Über den lösungsmitteleffekt bei der silylierung von cellulose mit hexamethyl‐disilazan

Nagy, József; Borbély‐Kuszmann, A.; Becker-Pálossy, Katalin; Zimonyi‐Hegedüs, E.

doi:10.1002/macp.1973.021650131

Cited by 11 publications

(8 citation statements)

References 4 publications

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“…Finally, we note that the solvent-dependent formation of 1 is consistent with the silylation literature. − For example, Nagy et al reported that the silylation of cellulose with HN(SiMe 3 ) 2 in the presence of a Me 3 SiCl catalyst proceeded smoothly in pyridine, DMSO, and DMF, while no reaction was observed in acetonitrile, nitromethane, and nitrobenzene . Similarly, Zipse et al reported that the silylation of various primary and secondary alcohols with t BuMe 2 SiCl was slow in CHCl 3 and CH 2 Cl 2 but proceeded much faster in DMF .…”

Section: Resultssupporting

confidence: 86%

Uranyl Oxo Silylation Promoted by Silsesquioxane Coordination

Assefa

Hayton

2020

J. Am. Chem. Soc.

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The reaction of [UO2(N(SiMe3)2)2(THF)2] with 1 equiv of Cy7Si7O9(OH)3 in THF affords [U(OSiMe3)3(Cy7Si7O12)] (1) as orange plates in 24% isolated yield. Its X-ray crystal structure reveals three silylated Oyl ligands, confirming the unprecedented conversion of the uranyl ion to a U(VI) silyloxide. We propose that the formation of 1 proceeds through a transient uranyl silsesquioxide intermediate, [{Cy7Si7O11(OH)}UO2], which undergoes rapid oxo silylation by HN(SiMe3)2, followed by silyloxy ligand scrambling, to form 1 and the U(VI) bis(silsesquioxane) complex, [U(Cy7Si7O12)2] (3), among other products. The formation of 3 was confirmed by its independent synthesis and comparison of its 29Si{1H} NMR spectrum with that of the in situ reaction mixture. In contrast to the reaction in THF, the reaction of [UO2(N(SiMe3)2)2(THF)2] with Cy7Si7O9(OH)3 in hexanes, followed by recrystallization from Et2O/MeCN, results in the formation of the uranyl cluster, [(UO2)3(Cy7Si7O12)2(Et2O)(MeCN)2] (2), as yellow rods in 42% isolated yield. Complex 2 features two Oyl···U dative interactions, but in contrast to 1, none of its three uranyl fragments are silylated. Overall, the conversion of [UO2(N(SiMe3)2)2(THF)2] to 1 and 3 is likely promoted by the strong electron donor ability of the silsesquioxane ligand and suggests that the actinide coordination chemistry of mineral surface mimics, such as silsesquioxane, is a fruitful arena for the discovery of new reactivity.

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Section: Resultssupporting

confidence: 86%

Uranyl Oxo Silylation Promoted by Silsesquioxane Coordination

Assefa

Hayton

2020

J. Am. Chem. Soc.

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“…One of the main reagents, HMDS, was used to prepare trimethylsilyl cellulose (TMSC) since the 1950s [25]. Various catalysts (mostly acidic, such as HCl) and heating should be used to increase the silylation efficiency of HMDS [26,27]. The silylation reactions of the cellulose fibers of the filter paper with HMDS were summarized in Scheme 2a.…”

Section: Silylation Of Cellulose With Hmdsmentioning

confidence: 99%

Rapid and alternative fabrication method for microfluidic paper based analytical devices

