W-Dodecyl bromide

A mixture of 125 g. (0.5 mole) of w-dodecyl bromide (Note 1), 38 g. (0.5 mole) of thiourea, and 250 cc. of 95 per cent ethyl alcohol is refluxed on a steam cone for three hours (Notes 2, 3, and 4). A solution of 30 g. (0.75 mole) of sodium hydroxide in 300 cc. of water is added, and the mixture is refluxed for two hours. During this period the mercaptan separates as a pink to red oil. The layers are separated, and the aqueous layer is acidified with dilute sulfuric acid (7 cc. of concentrated acid to 50 cc. of water) and then extracted with one 75-cc. portion of benzene (Note 5). The extract is added to the crude mercaptan layer, and the whole is washed twice with 200-cc. portions of water and... 

The above method for preparing w-dodecyl bromide is an adaptation of that of Ruzicka1 and has been published recently.2 It is thought to present some advantages in ease of manipulation and quality of product over the older method involving the action of aqueous hydrobromic acid on the alcohol in the presence of sulfuric acid.3... 

Polymeric quaternary ammonium surfactants, made from w-dodecyl bromide and poly(2-vinylpyridine), are better solubilizers for aliphatic and aromatic hydrocarbons than AMaurylpyridinium chloride, with the extent of solubilization increasing as the alkyl content of the polymeric quaternary is increased (Strauss, 1951 Inoue, 1964). 

Cationic Cetyl trimethyl ammonium bromide [CTAB]/w-alkanol w-Benzyl-w-dodecyl-w-bis(2-hydroxyethyl) ammonium chloride [BDB AC]/1 -hexanol [13-15] [16]... 

W-DODECYL MERCAPTAN, 21, 36 S-Dodecylthiuronium bromide, 21, 37 -Dodecyl /,-toluenesulponate, 20,... 

Laurylimidazoline sulfobetaine. See Sodium lauroamphohydroxypropylsulfonate Lauryl isoquinolinium bromide CAS 93-23-2 EINECS/ELINCS 202-230-9 Synonyms Dodecylisoquinolinium bromide 2-Dodecylisoquinolinium bromide Isoquinolinium, 2-dodecyl-, bromide Classihcation Quaternary ammonium compd. Empirical C21H32N Br Properties M.w. 378.40 Toxicology LD50 (oral, rat) 230 mg/kg primary irritant may cause Gl changes TSCA listed Uses Antimicrobial, antistat, surfactant in cosmetics... 

The Diels-Alder reaction of methyl methacrylate with cyclopentadiene was studied [72] with solutions from three different regions of the pseudophase diagram for toluene, water and 2-propanol, in the absence and in the presence of surfactant [sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (HTAB)]. The composition of the three solutions (Table 6.11) corresponds to a W/O-fiE (A), a solution of small aggregates (B) and a normal ternary solution (C). The diastereoselectivity was practically constant in the absence and in the presence of surfactant a slight increase of endo adduct was observed in the C medium in the presence of surfactant. This suggests that the reaction probably occurs in the interphase and that the transition state has a similar environment in all three media. 

Formation of BaS04 fibers and other morphologies from supersaturated reverse micelles and microemulsions has been studied in detail by Hopwood and Mann [216]. Three surfactant systems were used Ba(AOT>2 and NaAOT in isooctane, poly(oxyethylene-4-dodecyl ether), i.e. C,2E04 in decane and didodecyldimethylammonium bromide, i.e. DDAB in dodecane. In case of AOT/ isooctane system, two procedures were adopted. In one of them, a Ba(AOT)2 solution in isooctane was added to a reverse micelle solution comprised of NaAOT/isooctane/ aqueous solution of Na2S04. In another, a microemulsion NaAOT/isooctane/aqueous solution of BaCl2 was rapidly mixed with another microemulsion of the same type with an aqueous solution of Na2S04(same surfactant concentration and w value). 

FIGURE 2.3 Freeze-fracture transmission electron micrographs of a biocontinuous microemulsion consisting of (A) 37.2% n-octane, 55.8% water, and smfactant pentathylene glycol dodecyl ether (From Vinson, P.K., Sheehan, J.G., Miller, W.G., Scriven, L.E., and Davis, H.T., J. Phys. Chem., 95, 2546, 1991. With permission.) (B) 43.05% n-dodecane, 43.05% water and 13.9% didodecyl-methylammonium bromide. (From Jahn, W. and Strey, R., J. Phys. Chem., 92, 2294, 1988. With permission.) In both cases 1 cm = 2000 A. 

Figure 7.43 Association curves of chloramphenicol with the albumin-lecithin complex (3 % w/v) in phosphate buffer (pH = 6.8) at 25° C, in the presence of increasing amounts of sodium dodecyl sulphate (NaDS). Plots a (O)and b ( ) refer to different initial concentrations of the antibiotic, i.e.—3.1 x 10 and 6.2 x 10" m, respectively. Inset. Association curves of chloramphenicol with the albumin-lecithin complex (3% w/v) in phosphate buffer (pH 6.8) at 25° C, in the presence of increasing amounts of surfactants. Plots a and b refer to cetyltrimethylammonium bromide ( ) (CTAB) and polysorbate 80 (O) (concn in mgrnl" x 10 ), respectively. In all cases, the initial concentration of the antibiotic was 3.1 x 10 m. From Alhaique et al. [195] with permission.

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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