Benzene hexadecyl

The development of alkylbenzenesulfonates (ABSs) goes back to 1923, when the British chemist Adams discovered that it was possible to obtain water-soluble products by the sulfonation and neutralization of hexadecyl- and octadecyl-benzene. Such products have also soap-like characteristics [1]. In 1926 IG-Farbenindustrie (Hoechst) and Chemische Fabrik Pott, Pirna/Sachsen simultaneously discovered that long-chain ABSs have excellent surface-active properties. 

Ethoxylation of the base alcohol always improves the solubility of the sulfate. As an example, sodium hexadecyl ether (2 EO) sulfate gives a clear 10% solution in water at 40°C, which becomes a viscous gel at 30°C [59]. Alcohol ether sulfates are also more soluble in organic solvents than the corresponding alcohol sulfates. Sodium hexadecyl and octadecyl ether (2 EO) sulfates are soluble at 1% concentration in lubricating oil, at 2.5% in benzene and chloroform, and at 5% in tetrachloroethylene, whereas alcohol-ethoxylated sulfates with 10 mol of ethylene oxide are soluble at 5% in lubricating oil [59]. 

The product structures available in this process are primarily determined by components in the paraffinic distillates used. The heterogeneity of virgin distillates has been illustrated by API sponsored work on distillate components 21). The preferred predominance of relatively straight-chain alkyl groups may be effected by combinations of selection of paraffin distillate source, and use of acid or solvent refining to effect enrichment of paraffinic components. With the advent of the urea precipitation technique of isolating the n-paraffins 26), particularly those in the decyl to hexadecyl range, it is now possible to produce products which are limited principally to the isomeric secondary phenyl alkanes a dodecyl benzene mixture prepared by this process from a 95+% n-dodecane would consist essentially of the 2-, 3-, 4-, 5-, and 6-phenyl-substituted dodec-anes. 

Figure 8.6 shows some data measured for benzene solubilized in hexadecyl pyridinium chloride. The abscissa in the figure shows the extent of solubilization expressed as moles of solubilizate per mole of surfactant. The ordinate values show shifts in the resonance frequencies from water taken as an internal standard. Shifts of peaks arising from protons in the pyridinium ring, in benzene, and in methylene groups in the alkyl tail are shown versus the extent of solubilization. 

FIG. 8.6 Chemical shifts of protons in benzene, pyridium rings, and methylene groups versus the ratio of moles of solubilized benzene to moles of hexadecyl pyridinium chloride. (Redrawn, with permission, from J. C. Eriksson, Acta Chem. Scand., 17, 1478 (1963).)... 

A slurry of sodium bicarbonate comprising 39.8 g sodium bicarbonate and 254 ml water was placed in an autoclave. 96.3 g hexadecyl bromide and 635 ml acetone were then added. The autoclave was sealed and while stirring (590 r.p.m.) it was heated to a temperature of 218°C over a period of 1 hour 15 min. The temperature was maintained at 218-220°C for an additional hour. At the end of the reaction the autoclave was cooled to about 50°C, that is, to a temperature at which the alcohol remains molten. The autoclave was then rinsed with acetone and 1 N hydrochloric acid add to neutralize the sodium bicarbonate. The reaction mixture was diluted with an equivalent volume of water and then extracted with n-pentane. (Other suitable water insoluble solvents such as benzene, carbon tetrachloride, chloroform, petroleum ether and the like can be used for extraction). The pentane extract was washed with water and then dried over magnesium sulfate. The dried solution was filtered and evaporated. The residue was melted and a vacuum applied to remove the last traces of pentane. On distillation a yield of 94.8% of the theoretical yield white crystals of hexadecanol was recovered M.P. 49°C, B.P. 344°C, nD79 = 1.4283. 

A mixture consisting of water (190 g), ethyl alcohol (10 g), hexadecyl acrylate (70 g), hexyl acrylate (25 g), methyacrylic acid (5g), 3.2% sodium dodecyl sulfate, and ammonium dodecyl benzene sulfonate (5 g) was charged into a reactor and degassed for 30 minutes. Potassium persulfate (0.4 g) was then added, and the polymerization was conducted for 4 hours at 70°C under nitrogen. After the polymer was isolated, a sharp DSC endotherm was observed at 22.5°C. 

Many surfactants have been used to formulate microemulsions (1). They were of three types anionic surfactants such as petroleum sulfonates, sodium octyl benzene sulfonate, sodium dodecyl sulfate, alkaline soaps cationic surfactants such as dodecyl ammonium and hexadecyl eimmonium chlorides or bromides and nonionic surfactants such as polyoxyethylene glycols. Furthermore, many exhibit liquid-crystalline properties (2) and in some cases the structure of the mesophases has been established (3). Nevertheless, nearly nothing is known about their compatibility with blood and tissues, and, from our own experience, some exhibit a high lytic power for red cells... 

Figure 7. Comparison between the free energies of adsorption of benzene and cyclohexane on precipitated silice (PI), methylated (PCj), and hexadecylated (PCjg) silica samples.

TDP tetradecyl-, HDP hexadecyl-, ODP octadecylpyridinium cation, DMDH dimethyldi-hexadecylammonium cation dL i (i=l,2)-basal spacing in benzene (i=l) and in methanol (i=2)... 

