Sodium cetyl sulphate

Sodium cetyl sulphate [1120-01-0] M 344.5. Crystd from MeOH. 

Further observations on films at oil-water interfaces. Alexander and Teorell3 find that proteins spread more easily and completely on these interfaces than at air-water surfaces and that lecithin (a liquid-expanded film at the air-water surface) is a gaseous film. Sodium cetyl sulphate is also gaseous but it would form a gaseous adsorbed film at the air-wrater surface also. 

Figure 9.19 The relationship between (a) Tween 80 concentration, (b) benzethonium chloride concentration, (c) the concentration of several poloxamers as marked and adhesion from a 15% suspension of chloramphenicol in a container with 6.5 cm glass wall, (d) the effect of anionic surface-active agents SLS (sodium lauryl sulphate) and SCS (sodium cetyl sulphate) on adhesion (Ad) and the amount of trapped and retained suspension (Re) x 0.25. Adhesion determined at 40° C after 48 h after a single wetting of the surface. From Uno and Tanaka [47] with permission.

An example of the first type is the emulsion stabiliser as exemplified by sodium oleyl sulphate, cetyl pyridinium chloride and poly(ethylene oxide) derivatives. For a number of applications it is desirable that the latex be thickened before use, in which case thickening agents such as water-soluble cellulose ethers or certain alginates or methacrylates may be employed. Antifoams such as silicone oils are occasionally required. 

Surfactants such as cetyl trimethyl ammonium bromide (CTAB), Triton X-100 (TX-lOO) and sodium dodecyl sulphate (SDS) are the most commonly used. CTAB forms large micelles [24-26] with aggregation number 61, cmc 9.2 X 10 M, and a positive micellar Stem layer TX-lOO has aggregation number 139 with neutral OH groups on the Stern layer, and SDS forms negative micelles with cmc 8.3 x 10 M and aggregation number 131. The... 

SDS sodium dodecyl sulphate CTAB cetyl trimethyl ammonium bromide TX-lOO Triton X-100 Mb myoglobin... 

Cetyl alcohol, mono- and di-glycerides, oleyl alcohol, sodium cetostearyl sulphate, stearyl alcohol... 

Competitive displacement of spread (3-lactoglobulin from an air-water interface by (a) nonionic and (b) ionic surfactants. The collapse of the protein network is indicated by showing the change in area occupied by the protein at the interface as a function of surface pressure, (a) Data for A-Tween 20 (polyoxyethylene sorbitan monolaurate) and B-Tween 60 (polyoxyethylene sorbitan momostearate). (b) Data for A-cetyl-trimethyl-ammonium bromide (CTAB), B-lyso-phosphatidylcholinelauroyl (LPC-L), and -sodium dodecyl sulphate (SDS). 

Surfactants Ionic, anionic (e.g., sodium dodecyl sulphate, Cj2H250S03 Na ), cationic (e.g., cetyl trimethyl ammonium chloride, Ci,H33-N+(CH3)3C1-), zwitterionic [e.g., 3-dimethyldodecylamine propane sulphonate (betaine CJ2H25-N" (CH3)2-CH2-CH2-CH2-S03)], nonionic, alcohol ethoxylates C H2 +i-0-(CH2-CH2-0) -H, alkyl phenol ethoxylates C H2 +i-CgH4-0-(CH2-CH2-0) -H, amine oxides (e.g., decyl dimethyl amine oxide, C10H21-N ( 113)2 0), and amine ethoxylates. 

Fig. 1.4. Main types of surfactants a- nonionic on the basis of long-chain alcohol and ethylene oxide, b -anionic represented by sodium dodecyl sulphate, cationic represented by cetyl trimethyl ammonium bromide, d - betain surfactant represented by fatty acid amidopropyl dimethyl ammonio acetate, e - siloxane surfactant represented by N,N,N-trimethyl-3-(1.1.1.3.5.5.5-heptamethyl trisiloxane-3-yl) propylammonium bromide...

Another example is the spontaneous emulsification of xylene/cetyl alcohol mixtures in an aqueous solution of sodium dodecyl sulphate. Here the extreme reduction of the interfacial... 

For the evaluation of the foamability of a surfactant the bulk concentration is used at which the relative rate of foam collapse is equal to 50% of its formation (cw °). The cw ° values determined from foam formation isotherms of a number of products are given in Table 6.1. As it is seen, typical representatives of anionics (sodium dodecyl sulphate), cationics (cetyl trimethyl ammonium bromide) and nonionics (ethoxylated alkylphenols) give bubble foams at very low concentrations, and the foam stability of ionic surfactants does not differ much from that of nonionics. For anionics, the highest concentrations are required for soaps of higher carboxylic acids. 

Oxidation of terminal olefins to methyl ketones by aqueous palladium chloride and oxygen is very slow, but addition of micellar sodium lauryl sulphate increases the rate of formation of 2-octanone from 1-octene twentyfold at 50 °C. There is weaker catalysis by the non-ionic surfactant Brij-35 and inhibition by cationic surfactants. " Oxidation of diosphenol (35) in basic aqueous tetradecyltrimethylammonium chloride is faster and more effective than in water, giving a higher yield of (36). Two attempts at effecting the enantioselective reduction of aromatic ketones, one in micelles of R-dodecyl-dimethyl-a-phenylethylammonium bromide and the other in sodium cho-late micelles, both give optical yields of less than 2%. Rather more success was obtained in the catalysed oxidation of L-Dopa, 3,4-dihydroxyphenyI-alanine. In the presence of the Cu complex of N-lauroyl-L-histidine in cetyl-trimethylammonium bromide micelles reaction was 1.42 (pH 6.90, 30 °C) to... 

Much of the early work on amphiphiles was undertaken on soaps and lipids based on fatty acids, and the corresponding non-systematic chemical names of these parent compounds and their derivatives are still commonly encountered. For convenience, Table 4.1 lists the systematic and trivial names of fatty acids, along with their structures. The names of derivatives are based on these for example sodium dodecyl sulphate is (still ) sometimes referred to as sodium lauryl sulphate. Other non-systematic names also exist to cause further confusion For example, hexadecyl (Cie chain) compounds are often termed cetyl derivatives. The use of the term fatty here and elsewhere is used to indicate an alkyl chain with 12 or more carbon atoms, i.e. a hydrocarbon that forms fats. 

Sodium dodecyl sulphate. + Cetyl trimethylammonium chloride. t Sodium myristyl sulphate. Non-ionic surfactant with average composition of Ci2H2 5(0CH2CH2)230H. 

Lissapol C (mainly sodium salt of cetyl oleyl alcohol sulphate) [2425-51-6],... 

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