- Microwave rehydrated Mg-Al-LDH as base catalyst for the acetalization of glycerol
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Acetalization of glycerol with aldehydes to form cyclic acetals is an industrially important reaction and is generally carried out using acid catalysts. Base catalysts such as LDH can bring about microwave-assisted acetalization of glycerol and aldehydes to form 5-membered and 6-membered cyclic acetals. Among the different LDHs used, Mg-Al-LDH was found to exhibit maximum conversion of glycerol into 5-membered cyclic acetal. Modification of Mg-Al-LDH involving calcination at 450°C and subsequent microwave-assisted rehydration showed improved glycerol conversion rate under similar reaction conditions. Rehydration of calcined Mg-Al-LDH by microwave irradiation was found to result in LDH regaining its layered structure with higher basicity possibly exposing more hydroxyl ions responsible for basicity. Multiple use of methanol washed spent catalyst showed good repeatability for conversion up to three cycles which subsequently showed a marginal decrease in the conversion. Further dehydration followed by rehydration of the spent LDH catalyst under microwave irradiation was found to rejuvenate the catalytic activity to its initial level.
- Prakruthi,Chandrashekara,Jai Prakash,Bhat
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- Sustainable valorisation of glycerol via acetalization as well as carboxylation reactions over silicotungstates anchored to zeolite Hβ
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A simple, green and effective pathway towards valorisation of glycerol to value added products has been demonstrated. In this context, catalysts comprising parent as well as lacunary silicotungstates anchored to large pore zeolite Hβ have been synthesized and characterized by various physicochemical methods. Parent silicotungstic acid based catalyst proved to be better catalyst in terms of conversion of glycerol showing 73% conversion for carboxylation reaction and 97% conversion of glycerol towards acetalization reaction. The better activity of the catalyst was correlated with its strong acidic character. It was observed that by tuning the acidity of parent silicotungstate by formation of lacunary silicotungstate leads to the increase in the selectivity of 5-membered dioxolane from 68% to 78% and selectivity of glycerol carbonate from 72% to 75%. Both the catalysts were reusable up to four cycles under the investigated reaction conditions. The probable mechanisms for both the reactions are also discussed.
- Narkhede, Nilesh,Patel, Anjali
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- Glycerol acetals and ketals as bio-based solvents: Positioning in Hansen and COSMO-RS spaces, volatility and stability towards hydrolysis and autoxidation
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Four recently launched cyclic glycerol acetals or ketals are evaluated as bio-based solvents. Three of them are industrially available and result from the condensation of glycerol with formaldehyde, acetone and isobutyl methyl ketone. The fourth is under development and is prepared by the reaction of glycerol with benzaldehyde under heterogeneous acidic catalysis. Their solvent properties are evaluated through Hansen and COSMO-RS (COnductor-like Screening MOdel for Real Solvents) approaches, in comparison with traditional petrochemical solvents. Dioxolane- and dioxane-type isomers have close solubility parameters; however the nature of the starting aldehyde/ketone significantly impacts the solvency properties. The stability to hydrolysis depends heavily on both the aldehyde/ketone part and on the size of the ring. In acidic medium, acetals are found to be more stable than ketals and glycerol-based ketals are more stable than ethylene glycol-based ketals. In the case of benzaldehyde glycerol acetal, it is shown that the 6-membered ring isomer (dioxane-type) is approximately 8 times more stable than the 5-membered ring counterpart (dioxolane-type) at low pH. Stability towards autoxidation by O2 is high for formaldehyde and acetone-derived acetals and drops for the other two compounds. Glycerol acetals and ketals are promising potential alternatives to some harmful solvents such as glycol ethers and aniline. This journal is
- Moity, Laurianne,Benazzouz, Adrien,Molinier, Valérie,Nardello-Rataj, Véronique,Elmkaddem, Mohammed Kamal,De Caro, Pascale,Thiébaud-Roux, Sophie,Gerbaud, Vincent,Marion, Philippe,Aubry, Jean-Marie
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- One-step synthesis of solid sulfonic acid catalyst and its application in the acetalization of glycerol: Crystal structure of cis-5-hydroxy-2-phenyl-1,3- dioxane trimer
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A one-pot method was employed to immobilize sulfonic acid onto silica obtained from rice husk ash using 3-(mercaptopropyl)trimethoxysilane to form a solid catalyst denoted as RHASO3H. BET measurements of the catalyst showed the surface area to be 340 m2 g-1 with the average pore volume of 0.24 mL g-1 and the pore diameter of 2.9 nm. Acidity test of cation exchange capacity and pyridine adsorption studies revealed the presence of Bronsted acid sites on the catalyst surface. The catalyst was used in the acetalization reaction of glycerol with benzaldehyde. Under optimized conditions, the reaction showed the maximum conversion of 78 % after 8 h with 67 % selectivity towards the five membered ring isomer. Variation in the glycerol concentration had a significant effect on the reactants conversion. A single crystal X-ray study of one of the products proved the existence of a unique trimer formed by hydrogen bonding by the six-membered cis-isomer. The catalyst was several times recycled without any loss of its catalytic activity.
