A product and time-resolved kinetic study on the reactivity of tertiary arylcarbinyloxyl radicals bearing alpha-cyclopropyl and alpha-cyclobutyl groups has been carried out. Both the 1-cyclopropyl-1-phenylethoxyl (1.) and alpha,alpha-dicyclopropylphenylmethoxyl (2.) radicals undergo beta-scission to give cyclopropyl phenyl ketone as the major or exclusive product with rate constants higher than that measured for the cumyloxyl radical. It is proposed that in the transition state for beta-scission of 1. and 2., formation of the C=O double bond is assisted by overlap with the C-C bonding orbitals of the cyclopropane ring. With tertiary arylcarbinyloxyl radicals bearing alpha-cyclobutyl groups such as the 1-cyclobutyl-1-phenylethoxyl (4.) and 1-cyclobutyl-1-phenylpropoxyl (5.) radicals, the fragmentation regioselectivity is essentially governed by the stability of the radical formed by beta-scission. Accordingly, 4. undergoes exclusive C-cyclobutyl bond cleavage to give acetophenone, whereas with 5., competition between C-cyclobutyl and C-ethyl bond cleavage, leading to propiophenone and cyclobutylphenyl ketone in a 2:1 ratio, is observed.

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Mixtures containing water, lysozyme (LYS), and a fluorinated surfactant (LiPFN) have been investigated in a wide range of protein-to-surfactant ratios. Depending on composition, sample consistency and coexistence of the different phases, different experimental methods were used. Volumetric, viscometric, surface tension, potentiometric (by a home-built ion-selective electrode), turbidity, optical polarizing microscopy, and 19F NMR experiments were used. The results obtained from the above methods have been interpreted in terms of a combination of electrostatic and hydrophobic contributions to the stability of the different phases formed in the water−LYS−LiPFN system. Solutions, gel phases, and precipitates have been observed in the range investigated in more detail. Multiphase regions have also been observed. Such rich polymorphic behavior implies the existence of interactions between the protein and surfactant. The gel phase is presumably formed by interconnections between micelles and protein-surfactant complexes, held together by protein-bound micelles and forming, presumably, interconnected necklace structures. The overlapping of different protein-surfactant aggregates to form gels requires a significant amount of time. Its formation obeys a volume fraction statistics; the width of the gel phase, in fact, is controlled by the amount of protein−surfactant complex.

Pullulan was hydrophobically modified by reaction with dodecanoic acid, modulating the polymer-to-acid ratio. The resulting products, termed PULAU N , have been characterized, and their physicochemical properties in aqueous solution, at 25 °C, are reported. The hydrophobic substitution was determined by Fourier transform infrared, FTIR, and NMR analyses. NMR also quantifies the substitution degree, N. Viscosity, surface tension, quasi-elastic light scattering, QELS, and gel permeation chromatography, GPC, methods were used to characterize the solution properties of PULAU N . Depending on the polymer concentration and N, PULAU N form micelle-like aggregates. The critical micelle concentration, cmc, decreases with increasing N. Addition of sodium dodecyl sulfate, SDS, results in the formation of mixed micelles. In the investigated concentration range, no polymer−surfactant-based gels are formed by mixing PULAU N and SDS. According to NMR self-diffusion and QELS findings, the number-average aggregation numbers of PULAU N micelles, 〈Z〉, depend on the concentration and substitution degree. Large 〈 Z〉 values are observed in the more substituted PULAU5.0. A very slow kinetics of adsorption at the air−solution interface (some days long) is observed for PULAU5.0. The effect, observed at concentrations below the cmc, is modulated by the concentration of hydrophobically modified polymer. The kinetics of adsorption is related to the combination of different effects. A thermodynamic model was developed to account for the above behavior. The process was rationalized by taking into account terms due to the surface spreading, self-diffusion, and elastic properties of the PULAU5.0 chains.

The reactivity of cumyloxyl radicals bearing cyclopropyl and 2,2-diphenylcyclopropyl groups in the para position has been investigated. Depending on radical structure, products deriving from C-C beta-scission and/or cyclopropyl ring-opening are observed, supporting the hypothesis that cumyloxyl (and, more generally, arylcarbinyloxyl) radicals exist in equilibrium with 1-oxaspiro[2,5]octadienyl radicals, in full agreement with the previously proposed mechanism for the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals.