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The examination of 19F chemical shifts for ca. 650 F-alkylated compounds of general formula CF3(CF2)nCF2X led to the following conclusions: the CF2 groups α to X are very sensitive to the nature of X, and are spread over a range of 85 ppm. The effect of the length of the F-alkyl chain decreases rapidly, so that δCF2(α) can already be considered as characteristic of X for n = 1 or 2 for most practical purposes. Solvent effects (in 9 different solvents having ε = 1.8 to 52.1) were found to be rather small except for the F-alkyl iodides. A chart which indicates the domain in which the CF2(α) resonance signal is to be expected is given for 42 different series of F-alkylated compounds; it is expected to provide the synthetic chemist with a useful tool for the identification and characterization of such compounds. 相似文献
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Santini Jr Richards AC Scheidt R Cima MJ Langer R 《Angewandte Chemie (International ed. in English)》2000,39(14):2396-2407
Controlled-release systems are common in a number of product areas, including foods, cosmetics, pesticides, and paper. Microencapsulated systems, for example, are used for the release of flavors and vitamins in foods, fragrances in perfumes, and inks in carbonless copy paper. Controlled-release systems for drug delivery first appeared in the 1960s and 1970s. In the past three decades, the number and variety of controlled release systems for drug-delivery applications has increased dramatically. Many of these use polymers having particular physical or chemical characteristics such as biodegradability, biocompatibility, or responsiveness to pH or temperature changes. However, recent advances in the field of microfabrication have created the possibility of a new class of controlled-release systems for drug delivery, namely, that of small, programmable devices. Their small size, potential for integration with microelectronics, and ability to store and release chemicals on demand could make controlled-release microchips useful in a number of areas, including medical diagnostics, analytical chemistry, chemical detection, industrial process monitoring and control, combinatorial chemistry, microbiology, and fragrance delivery. More importantly, drug-delivery microchips resulting from this convergence of controlled release and microfabrication technologies may provide new treatment options to clinicians in their fight against disease. 相似文献
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A series of new polyfluorinated dienes 3, containing the novel -CFCHCHCF-, pattern has been synthesized (50–70% yields) by reacting perfluoroalkyl iodides with perfluoroalkyl-ethylenes in the presence of copper. The monoalkenes RfCFCHCH2CF2R′f and the saturated compounds RfCF2CH2CH2CF2R′f were obtained by varying the experimental conditions. The 1H and 19F NMR spectra are analysed and the reaction mechanism is discussed. 相似文献
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Millot N Cox A Santini CC Molard Y Basset JM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(6):1438-1442
The reaction of the Lewis acid B(C(6)F(5))(3) with silanol groups of silica surfaces, dehydroxylated at different temperatures (300, 500, 700, and 800 degrees C), has been investigated in presence of the Br?nsted base NEt(2)Ph. The structure of the resulting modified silica supports [triple bond Si-OB(C(6)F(5))(3)](-)[HNEt(2)Ph](+) (1) has been carefully identified by IR and multinuclear solid-state NMR spectroscopies, isotopic (2)H and (18)O labeling, elemental analysis, molecular modeling, and comparison with synthesized molecular models. Highly dehydroxylated silica surfaces were required to transform selectively each silanol group into unique [triple bond Si-OB(C(6)F(5))(3)](-)[HNEt(2)Ph](+) fragments. For lower dehydroxylation temperatures, two sorts of surface sites were coexisting on silica: the free silanol groups [triple bond SiOH] and the ionic species 1. 相似文献
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Bibal C Santini CC Chauvin Y Vallée C Olivier-Bourbigou H 《Dalton transactions (Cambridge, England : 2003)》2008,(21):2866-2870
A new family of hydroxytris(pentafluorophenyl)borate anions [B(C6F5)3OH](-) associated with organic and aprotic cations c+ (imidazolium, pyrrolidinium and phosphonium) has been prepared by a general one-pot synthesis that implies the chloride borate analogues [B(C6F5)3Cl](-)[c]+. The [c]+[B(C6F5)3OH](-) salts have been isolated and fully characterized. The borate anion [B(C6F5)3OH](-) has been shown to protonate the Zr-Me bond in the Cp2ZrMe2 complex forming CH4 and the first published example of anionic [Cp2Zr(Me)OB(C6F5)3](-) species. Standard spectroscopic methods demonstrate the covalent character of the Zr metal center and the anionic character of the boron atom. This protonolysis methodology using [B(C6F5)3OH](-) anion affords a new route for the incorporation of a covalently bonded anionic functionality on organometallic complexes. This provides a new way to immobilize transition metal complexes in ionic liquids. 相似文献