112-53-8Relevant articles and documents
Kinetics of the Acid-catalysed Hydrolysis of Dodecylsulphate and Dodecyldiethoxysulphate Surfactants in Concentrated Micellar Solutions. Part 1. - Effects of Acid and Surfactant Concentrations and of the Nature and Concentration of Counterions
Garnett, Christopher J.,Lambie, Alan J.,Beck, William H.,Liler, Milica
, p. 953 - 964 (1983)
The rates of the acid-catalysed hydrolysis of sodium dodecylsulphate (SDS) and sodium dodecyldiethoxysulphate (SDE2S) have been investigated in concentrated surfactant solutions (0.035 - 0.6 mol dm-3).The acid concentration dependence of the initial rates shows a 'saturation' effect, whereas increasing surfactant concentrations above the c.m.c. lead to a maximum in the k2,obs values, beyond which they decrease sharply.These results are discussed in terms of the ion-exchange pseudophase model of the miceller reaction.The nature of the counterion has an effect on k2,obs, the values following the sequence NH4 > Li > Na >> Mg.This has been ascribed to differences in the ion-exchange constants, KH/X, of these cations in the Stern layer of the micelles with the hydrogen ion.Maintaining the total counterion concentration and the ratio of concentrations of surfactant counterion to the concentration of hydrogen ion constant (at 30, i.e. 0.6 : 0.02 mol dm-3) largely eliminates the decrease in the k2,obs values with increasing surfactant concentration, as expected from the pseudo-phase ion-exchange model.Quantitative agreement between theory and experiment is less good, however, owing at least partly to deviations from ideality in solutions of high ionic strength.
Acid-catalyzed hydrolysis of sodium dodecyl sulfate
Nakagaki,Yokoyama
, p. 1047 - 1052 (1985)
The acid-catalyzed hydrolysis of sodium dodecyl sulfate (1) and the effect of 1-dodecanol (2) on this hydrolysis were investigated. The rate of hydrolysis was followed by measuring the rate of production of HSO4- using a pH-stat. The rate constant (κ(H+)) below the critical micelle concentration (CMC) increased with increasing concentrations of 2, up to a mole ratio of 0.5 for 2 to 1, after which the hydrolysis rate was independent of the concentration of 2. These results suggest the possible formation of a complex between 1 and 2. A micellar solution of pure sodium dodecyl sulfate (20 mM) hydrolyzed 50 times faster than that of a premicellar solution at the same pH. Plots of log κ versus pH were linear with a slope of -1 at pH 4.3. At a constant pH, the addition of NaCl resulted in a decrease in the rate of hydrolysis of a micellar solution. This is probably due to the reduction of concentration of protons at the micelle surface. Furthermore, κ(H+) was also decreased by the addition of 2 in the region where 2 is solubilized in the micelle; again, this was probably due to the reduction of the charge density (σ) on the surface of the micelle.
The hydrolysis of C12 primary alkyl sulfates in concentrated aqueous solutions. Part 1. General features, kinetic form and mode of catalysis in sodium dodecyl sulfate hydrolysis
Bethell,Fessey,Namwindwa,Roberts
, p. 1489 - 1495 (2001)
As part of an investigation into the observed rapid hydrolysis of sodium primary alkyl sulfates in commercial concentrated aqueous mixtures (typically 70% by weight of surfactant) at 80 °C, the rate of hydrolysis of sodium dodecyl sulfate (SDS) in water has been followed acidimetrically over a wide range of initial SDS concentrations in aqueous buffers, in the presence of added sulfuric acid (0.20 mol kg-1) and also in unbuffered, initially neutral solution. First order rate coefficients derived from the initial rates of sulfuric acid-catalysed reactions showed unexpected, non-monotonic variations with increasing initial [SDS] at constant [H2SO4] and with [H2SO4] at 70% SDS. Reactions in initially neutral solutions were found to have an autocatalytic form arising from the existence of both an uncatalysed and an acid catalysed pathway from reactants to products. Both pathways are characterised by rate coefficients (derived by computer simulation of the initial phase of the hydrolysis) that vary with the initial [SDS]; those for the acid-catalysed pathway show similar but less dramatic variation than observed in reactions in the presence of sulfuric acid. Possible reasons for the difference in behaviour are discussed. The autocatalysis observed in initially neutral solutions is shown to arise from the production of hydrogen sulfate ions during the hydrolysis, but experiments in buffer solutions at both high and low SDS concentrations show the characteristics of specific hydrogen ion catalysis. Solvent kinetic deuterium isotope effects on both pathways are, however, small. Examination of the dodecanol produced by SDS hydrolysis at low and high initial concentrations in18O-enriched water showed no incorporation of the label, signifying exclusive S-O cleavage in the acid-catalysed pathway. It is argued that the results, taken in conjunction with literature data, are consistent with an SN2 displacement of sulfate ion by water in the uncatalysed hydrolysis pathway. While, for the hydrogen ion catalysed pathway, a previously suggested unimolecular cleavage of SO3 from dodecyl hydrogen sulfate, with concerted intramolecular proton transfer, appears more consistent with the observations, proton transfer concerted with direct transfer of SO3 to a preassociated water molecule is a plausible alternative.
