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Thomas Heinze - One of the best experts on this subject based on the ideXlab platform.
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comparison of benzyl celluloses synthesized in aqueous naoh and dimethyl sulfoxide Tetrabutylammonium Fluoride
Macromolecular Symposia, 2010Co-Authors: Esther Rohleder, Thomas HeinzeAbstract:Cellulose was benzylated starting from the dissolved polymer in dimethyl sulfoxide (DMSO)/Tetrabutylammonium Fluoride trihydrate (TBAF) and heterogeneously in aqueous NaOH as reaction media. Differences in the distribution of benzyl moieties within the anhydroglucose unit in dependence on the synthesis pathway couldn't be found. However, as revealed by means of 1 H-NMR spectroscopy, significant differences in the distribution of substituents along the cellulose chains occurred. Conventionally synthesized samples (in aqueous NaOH), even in the presence of a phase transfer catalyst, possess a block-wise distribution of substituents, while a dissolution of cellulose in DMSO/TBAF prior to the reaction gives products that are uniformly substituted along the cellulose chains.
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efficient allylation of cellulose in dimethyl sulfoxide Tetrabutylammonium Fluoride trihydrate
Polymer Bulletin, 2008Co-Authors: Thomas Heinze, Thorger Lincke, Dominik Fenn, Andreas KoschellaAbstract:The cellulose solvent dimethyl sulfoxide (DMSO)/Tetrabutylammonium Fluoride trihydrate (TBAF) was successfully applied as reaction medium for the synthesis of allyl cellulose by conversion of the polymer with allyl chloride in the presence of solid NaOH. Samples with degree of substitution from 0.50 to 2.98 were accessible by varying the molar ratio anhydroglucose unit:allyl chloride:NaOH and reaction time. DMSO/TBAF was found to be an efficient reaction medium for the preparation of highly functionalized samples from spruce sulfite pulp with degree of polymerization of about 500 even in a scale of 50 g. The allyl cellulose samples were characterized by means of FTIR- and NMR spectroscopy. Size exclusion chromatography revealed negligible polymer degradation during synthesis and purification of the samples.
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benzylation of cellulose in the solvent dimethylsulfoxide Tetrabutylammonium Fluoride trihydrate
Cellulose, 2005Co-Authors: Luiz Antonio Ramos, Andreas Koschella, Elisabete Frollini, Thomas HeinzeAbstract:The cellulose solvent dimethylsulfoxide/Tetrabutylammonium Fluoride trihydrate (TBAF·3 H2O) was studied as reaction medium for the synthesis of benzyl cellulose (BC) by treating the dissolved polymer with benzyl chloride in the presence of solid NaOH or aqueous NaOH solution. BC samples with degree of substitution (DS) between 0.40 and 2.85 were accessible applying different molar ratios. The studies show that both the TBAF·3 H2O concentration and the molar ratio of the reagents to repeating unit influence the DS. The solubility of the BC synthesized in a different way, however, of comparable DS is different. Structural analyses were carried out by means of FTIR-, 1H- and 13C NMR spectroscopy. SEC measurements revealed polymer aggregation in samples of low DS synthesized in a solvent containing 9.0% TBAF·3 H2O. At higher concentration of TBAF·3 H2O in the solvent, the BC samples obtained do not form aggregates. BC of high DS is crystalline and shows thermotropic liquid crystalline behavior as analyzed by means of DSC. Melting point and degradation temperature are not related to the DS.
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carboxymethylation of cellulose in the new solvent dimethyl sulfoxide Tetrabutylammonium Fluoride
Carbohydrate Polymers, 2005Co-Authors: Elisabete Frollini, Luiz Antonio Ramos, Thomas HeinzeAbstract:Abstract The new cellulose solvent dimethyl sulfoxide (DMSO)/Tetrabutylammonium Fluoride (TBAF) was applied as reaction medium for the carboxymethylation of mercerized cellulose from sisal and cotton linters. The reaction parameters studied were the molar ratio of reagent and NaOH to anhydroglucose unit (AGU) and the addition of the NaOH either as an aqueous solution or as solid particles. Size Exclusion Chromatography results (SEC) indicated that the dissolution medium and/or derivatizing method used in the present work causes a certain depolymerization on the cellulose chains The pattern of substitution within the AGU and along the polymer chains of the carboxymethylcellulose (CMC), which was analyzed by 1H NMR spectroscopy and HPLC after acidic depolymerization of the CMC, is in the order O-6>O-2≥O-3. With regard to the mole fractions of the different repeating units, samples prepared using aqueous NaOH possess a statistic content, while by using solid NaOH a deviation from statistically calculated values was observed. As a consequence of the non-statistics, the solubility in water of these samples starts at a DS 0.85, while conventionally prepared CMC are water-soluble at a DS as low as 0.4.
