Chemical Synthesis of Sulfonic Acid Derivatives

Structural modifications of polyaniline have mainly been exploited to achieve improved processability and environmental stability. In general, the substituted polyanilines can be obtained via oxidative polymerization of the corresponding monomer. However, inductive and steric effects can make such monomers difficult to polymerize [42]. Several substituted polyanilines have been prepared by varying the nature (alkyl, alkoxy, halogen, etc.) and the position (2- vs 3-, 5-positions) of the substituent [24, 27-32, 34, 37, 43, 44]. These studies have shown that regardless of the nature and position of the substituent group, there is an adverse effect on polymerization and the properties of the polymer such as conductivity and electroactivity. To overcome these limitations, various synthetic methods have been developed to prepare self-doped sulfonated polyanilines. These methods involve controlled postpolymerization modifications by synthetic reactions on the whole polymer and copolymerization of less reactive monomers with aniline as described below. 

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Postsulfonation of polymers to form PEMs can lead to undesirable side reactions and may be hard to control on a repeatable basis. Synthesis of sulfonated macromolecules for use in PEMs by the direct reaction of sulfonated comonomers has gained attention as a rigorous method of controlling the chemical structure, acid content, and even molecular weight of these materials. While more challenging synthetically than postsulfonation, the control of the chemical nature of the polymer afforded by direct copolymerization of sulfonated monomers and the repeatability of the reactions allows researchers to gain a more systematic understanding of these materials properties. Sulfonated poly(arylene ether)s, sulfonated poly-(imide)s, and sulfonated poly(styrene) derivatives have been the most prevalent of the directly copolymerized materials. 

For the analytical characterization of sulfated tyrosine peptides, spectroscopic methods as well as amino acid analysis and, more recently, mass spectrometry are employed. In Table 2 the spectroscopic data of tyrosine 0-sulfate are compared to those of the related sulfonic acid derivatives as possible byproducts in the chemical sulfation of the tyrosine or tyrosine peptides.[361 In the course of the synthesis of tyrosine 0-sulfate peptides and, particularly in the final deprotection step, desulfation may occur which limits the characterization of the final compounds in terms of quantitative identification of the tyrosine 0-sulfate. This is achieved by amino acid analyses of basic hydrolysates of the sulfated tyrosine peptides or preferably by analyses of the enzymatic hydrolysates with aminopeptidase M or leucine-aminopeptidase. 

Sendai, M., Hashiguchi, S., Tomimoto, M., Kishimoto, S., Matsuo, T., Kondo, M., Ochiai, M. Chemical Modification of Sulfazecin. Synthesis of 4-(substituted Methyl)-2-azetidinone-l-sulfonic acid Derivatives. J. Antibiotics 1985, 38, 347. 

Sulfonic acid esters are more versatile than carboxylic acid esters due to their stability toward acids and bases and the way they are cleaved. Cleavage of carboxylic acid esters occurs by carbonyl-oxygen fission (reaction 4.11), while cleavage of sulfonic acid esters occurs by alkyl-oxygen fission (reaction 4.12). This latter chemical property makes them very useful in the synthesis of many carbohydrate derivatives and analogues in which the nucleophile is substituted onto the carbon atom of the carbohydrate. 

The development of sulfone linkers, the exploration of sulfone based chemical transformations and cleavage strategies are an important objective in soHd-phase organic synthesis. This kind of Hnker (Tab. 3.7) has been used with thioethers [108], sulfoxides [109], sulfones [110], sulfonic acids and their corresponding derivatives [111]. Because carbon-sulfur bonds can be cleaved under very mild conditions, some Hnkers have been based on this effect. They can be cleaved under reductive conditions ]112, 113], photolytic conditions [114, 115] or with strong bases [116]. Various safety catch Hnkers have been developed based on the fact that thiols can be oxidized to sulfoxides and sulfones [112, 113]. 

Most reported phthalocyanine derivatives (sulfo-, nitro-, amino-, triphenylmethyl-, polymeric, etc.) are copper complexes, although at present the synthetic chemistry of other d- and /-metal Pc derivatives is being rapidly developed (Examples 30-36) [5,6,116-118]. Some of them (in particular, copper phthalocyanine sulfonic acids) are of industrial interest because of their usefulness as dyes. Phthalocyanine sulfonic acids themselves are prepared both by urea synthesis from sulfonated phthalic anhydride and by the sulfonation of the phthalocyanine [6], Some substituted metal phthalocyanines can be obtained by chemical or electrochemical reduction [118e]. Among a number of reported peculiarities of substituted phthalocyanines, the existence of three electronic isomers for magnesium derivative PcMn was recently confirmed [118f]. 

Sulfonic acids and their derivatives are used in innumerable industrial applications in chemical synthesis, electroplating of metals, surfactants, ion-exchange resins, and preparation of dyes, animal feeds, pesticides, and pharmaceuticals. 

The model monosaccharides just listed were prepared from common precursor IV.l (Scheme 39), which was readily obtained by azidonitration of 3,4,6-tri-O-acetyl-D-galactal followed by deacetylation with sodium methoxide. Treatment of IV.l with acetone and toluene p-sulfonic acid monohydrate at room temperature led to predominant formation of the thermodynamically favored 3,4-O-isopropylidene (IV.2) in 61% yield while also producing 27% of the 4,6-O-isopropylidene derivative IV.3. The position of the isopropylidene IV.2 was verified by the use of NMR chemical shift analysis to confirm the position of the acetate group in the resultant acetylated adduct IV.4. Synthesis of the 4-O-sulfate derivative (IV.7) from IV.2 utilized a step that differentiated the 3-OH and 4-OH positions after benzylation and de-isopro-pylidination of IV.2, a selective methylation at the 3-OH of diol IV.5 was achieved via a tin procedure [91] to give methyl glycoside IV.6. Conversion of the azide into... 

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