Carboxylic sulfonic

Carboxylate, sulfonate, sulfate, and phosphate ate the polar, solubilizing groups found in most anionic surfactants. In dilute solutions of soft water, these groups ate combined with a 12—15 carbon chain hydrophobe for best surfactant properties. In neutral or acidic media, or in the presence of heavy-metal salts, eg, Ca, the carboxylate group loses most of its solubilizing power. 

The synthesis of (+)-N-methylmaysenine, a preliminary for the later synthesis of the antitumor agent maytansine, was accomplished by the joining of fragments A and B, chain extension and macrolactam closure using a mixed carboxylic-sulfonic acid anhydride. 

These authors suggest that the reaction may proceed through the formation of their mixed anhydrides , and illustrate a metal ion templated, mixed carboxylic-sulfonic anhydride. 

Sulfur compounds have also been widely studied as activating agents for polyesterification reactions. p-Toluenesulfonyl chloride (tosyl chloride) reacts with DMF in pyridine to form a Vilsmeir adduct which easily reacts with carboxylic acids at 100-120° C, giving highly reactive mixed carboxylic-sulfonic anhydrides.312 The reaction is efficient both for aromatic dicarboxylic acid-bisphenol312 and hydroxybenzoic acid314 polyesterifications (Scheme 2.31). The formation of phenyl tosylates as significant side products of this reaction has been reported.315... 

Carboxylic-sulfonic anhydrides, 80 Cardiovascular surgery, 27 Cardo diamines, 277, 278 Carothers, Wallace, 198 Carothers equation, 11, 59 Carothers group, 1 Carpet waste... 

As shown, an asymmetric carboxylic-sulfonic acid anhydride is formed, but the cellulose attack occurs on the C = O group, since a nucleophilic attack on sulfur is slow, and the tosylate moiety is a much better leaving group than the carboxylate group [193]. Similar to other acylation reactions, there is a large preference for tosylation at the 5 position, and cellulose tosylates... 

This separation technique produces very good results for acidic or anionic dye molecules containing carboxylic, sulfonic, and hydroxy groups that can be separated within short run times in an aLkaline medium in a single analysis step. - Natural colorants usually do not contain these functional groups they are usually more voluminous and strongly hydrophobic, properties that complicate their determination by CE. The sample pretreatment is more difQcult when CE (compared to HPLC) is used. 

The amount of added water required for desalting may be minimized by adding a chemical emulsion breaker to the crude that is capable of displacing the surface-active components from the brine droplets. Quatemized carboxylic-sulfonic acid salts, shown in Figure 22-9, are useful for desalting [1791]. Preferably, the chemical emulsion breaker is used in combination with a delivery solvent, such as diethylene glycol monobutyl ether. 

Figure 22-9. Quatemized carboxylic-sulfonic acid salts.

Table 21-1. Halides prepared from alcohols via imidazole-V-carboxylates, -sulfonates and -sulfinates.

The ion-exchange process is applicable for removing a broad range of ionic species from water containing all metallic elements, inorganic anion such as halides, sulfates, nitrates, cyanides, organic acids such as carboxylics, sulfonics, some phenols at sufficiently alkaline pH conditions, and organic amines at sufficiently acidic conditions. 

The fluorescence spectrum of the tris-acridine cryptand A-13 shows the characteristic monomer and excimer bands. Upon complexation with various organic anions (carboxylates, sulfonates, phosphates), the monomer band increases at the expense of the excimer band. The stability of the complexes depends on the contribution of the electrostatic and hydrophobic forces and on the structural complementarity. Stability constants of the complexes ranging from 103 to 107 have been measured. In particular, A-13 binds tightly to mono- and oligonucleotides, and it can discriminate by its optical response between a pyridimic and a purinic sequence. 

Other tetraalkylammonium salts are also used in electrochemical measurements they are tetraalkylammonium nitrates, picrates, carboxylates, sulfonates, etc. They can be prepared in the laboratory, by neutralizing the corresponding acid in water with ftjNOH just to the equivalence point, removing water, and then drying. If necessary, the products are recrystallized. Some tetraalkylammonium salts form hydrates and are difficult completely to dehydrate. For practical information, see, for example, Ref. [19]. 

Proton acids can be used as catalysts when the reagent is a carboxylic acid. The mixed carboxylic sulfonic anhydrides RCOOSO2CF3 are extremely reactive acylating agents and can smoothly acylate benzene without a catalyst.265 With active substrates (e.g., aryl ethers, fused-ring systems, thiophenes), Friedel-Crafts acylation can be carried out with very small amounts of catalyst, often just a trace, or even sometimes with no catalyst at all. Ferric chloride, iodine, zinc chloride, and iron are the most common catalysts when the reactions is carried out in this manner.266... 

Other less commonly used coupling reagents include EEDQ (formation of mixed carboxylic carbonic anhydrides), Bop-Cl (formation of mixed carboxylic phosphinic anhydrides [52,53]), DPPA (formation of acyl azides), DECP (formation of acyl cyanides), MSNT (formation of mixed carboxylic sulfonic anhydrides), and benzisoxazo-lium salts (generation of phenyl esters [54]). 

Chemically, the triarylmethane dyes are monomethine dyes with three terminal aryl systems of wind] one or more arc substituted with primary, secondary, or tertiary amino groups or hydroxyl groups in the para position to the methine carbon atom. Additional substituents such as carboxyl, sulfonic acid, halogen, alkyl, and alkoxy groups may be present on the aromatic rings. The number, nature, and position of these substituents determine both the hue or color of the dye and the application class to which the dye belongs. 

In addition to the preceding products, many other specialist chemical formulations are available. For example, products may incorporate a proprietary polymer for high silica control or blend in a carboxylate/sulfonate/nonionic functional terpolymer for high iron control. 

A number of experimental techniques by measurements of physical properties (interfacial tension, surface tension, osmotic pressure, conductivity, density change) applicable in aqueous systems suffer frequently from insufficient sensitivity at low CMC values in hydrocarbon solvents. Some surfactants in hydrocarbon solvents do not give an identifiable CMC the conventional properties of the hydrocarbon solvent solutions of surfactant compounds can be interpreted as a continuous aggregation from which the apparent aggregation number can be calculated. Other, quite successful, techniques (light scattering, solubilization, fluorescence indicator) were applied to a number of CMCs, e.g., alkylammonium salts, carboxylates, sulfonates and sodium bis(2-ethylhexyl)succinate (AOT) in hydrocarbon solvents, see Table 3.1 (Eicke, 1980 Kertes, 1977 Kertes and Gutman, 1976 Luisi and Straub, 1984 Preston, 1948). 

Because the sensitivity of the detector decreases with decreasing analyte ionization, the pH of the mobile phase should be chosen to maximize solute dissociation. For example, anions with pKa values above 7 are not detectable by conductivity detection. However, conductivity detection is often the preferred method for organic acids with carboxylate, sulfonate, or phospho-nate functional groups, since the pKa values are below 5. For cations, most aliphatic amines have pKa values around 10 and are readily detected by conductivity detection. The pKa values of aromatic amines, however, are in the range 2 to 7, which is too low to be detected by suppressed conductivity. Sensitivity by nonsuppressed conductivity is also poor, so these amines are monitored by UV absorption or pulsed amperometric detection. 

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