Dipole moments in benzene of di-n-hexadecyl mono-, di-, tri-, and tetrasulfide have been reported by Woodrow, Carmack, and Miller (230), of dimethyl and diethyl di- and trisulfide and di-n-propyl disulfide by Smyth and co-workers (160, 225), of the three isomeric dibutyl disulfides by Rogers and Campbell (193), and of diphenyl disulfide and p-substituted diphenyl disulfides by Gur yanova (137). 

For bile salt mixtures, total concentration of bile salts is given. CTAB, cetyl trimethylam-monium bromide HDPC, hexadecyl pyridinium chloride lauryl taurate, sodium lauryl taurate TC-TDC, sodium taurocholate-sodium taurodeoxycholate ABS, sodium p-(H-octyl) benzene sulfonate SIC, a mixture of sodium taurocholate, sodium taurodeoxycholate, sodium taurochenodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium glycochenodeoxycholate composed to resemble human small intestinal content during fat digestion and absorption (19). 

Fig ure 5. Viscosity ratios of solutions containing (a) non-ionic dextran polymer and anionic sodium dodecyl benzene sulfonate micelles and (b) dextran polymer with cationic ethyl hexadecyl dimethyl ammonium bromide micelles. The polymer concentration is 1000 ppm in both cases. 

Pharmaceutical preparations containing riboflavin have been analyzed by TLC using concentrated ethanolic extracts on silica gel plates developed in butanol-benzene-acetic acid-water (8 7 S 3) or butanol-acetic acid-water (9 4 5) (7). Foods, tissue samples and urine each require particular methods of sample preparation and these, together with a number of solvent systems have been reviewed (8). A darkroom is required for sample preparation and chromatography of flavins to prevent photolytic degradation. The fluorescent property of flavins provides a convenient means of detection and spots have been located under radiation at 254 and 366nm (4). HPTLC followed by fiberoptic fluorimetry has been used to quantitate riboflavin in vitamin mixtures and can detect 48-320 ng (6). Recently, a method has been described using mixed-layer plates of GDX-102 and silica gel G (1 1) precoated with hexadecyl-trimethylammonium bromide developed in 60-70% ethanol (9). 

Use of surfactants is an effective way for dispersing CNTs [39]. Reports show that the outer most nanotubes in a bundle are treated more than the innermost tubes and the nanotube remains predominantly btmdled even after surfactant treatment. But mechanical methods like ultrasonication can debundle the nanotubes by steric or electrostatic repulsions [40]. On sonication the high local shear will unravel the outer carbon nanotubes in a bundle and expose other sites for additional surfactant adsorption, thus the surfactant molecules gradually exfoliate the bundle in an unzippering mechanism [41]. Some of the common surfactants used for the dispersion of carbon nanotubes are sodium dodecyl benzene sulfonate (SDBS) [42], dodecyl trimethyl ammonium bromide (DTAB) [43], hexadecyl trimethyl ammonium bromide (CTAB) [44], octylphenol ethoxylate (Triton X-100) [45] and sodium dodecyl sulfate (SDS) [46]. Covalent modification is another way to solubilize the CNTs in different solvents and to improve the interaction with the matrix in composites [47]. 

In order to clarify the relation between the phase behavior, interactions between droplets, and the Ginzburg number, we have undertaken further SANS studies of critical phenomenon in a different three-component microemulsion system called WBB, consisting of water, benzene, and BHDC (benzyldimethyl-n-hexadecyl ammonium chloride). This system also has a water-in-oil-type droplet structure at room temperature and decomposes with decreasing temperature. Above the (UCST) phase separation point, critical phenomena have been investigated by Beysens and coworkers [9,10], who obtained the critical indexes, 7 = 1.18 and v = 0.60, and concluded that their data could be interpreted within the 3D-Ising universality. However, Fisher s renormalized critical exponents were not obtained. 

Hexadecyl bromide see 1-Bromohexadecane Hexadecyl chloride see 1-Chlorohexadecane Hexadecyl iodide see 1-Iodohexadecane Hexadeuteroacetone see (2H6)Propan-2-one Hexadeuterobenzene see (2H6)Benzene Hexadeuteropropan-2-one see (2H6)Propan-2-one Hexa-1,5-diene Hexafluorobenzene syn. Perlluorobenzene Hexafluoroethane... 

Slightly different values can be attained with more or less branched alkyl chains [120-124]. Figure 18 [125] illustrates the variation of optimum formulation, detected by the position of the minimum interfacial tension that is equivalent to the center of the three-phase behavior region for a series of isomers of the sodium n-hexadecyl benzene-para-sulfonate X< )Ci6S03Na, where X indicates the position of attachment of the benzene ring on the hexadecane chain. The correlation for optimum formulation can be written at constant salinity, constant alcohol content, and constant temperatures as... 

Figure 18 Inteifacial tension curves along a formulation scan for different isomers of hexadecyl benzene sulfonate sodium salt. (From Ref. 118.)...

We have studied three model systems of five-component mixtures oil -water - surfactant - alcohol - salt. Three different ionic surfactants have been used dodecyltrimethyl ammonium bromide (DTAB), sodium dodecyl sulfate (SDS) and sodium hexadecyl benzene sulfonate (SHBS). The alcohol used was butanol its addition was necessary because the above surfactants alone could form microemulsions. The salt screened the electrostatic interactions between surfactant polar heads it reduced Cq In this way, a continuous structural evolution o/w - bicontinuous - w/o could be obtained by addition of salt. At each salinity, the size of the structural elements was the largest (maximum swelling Rq for droplets, bicontinuous structures) because the microemulsions coexisted with excess oil and/or water. 

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