Solvents, organic, basic Nitrobenzene

Cyclohexanoae is miscible with methanol, ethanol, acetone, benzene, / -hexane, nitrobenzene, diethyl ether, naphtha, xylene, ethylene glycol, isoamyl acetate, diethylamine, and most organic solvents. This ketone dissolves cellulose nitrate, acetate, and ethers, vinyl resias, raw mbber, waxes, fats, shellac, basic dyes, oils, latex, bitumea, kaure, elemi, and many other organic compounds. 

Radical cations that are produced by electrochemical oxidation are not stable in solvents with appreciable base character. This results because such radicals are subject to attack by available nucleophiles, and solvents that contain donor electron pairs are good nucleophiles. Cation radicals are most stable in solvents that are good Lewis acids and show negligible basic properties. Some of the solvent systems that have been employed to stabilize electrochemically produced cation radicals include nitromethane and nitrobenzene,21 dichloro-methane,22 trifluoroacetic acid-dichloromethane (1 9),23 nitromethane-AlCl3,24 and AlCl3-NaCl (1 l).25 Organic chemists should be familiar with the stabilization of carbonium ions by superacid media.26 These media usually contain fluorosulfuric acid, or mixtures of fluorosulfuric acid with antimony pen-tachloride and sulfur dioxide, and are potent solvents for the production and stabilization of organic cations. 

After completion of the reaction, the mixture was cooled to 25° C., 140 mL. (1.00 mol) of a 25% by weight aqueous sodium hydroxide solution was added to the mixture to make up the whole reaction mixture weak basic (pH=7.9). Subsequently, 4-methyl-2-pentanone layer (an organic solvent layer) and an aqueous layer were separated, and the organic solvent layer was analyzed by gas chromatography, then no l,2-methylenedioxy-4-nitrobenzene which is a by-product was detected. Also, when it was analyzed by high performance liquid chromatography, a conversion of 1,2-methylenedioxybenzene was 97%, and a yield of piperonal was 78% (in terms of mole). 

In spite of the wide applicability of phase-transfer techniques in polymer synthesis, there have not been reported many basic works. In order to identify important reaction variables and to improve our knowledge on the reaction mechanism of PTP technique, we have conducted an investigation on biphasic heterogeneous polymerizations between various blsphenolate anions and 1,6-dibromohexane in the presence of tetrabutylaramonium bromide (Q r ),l tetrabutylphos-phonium bromide (P+Br") and dlbenzo-18-croxm-6 (DBC)26 (Equation 1). Nitrobenzene was chosen as an organic phase because it was found in preliminary experiments to be a reasonably good solvent for polymers at the reaction temperatures. 

Several other lines of evidence attest to the low basicity of nitrobenzene. The hydrohalogenic acids are very feebly conducting in this solvent (195) and the heat of formation of its BF3 adduct (48) is quite low relative to many other organic bases (329). 

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