Alcohol addition, photo

While most vesicles are formed from double-tail amphiphiles such as lipids, they can also be made from some single chain fatty acids [73], surfactant-cosurfactant mixtures [71], and bola (two-headed) amphiphiles [74]. In addition to the more common spherical shells, tubular vesicles have been observed in DMPC-alcohol mixtures [70]. Polymerizable lipids allow photo- or chemical polymerization that can sometimes stabilize the vesicle [65] however, the structural change in the bilayer on polymerization can cause giant vesicles to bud into smaller shells [76]. Multivesicular liposomes are collections of hundreds of bilayer enclosed water-filled compartments that are suitable for localized drug delivery [77]. The structures of these water-in-water vesicles resemble those of foams (see Section XIV-7) with the polyhedral structure persisting down to molecular dimensions as shown in Fig. XV-11. 

Photo-addition of allene to the enone (90) yield adduct (91) in 75 % yield, which was subjected to ketalization in 77% yield. Epoxidation of (92) with perbenzoic acid followed by chromatography on alumina afforded two expoxides (93) and (94). Both (93) and (94) could be converted separately through (95) and (96) respectively which was the common intermediate leading to isoishwarane (98) and ishwarane following a deketalization-retroaldol-aldol process to furnish the keto-alcohol (97) (99) 30>. 

Indeed, recent results from our laboratory indicate that dendrimer-encapsulated CdS QDs can be prepared by either of two methods [192]. The first approach is analogous to the methodology described earlier for preparing dendrimer-encapsulated metal particles. First, Cd and S salts are added to an aqueous or methanolic PAMAM dendrimer solution. This yields a mixture of intradendrimer (templated) and interdendrimer particles. The smaller, dendrimer-encapsulated nanoparticles may then be separated via size-selective photo etching [193], dendrimer modification and extraction into a nonpolar phase [19], or by washing with solvent in which the dendrimer-encapsulated particles are preferentially soluble. An alternative, higher-yield method relies on sequential addition of very small aliquots of Cd + and S " to alcoholic dendrimer solutions. 

Various substituted cyclopropanes have been shown to undergo nucleophilic addition of alcoholic solvents. For example, the electron transfer reaction of phenylcyclopropane (43, R = H) with p-dicyanobenzene resulted in a ring-opened ether 44. This reaction also produced an aromatic substitution product (45, R = H) formed by coupling with the sensitizer anion. This reaction is the cyclopropane analog of the photo-NOCAS reaction, but preceded it by almost a decade. 

The photo-induced reaction of 2-sulfinylcyclopentenones in alcohols in the presence of Ph2CO gives addition products (eq 10). Reagent 1 shows low stereoselectivity, whereas complete diastere-oselection can be achieved in the reaction of 4 and 5 (Table 3). ... 

Alcohol decomposition does provide additional insight into the interaction of adsorbates with metal oxide surfaces. The reactions of alkoxides on titanium dioxide have been used to probe thermal and photo-reactivity of powder and single crystal samples. 

The photolysis of the 6-oxo-3a,5a-cyclo-19-oic acid (520) gives initially the 4-en-6-one (521), but in t-butanol a rapid photo-addition then affords the 4a-t-butoxy-6-hydroxy-lactone (522). Similar reactions transformed the methyl ester (523) into the ketonic derivative (525). Photolysis of the saturated keto-acid (526), in an alcohol as solvent, gave first the corresponding 6-monoester (527) of the 5,6-seco-6,19-dioic acid, and finally the 6,19-anhydride (528). Formation of the 6-ester (527) probably involves addition of the solvent alcohol to a keten intermediate. ... 

The instability of some compounds under further irradiation is especially remarkable. We found that at first the secondary photo roduct is formed from the primary product and therefore has to be considered as a final product. Under these conditions benzaldehyde, the primary photoqrroduct of toluene, produces benzyl alcohol in the presence of H2O2. The addition of oxygen considerably accelerates the degradation rate, whereas the formation of phenols and hydroxylated biphenyls as well as the dimerization reactions under extended irradiation will increase. At X> 290 nm under normal conditions, we found in experiments with xylenes in aqueous H2O2, transformation rates up to 60% whereas in the corresponding reaction in dark no transformation occurred (Table 2). 

This methodology was extended to the addition of functionalized carbon-based radicals generated by photo-irradiation of alcohols in the presence of benzophe-none [58], The general reaction mechanism is shown in Eq. (13.46). High diaste-reoselectivities of >98 2 and yields of 97-99% are obtained. This photo-induced addition of hydroxyalkyl radicals also proceeded with high selectivity and yield with acyclic substrates, contrary to what was observed with simple alkyl radicals. 

Initial studies were made with purine in methanol exposed to shortwave (>250 nm) UV light, - the photo product being derived from addition of the alcohol across the 1,6-double bond. This work was later extended to purine nucleoside (nebularine) and 2-aminopurine and the use of other... 

Uranyl chloride is a bright yellow substance which crystallizes in the orthorhombic system. The compound is only slightly volatile in oxygen or chlorine below 500°, and volatility is appreciable only above 775°. It decomposes in vacuo above 450° to give chlorine and the oxides U02 and UgOg. Uranyl chloride is very hygroscopic and dissolves extensively in water. The compound is soluble in polar organic solvents such as acetone and the alcohols but does not dissolve in less polar solvents such as benzene. Its aqueous solutions are both thermally and photo-chemically unstable. A number of hydrates and addition compounds with halides and amines have been described. 

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