Hydrochloric Acid → 4,4'-Diazenediyldianiline

Participants

Reaction Steps

Without further purification, 4,4′-bis(acetamido)azobenzene (II) (16.0 g, 0.054 mol) is placed in a 500-mL round-bottomed flask equipped with a condenser and a magnetic stirrer, along with methanol (150 mL) and 6N hydrochloric acid (150 mL). The mixture is heated under reflux for 1.5 hours. The reaction mixture is cooled, and the violet solid is collected on a Büchner funnel. The mixture is heated under reflux for 1.5 hours. The reaction mixture is cooled, and the violet solid collected on a Büchner funnel. The damp product is suspended in 500 mL of water in a 1 L beaker equipped with a stirrer, and the mixture is slowly neutralized by the addition of 2.5N sodium hydroxide, during which the salt dissolves and the free base separates. The crude product is collected on a Büchner funnel, washed with water, and dried under reduced pressure. The yellow powder is then recrystallized from N-methylpyrrolidinone to afford yellow crystals of DAAB (III) (8.8 g, 42%), m.p. 244.5-247.9° C. (dec.). FT-IR (KBr, cm−1): 3417, 3333, 3212 (NH2), 3040, 1627, 1592, 1502, 1294, 1150, 839. 1H-NMR (DMSO-d6, δ in ppm): 5.72 (s, 4H, NH2), 6.61-6.63 (d, 4H, Ar—H), 7.51-7.53 (d, 4H, Ar—H). 13C-NMR (DMSO-d6, δ in ppm): 113.4, 123.7, 143.1, 150.9. Purification of (III) by column chromatography met with limited success due to its poor solubility in most organic solvents.

Provenance & Evidence