Properties of Sulfonic Acid Derivatives

The discovery of self-doped polyanilines was a major breakthrough in the field of conducting polymers due to their desirable properties such as water solubility, pH and temperature independent conductivity, redox activity over a wider pH range and thermal and environmental stability. These polymers can be prepared chemically and electrochemically by various methods discussed in the above sections 2.2-2A. The distinctive properties of self-doped sulfonated polyanilines are discussed in this section. 

Epstein et al. [41, 54, 71] suggested that the sulfonated polyanilines have much stronger temperature dependence conductivity than emeraldine hydrochloride due to greater electron localization. The temperature dependence of the conductivity of 50 % [41], 75 % [54] and fully ring sulfonated polyanilines [71] was best fit by the quasi one-dimensional variable range hopping model described by Equation (2.1)  

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Sulfosahcyhc acid is prepared by heating 10 parts of sahcyhc acid with 50 parts of concentrated sulfuric acid, by chlorosulfonation of sahcyhc acid and subsequent hydrolysis of the acid chloride, or by sulfonation with hquid sulfur trioxide in tetrachloroethylene. It is used as an intermediate in the production of dyestuffs, grease additives, catalysts, and surfactants. It is also useful as a colorimetric reagent for ferric iron and as a reagent for albumin. Table 9 shows the physical properties of sahcyhc acid derivatives. 

The physical properties of sulfonic acids vary greatly depending on the nature of the R-group. Sulfonic acids can be described as having similar acidity characteristics to sulfuric acid. Sulfonic acids are prone to thermal decomposition, i.e., desulfbnation, at elevated temperatures. However, several of the alkane-derived sulfonic acids show excellent thermal stability, as shown in Table 1. Arene-based sulfonic acids are thermally unstable. 

Stereochemistry, conformation, and chiroptical properties of sulfonic acids and derivatives... 

This chapter describes the acidity and hydrogen-bonding properties of sulfonic acids and their derivatives including metal complexation. 

There are three main uses for naphthalene sulfonic acid derivatives (75—79) as naphthalenic tanning material alkyl naphthalene sulfonates for industrial appHcations as nondetergent wetting agents and as dye intermediates. Consumption of naphthalene sulfonates as surfactants accounts for a large portion of usage. Naphthalene sulfonate—formaldehyde condensates are also used as concrete additives to enhance flow properties. Demand for naphthalene sulfonates in surfactants and dispersent appHcations, particularly in concrete, was expected to increase into the twenty-first century. Consumption as of 1995 was 16 x 10 kg/yr. 

Normally, reactive derivatives of sulfonic acids serve to transfer electrophilic sulfonyl groups259. The most frequently applied compounds of this type are sulfonyl halides, though they show an ambiguous reaction behavior (cf. Section III.B). This ambiguity is additionally enhanced by the structure of sulfonyl halides and by the reaction conditions in the course of electrophilic sulfonyl transfers. On the one hand, sulfonyl halides can displace halides by an addition-elimination mechanism on the other hand, as a consequence of the possibility of the formation of a carbanion a to the sulfonyl halide function, sulfenes can arise after halide elimination and show electrophilic as well as dipolarophilic properties. 

As with the carboxyhc acid group, the reactivity of these sulfonic acid derivatives may be predicted from the properties of the leaving group, and sulfonyl chlorides are the most reactive (see... 

C6o fullerene surfaces were thermally functionalized with perfluoro-(3-oxo-penta-4-ene)sulfonyl fluoride and then converted into sulfonic acid derivatives by basic hydrolysis. The product mimiced the electroconductive properties of perfluorosulfonyl Nation 1100 resins. When the modified fullerence was blended with platinum nanoparticles imbedded in Nation 1100 the material was effective as electrodes in fuel cells. 

TABLE 1. Physical Properties of Selected Polyhydroxyalkanoate Derivatives Containing Amide or Sulfonic Acid Components Prepared According to the Current Invention... 

All other sulfonic acid derivatives of 1,2- and 2,1-aminonaphthols, as well as the unsubstituted 1,2- and 2,1-aminonaphthols (the latter in the form of their hydrochlorides), can be diaMtized in this way. It is necessary to modify the conditions used in isolating the various diazo compounds because of their differing solubility properties. In cases where the free acid is too soluble, it can frequently be isolated satisfactorily as the barium salt. 

Sulfur Compounds in Which Sulfur Is the Central Atom. Although sulfur compounds may resemble oxygen compounds in their formulas, they differ in many ways. One of the principle differences is that the sulfur atom can be oxidized whereas generally the oxygen atom cannot. This property of sulfur gives rise to the multivalent series of sulfur compounds which includes sulfoxides, sulfones, sulfonic acid derivatives. 

A thermopolastic elastomer based on sulfonated-EPDM, S-EPDM, was developed in the 1970 s by Exxon and more recently by Uniroyal. Unlike the synthesis of the carboxylate ionomers described above, S-EPDM is prepared by a post-polymerization sulfonatlon reaction(28). Compared to the metal neutralized S-EPDM, the sulfonic acid derivative is not highly associated. The free acid materials possess low strengths and are less thermally stable. The metal salts of S-EPDM have properties comparable to crosslInked elastomers, but they do exhibit viscous flow at elevated temperatures. In the absence of a polar cosolvent, such as methanol, hydrocarbon solutions of the metal salts of S-EPDM are solid gels at polymer concentrations above several percent(31). With the addition of 1 to 5% alcohol the polymer solution becomes fluid with solution viscosities of the order of 10 to 100 poise. 

The plasticizing effects of a larger number of metal stearates on the zinc sulfonate ionomer were examined, and the results are given in Table III in terms of flow and mechanical properties. Lead stearate, zinc stearate, and ammonium stearate significantly improved melt flow along with the stearic acid control. The barium, magnesium, sodium, lithium, and calcium stearates showed little, if any, improvement in melt flow. Of the four melt flow improvers, both stearic acid and ammonium stearate exerted deleterious effects on tensile properties. Only the zinc and lead stearates substantially improved tensile properties. Thus, while zinc stearate is not unique, the number of fatty acid derivatives that improve both melt flow and mechanical properties is limited. 

In the previous section it was suggested that the parent polymer structure considerably influence the physical properties of the derived polysulfonates, imparting to them some of the mechanical and thermal properties of the precursors. This trend is particularly evident in the case of the perfluorinated hydrocarbon polymers. Polymers of this kind, such as e.g., poly(tetrafluoroethylene) (PTFE) are exceptional in their inertness to offensive environment, solvent resistance and high-temperature stability. These considerations led in the sixties to the development of unique sulfonic-acid derivatives of fluorocarbon copolymers by the DuPont Company. While several compositions were disclosed in the patent literature51, the preferred composition, which is the basis for the commercial Nafion ion-exchange membrane, is a copolymer of tetrafluoroethylene with a perfluorinated vinyl ether/sulfonyl fluoride52 ... 

Sulfonyl chlorides are highly reactive derivatives of sulfonic acid and possess similar properties and reactivity to acid chlorides of carbo Q lates. The reaction with nucleophiles such as amines requires alkaline conditions (pH 9-10) and proceeds through the formation of an unstable pentavalent transition state (Scheme 1.10). Hydrolysis is a major competing reaction in water therefore the reaction with amines proceeds with better yield when done in organic solvents. Sulfonyl chlorides have played an important role in bioconjugation chemistry, since sulfonic acids can be easily converted into sulfonyl chlorides using thionyl chloride or phosphorus pentachloride in non-aqueous conditions. ... 

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