Dodecylpyridinium bromide

Surfactants greatly improve the performance of trans-cinnamaldehyde as a corrosion inhibitor for steel in HCl [741,1590,1591]. They act by enhancing the adsorption at the surface. Increased solubility or dispersibility of the inhibitor is an incidental effect. N-dodecylpyridinium bromide is effective in this aspect far below its critical micelle concentration, probably as a result of electrostatic adsorption of the monomeric form of N-dodecylpyridinium bromide. This leads to the formation of a hydrophobic monolayer, which attracts the inhibitor. On the other hand, an ethoxylated nonylphenol, a nonionic surfactant, acts by incorporating the inhibitor into micelles, which themselves adsorb on the steel surface and facilitate the adsorption of trans-cinnamaldehyde. 

Mixtures of aldehydes with surfactants are active in preventing corrosion, in particular in the presence of mineral or organic acids [646]. The aldehyde may be trans-cinnamaldehyde. The surfactant may be N-dodecylpyridinium bromide or the reaction product of trimethyl-1-heptanol with ethylene oxide [645]. Such aldehyde and surfactant mixtures provide greater and more reliable corrosion inhibition than the respective compositions containing aldehydes alone. 

FIGURE 9-5 Stability [log(dt/dD)t 0 of a negatively charged colloid dispersion of Agl as a function of log C), the concentration of added cationic surfactant, dodecylpyridinium bromide. Reprinted with permission from R. H. Ottewill and M. C. Rastogi, Trans. Faraday Soc. 56, 866 (1960). 

The transfer from CTAB and CPB (cmc 0.00085 M) to dodecylpyridinium bromide (DDPB cmc 0.018 M) results in a marked increase in the Fm value for substrate 1, followed by changes from the extremum type of kinetic dependences to S-shaped curves." While in the case of the more hydrophobic substrate 3 in the DDPB micellar solution, the maximum type kinetic curve and the negative effect of the micellar microenvironment (Fm < 1) are preserved (Table 15.1). 

The preparation, X-ray crystal structure and ab initio calculation of the charge distribution of lV-(2-acetamido-3,4,6-tri-0-acetyl-2-deoxy-p-D-glucopyranosyl)-pyridinium chloride have been reported. The anomeric iV-(2,3,4,6-tetra-0-acetyl-D-glucopyranosyl)-4-dodecylpyridinium bromides were prepared as novel cationic surfactants. The panel of five substituted-pyridinium salts 15 were synthesized from the peracetylated glycosyl chloride of p-D-lV-acetyl-neuraminic acid and used to probe the mechanisms of enzymatic and non-enzymatic hydrolysis of neuraminides. " Detailed analysis of the solvolysis of Af-(2-deoxy-a- and p-D-glucopyranosyl)-4-bromoisoquinolinium tetra-fluoroborate in aqueous alcoholic solvents indicated Sjv2-like transition states. 

Adderson, J.E. and Taylor, H., The effect of temperature on the critical micelle concentration of dodecylpyridinium bromide, J. Colloid Sci., 19, 495, 1964. 

Materials. Dodecylpyridinium bromide was synthesized by treating fractionally distilled 1-dodecane bromide in dry pyridine for 12 hr. The crude surfactant was recrystallized twice from acetone followed by decolorization with active charcoal in methanol solution. The resulting white crystal is a monohydrate of DoPBr. The critical micelle concentration (CMC) in aqueous solution as determined by electric conductivity method is 17.4 mM at 30°C in agreement with literature. Calf thymus DNA (sodium salt, SIGMA) was used as received. Residual (nucleotide) concentration was determined by a colloid titration using poly(potassium vinyl sulfate) as a titrant and Toluidine Blue as an indicator. 4 Propionyl- a-cyclodextrin (prop- a-CD) used as a neutral carrier was prepared by esterification of a-cyclodextrin (Tokyo Kasei Co.) with propionic anhydride in dry pyridine at room temperature for 12 hr. The reaction mixture was poured onto ice to obtain a gummy product which was then dissolved in acetone and precipitated in cold water. The dissolution-precipitation was repeated three times. The hydrophobicized oc-CD is a white powder. 

Fig. 3 Comparision between lorentzian-envelop generated Raman spectra, using a fixed line-width of 8 1/cm from heptylpyridinium and the Raman spectrum from a polycrystalline sample of dodecylpyridinium-bromide. A shows the C-C stretching spectral range and B corresponds to the C-H stretching range. The excitation source was the 488 nm line from an Ar ion laser, the scanning rate was 2 l/cm/2s...

Abstract Surfactant mixtures are commonly used in many industrial applications. At the same time, the methods for surfactant analysis are rather laborious and often do not permit the determination of the individual surfactant content in mixed solutions. In the present work capillary zone electrophoresis (CZE) instrumentation was applied for the quantitative analysis of a cationic surfactant (dodecylpyridinium bromide) and a nonionic surfactant (Triton X-100) in aqueous solutions. The linear dependence of the analytical signal (electrophoregram peak area) versus the surfactant concentration was established for both surfactants over a wide concentration range. The analytical signal of an individual surfactant was... 

Keywords Capillary electrophoresis Surfactant analysis Dodecylpyridinium bromide Triton X-100 Critical micelle concentration... 

Dodecylpyridinium bromide (DDPB) and Triton X-100 (TX) were used as cationic and nonionic surfactants, correspondingly. DDPB (Mr = 328.3), pure grade (Chemapol, Czech Republic), was purified by recrystaUization from ethyl acetate according to the method in Ref. [6]. The degree of purity was determined by the absence of the minimum on the surface tension isotherm of the solutions. TX (the average number of ethylene oxide groups is 9.5, Mr = 646), pure for analysis (Ferak, Germany), was used as received. 

Fig. 1 UY spectra of a dodecylpyridinium bromide and b Triton X-100 in aqueous solution...

Table 1 Dependence of the observed electrophoretic mobilities of dodecylpyridinium bromide and Triton X-100 on the carrier electrolyte solution pH and ionic strength...

Figure 15.9. TRFQ results obtained from a 0.044 molal dode-cyltrimethylammonium bromide solution. The probe used is pyrene and the quencher is dodecylpyridinium bromide at 25°C. The fit of equation (15.19) to the data yields the following for the unquenched curve, /q = 1.01 x 10 (normalized to the same value as for the quenched curve), and ro = 117 ns, while for the quenched curve, we obtain Iq = 1.01 x 10, T() = 116 ns, / = 0.70, and kq = 0.029 ns (By courtesy of Per Hansson, Uppsala University, Sweden)...

Figure 3.10 The CMC of dodecylpyridinium bromide as a function of pressure at 303 K (O) optical method ( ) electroconductivity method. From Nishikido et al. [158] with permission.

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