Unsaturated carboxylic acids structural effects

Intramolecular cyclization of unsaturated carboxylic acid derivatives using strong electrophiles is one of the most effective and common approaches to y-lactones. Not to mention, reactions of the unsaturated carboxylic acids with halonium sources such as X2 and NXS, the so-called halolactonization, produce the synthetically useful halolactones [4], N-Halosuccinimide (NXS) reaction is also commonly utilized for the construction of y-lactone structures. These days, development of effective catalysts, especially for enantioselective cyclization of unsaturated carboxylic acids including halolactonization reaction, is a hot topic in synthetic organic chemistry. 

In view of the fact that one would expect interference with surfactant action by Ca(ll), Mg(ll), and other multivalent ions to be more severe with carboxylates than with sulfonates, the high interfacial tensions observed are discouraging from a practical point of view. However, there are interesting effects of structure between the salts studied, in particular between the cis and trans isomers, elaidate and oleate, and between compounds of different degrees of unsaturation. We are now preparing derivatives of these acids, in order to get more information on the effect of minor structure modifications. In addition, the possibilities of beneficial effects of cosurfactants have been as yet little explored. We believe it premature to conclude that carboxylate surfactants are of no utility. 

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