- Preparation and characterization of nonpolar fluorinated carbosilane dendrimers by APcI mass spectrometry and small-angle X-ray scattering
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The following highly fluorinated nonpolar dendrimers were obtained in high yields from multiple hydrosilylation reactions between core hydride terminated carbosilane dendrimers and allyl-1,1-dihydrotrifluoroethyl ether or allyl-1,1-dihydroheptadecafluorononyl ether through divergent synthetic routes: Si[CH2-CH2SiMe2(CH2CH 2CH2OCH2CF3)]4 (7), Si{CH2CH2SiMe[CH2CH2SiMe(CH 2CH2CH2OCH2CF3) 2]2}4 (8), Si[CH2CH2Si(CH2CH2CH 2OCH2C8F17)3]4 (9), Si[CH2CH2SiMe2(CH2CH 2CH2OCH2C8F17)] 4 (10), and Si{CH2-CH2Si[CH2CH2Si(CH 2CH2CH2OCH2C8F 17)3]3}4 (11). These compounds were characterized by elemental and spectroscopic analyses. Valuable mass spectral data were obtained by using atmospheric pressure chemical ionization (APcI). The fluorinated dendrimer molecule and the nonfluorinated core scatter X-ray light differently and present unique slopes on the Guinier Plot of data from small-angle X-ray light scattering (SAXS) in hexafluorobenzene. Glass transition temperatures (Tg) and thermogravimetric analyses (TGA) of the dendrimers were determined.
- Omotowa, Bamidele A.,Keefer, Keith D.,Kirchmeier, Robert L.,Shreeve, Jean'ne M.
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- Rate and product studies on the solvolyses of allyl chloroformate
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The solvolysis rate constants of allyl chloroformate (CH 2=CHCH2OCOCl, 3) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and YCl solvent ionizing scale, with the sensitivity values of 0.93 ± 0.05 and 0.41 ± 0.02 for l and m, respectively. These l and m values can be considered to support a S N2 reaction pathway. The activation enthalpies (ΔH≠) were 12.5 to 13.4 kcal·mol-1 and the activation entropies (ΔS≠) were -34.4 to -37.3 cal·mol-1·K -1, which is also consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effect (SKIE, kMeOH/k MeOD) of 2.16 was also in accord with the SN2 mechanism. The values of product selectivity (S) for the solvolyses of 3 in alcohol/water mixtures was 1.3 to 3.9, which is also consistent with the proposed bimolecular reaction mechanism.
- Koh, Han Joong,Kang, Suk Jin
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p. 4117 - 4121
(2013/08/23)
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- A direct and rapid route to α,α-difluoroacylsilanes from trifluoroethanol
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α,α-Difluoroacylsilanes were synthesised directly from a range of allyl ethers of trifluoroethanol via dehydrofluorination/metallation procedures, followed by thermal [3,3]-sigmatropic rearrangement of the intermediate vinylmetals. The scope and limitatio
- Audouard, Christophe,Garayt, Maxime R.,Kérourédan, Erwan,Percy, Jonathan M.,Yang, Hongli
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p. 611 - 623
(2007/10/03)
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- ROMP WITH FLUORINATED GROUPS
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The instant invention relates to new metathesis oligomers which are substituted with fluori-nated groups. Also disclosed is a polymerisable composition comprising a catalytically effec-tive amount of a penta- or hexavalent ruthenium or osmium carbene catalyst, the process for preparing the metathesis oligomers by applying the reaction conditions of Ring Opening Metathesis Polymerisation (ROMP) to the polymerisable composition. These new methathe-sis oligomers are useful for increasing the oil and water repellency of organic materials.
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Page/Page column 36-37
(2010/02/11)
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- A potentially divergent and rapid route to analogues of deoxycyclitols, pentopyranoses, 6-deoxyhexoses, and hexoses
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(Chemical Equation Presented) Direct precursors to analogues of pentopyranoses, 6-deoxyhexoses, and hexoses, in which a CF2 center replaces the pyranose oxygen, have been synthesized rapidly from trifluoroethanol. A simple scaleable allylation
- Audouard, Christophe,Fawcett, John,Griffith, Gerry A.,Kerouredan, Erwan,Miah, Afjal,Percy, Jonathan M.,Yang, Hongli
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p. 4269 - 4272
(2007/10/03)
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- Synthesis of model organosiloxanes containing perfluoroether side-chains
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A series of organotrisiloxanes [(Me3SiO)2MeSi(CH2)(n)O(CH2)(m)R(f)], (n = 3, m = 1, R(f) = CF3; n = 3, m = 2, R(f) = C4F9, C6F13, C8F17, C10F21, C7F15; n = 5, m = 1, R(f) = CF3; n = 10, m = 0, R(f) = C3HF6; n = 10, m = 1, R(f) = CF3) have been prepared by the [Pt(cyclooctadiene)Cl2] catalysed hydrosilylation reaction between heptamethyltrisiloxane and CH2=CH(CH2)(n-2)O(CH2)(m)R(f). Yields are dependent upon the alkene chain length and degree of branching of the R(f) group. Isomeric products [(Me3SiO)2MeSi(CH2)3OCH2CF3] and [(Me3SiO)2MeSiCH(Me)CH2OCH2CF3] were detected in reactions involving CH2=CHCH2OCH2CF3 only.