An effective hydrolysis of crowded chiral esters
Vávra, Jan,Streinz, Ludvík,Vodi?ka, Petr,Budě?ínsky, Milo?,Koutek, Bohumír
, p. 1886 - 1888 (2002)
Trifluoromethanesulfonic acid-coated silica in the absence of solvents is an effective reagent for hydrolysis of sterically crowded chiral esters giving chiral acids in good chemical and optical yield. On the other hand, the method was unsuitable for the
A practical and efficient procedure for reduction of carboxylic acids and their derivatives: use of KBH4-MgCl2
Qiu, You-Chun,Zhang, Fu-Li,Zhang, Chun-Nian
, p. 7595 - 7598 (2007)
The use of KBH4-MgCl2 to reduce carboxylic acids and their derivatives to the corresponding alcohols or the respective reduced products is described. Methyl (S)-3,4-O-isopropylidene-3,4-dihydroxy butanoate 2 used as a reference substrate was reduced with KBH4 and MgCl2 in 1:1 mol ratio to (S)-1,2-O-isopropylidene-1,2,4-butanetriol 1.
Cleavage of protecting groups catalysed by π-acceptors
Tanemura, Kiyoshi,Nishida, Yoko,Suzuki, Tsuneo,Satsumabayashi, Koko,Horaguchi, Takaaki
, p. 40 - 41 (1999)
The cleavage of protecting groups is caused by the acidic adducts produced from the methanolysis of acceptors.
Selective conversion of coconut oil to fatty alcohols in methanol over a hydrothermally prepared Cu/SiO2 catalyst without extraneous hydrogen
Wu, Liubi,Li, Lulu,Li, Bolong,Zhao, Chen
, p. 6152 - 6155 (2017)
A novel one-pot approach selects a hydrothermally synthesized Cu/SiO2 catalyst (consisting of Cu2O·SiO2 and Cu0 surface species) to catalyze the reduction of a series of fatty esters, fatty acids, and coconut oil to fatty alcohols at 240 °C in methanol without extraneous hydrogen, attaining around 85% conversion and 100% selectivity.
Thermodynamics of the lipase-catalyzed esterification of 1-dodecanoic acid and 1-dodecanol in organic solvents
Tewari
, p. 750 - 755 (1998)
Lipase immobilized on controlled-pore glass beads was used to catalyze the esterification of 1-dodecanol and 1-dodecanoic acid in organic solvents. Equilibrium measurements were performed in hexane, heptane, cyclohexane, 2,2,4-trimethylpentane, and toluene at the temperature T = 298.15 K. The equilibrium constants correlate well with the (octanol+water) partition coefficients and the dielectric constants of the solvents. The saturation molalities and the (2,2,4-trimethylpentane+water) partition coefficients of 1-dodecanol, 1-dodecanoic acid, and dodecyl dodecanoate have been determined at T = 298.15 K. The equilibrium constant of the esterification reaction in water has also been calculated.
A glucose-activatable trimodal glucometer self-assembled from glucose oxidase and MnO2 nanosheets for diabetes monitoring
Chen, Jin-Long,Li, Li,Wang, Shuo,Sun, Xiao-Yan,Xiao, Lu,Ren, Jia-Shu,Di, Bin,Gu, Ning
, p. 5336 - 5344 (2017)
Daily monitoring of blood glucose is of great importance for the treatment of diabetes mellitus. Herein, we present an ensemble glucometer with a sandwich structure formed by the spontaneous entrapment of glucose oxidase (GOD) onto manganese dioxide nanosheets (MnO2 NSs) via the hydrophobic effect and hydrogen bond interaction. Within the hybrid glucometer, the ultrathin MnO2 NSs act as an enzyme nanosupport and target-activated signal transducer. Trimodal self-indication by fluorescence (FL) and UV-absorbance (UV) and magnetic resonance signal (MRS) activation with glucose-specificity provides multiple response signals to glucose. Taking account of its operational simplicity and convenience, even being observable by the naked eye, a detection limit as low as 0.1 ;M was obtained by using the ensemble glucometer in a colorimetric assay, whilst the precision for 11 replicated detections of 10 M glucose was 3.5% (relative standard deviation, RSD). Notably, the value of the Michaelis-Menton constant of GOD involved the presented glucometer is estimated to be 0.051 mM, showing an exceptional enhanced enzymatic activity of free GOD measured by far. The designed glucometer, with its high sensitivity and simplicity highlighted, was capable of routine blood glucose monitoring for type-I diabetes mellitus in rats. Furthermore, the fully integrated platform can be readily generalized in principle for a number of biomarkers for point of care diagnostics in the future.
NEW GLYCOSPHINGOLIPIDS FROM MARINE ORGANISM
Hirsch, S.,Kashman, Y.
, p. 3897 - 3906 (1989)
The structure of several ceramides and cerebrosides, from three marine sponges and a soft coral collected in the Red Sea, are reported.Specifically, the structure detemination of ptiloceramide, halicerebroside A and amphicerebrosides B-F was achieved folloving suitable degradations and NMR measurements.