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studies on the homogeneous acetylation of cellulose in the novel solvent dimethyl sulfoxide Tetrabutylammonium Fluoride trihydrate
Macromolecular Bioscience, 2004Co-Authors: Beatriz A P Ass, Thomas Heinze, Elisabete FrolliniAbstract:Summary: The novel solvent dimethyl sulfoxide (DMSO)/Tetrabutylammonium Fluoride trihydrate (TBAF · 3H2O) was studied for acetylation of linters cellulose. In order to control the degree of substitution (DS), acetylation of the macromolecule was carried out at different reaction time and temperature, molar ratio of reactants, as well as under variation of the concentration of TBAF · 3H2O in solution. Cellulose acetate (CA) was accessible with DS ranging from 0.43 to 2.77. The change in concentration of TBAF · 3H2O in DMSO showed a strong influence on DS. The most appropriate reaction conditions for acetylation of linters cellulose regarding maximal DS were evaluated. The structure of the CA was characterized by means of FTIR and NMR spectroscopy. The solubility of the CA depends not only on the DS but also on the reaction conditions applied, indicating a different distribution of acetate moieties both within and between polymer chains.
Frédéric Violleau - One of the best experts on this subject based on the ideXlab platform.
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characterization of non derivatized cellulose samples by size exclusion chromatography in Tetrabutylammonium Fluoride dimethylsulfoxide tbaf dmso
Molecules, 2017Co-Authors: Jeremy Rebiere, Antoine Rouilly, Vanessa Durrieu, Frédéric ViolleauAbstract:This paper deals with the use of Tetrabutylammonium Fluoride/dimethylsulfoxide (TBAF/DMSO) to characterize the molar mass distribution of non-derivatized cellulosic samples by size exclusion chromatography (SEC). Different cellulose samples with various average degree of polymerization (DP) were first solubilized in this solvent system, with increasing TBAF rates, and then analyzed by SEC coupled to a refractive index detector (RID), using DMSO as mobile phase. The Molar Masses (MM) obtained by conventional calibration were then discussed and compared with suppliers’ data and MM determined by viscosimetry measurements. By this non-classic method, molar mass of low DP samples (Avicel® and cotton fibers) have been determined. For high DP samples (α-cellulose and Vitacel®), dissolution with TBAF concentration of 10 mg/mL involved elution of cellulose aggregates in the exclusion volume, related to an incomplete dissolution or the dilution of TBAF molecules in elution solvent, preventing the correct evaluation of their molar mass.
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Characterization of Non-Derivatized Cellulose Samples by Size Exclusion Chromatography in Tetrabutylammonium Fluoride/Dimethylsulfoxide (TBAF/DMSO)
Molecules, 2017Co-Authors: Jeremy Rebiere, Antoine Rouilly, Vanessa Durrieu, Frédéric ViolleauAbstract:This paper deals with the use of Tetrabutylammonium Fluoride/dimethylsulfoxide (TBAF/DMSO) to characterize the molar mass distribution of non-derivatized cellulosic samples by size exclusion chromatography (SEC). Different cellulose samples with various average degree of polymerization (DP) were first solubilized in this solvent system, with increasing TBAF rates, and then analyzed by SEC coupled to a refractive index detector (RID), using DMSO as mobile phase. The Molar Masses (MM) obtained by conventional calibration were then discussed and compared with suppliers’ data and MM determined by viscosimetry measurements. By this non-classic method, molar mass of low DP samples (Avicel® and cotton fibers) have been determined. For high DP samples (α-cellulose and Vitacel®), dissolution with TBAF concentration of 10 mg/mL involved elution of cellulose aggregates in the exclusion volume, related to an incomplete dissolution or the dilution of TBAF molecules in elution solvent, preventing the correct evaluation of their molar mass.
Jeremy Rebiere - One of the best experts on this subject based on the ideXlab platform.
