Alkyl alcohols hydrocarbon surfactants

However, no systematic investigation of adsorption and micellization of the alcohol-fluorocarbon (FC) surfactant mixture has been made. Other studies have examined the "mutual phobicity" between the hydrocarbon (HC) and FC chain in the mixed system of FC and HC surfactants (5-10) It is expected that "mutual phobicity" should be observed in the alkyl alcohol-FC surfactant system.too. In this... 

The Effect of Alkyl Alcohols on the Surface Adsorption and Micellization of Fluorocarbon and Hydrocarbon Surfactants... 

A wide variety of long-chain fatty acids increase transdermal delivery the most popular is oleic acid. It is relevant that many penetration enhancers contain saturated or unsaturated hydrocarbon chains and some structure-activity relationships have been drawn from the extensive studies of Aungst et al. [22,23] who employed a range of fatty acids and alcohols, sulfoxides, surfactants, and amides as enhancers for naloxone. From these experiments, it appears that saturated alkyl chain lengths of around Cio to C12 attached to a polar head... 

Secondary alcohols (C q—for surfactant iatermediates are produced by hydrolysis of secondary alkyl borate or boroxiae esters formed when paraffin hydrocarbons are air-oxidized ia the presence of boric acid [10043-35-3] (19,20). Union Carbide Corporation operated a plant ia the United States from 1964 until 1977. A plant built by Nippon Shokubai (Japan Catalytic Chemical) ia 1972 ia Kawasaki, Japan was expanded to 30,000 t/yr capacity ia 1980 (20). The process has been operated iadustriaHy ia the USSR siace 1959 (21). Also, predominantiy primary alcohols are produced ia large volumes ia the USSR by reduction of fatty acids, or their methyl esters, from permanganate-catalyzed air oxidation of paraffin hydrocarbons (22). The paraffin oxidation is carried out ia the temperature range 150—180°C at a paraffin conversion generally below 20% to a mixture of trialkyl borate, (RO)2B, and trialkyl boroxiae, (ROBO). Unconverted paraffin is separated from the product mixture by flash distillation. After hydrolysis of residual borate esters, the boric acid is recovered for recycle and the alcohols are purified by washing and distillation (19,20). 

Alkyl polyglycosides have long been known but only now, following several years research, has it been possible to develop reaction conditions that allow manufacture on a commercial scale. The structure on which these compounds are based corresponds exactly to the surfactant model described above. The hydro-phobic (or lipophilic) hydrocarbon chain is formed by a fatty alcohol (dodecanol/ tetradecanol) obtained from palm kernel oil or coconut oil. The hydrophilic part of the molecule is based on glucose (dextrose) obtained from starch (Fig. 4.14). 

On the other hand, with microemulsions based on an anionic surfactant and a long chain alcohol, was fairly low for certain concentrations, indicating that distinct water droplets in a hydrophobic medium may form. The system investigated by Lindman et al (29-34) was based on octanoic acid - decanol -octane-water. This means that the anionic "surfactant" used contains only seven carbon atoms in the alkyl chain which is fairly short. With longer chain surfactants, one would expect well defined "water cores" provided the alcohol is also long-chain. Such well defined "water cores" have also been confirmed by Lindman et a (34) for the Aerosol OT - hydrocarbon system. 

A surfactant molecule is an amphiphile, which means it has a hydrophilic (water-soluble) moiety and a hydrophobic (water-insoluble) moiety separable by a mathematical surface. The hydrophobic tails of the most common surfactants are hydrocarbons. Fluorocarbon and perfluorocarbon tails are, however, not unusual. Because of the hydrophobic tail, a surfactant resists forming a molecular solution in water. The molecules will tend to migrate to any water-vapor interface available or, at sufficiently high concentration, the surfactant molecules will spontaneously aggregate into association colloids, i.e., into micelles or liquid crystals. Because of the hydrophilic head, a surfactant (with a hydrocarbon tail) will behave similarly when placed in oil or when put in solution with oil and water mixtures. Some common surfactants are sodium or potassium salts of long-chained fatty acids (soaps), sodium ethyl sulfates and sulfonates (detergents), alkyl polyethoxy alcohols, alkyl ammonium halides, and lecithins or phospholipids. 

A microemulsion is water/hydrocarbon dispersion stabilized by an ionic surfactant such as a soap, alkyl sulphate or sul-phonate and most often also contains a cosurfactant in the form of a medium chain length alcohol (pentanol). Of these four components water, surfactant and cosurfactant are called the structure forming elements since they form colloidal association structures similar to the microemulsions with no hydrocarbon present. The formulation and preparation of microemulsions is greatly enhanced by a knowledge of these composition dependent structures, hence an introductory description of them will be given. 

Fig. 4. Variation of In(cmc) versus hydrocarbon chain length at 25 °C for various surfactants in aqueous media (A) n-alkyl hexa-oxyethylene glycol monoethers [19]. (B) n-alkylsulfinyl alcohols [20], (C) n-alkyl glycosides [19], (D) n-alkyltrimethylammoniurn bromides in 0.5 M NaBr [17,21], (E) n-alkyl betaines [221, (F) alkyl sulfates in pure water [2]. (Redrawn with changes)...

There are various synthetic routes to introduce hydrocarbon long chains into amino acid-based surfactants. For example, a long-chain fatty acyl group is introduced on the amino part of amino acids by using an acid chloride. To obtain amino acid esters or amides, the carbonyl parts of amino acids are reacted with fatty alcohol or amines, respectively. For example, C-alkylation of an amino acid is obtained by the reaction of a-bromo fatty acid with ammonia or by a transmission reaction of the amino part of the amino ester with a stable Schiff base followed by deprotonation with a strong base. This is followed by alkylation with an alkyl halide. N-Alkylation of an amino acid is generally obtained by the reaction of fatty amines with monochloroacetic acid, methyl acrylate, or maleic acid or by the addition of 1,2-epoxy alkane to amino acids. 

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