Soxhlet extraction polymer purification

B, products giving positive Tollen s Reagent tests were obtained. No attempts were made to isolate either 9A or 9B since previous work had indicated that such compounds were subject to decomposition, and bromine oxidation was attempted on the crude reaction mixture. For both systems, as bromine addition was carried out, a transient blue color was noticed and white precipitates appeared in the reaction mixtures. In order to obtain 11A and IIB in purer form, the precipitated crude polymer was subjected to Soxhlet extraction with ethanol. This was followed by azeotropic distillation of benzene over the insoluble products. These two purification steps removed most of the non-polymeric by-products including unreacted or partially reacted nitro compounds as well as water and ethanol. Both llA and IIB showed strong IR absorption at 1200 cm" characteristic of the trans nitroso dimer bond, and a medium sharp absorption... 

As described briefly in Chapter 1, the more common typical chemical polymerization is relatively simple, involving monomer and an oxidant (usually also the dopant) in a suitable solvent medium, frequently aqueous, and temperatures in the region of -20 °C to 4-80 °C. Thus for instance, a 0.25 M solution of an oxidant such as ammonium peroxydisulfate ((NH4)2S20g) is added with stirring to a solution of 0.5 M aniline monomer in 0.5 M aqueous /7-toluene sulfonic acid solution (dopant electrolyte) at room temperature. As reaction temperature rises, the reaction bath is cooled with an ice-bath. After 2 hrs of stirring, the polymer is filtered, washed with dopant electrolyte solution, and dried in vacuo at 60 C. An optional procedure of Soxhlet extraction may be used for further purification. The polymer is then neutralized with 2 M NH4OH to yield the emeraldine base form of P(ANi). 

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