- Smith,Brisdon,Brewer,Willis
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p. 1765 - 1769
(2007/10/03)
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- SYNTHESE D'ETHERS ET DE THIOETHERS ALLYLIQUES FLUORES PAR CATALYSE PAR TRANSFERT DE PHASE
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Several fluorinated allylic ethers, thioethers and diethers have been prepared in excellent yields by phase transfer catalysis (CTP).The used halogenated compounds are allyl chloride and bromide, p-chloromethylstyrene.The used fluorinated alcohols are aromatic pentafluorophenol and various aliphatics: CF3-CH2OH, CF2H-CF2-CH2-OH, ClCF2-CF2-CH2OH, C6F13C2H4OH, HO-CH2-CF2-CFCl-CF2-CH2OH and HO-C6H4-C(CF3)2-C6H4-OH.All these new compounds have been characterized by 1H and 13C NMR.We conclude that CTP is the best method to obtain allylic and diallylic compounds.
- Boutevin, B.,Youssef, B.,Boileau, S.,Garnault, A. M.
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p. 399 - 410
(2007/10/02)
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- Solvolysis of Allyl Arenesulfonates. Cautionary Comments concerning the NOTs Scale of Solvent Nucleophilicities
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The rates of solvolysis of five allyl arenesulfonates are analysed in terms of the extended Grunwald-Winstein equation.The l values are constant but the m values decrease slightly as the nucleofugality of the leaving group increases.The solvent nucleophilicity (NOTs) values presently available in the literature are based upon a m value for methyl p-toluenesulfonate (tosylate) solvolysis of 0.3; it is demonstrated that a value of 0.55 is more appropriate.The previously reported l values and correlation coefficients for tosylate ester solvolyses are accurate and the "ap parent" sensitivities to solvent ionizing power (m values) are easily corrected.However, for use in conjunction with solvent ionizing power scales for other leaving groups, NTs values based on the appropriate m value or, alternatively, NEt3O+%& values (based on triethyloxonium ion solvolysis) are required.
- Kevill, Dennis N.,Rissmann, Thomas J.
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p. 3062 - 3064
(2007/10/02)
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- CORRELATION OF THE RATES OF SOLVOLYSIS OF ALLYL AND BENZYL ARENESULPHONATES
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Analysis of the specific rates of solvolysis of allyl arenesulphonates in terms of the extended Grunwald-Winstein equation indicates a marked dependence on both the solvent nucleophilicity (high/value) and the solvent ionizing power (high m value).As the charge delocalization in the leaving group increases, both l and m values fall.For allyl toluene-p-sulphonate solvolysis in 28 solvents at 50.0 deg C, values for l(0.83) and for m (0.63), based on the use of NKL and Y values, are very similar to the equivalent values of 0.90 and 0.67 previously reported for benzyl toluene-p-sulphonate solvolysis.Related extended Grunwald-Winstein analyses are considered and the need for variety in the choice of solvents is emphasized.
- Kevill, Dennis N.,Rissmann, Thomas J.
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p. 717 - 720
(2007/10/02)
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- Acid-Catalyzed Reaction of 2,2,2-Trifluorodiazoethane for Analysis of Functional Groups by 19F Nuclear Magnetic Resonance Spectrometry
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The acid-catalyzed reactions of trifluorodiazoethane with alcohols, phenols, thiols, and carboxylic acids are reported.The yield data for these trifluoroethyl derivatives suggest a simple, and in many cases, quantitative method for introduction of a fluorine tagging group.The 19F chemical shifts indicate that most functional groups (e.g., phenols, alcohols, etc.) have fairly well resolved chemical shifts regions.In addition, paramagnetic shift reagents have been utilized to selectively differentiate carboxylic acids from other active hydrogen functional groups.
- Koller, K. L.,Dorn, H. C.
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p. 529 - 533
(2007/10/02)
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