Direct Formation of Pinacols from Olefins over Various Titano–Silicates

Sasidharan, Manickam; Wu, Peng; Tatsumi, Takashi

doi:10.1006/jcat.2002.3595

Cited by 14 publications

(4 citation statements)

References 16 publications

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“…In addition, excess of NaOH also leads to cleavage of epoxide ring to diols by base-catalyzed mechanism. 53 The optimum pH for epoxidation was found to be in the range of 8.5−9.0 for the formation of epoxide.…”

Section: ■ Results and Discussionmentioning

confidence: 95%

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Novel and Mild Synthetic Strategy for the Sulfonic Acid Functionalization in Periodic Mesoporous Ethenylene-Silica

Sasidharan

Bhaumik

2013

ACS Appl. Mater. Interfaces

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A new postsynthetic method has been developed for sulfonic acid functionalization of hybrid periodic mesoporous organosilica (PMO) materials containing carbon-carbon double bonds (-C═C-) located in mesoporous wall structures. Hexagonal mesoporous ethenylene-silicas (HME) with different pore sizes were synthesized by using P123, Brij76, and Brij56 surfactants and investigated for postsynthetic functionalization. The present functionalization strategy involves epoxidation of double bonds at -5 °C followed by conversion of the resulting epoxide with bisulfite ions at 65 °C and involves neither the use of well-known mercaptol/H2O2 nor harsh concentrated H2SO4 reagents during the course of -C═C- functionalization. The epoxidation step plays a crucial role in determining the amount of -SO3H groups functionalized onto the silica support which is optimized with respect to different synthesis parameters. The ethenylene-silicas both before and after chemical modification were thoroughly characterized by powder XRD, TEM, N2 adsorption, Raman spectroscopy, 13C and 29Si MAS NMR, and catalytic test reactions. X-ray powder diffraction measurements and sorption data indicated that the mesostructure was intact during the postsynthetic chemical modification. Raman spectra exhibited two strong bands at 1567 and 1290 cm(-1) for ethenylene-silica attributed to -C═C and -C-H stretching vibrations, respectively; whereas after epoxidation and sulfonation, new bands were observed at 1215 and 1035 cm(-1) corresponding to the epoxide and -SO3 stretching vibrations, respectively. 13C CP MAS NMR of surfactant extracted ethenylene-silica exhibits a signal at 146 ppm along with signals at 16.4 and 17.4 ppm. The appearance of new signals at 47.7 and 46.5 ppm is attributed to carbon atom with ≡C-OH and ≡C-SO3H groups, respectively. 29Si MAS NMR spectra exclusively showed T2 and T3 species at -73 and -82 ppm, respectively both before and after chemical modification and negligible amount of Q3 or Q4 species confirms the stability of Si-C bonds during the functionalization. The sulfonic acid-functionalized mesoporous ethenylene-silicas show high catalytic activity in esterification of acetic acid with ethanol under liquid-phase reaction conditions.

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Section: ■ Results and Discussionmentioning

confidence: 95%

“…The use of pH below 8 fails to accelerate the nucleophilic oxidative epoxidation50 under the reaction conditions. In addition, excess of NaOH also leads to cleavage of epoxide ring to diols by base-catalyzed mechanism . The optimum pH for epoxidation was found to be in the range of 8.5–9.0 for the formation of epoxide.…”

Section: Resultsmentioning

confidence: 98%

Novel and Mild Synthetic Strategy for the Sulfonic Acid Functionalization in Periodic Mesoporous Ethenylene-Silica

Sasidharan

Bhaumik

2013

ACS Appl. Mater. Interfaces

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“…However, hydrogen peroxide alone exhibits a weak oxidative ability and a catalytic activation is required to realize its full potential. In this context, the dihydroxylation of olefins with hydrogen peroxide catalyzed by homogeneous transition metal complexes has been reported . Although homogeneous catalysts display favorable catalytic abilities, heterogeneous catalysts are of significant industrial interest since they can be easily separated from the reaction mixture and recycled.…”

Section: Introductionmentioning

confidence: 99%

Peroxophosphotungstate held in an ionic liquid brush: an efficient and reusable catalyst for the dihydroxylation of olefins with H₂O₂ in neat water

Wang

Liu

Dong

et al. 2014

Applied Organom Chemis

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A reusable heterogeneous catalytic assembly of [PO4{WO(O2)2}4]3− held in an ionic liquid brush was synthesized and an environmentally friendly procedure was developed for the dihydroxylation of several olefins with 30 wt% H2O2. These reactions were conducted in neat water under mild conditions without any organic co‐solvent or other additive. Several factors that affect the dihydroxylation were investigated in detail. The catalyst is easily recovered after the reaction via simple filtration, and can be reused at least eight times without a noticeable loss of activity. The experimental results demonstrate that this dihydroxylation process has no apparent scale‐up effect. Copyright © 2014 John Wiley & Sons, Ltd.

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“…Terpenes are widely distributed in nature and their epoxides often serve as starting materials for the synthesis of fragrances, flavors and therapeutically active substances [10]. In this way, one can design the required product by taking advantage of the highly reactive oxirane ring (epoxides) and choosing the right conditions to promote reactions, such as isomerization, condensation and nucleophilic substitution [11]. One of these terpenes is the limonene, extracted from citrus oil.…”

Section: Introductionmentioning

confidence: 99%

Ti-MCM-41 silylation: Development of a simple methodology for its estimation

Cagnoli

Casuscelli²,

Álvarez

et al. 2005

Catalysis Today

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Direct Formation of Pinacols from Olefins over Various Titano–Silicates

Cited by 14 publications

References 16 publications

Novel and Mild Synthetic Strategy for the Sulfonic Acid Functionalization in Periodic Mesoporous Ethenylene-Silica

Novel and Mild Synthetic Strategy for the Sulfonic Acid Functionalization in Periodic Mesoporous Ethenylene-Silica

Peroxophosphotungstate held in an ionic liquid brush: an efficient and reusable catalyst for the dihydroxylation of olefins with H₂O₂ in neat water

Ti-MCM-41 silylation: Development of a simple methodology for its estimation

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Direct Formation of Pinacols from Olefins over Various Titano–Silicates

Cited by 14 publications

References 16 publications

Novel and Mild Synthetic Strategy for the Sulfonic Acid Functionalization in Periodic Mesoporous Ethenylene-Silica

Novel and Mild Synthetic Strategy for the Sulfonic Acid Functionalization in Periodic Mesoporous Ethenylene-Silica

Peroxophosphotungstate held in an ionic liquid brush: an efficient and reusable catalyst for the dihydroxylation of olefins with H2O2 in neat water

Ti-MCM-41 silylation: Development of a simple methodology for its estimation

Contact Info

Product

Resources

About

Peroxophosphotungstate held in an ionic liquid brush: an efficient and reusable catalyst for the dihydroxylation of olefins with H₂O₂ in neat water