Cetyl pyridium chloride

C16-alkylpyridinium chloride Cepacol Cepacol chloride Cetamiun cetyl pyridium chloride Dobendan hexadecylpyr-idinium chloride 1-hexadecylpyridinium chloride Medilave Pristacin Pyrisept. 

Whereas communal entropy and micelle interaction energy play a role in the transformation of spheres to cylinders with increasing surfactant concentration, cyhndrical micelles also form in dilute systems. One explanation has been offered by Debye and Anacker (1951). Crystallographic data show the volume of the hydrocarbon tail to be = [27.4 + 26.9(n -1)] x 10 nm and a fully stretched length of 4 = 0.15 + 0.1265( - 1) nm (see Tanford, 1960). Calculate the maximum possible aggregation number allowable in a sphere for SDS, cetyl pyridium chloride, and sodium octyl sulfate. 

The fully stretched length of the tail is 1.5415 nm. The radius of the micelle is R = 0.4258// nm, but it is required that i 7 or 3.621 or TV 58 at 25°C, which is less than the reported value of 62 and the similar value foimd in Example 4.1. Hence relatively short cylindrical micelles are expected for SDS. For cetyl pyridium chloride, = 16, 4 = 2.68 nm, and N 249. Its aggregation number is 138, and such micelles are correctly predicted to be spherical. For sodium octyl sulfate, N < 21.5. Actual values lie in the range of 24 to 31 and experimental measurements indicate that it forms spherical micelles and not cylindrical ones, showing that the simple geometric criterion employed is not always adequate. 

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