Poly sulfonium

The synthesis of high molecular weight PPS via a cationic oxidative polymerization route was inhibited by premature precipitation of PPS. A method for the synthesis of high molecular weight PPS from a soluble precursor under mild conditions was developed. Poly(sulfonium cation) was used as a precursor to PPS [Eq. (31)] [118]. 

A polymer with a sulfone group on every other unit of the chain was obtained by the oxidation of 214 with H202 [Eq. (32)]. Thus, poly(sulfonyl-l,4-phenylenethio-l,4-phenylene) (PSPT) was synthesized in the presence of H202 and CF3C02H in CHC13 via a poly(sulfonium cation) [121]. 

K. Miyatake, H. Iyotani, K. Yamamoto, E. Tsuchda, Synthesis of poly(phenylene sulfite sulfonic acid) via poly(sulfonium cation) as a thermostable proton-conducting polymer, Macmmolecules, 1996, 29, 6969 K. Miyatake, K. Shouji, K. Yamamoto, E. Tsuchda, Synthesis and proton conductivity of highly sulfonated poly(thiopheny-lene), Macmmolecules, 1997, 30, 2941 K. Miyatake, K. Fukushima, S. Takeoka and... 

Tsuchida et al. [95,96] reported the synthesis of poly(thiophenylene sulfonic acid) containing up to two sulfonic acid groups per repeating unit. Polymerisation of 4-(methylsulfinyl)diphenyl sulfide in sulfuric add upon heating or in the presence of SO3 resulted in sulfonated poly(sulfonium cation), which was then converted into the corresponding sulfonated poly(phenylene sulfide). 

The synthesis of PPS via poly(sulfonium cation) as a soluble precursor (221) was developed through oxidative polymerization of methyl 4-(phenylthio)phenyl sulfide (222), followed by dealkylation (eq. 9) (223-225). 

The poly(sulfonium salt) is obtained by the reaction if a,a-dichloro-/ -xylene with excess dimethyl sulfide (50 °C, 20 h) and polymerization with sodium hydroxide (0 °C, 1 h). 

The starting precursor poly(sulfonium salt)s are prepared by polymerizing the monomer sulfonium salt with an equimolar amount of NaOH in aqueous solution at 0°C for 1 h. Further details and similar preparation techniques are cited in [20]. 

K. Miyatake, H. lyotani, K. Yamamoto, E. Tsuchida, Synthesis of poly(phenylene sulfide sulfonic acid) via poly(sulfonium cation) as a thermostable proton-conducting polymer. Macromolecules 29(21), 6969-6971 (1996). 

Yamamoto, K., Shouji, E., Suzuki, F., Kobayashi, S., Tsuchida, E. (1995) Synthesis of poly(sulfonium cation) by oxidative polymerization of aryl alkyl sulfides. The Journal of Organic Chemistry, 60, 452-453. 

Poly(sulfonium cation) for the Synthesis of High-Molecular-Weight Pofy(phenylene... 

Methylation of Nucleophfles. A 100 ml round-bottomed flask with a Teflon-covered magnetic stirrer bar was charged with poly(sulfonium cation) (1 g, 2.6 mmol as unit of poly(sulfonium cation)). Acetonitrile (20 ml) was added at room temperature and stirred. Nucleophiles such as phenol and aniline were added to the reaction mixture, which was filtrated by silica gel colunm (2 x 20 cm, benzene eluent) and the filtrate was evaporated. Conversion of obtained compounds were evaluated by gas chromatography. 

Measurement of Viscosity of Polysulfonium CFsSOsNa (905 mg, 5.26 mmol) was dissolved in acetonitile / waster = 50/50 (vol %) 100 mL as solution A. Poly(sulfonium cation) 200 mg was dissolved in the solution 10 mL and was added into an Ubbelohde viscometer. For all measurement of the viscosity at 25 <>C, the solution was diluted to half concentration with solution A. On the basis of the correlation plot of c(g dl -i, concentration of polycation) and Tjsp (specific viscosity)/c, limiting viscosity number [T]] can be obtained from the intersection of vertical axis. 

Solvent Properties of Polysulfoniunt The poly(sulfonium cation) is soluble in common solvents such as acetonitrile, DMSO, formic acid and sulfuric acid. However, PPS has poor solubility in various solvents, which not only make it difficult to synthesize under mild conditions but also to characterize, determination of molecular weight The viscosity of poly(sulfonium cation) as a novel polyelectrolyte which is a useful precursor of PPS synthesis was determined in acetonitrile solution ( 50 vol% aqueous) and in formic acid. PPSs with Mw=1.14 x 10, 2.01 x 10, 2.83 x 104, 3.91 X 104, 7.01 X 104, 9.52 x 104 which were determined by high temperature GPC were prepared by polymerization of the sulfoxide. 

The poly(sulfonium cation) with trifluoromethanesulfonate anion is a new type polyelectrolyte which has alternative structure of positively charged phenylsulfonium and phenylsulfide. The solution viscosity and solubility of a polyelectrolyte are influenced by a co-existence of supporting electrolyte and solvent species. The poly( sulfonium cation) is insoluble in aqueous solution but soluble in polar organic solvents, e,g. acetone, acetonitrile and dimethyl sulfoxide (DMSO). In particular, the polycation is very soluble in acetonitrile and formic acid (solubility more than 100 mg mL-i)-... 

Demethylation of Polysulfonium. The demethyladon to PPS moiety was also carried out in acetonitrile to examine the reacdvity using high-molecular weight poly( methyl-4-phenylthiophenl trifluoromethanesulfonate) (poly(sulfonium cadon)) (Afw > 2 X 10 ). The poly(sulfonium cadon) was demethylated through nucleophilic reacdon with pyridine at reflux. An equimolar amount of pyridine when added to a soludon at... 

Figuie 4 Relationship between Viscosity of Poly(sulfonium cation) and Molecular Weight of PPS(after demethylation)(a, ), and between the viscosity of Poly(sulfonium cation) (b, O) and the Molecular Weight of Poly(sulfonium cation) wMch is calculated on the basis of the molecular weight of PPS. in formic acid containing sodium trifluoiomethanesulfonate (50 mM, 23 <>C)... 

Demethylation of poly(sulfonium cation) occurs by nucleophile substitution reaction via Sn2 mechanism The demethylation is also classified as a transmethylation to nucleophiles. Using nucleophiles that have a mobile proton such as phenol, aniline and benzoic acid derivatives in the presence of potassium carbonate, demediyladon of poly( sulfonium cation) proceeds efficiently to yield the methylated products of phenol and benzoic acid with 100 % conversion (Scheme 2). In the case of aniline, both N-methyl and M -dimethyl aniline are obtained and methylation of -methyl aniline occurs more easily than aniline because of the higher Lewis basicity. 

---