Malekghasemi

Kahveci

Duman

2016

Talanta

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A major application of microfluidic paper-based analytical devices (µPADs) includes the field of point-of-care (POC) diagnostics. It is important for POC diagnostics to possess properties such as ease-of-use and low cost. However, µPADs need multiple instruments and fabrication steps. In this study, two different chemicals (Hexamethyldisilazane and Tetra-ethylorthosilicate) were used, and three different methods (heating, plasma treatment, and microwave irradiation) were compared to develop µPADs. Additionally, an inkjet-printing technique was used for generating a hydrophilic channel and printing certain chemical agents on different regions of a modified filter paper. A rapid and effective fabrication method to develop µPADs within 10min was introduced using an inkjet-printing technique in conjunction with a microwave irradiation method. Environmental scanning electron microscope (ESEM) and x-ray photoelectron spectroscopy (XPS) were used for morphology characterization and determining the surface chemical compositions of the modified filter paper, respectively. Contact angle measurements were used to fulfill the hydrophobicity of the treated filter paper. The highest contact angle value (141°±1) was obtained using the microwave irradiation method over a period of 7min, when the filter paper was modified by TEOS. Furthermore, by using this method, the XPS results of TEOS-modified filter paper revealed Si2p (23%) and Si-O bounds (81.55%) indicating the presence of Si-O-Si bridges and Si(OEt) groups, respectively. The ESEM results revealed changes in the porous structures of the papers and decreases in the pore sizes. Washburn assay measurements tested the efficiency of the generated hydrophilic channels in which similar water penetration rates were observed in the TEOS-modified filter paper and unmodified (plain) filter paper. The validation of the developed µPADs was performed by utilizing the rapid urease test as a model test system. The detection limit of the developed µPADs was measured as 1unitml(-1) urease enzyme in detection zones within a period of 3min. The study findings suggested that a combination of microwave irradiation with inkjet-printing technique could improve the fabrication method of µPADs, enabling faster production of µPADs that are easy to use and cost-effective with long shelf lives.

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“…It was obvious that with the increase of catalyst contents, silylation yield was increased. For the mechanism of TMSCl as catalyst, Nagy et al54 gave an explanation in their work. First, TMSCl with high reaction activity reacted with hydroxyl groups and released HCl as byproduct.…”

Section: Resultsmentioning

confidence: 99%

Well‐defined amphiphilic poly(p‐dioxanone)‐grafted poly(vinyl alcohol) copolymers: Synthesis and micellization

Chen

Zhan

et al. 2010

J. Polym. Sci. A Polym. Chem.

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A series of amphiphilic biodegradable and biocompatible poly(p-dioxanone)-grafted poly(vinyl alcohol) (PVA) copolymers with well-defined structure were obtained by a three-step synthesis based on the ''grafting from'' concept. The first step (protection step), called the partial silylation of PVA hydroxyl groups, was accomplished by 1,1,1,3,3,3-hexamethyldisilazane and catalyst chlorotrimethylsilane in dimethyl sulfoxide using THF as cosolvent. The second step was the ringopening polymerization of p-dioxanone (PDO) initiated from the remaining OH groups of the partially silylated PVA. Finally, a deprotection step was followed: the silylether group was deprotected easily under very mild conditions. The synthetic conditions of the first two steps were investigated, and the structures of polymers formed in each step were characterized by various analytical methods. The results showed that the molecular structure of the PVA-g-PPDO could be controlled easily by the degree of silylation and the feed ratio. In addition, the micellization of amphiphilic PVA-g-PPDO copolymers in water was proved by fluorescence spectra and dynamic light scattering, and the relationship between structural parameters of copolymers and micellar properties was studied preliminarily. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [4811][4812][4813][4814][4815][4816][4817][4818][4819][4820][4821][4822] 2010

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Über den lösungsmitteleffekt bei der silylierung von cellulose mit hexamethyl‐disilazan

Cited by 11 publications

References 4 publications

Uranyl Oxo Silylation Promoted by Silsesquioxane Coordination

Uranyl Oxo Silylation Promoted by Silsesquioxane Coordination

Rapid and alternative fabrication method for microfluidic paper based analytical devices

Well‐defined amphiphilic poly(p‐dioxanone)‐grafted poly(vinyl alcohol) copolymers: Synthesis and micellization

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