Sulfates group

The sulfate groups are beUeved to be important in gelation with potassium and in reaction with protein. The 3,6-anhydrogalactose units increase hydrophobicity and reduce solubiUty whereas the sulfate groups increase hydropltilicity and solubiUty. 

The second generation includes latices made with functional monomers like methacrylic acid, 2-hydroxyethyl acrylate [818-61 -17, acrylamide/75 -(9ti-/7, 2-dimethylaminoethylmethacrylate [2867-47-2] and sodiumT -vinyl-benzenesulfonate [98-70-4] that create in polymeric emulsifier. The initiator decomposition products, like the sulfate groups arising from persulfate decomposition, can also act as chemically bound surfactants. These surfactants are difficult to remove from the latex particle. 

Reactions other than those of the nucleophilic reactivity of alkyl sulfates iavolve reactions with hydrocarbons, thermal degradation, sulfonation, halogenation of the alkyl groups, and reduction of the sulfate groups. Aromatic hydrocarbons, eg, benzene and naphthalene, react with alkyl sulfates when cataly2ed by aluminum chloride to give Fhedel-Crafts-type alkylation product mixtures (59). Isobutane is readily alkylated by a dipropyl sulfate mixture from the reaction of propylene ia propane with sulfuric acid (60). 

Methylation of free OH groups, followed by denitration, hydrolysis, reduction, and glc analysis has been suggested as a method for determining the location of nitrate (82). This method has been suggested for CP and CS (82) as the phosphate and sulfate groups are stable to methylation and can then be removed. Periodate oxidation has been used to determine the DS of CS (81). 

Poly(hydroxyethyl methacrylate)-dye copolymers —The color additives formed by reaction of one or more of the foUowiag reactive dyes with poly(hydroxyethyl methacrylate), so that the sulfate group (or groups) or chlorine substituent of the dye is replaced by an ether linkage to poly(hydroxyethyl methacrylate) (see Dyes, reactive). The dyes that may be used alone or ia combination are... 

To measure the amount of the enol-sulfate of coelenterazine in a tissue, the methanol homogenate prepared in Section C5.1 is centrifuged, and 10 pi of the supernatant is heated with 0.1 ml of 0.5 M HC1 at 95° C for one minute under argon gas, in order to hydrolyze the enol-sulfate group. The material is quickly cooled in ice water, neutralized with a small amount of solid NaHCO , and then the amount... 

Hori, K., Nakano, Y., and Cormier, M. J. (1972). Studies on the bioluminescence of Renilla reniformis. XI. Location of the sulfate group in luciferyl sulfate. Biochim. Biophys. Acta 256 638-644. 

Sodium lauryl sarcosinate is very similar to the lauryl sulfate class of detergents and surfactants. The sulfate group is replaced with the amino acid sarcosinic acid, and the ammonium group is replaced with a sodium atom. The result is a detergent that is milder on the skin and oral membranes, and can be used in toothpastes without causing irritation of the gums. 

The bottom views show how the zigzag chains are linked by bridging sulfate groups. 

Evans studied the influence of the position of the sulfate group on the CMC at 40°C for a large number of sodium alcohol sulfates [92]. The results are given in Table 10. From these results it is possible to determine the constants A and B of Eq. (11) at 40°C as shown in Table 11. Observation shows a slight constant decrease of the slope (B) of the lines as the sulfate group is shifted toward the middle of the chain whereas the values of A are almost constant for all homologous series. 

TABLE 9 Effect of the Position of the Sulfate Group of Sodium Tetradecyl Sulfates on CMC (mol/L x 103)... 

TABLE 10 Effect of Position of Sulfate Group on the CMC at 40 °C for Different Sodium Alcohol Sulfates... 

TABLE 11 Constants A and B of Sodium Alcohol Sulfates for Various Positions of the Sulfate Group at 40°C... 

Fig. 24.—(a) Stereo view of slightly over a turn of the 3-fold double helix of i-carrageenan (23). The two chains are distinguished by open and filled bonds for clarity. The vertical line is the helix axis. Six interchain hydrogen bonds per turn among the galactose residues stabilize the double helix. The sulfate groups lined up near the periphery are crucial for intermolecular interactions. 

Fig. 24. (continued)—(b) An axial projection of the unit cell contents. The double helix at each corner can be either up- or down-pointing," in terms of the X-ray data. All are, however, up in this diagram so that a calcium ion (crossed circle) is connected to the sulfate groups in three surrounding... 

Consistent with their chemical differences, the molecular structures of i- and K-carrageenans are not identical. A shorter pitch and an offset positioning of the two chains in the kappa helix is compatible with the lack of sulfate group on every 3,6-anhydrogalactose residue. The variations in molecular structures mirror the types of junction zones formed by these polymers and relate to the observed gelation properties. 

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