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characterization of non derivatized cellulose samples by size exclusion chromatography in Tetrabutylammonium Fluoride dimethylsulfoxide tbaf dmso
Molecules, 2017Co-Authors: Jeremy Rebiere, Antoine Rouilly, Vanessa Durrieu, Frédéric ViolleauAbstract:This paper deals with the use of Tetrabutylammonium Fluoride/dimethylsulfoxide (TBAF/DMSO) to characterize the molar mass distribution of non-derivatized cellulosic samples by size exclusion chromatography (SEC). Different cellulose samples with various average degree of polymerization (DP) were first solubilized in this solvent system, with increasing TBAF rates, and then analyzed by SEC coupled to a refractive index detector (RID), using DMSO as mobile phase. The Molar Masses (MM) obtained by conventional calibration were then discussed and compared with suppliers’ data and MM determined by viscosimetry measurements. By this non-classic method, molar mass of low DP samples (Avicel® and cotton fibers) have been determined. For high DP samples (α-cellulose and Vitacel®), dissolution with TBAF concentration of 10 mg/mL involved elution of cellulose aggregates in the exclusion volume, related to an incomplete dissolution or the dilution of TBAF molecules in elution solvent, preventing the correct evaluation of their molar mass.
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Characterization of Non-Derivatized Cellulose Samples by Size Exclusion Chromatography in Tetrabutylammonium Fluoride/Dimethylsulfoxide (TBAF/DMSO)
Molecules, 2017Co-Authors: Jeremy Rebiere, Antoine Rouilly, Vanessa Durrieu, Frédéric ViolleauAbstract:This paper deals with the use of Tetrabutylammonium Fluoride/dimethylsulfoxide (TBAF/DMSO) to characterize the molar mass distribution of non-derivatized cellulosic samples by size exclusion chromatography (SEC). Different cellulose samples with various average degree of polymerization (DP) were first solubilized in this solvent system, with increasing TBAF rates, and then analyzed by SEC coupled to a refractive index detector (RID), using DMSO as mobile phase. The Molar Masses (MM) obtained by conventional calibration were then discussed and compared with suppliers’ data and MM determined by viscosimetry measurements. By this non-classic method, molar mass of low DP samples (Avicel® and cotton fibers) have been determined. For high DP samples (α-cellulose and Vitacel®), dissolution with TBAF concentration of 10 mg/mL involved elution of cellulose aggregates in the exclusion volume, related to an incomplete dissolution or the dilution of TBAF molecules in elution solvent, preventing the correct evaluation of their molar mass.
Luiz Antonio Ramos - One of the best experts on this subject based on the ideXlab platform.
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benzylation of cellulose in the solvent dimethylsulfoxide Tetrabutylammonium Fluoride trihydrate
Cellulose, 2005Co-Authors: Luiz Antonio Ramos, Andreas Koschella, Elisabete Frollini, Thomas HeinzeAbstract:The cellulose solvent dimethylsulfoxide/Tetrabutylammonium Fluoride trihydrate (TBAF·3 H2O) was studied as reaction medium for the synthesis of benzyl cellulose (BC) by treating the dissolved polymer with benzyl chloride in the presence of solid NaOH or aqueous NaOH solution. BC samples with degree of substitution (DS) between 0.40 and 2.85 were accessible applying different molar ratios. The studies show that both the TBAF·3 H2O concentration and the molar ratio of the reagents to repeating unit influence the DS. The solubility of the BC synthesized in a different way, however, of comparable DS is different. Structural analyses were carried out by means of FTIR-, 1H- and 13C NMR spectroscopy. SEC measurements revealed polymer aggregation in samples of low DS synthesized in a solvent containing 9.0% TBAF·3 H2O. At higher concentration of TBAF·3 H2O in the solvent, the BC samples obtained do not form aggregates. BC of high DS is crystalline and shows thermotropic liquid crystalline behavior as analyzed by means of DSC. Melting point and degradation temperature are not related to the DS.
