Aniline-2,5-disulfonic acid

Anilinesulfonic acids, al 18, al 19, al20 Aniline-2,5-disulfonic acid, al 17... 

Aniline-2,5-disulfonic acid, the preparation of which is described above, is used as a starting material for azo dyes, especially disazo and trisazo dyes of the type of Sirius light blue (see page 279). 

The amount of aniline-2,5-disulfonic acid (monosodium salt, see page 106) corresponding to 50 cc. 1 N nitritef is dissolved in 150 cc. hot water, and the solution (filtered if necessary) is treated with stirring with 8 cc. 30 per cent hydrochloric acid. The solution is cooled to 0°C. and 17.5 cc. 20 per cent sodium nitrite solution is added rapidly. The diazotization takes about 15 minutes. 

Derivation Boiling sodium salt of 4-chloro-3-nitro-benzene sulfonate with sodium sulfite, resulting in formation of sodium-2-nitrobenzene disulfonate, which is reduced with iron and acetic acid to aniline-2,5-disulfonic acid. 

H. Tang, A. Kitani, T. Yamashita, S. Ito, Highly sulfonated polyaniline electrochemically synthesized by polymerizing aniline-2,5-disulfonic acid and copolymerizing it with aniline, Synthetic Metals 1998, 96, 43. 

H. Q. Tang,T. Yamashita,A. Kitani, S. Ito, Electrosynthesis of water-soluble self-doped poly(aniline-2,5-disulfonic acid), Electrochimica Acta 1998, 43, 1137. 

A. Kitani, K. Iwai, S. Ito, Electrochemical behaviors of polyaniline/poly (aniline-2,5-disulfonic acid) composites, Electrochemistry 1999, 67, 1262. 

Example 2 Homopolymer of Sulfonated Aniline - Electrochemical Polymerization of Aniline-2,5-Disulfonic Acid (ADSA)... 

The electrochemical polymerization of aniline-2,5-disulfonic acid (ADSA) is performed by applying a constant current density of 0.3 mA cm on a Pt plate electrode in 0.1 M monomer containing 0.5 M HCl electrolyte. The polymerization is carried out at room temperature under inert atmosphere. After polymerization, ethanol is added to precipitate the polymer from solution, and the polymer is vacuum dried at 70 °C for 24 h. The molecular weight of the poly(ADSA) obtained varies from 5000 to 12000 depending on synthetic conditions, and the conductivity ranges in between 0.04 and 0.3 S cm , which is also independent up to pH 10." ... 

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