- Kinetics of hydrolysis of procaine in aqueous and micellar media
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The kinetics of alkaline hydrolysis of procaine under the pseudo-first-order condition ([OH-] a [procaine]) has been carried out. N,N-Diethylaminoethanol and p-aminobenzoate anion were obtained as the hydrolysis product. The rate of hydrolysis was found to be linearly dependent upon [NaOH]. The addition of cationic cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DDTAB) and tetradecyltrimethylammonium bromide, and anionic sodium dodecyl sulfate (SDS) micelles inhibited the rate of hydrolysis. The maximum inhibitive effect on the reaction rate was observed for SDS micelles, whereas among the cationic surfactants, CTAB inhibited most. The variation in the rate of hydrolysis of procaine in the micellar media is attributed to the orientation of a reactive molecule to the surfactant and the binding constant of procaine with micelles. The rate of hydrolysis of procaine is negligible in DDTAB micelles. The observed results in the presence of cationic micelles were treated on the basis of the pseudophase ion exchange model. The results obtained in the presence of anionic micelles were treated by the pseudophase model, and the various kinetic parameters were determined.
- Al-Blewi, Fawzia Faleh,Al-Lohedan, Hamad A.,Rafiquee,Issa, Zuheir A.
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- Odd-even effect and unusual behavior of dodecyl-substituted analogue observed in the crystal structure of alkyltrimethylammonium-[Ni(dmit) 2]- salts
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A series of [Ni(dmit)2]- (dmit: 1,3-dithiole-2- thione-4,5-dithiolato) salts of alkyltrimethylammonium (Cn: n represents the alkyl chain length; n = 3 and 518) have been prepared and analyzed by X-ray structural analysis. All complex salts have been found to be composed of alternate sheets of [Ni(dmit)2]- anions and sheets of cations with a pronounced interdigitation of the alkyl chains. However, molecular arrangement differed between (C3)[Ni(dmit)2] and other (Cn)[Ni(dmit)2] (n = 518). Adjacent cations were aligned along the long axis of [Ni(dmit)2]- anion in C3 complex salt, while in others (C5-C18 complex salts), they were aligned toward the short axis. Such a difference in arrangement arose from correlativity between the lengths of the long axis of cation and anion, namely CLCA. Furthermore, relative orientation between the alkyl chain of cation and [Ni(dmit)2]- anion differed between the odd- and even-numbered cations for C10-C18. Whereas the plane of alkyl chain for odd-numbered cation was normal to the plane of [Ni(dmit)2]- anion, that of even-numbered cation was parallel. It was also found that C12 analog behaved like odd-numbered cations. However, in C12 salt, the end methyl group of the dodecyl group adopted unusual end-gauche conformation.
- Dai, Kotaro,Nomoto, Kuniharu,Ueno, Shinji,Tomono, Kazuaki,Miyamura, Kazuo
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experimental part
p. 312 - 319
(2011/05/13)
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- A convenient laboratory synthesis of deuterium-labelled trimethyl tetradecyl ammonium sulphate
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A convenient and practical laboratory synthesis of deuterium-labelled trimethyl tetradecyl ammonium sulphate is reported. Copyright
- Chavda, Sameer,Coumbarides, Gregory S.,Dingjan, Marco,Eames, Jason,Zarbakhsh, Ali
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p. 147 - 151
(2007/10/03)
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- Synthesis of ω-hydroxy quaternary ammonium bolaform surfactants
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Several members of a novel class of ω-substituted asymmetric bolaform surfactants have been synthesized in order to investigate their surfactant and biological properties. The ω-hydroxy trialkylammonium and pyridinium surfactants have significant antimicrobial and antifungal activity relative to their conventional analogues. For conventional quaternary ammonium alkyl surfactants, increasing the hydrocarbon chain length causes a decrease in the surfactant monomer solubility and a corresponding decrease in the biological activity. No such trend is observed for the ω-hydroxy quaternary ammonium bromide series.
- Davey, Tim W.,Hayman, Alan R.
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p. 581 - 586
(2007/10/03)
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- Interaction of Methyl Orange with Submicellar Cationic Surfactants
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The interaction of aqueous Methyl Orange (MO), an azo dye, with alkyltrimethylammonium and N-hexadecylpyridinium halide surfactants in submicellar concentration ranges has been investigated.The interaction gives rise to a new absorption band of MO with a maximum at ca. 370 nm, and the appearance of the new band has been attributed to change in the chromophore microenvironment in water structure enforced closely packed ion pairs of the dye with submicellar cationic surfactant.The strength of the interaction depends on the alkyl chain length of the surfactant, the surfactant head group and the counter ions.
- Dutta, Robin K.,Bhat, Subray N.
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p. 2457 - 2460
(2007/10/02)
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- Effects of Single-Stranded n-Alkyl Amphiphiles on the Conformational and Dynamic Behavior of Lecithin Sonicated Bilayers and Micelles Studied by 13C NMR. A Measure of Lipid Resistance against Disruption of the Bilayer Orientation
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The triplet fine structures in the 13C NMR spectra of carbons in the ?-position to nitrogen in several n-alkyltrimethylammonium bromides (TAB's), DMPC, and DPPC have been studied in different aggregational states under conditions of enhanced proton noise decoupling.Under the same conditions, the signals of the hydrophobic tails of the lecithins could also be studied better than hitherto, mainly by virtue of relatively narrow signals.It is shown that relatively small changes in packing and lateral motions can be detected.Intercalation of several n-alkyltrimethylammonium bromides in lecithin vesicles causes no decrease of the lipid -N+(CH3)3 mobility around the CH2-CH2 head-group linkage nor a decrease in acyl chain mobility.Moreover, no changes in acyl chain kinking are detected.On the other hand, the incorporated TAB molecules are forced by the lecithin molecules toward severely restricted head-group and tail mobilities.For those combinations of PC and TAB's where the TAB 13C NMR signals are detectable, a change in the conformational equilibrium toward more extension is found.A packing model for the incorporation of TAB's in PC vesicles is presented which probably has a rather general validity.The behavior of mixed micelles of PC's and TAB's, originating from enhancing the latter's concentration, is also described.In these systems, mobilities and chain kinking are increased with respect to the vesicular state.
- Haan, Jan W. de,Weerd, Roel J. E. M. de,Ven, Leo J. M. van de,Buck, Henk M.
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p. 5093 - 5099
(2007/10/02)
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