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For example, reaction of aniline with sulfuric acid at 180 °C produces sulfanilic acid, H 2 NC 6 H 4 SO 3 H. If bromine water is added to aniline, the bromine water is decolourised and a white precipitate of 2,4,6-tribromoaniline is formed. To generate the mono-substituted product, a protection with acetyl chloride is required:
The reaction mechanism is not exactly known; two proposals are presented here. One possibility is at first an aldol condensation, starting from the enol form of the pyruvic acid (1) and the aldehyde, forming an β,γ-unsaturated α-ketocarboxylic acid (2). This is followed by a Michael addition with aniline to form an aniline derivative (3).
2,4,6-Tribromoaniline is a brominated derivative of aniline with the formula C 6 H 4 Br 3 N. It is used in organic synthesis of pharmaceuticals, agrochemicals and fire-extinguishing agents. It is used in organic synthesis of pharmaceuticals, agrochemicals and fire-extinguishing agents.
Steam distillation is a separation process that consists of distilling water together with other volatile and non-volatile components. The steam from the boiling water carries the vapor of the volatiles to a condenser ; both are cooled and return to the liquid or solid state, while the non-volatile residues remain behind in the boiling container.
This reaction is also known as the Skraup-Doebner-Von Miller quinoline synthesis, and is named after the Czech chemist Zdenko Hans Skraup (1850–1910), and the Germans Oscar Döbner (Doebner) (1850–1907) and Wilhelm von Miller (1848–1899).
Sulfanilic acid can be produced by sulfonation of aniline with concentrated sulfuric acid. [5] This proceeds via phenylsulfamic acid; a zwitterion with a N-S bond. Eugen Bamberger originally proposed a mechanism involving a series of intramolecular rearrangements, with phenylsulfamic acid forming orthanilic acid, which rearranged to sulfanilic acid on heating.
The Béchamp reduction (or Béchamp process) is a chemical reaction that converts aromatic nitro compounds to their corresponding anilines using iron as the reductant: [1] 4 C 6 H 5 NO 2 + 9 Fe + 4 H 2 O → 4 C 6 H 5 NH 2 + 3 Fe 3 O 4. This reaction was once a major route to aniline, but catalytic hydrogenation is the preferred method. [2]
The Piria reaction. In the Tyrer sulfonation process (1917), [7] at some time of technological importance, benzene vapor is led through a vessel containing 90% sulfuric acid the temperature of which is increased from 100 to 180°C. Water and benzene are continuously removed and the benzene fed back to the vessel. In this way an 80% yield is ...