2000.
For this reason, NA2 was replaced by a different curing agent, o-tolidine [ILLUSTRATION FOR FIGURE 2 OMITTED].