A Practical and Green Chemical Process: Fluoroalkyldistannoxane-Catalyzed Biphasic Transesterification

Xiang, Junfeng; Toyoshima, Shinji; Orita, Akihiro; Otera, Junzo

doi:10.1002/1521-3757(20011001)113:19<3782::aid-ange3782>3.0.co;2-f

Cited by 11 publications

(5 citation statements)

References 22 publications

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“…Because hydroxyl groups are much more hydrophilic than ester groups, the static water contact angle of the resulting Si−CH 2 OH surface decreases from about 60° to only about 25°. Efficient esterification of hydroxyl groups with carboxyl acid occurs only in the presence of certain catalysts. − In the present study, the carboxylic acid group of ACPA was first transformed into an acid chloride by reaction with thionyl chloride, because the latter is more reactive toward esterification of the hydroxyl group, especially at room temperature. , …”

Section: Resultsmentioning

confidence: 75%

“…Efficient esterification of hydroxyl groups with carboxyl acid occurs only in the presence of certain catalysts. [33][34][35][36][37] In the present study, the carboxylic acid group of ACPA was first transformed into an acid chloride by reaction with thionyl chloride, because the latter is more reactive toward esterification of the hydroxyl group, especially at room temperature. 38,39 Figure 2c shows the C 1s and N 1s core-level spectra of the silicon surface after immobilization of the azo initiator (Si-azo surface).…”

Section: Functionalization Of the Hydrogen-terminated Silicon Surface...mentioning

confidence: 99%

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Functionalization of Hydrogen-Terminated Silicon with Polybetaine Brushes via Surface-Initiated Reversible Addition−Fragmentation Chain-Transfer (RAFT) Polymerization

Zhai¹,

Yu²,

Kang³

et al. 2004

Ind. Eng. Chem. Res.

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Controlled grafting of polybetaine brushes onto hydrogen-terminated Si(100) substrates (Si-H substrates) was carried out via surface-initiated reversible addition-fragmentation chain-transfer (RAFT) polymerization. The azo initiator was immobilized on the Si-H surface through a threestep process: (i) coupling of an ω-unsaturated alkyl ester to the Si-H surface under UV irradiation, (ii) reduction of the alkyl ester into a hydroxyl group by LiAlH 4 , and (iii) esterification of the hydroxyl group with the initiator 4,4′-azo-bis(4-cyanopentanoic acid) after acid chlorination. In the presence of the chain-transfer agent, RAFT-mediated polymerization of the sulfobetaine monomer N,N′-dimethyl(methylmethacryloyl ethyl) ammonium propane sulfonate (DMAPS) was initiated from the surface-immobilized azo initiator to produce DMAPS polymer (PDMAPS) brushes on the silicon substrate (Si-g-PDMAPS). X-ray photoelectron spectroscopy (XPS) analysis indicated that the PDMAPS brushes had been successfully grafted onto the silicon surface. Atomic force microscopy (AFM) images revealed changes in the surface topography of the silicon substrates and the presence of polymer overlayers. Ellipsometry results indicated that the thickness of the polybetaine film increased linearly with the polymerization time. The "living" characteristics of the end functionality of the polybetaine brushes from the RAFT-mediated process was ascertained by block copolymerization with the anionic monomer sodium 4-styrene sulfonate (SS) to form the diblock polymer brushes (a Si-g-PDMAPS-b-PSS surface).

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Section: Resultsmentioning

confidence: 75%

Section: Functionalization Of the Hydrogen-terminated Silicon Surface...mentioning

confidence: 99%

Functionalization of Hydrogen-Terminated Silicon with Polybetaine Brushes via Surface-Initiated Reversible Addition−Fragmentation Chain-Transfer (RAFT) Polymerization

Zhai¹,

Yu²,

Kang³

et al. 2004

Ind. Eng. Chem. Res.

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“…[105] Palladium complex 19 b was used as the catalyst for the oxidation of terminal olefins to methyl ketones with tert-butylhydroperoxide (TBHP) as oxidant. [114,115] Fluorous tin oxides have been used in transesterifications [116] and in the monotosylation of 1,2-diols. [107,108] Selective epoxidation reactions of internal olefins in the presence of terminal double bonds was achieved by the use of ruthenium complex 19 c and excess iPrCHO/ oxygen.…”

Section: Reviewsmentioning

confidence: 99%

Modern Separation Techniques for the Efficient Workup in Organic Synthesis

Tzschucke

Märkert

Bannwarth

et al. 2002

Angew. Chem. Int. Ed.

