sodium-dodecyl-sulfate and benzaldehyde

The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.

Topics: 2,2'-Dipyridyl; Benzaldehydes; Benzoic Acid; Catalysis; Cetylpyridinium; Chromium; Kinetics; Micelles; Oxidation-Reduction; Phenanthrolines; Polyethylene Glycols; Sodium Dodecyl Sulfate; Surface-Active Agents

In this study, a microemulsion electrokinetic chromatography (MEEKC) method was developed to analyze and detect several aromatic acids (benzoic acid (BA), isophthalic acid (IPA), terephthalic acid (TPA), p-toluic acid (p-TA), 4-carboxylbenzaldehyde (4-CBA), trimesic acid (TSA), trimellitic acid (TMA), o-phthalic acid (OPA), and hemimellitic acid (HMA)), which are common organic impurities produced by liquid-phase catalytic oxidation of p-xylene to TPA. The effects of microemulsion composition, column temperature, column length and applied voltage were examined in order to optimize the aromatic acid separations. This work demonstrated that variation in the concentration of surfactant (sodium dodecyl sulfate (SDS)) and oil phase (octane) had a pronounced effect on separation of the nine aromatic acids. It was also found that a decrease in column length had the greatest effect on shortening separation time and improving separation resolution for these aromatic acids when compared to that of an increase in column temperature or applied voltage. However, the nature and concentration of cosurfactants and organic modifiers were found to play only minor roles in the separation mechanism. Thus, a separation with baseline resolution was achieved within 14 min by using a microemulsion solution of pH 2.0 containing 3.7% SDS, 0.975% octane, and 5.0% cyclohexanol; and a 50-cm capillary column (effective length of 40-cm) at 26 degrees C. As a result, the developed MEEKC method successfully determined eight impurities of aromatic acids in the mother liquors produced from the oxidation synthesis of TPA.

Topics: Benzaldehydes; Carboxylic Acids; Chromatography; Emulsions; Hydrogen-Ion Concentration; Octanes; Phthalic Acids; Sodium Dodecyl Sulfate; Temperature; Xylenes

Covalent modification of skin proteins by electrophiles is a key event in the induction of skin sensitisation but not skin irritation although the exact nature of the binding mechanisms has not been determined empirically for the vast majority of sensitisers. It is also unknown whether immunologically relevant protein targets exist in the skin contributing to effecting skin sensitisation. To determine the haptenation mechanism(s) and spectra of amino acid reactivity in an intact protein for two sensitisers expected to react by different mechanisms, human serum albumin (HSA) was chosen as a model protein. The aim of this work was also to verify for selected non-sensitisers and irritants that no protein haptenation occurs even under forcing conditions. HSA was incubated with chemicals and the resulting complexes were digested with trypsin and analysed deploying matrix-assisted laser desorption/ionization mass spectrometry, reverse phase high performance liquid chromatography and nano-electrospray tandem mass spectrometry. The data confirmed that different residues (lysine, cysteine, histidine and tyrosine) are covalently modified in a highly selective and differential manner by the sensitisers 2,4-dinitro-1-chlorobenzene and phenyl salicylate. Additionally, non-sensitisers 2,4-dichloro-1-nitrobenzene, butyl paraben and benzaldehyde and irritants benzalkonium chloride and sodium dodecyl sulphate did not covalently modify HSA under any conditions. The data indicate that covalent haptenation is a prerequisite of skin sensitisation but not irritation. The data also suggest that protein modifications are targeted to certain amino acids residing in chemical microenvironments conducive to reactivity within an intact protein. Deriving such information is relevant to our understanding of antigen formation in the immunobiology of skin sensitisation and in the development of in vitro protein haptenation assays.

Topics: Acetylation; Benzaldehydes; Chromatography, High Pressure Liquid; Dermatitis, Contact; Dinitrochlorobenzene; Haptens; Hydrolysis; Irritants; Mass Spectrometry; Models, Molecular; Molecular Weight; Nitrobenzenes; Parabens; Peptide Mapping; Salicylates; Serum Albumin; Skin; Sodium Dodecyl Sulfate; Trypsin

An accurate, sensitive and selective reversed-phase micellar liquid chromatographic method was developed for simultaneous determination of benzyl alcohol and benzaldehyde. This method was applied in different injectable formulations containing diclofenac, piroxicam, lincomycin and clindamycin. The method showed excellent linearity in the range of 10-100 microg mL(-1) and 1-20 microg mL(-1) with the limit of detection (S/N = 3) 0.25 microg mL(-1) (2.3 x 10(-6) mol L(-1)) and 0.12 microg mL(-1) (1.13 x 10(-6) mol L(-1)) for benzyl alcohol and benzaldehyde, respectively. The suggested method was successfully applied to the analysis of the studied drugs in bulk with average recoveries of 100.1 +/- 1.0% for benzyl alcohol and 100.4 +/- 1.6% for benzaldehyde, and to the determination of benzyl alcohol and benzaldehyde in injectable formulations with the respective average recoveries of 99.8 +/- 0.3 and 100.0 +/- 0.4%.

Topics: 1-Propanol; Algorithms; Anesthetics, Local; Benzaldehydes; Benzyl Alcohol; Calibration; Chromatography, Micellar Electrokinetic Capillary; Injections; Linear Models; Oxidation-Reduction; Preservatives, Pharmaceutical; Reproducibility of Results; Sodium Dodecyl Sulfate