The Dissolving of Large Molecules via Micelles One or Two per Micelle

One particular property of micelles stands out above all others their ability to solubilize organic compounds in water. Benzene, for example, dissolves in SDS to the extent of 0.90 mol/mol surfactant, resulting in around 40 benzene molecules per micelle . NMR chemical shift data situate most of the benzene at the micelle-water interface, but the localization of small solubilizates in micelles is never uniform. 

Porphyrins dissolved in SDS micelles have also been applied towards the determination of pKa values of the central atoms, which are around 5.5 for alkyl substituted porphyrins, but drop to 4.8 for divinyl substituted protoporphyrin dimethyl ester and to 3.0 for porphyrins with two p-pyrrolic carbethoxy or formyl substituents. 

Yokoyama, H. Kurata, Y. Harima, K. Yamashita, K. Hoshino, H. Kokado, Chem. Lett., 1990, 343 

SDS micelles were also employed for the light-induced cyclization of polyenes to steroids in low yield. No such reaction was observed in homogeneous organic solutions. Again, it is believed that only one polyene molecule is dissolved within one micelle. On the other hand, trans-cinnsimic acid produced dimeric products after UV irradiation in 1% aqueous CTAB, while no photodimers were formed in homogeneous solutions.  

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