Alkyl sulfates specifications

The pyrazolone 21 (R = Me, X = O, Scheme 8) gives 22 with Et30+BF ,32 while the thioxo analogs (21 X = S, R = Me or Et) are alkylated regio-specifically on sulfur with dimethyl sulfate to give products 23.33... 

Reversal of Specific Cation Effect in ir-A Isotherms. The reversal of the specific cation effect on the tt-A curves for the long-chain carboxylic acids (51) and the alkyl sulfates (45, 58) can be related to a model sug-... 

A number of emulsifying waxes are commercially available that contain different sodium alkyl sulfates and may not meet official compendial specifications. See also Section 18. 

In aqueous solution, the effectiveness of micellar systems as catalysts is quite often found to increase with the length of the alkyl chain. For example, the rate of acid hydrolysis of methyl o-benzoate in the presence of sodium alkyl sulfates increases in the order Cs < Cio < Cn < Cu < Cie. Such a result may be attributed to either electrostatic or solubilizing effects, or both. It might be expected that any effects due to electrostatic interactions would also increase. Alternatively (or additionally), the increasing aggregation number found in the series may result in a significant increase in the solubilizing power of the system. The importance of each mechanism will depend upon the specifics of the reaction. 

Alkyl sulfates/sulfonates added to the mobile phase form a micellar layer interacting with both the stationary phase and the amino acids (which under these conditions are pro-tonated). A mixed mechanism (ion-pairing and dynamic ion exchange) is observed. Furthermore, the ion-pairing reagent masks underivatized silanols of the ODS material, reducing non-specific unwanted interactions. Sodium dodecyl sulfate... 

Snrfactants are employed to stabihze the emulsion polymer particles anionic, cationic, and steric stabihzers are all used for the production of latexes, depending on whether one wants a negative, positive, or neutral potential surface on the formed pol5uner particle. The specific anionic options available for use are alkyl sulfates, alkyl sulfosuccinates, and alkylarene sulfonates and phosphates. Standard nonionic surfactants include alkyl or aryl polyoxyethylenes. In recent years, alkyl phenol ethoxylates have fallen into disfavor because of their reported problems with bioaccumulation in aquatic hfe. This still somewhat controversial, environmentally-driven issue has necessitated the use of alternative surfactants which have a lower impact on the environment. Typically, the aryl ring is eliminated to solve this problem. 

Further evidence that factors of specific affinity of the anions favor combination with protein is found in the observation that for the complete precipitation of serum albumin higher concentrations of pure octyl and decyl sulfates are required as compared to the effective concentration of dodecyl sulfate. The lower alkyl sulfates are not taken up quantita-... 

Liquid chromatography-mass spectrometry is still difficult to use for routine analysis. However, the technique is essential for special projects, as was demonstrated for determination of the total alkyl and ethoxy distribution of alkyl sulfate and alkylether sulfate in wastewater (66). Because of the specificity of MS detection, a simple SPE technique could be used for concentration, and an equally simple one-step HPLC separation was adequate. 

The most frequentiy used halo alkylating agents are aldehydes and hydrogen haUdes, haloalkyl ethers, haloalkyl sulfides, acetals and hydrogen haUdes, di- and polyhaloalkanes, haloalkenes, haloalcohols, haloalkyl sulfates, haloalkyl -tosylates, and miscellaneous further haloalkyl esters. Haloalkylations include halomethylation, haloethylation, and miscellaneous higher haloalkylations. Under specific conditions, bis- and polyhaloalkylation can also be achieved. 

Alkylation of pyrazinones and quinoxalinones may be carried out under a variety of conditions and it is usually observed that while O-alkylation may occur under conditions of kinetic control, to yield the corresponding alkoxypyrazines or alkoxyquinoxalines, under thermodynamic control the A-alkylated products are formed. Alkylation using trialkyl-oxonium fluoroborate results in exclusive O-alkylation, and silylation under a variety of conditions (75MI21400) yields specifically the O-silylated products. Alkylation with methyl iodide or dimethyl sulfate invariably leads to A-methylation. 

Although sulfate is formed by hydrolysis of both alkyl and aryl sulfates, the pathway of degradation for aryl sulfates is controlled by the source of sulfur (Cook et al. 1999). The complex issues surrounding the hydrolysis of sulfate esters have been discussed (Kertesz 1999), and are illustrated by the number and substrate specificity of alkyl sulfatases for the surfactant 2-butyloctyl sulfate in Pseudomonas sp. strain AE-A (Ellis et al. 2002). 

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