339

133

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The shift of paradigm in combinatorial chemistry, from large compound libraries (of mixtures) on a small scale towards defined compound libraries where each compound is prepared in an individual well, has stimulated the search for alternative separation approaches. The key to a rapid and efficient synthesis is not only the parallel arrangement of reactions, but simple work-up procedures so as to circumvent time-consuming and laborious purification steps. During the initial development stages of combinatorial synthesis it was believed that rational synthesis of individual compounds could only be achieved by solid-phase strategies. However, there are a number of problems in solid-phase chemistry: most notably there is the need for a suitable linker unit, the limitation of the reaction conditions to certain solvents and reagents, and the heterogeneous reaction conditions. Further disadvantages are: the moderate loading capacities of the polymeric support and the limited stability of the solid support. In the last few years several new separation techniques have been developed. Depending on the chemical problem or the class of compounds to be prepared, one can choose from a whole array of different approaches. Most of these modern separation approaches rely on solution-phase chemistry, even though some of them use solid-phase resins as tools (for example, as scavengers). Several of these separation techniques are based on liquid-liquid phase separation, including ionic liquids, fluorous phases, and supercritical solvents. Besides being benign with respect to their environmental aspects, they also show a number of advantages with respect to the work-up procedures of organic reactions as well as simplicity in the isolation of products. Another set of separation strategies involves polymeric supports (for example, as scavengers or for cyclative cleavage), either as solid phases or as soluble polymeric supports. In contrast to solid-phase resins, soluble polymeric supports allow reactions to be performed under homogeneous conditions, which can be an important factor in catalysis. At the same time, a whole set of techniques has been developed for the separation of these soluble polymeric supports from small target molecules. Finally, miscellaneous separation techniques, such as phase-switchable tags for precipitation by chemical modification or magnetic beads, can accelerate the separation of compounds in a parallel format.

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“…Es werden hohe Ausbeuten erzielt, und die Lewis‐Säure kann quantitativ zurückgewonnen und mehrmals wiederverwendet werden 114, 115. Fluorierte Zinnoxide katalysieren Umesterungen116 und die Monotosylierung von 1,2‐Diolen 117. Die enantioselektive Addition von Diethylzink an Aldehyde gelingt mit einer Reihe von fluormarkierten Katalysatoren 118–121…”

Section: Flüssig‐flüssig‐phasentrennungunclassified

Moderne Trennverfahren zur effizienten Aufarbeitung in der organischen Synthese

et al. 2002

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Die kombinatorische Synthese [1,2] wird als eine der Schl¸s-seldisziplinen f¸r den konstanten Nachschub an chemischen Verbindungen angesehen, die auf biologische Aktivit‰t gegen¸ber der immens wachsenden Zahl biologischer Zielmolek¸le getestet werden kˆnnen. Zusammen mit dem Hochdurchsatz-Screening und einem effizienten Datenmanagement wird ihre Anwendung den Prozess der Wirkstoffentdeckung zweifelsohne beschleunigen. Urspr¸nglich konzentrierte sich die Kombinatorische Chemie auf die schnelle Synthese von hochkomplexen Gemischen mit winzigen An-

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A Practical and Green Chemical Process: Fluoroalkyldistannoxane-Catalyzed Biphasic Transesterification

Cited by 11 publications

References 22 publications

Functionalization of Hydrogen-Terminated Silicon with Polybetaine Brushes via Surface-Initiated Reversible Addition−Fragmentation Chain-Transfer (RAFT) Polymerization

Functionalization of Hydrogen-Terminated Silicon with Polybetaine Brushes via Surface-Initiated Reversible Addition−Fragmentation Chain-Transfer (RAFT) Polymerization

Modern Separation Techniques for the Efficient Workup in Organic Synthesis

Moderne Trennverfahren zur effizienten Aufarbeitung in der organischen Synthese

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