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carboxymethylation of cellulose in the new solvent dimethyl sulfoxide Tetrabutylammonium Fluoride
Carbohydrate Polymers, 2005Co-Authors: Elisabete Frollini, Luiz Antonio Ramos, Thomas HeinzeAbstract:Abstract The new cellulose solvent dimethyl sulfoxide (DMSO)/Tetrabutylammonium Fluoride (TBAF) was applied as reaction medium for the carboxymethylation of mercerized cellulose from sisal and cotton linters. The reaction parameters studied were the molar ratio of reagent and NaOH to anhydroglucose unit (AGU) and the addition of the NaOH either as an aqueous solution or as solid particles. Size Exclusion Chromatography results (SEC) indicated that the dissolution medium and/or derivatizing method used in the present work causes a certain depolymerization on the cellulose chains The pattern of substitution within the AGU and along the polymer chains of the carboxymethylcellulose (CMC), which was analyzed by 1H NMR spectroscopy and HPLC after acidic depolymerization of the CMC, is in the order O-6>O-2≥O-3. With regard to the mole fractions of the different repeating units, samples prepared using aqueous NaOH possess a statistic content, while by using solid NaOH a deviation from statistically calculated values was observed. As a consequence of the non-statistics, the solubility in water of these samples starts at a DS 0.85, while conventionally prepared CMC are water-soluble at a DS as low as 0.4.
Takao Sakamoto - One of the best experts on this subject based on the ideXlab platform.
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selective monodesulfonylation of n n disulfonylarylamines with Tetrabutylammonium Fluoride
ChemInform, 2010Co-Authors: Akito Yasuhara, Mitsuyoshi Kameda, Takao SakamotoAbstract:The monodesulfonylation reaction of N, N-bis(methylsulfonyl)-, N, N-bis(phenylsulfonyl)-, and N, N-bis(p-tolysulfonyl)arylamines easily proceeded using Tetrabutylammonium Fluoride in tetrahydrofuran under mild conditions to give the corresponding N-monosulfonylarylamines in excellent yields.
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Convenient indole synthesis from 2-iodoanilines and terminal alkynes by the sequential Sonogashira reaction and the cyclization reaction promoted by Tetrabutylammonium Fluoride (TBAF).
Chemical & pharmaceutical bulletin, 2003Co-Authors: Naoyuki Suzuki, Sakura Yasaki, Akito Yasuhara, Takao SakamotoAbstract:The sequential Sonogashira reaction and the cyclization reaction of various 2-iodoanilines and terminal alkynes in the presence of a palladium catalyst and Tetrabutylammonium Fluoride (TBAF) gave the corresponding 2-substituted indoles in good yields.
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a concise synthesis of furostifoline by Tetrabutylammonium Fluoride promoted indole ring formation
ChemInform, 2002Co-Authors: Akito Yasuhara, Naoyuki Suzuki, Takao SakamotoAbstract:Furostifoline, a furo[3,2-a]carbazole alkaloid, was synthesized in 10% overall yield in four steps from 2-acetyl-3-bromofuran. The key step of this synthesis was the 2-substituted indole formation with Tetrabutylammonium Fluoride (TBAF) from 2-(2-propenyl)-3-((2-ethoxycarbonylamino)phenylethynyl)furan, which was easily prepared from ethyl 2-ethynylphenylcarbamate with 3-bromo-2-(2-propenyl)furan by the Sonogashira reaction.
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total syntheses of three natural products vignafuran 2 4 hydroxy 2 methoxyphenyl 6 methoxybenzofuran 3 carboxylic acid methyl ester and coumestrol from a common starting material
ChemInform, 2001Co-Authors: Kou Hiroya, Naoyuki Suzuki, Akito Yasuhara, Yuya Egawa, Atsushi Kasano, Takao SakamotoAbstract:Vignafuran 2, 2-(4-hydroxy-2-methoxyphenyl)-6-methoxybenzofuran-3-carboxylic acid methyl ester 3, and coumestrol 4 were efficiently synthesized from the same starting material, 4-bromoresorcinol 14a, through the common intermediate, diarylacetylene 7. The key steps of these syntheses were the Tetrabutylammonium Fluoride (TBAF)-catalyzed benzo[b]furan ring formation for 2 and the carbonylative ring closure methodology catalyzed by a Pd complex for 3 and 4.
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convenient synthesis of 2 substituted indoles from 2 ethynylanilines with Tetrabutylammonium Fluoride
Journal of The Chemical Society-perkin Transactions 1, 1999Co-Authors: Akito Yasuhara, Yuichi Kanamori, Masashi Kaneko, Atsushi Numata, Yoshinori Kondo, Takao SakamotoAbstract:The cyclization reaction of various 2-ethynylanilines, which were easily synthesized from 2-haloanilines by the palladium-catalyzed reaction with terminal alkynes, with Tetrabutylammonium Fluoride (TBAF) to yield 2-substituted indoles proceeded at refluxing or room temperature in THF in excellent yields without affecting the bromo, chloro, cyano, ethoxycarbonyl, and ethynyl groups.