I. Rico

Formamide, a water substitute in micelles and microemulsions xxx structural analysis using a diels-alder reaction as a chemical probe

Abstract We recently demonstrated that it is possible to prepare waterless microemulsions by replacing water with formamide. Using the Diels-Alder reaction between methyl acrylate and cyclopentadiene as a chemical probe, we were able to explore the monophasic areas of both ionic and non-ionic surfactant solutions in formamide. Discontinuities in reaction selectivity indicate the presence of structured phases.

Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

X-ray scattering was used to analyse the structures of aggregates of CTAB in various formamide-containing media.Firstly, CTAB micelles were detected in formamide solutions. A spherical micelle model was proposed; at values close to the CMC, smaller micelles were observed in formamide than in water.Secondly, the structure of microemulsions in the isooctane-rich zone of the system (formamide/CTAB=2, isooctane, 1-butanol) was studied by X-ray scattering. The structure was found to be quite different in this zone from that normally observed in aqueous microemulsions. Structures compatible with small filaments of formamide were detected. The results were related to previous measurements of electrical conductivity.

Waterless microemulsions - IV : diels-alder reaction of cyclopentadiene and methylacrylate as a probe of formamide microemulsions

Abstract The use of the Diels-Alder reaction between methyl acrylate and cyclopentadiene as a chemical probe has demonstrated two distinct zones in the formamide microemulsion system. Good selectivity and high yields can be obtained from Diels-Alder reactions in formamide.

Waterless microemulsions: V. Phase behavior of ionic and nonionic formamide microemulsions

Abstract We recently demonstrated that it is possible to prepare waterless microemulsions by replacing water by formamide. In this study we examined in more detail the phase behavior of these ionic and nonionic formamide microemulsions (demonstration of Winsor I, II, and III systems).

X-ray diffraction study of the intermediate phases formed by sodium dodecylsulphate in aqueous mixtures of N-methylformamide

Abstract We report the sequence of intermediate phases formed by sodium dodecylsulphate (SDS) in water on addition of N-methylformamide (NMF). Although only a single phase, Lα, is formed in the SDS/NMF system, the three sequences Hα ⇔ Mα ⇔ Rα, Hα ⇔ Mα ⇔ Qα and Hα ⇔ Qα (Ia3d) were observed with increase in concentration of NMF in the SDS/water/NMF mixtures. The sequences Hα ⇔Qα and Hα ⇔ Lα were identified in the water/NMF mixture, although they were not observed in the initial SDS/water system or in the SDS/NMF system. These results indicate that solvent mixtures could be profitably employed to investigate the conditions of formation of intermediate phases and to study the transitions of the Hα → Mα → Rα to the Hα → Mα → Qα sequences.

X-ray scattering analysis of micellization in water of hydrochlorides of amino derivatives of adamantane

Abstract X-ray scattering analysis of aqueous solutions of hydrochlorides of an unsaturated and a saturated amino derivative of adamantane confirmed the existence of micelles and made possible determination of their shape and size, as well as of the influence of the double bond on micellization.