- Adam, Farook,Batagarawa, Muazu Samaila,Hello, Kasim Mohammed,Al-Juaid, Salih S.
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- Low temperature synthesis of bio-fuel additives via valorisation of glycerol with benzaldehyde as well as furfural over a novel sustainable catalyst, 12-tungstosilicic acid anchored to ordered cubic nano-porous MCM-48
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The present article demonstrates designing of novel catalyst, 12-tungstosilicic acid (TSA) anchored to ordered nano-porous MCM-48 (nMCM-48); TSA/nMCM-48, characterization and evaluation for synthesis of bio-fuel additives via glycerol valorisation with aromatic aldehydes. The nanopores of support were confirmed by BET and TEM while the interaction between TSA and nMCM-48 was confirmed by decrease in the surface area and pore volume of the catalysts. Assessment of vital reaction parameters (% loading of active species, mole ratio of reactants, catalyst amount, temperature and time) were performed to achieve maximum conversion of glycerol. The catalyst showed noteworthy performance at 30 °C towards conversion (>85 %) and thermodynamically stable dioxane derivative (>60 %) with remarkable TON (5945 for benzaldehyde and 7355 for furfural). The catalyst was regenerated and used for successive four catalytic runs with almost same activity. The superiority of novel catalyst is because of its geometry and nano porosity.
- Patel, Anjali,Pithadia, Dhruvi
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- Modified boehmite: A choice of catalyst for the selective conversion of glycerol to five-membered dioxolane
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The choice of the active site and support matrix decides the activity of a catalyst. Any modifications on these will have a significant impact on the reactivity and selectivity of the catalyst. Here, we have synthesised WO3-loaded boehmite and applied it for the acetalization of a biomass-derived bulk chemical, glycerol. The well-characterized acid catalyst exhibits a selective acetalization of glycerol with good conversions into a five-membered dioxolane product. The cyclability of the catalyst up to six times along with the retention of the catalytic activity ensures the heterogeneity of the material.
- Barik, Manas,Chinnaraja, Eswaran,Dabas, Shilpa,Mishra, Jyotiranjan,Subramanian, Palani S.,Subramanian, Saravanan
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p. 695 - 703
(2022/01/22)
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- The Chiral Target of Daptomycin Is the 2R,2′S Stereoisomer of Phosphatidylglycerol
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Daptomycin (dap) is an important antibiotic that interacts with the bacterial membrane lipid phosphatidylglycerol (PG) in a calcium-dependent manner. The enantiomer of dap (ent-dap) was synthesized and was found to be 85-fold less active than dap against
- Moreira, Ryan,Taylor, Scott D.
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supporting information
(2021/12/09)
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- Preparation method of glycerol formal
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The invention discloses a preparation method of benzaldehyde glycerol acetal. The method adopts a solid catalyst composed of phosphomolybdic acid anions and polymeric ionic liquid cations to catalyzethe reaction of benzaldehyde and glycerol, and due to the fine adjustment of acid-base sites, the yield of benzaldehyde glycerol acetal prepared through the method reaches 95%, and meanwhile, the six-membered ring acetal has specific selectivity.
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Paragraph 0051-0058
(2021/07/21)
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- High-efficacy glycerol acetalization with silica gel immobilized Br?nsted acid ionic liquid catalysts - Preparation and comprehending the counter-anion effect on the catalytic activity
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Imidazolium sulfonate zwitterions (ZIs) with unconventional counter-anions were used to fabricate a series of mesoporous silica-gel-immobilized Br?nsted acid ionic liquid (SG@BAIL) nanocatalysts. In comparison to traditional heterogeneous catalysts, these immobilised heterogeneous catalysts have the advantage of ionic-liquid acidic sites and the advantage of solid silica gel as a support, increasing their catalytic activities. The catalysts were analysed using a series of physicochemical techniques and their catalytic efficiencies were evaluated during the acetalization of glycerol (G) with benzaldehyde (B). The influence of the counter-anions present in the SG@BAIL catalysts was initially investigated in terms of the percentage conversion vs. the reaction time at a particular temperature. Furthermore, different parametric studies relating to the acetalization reaction were carried out based on the catalyst with the maximum activity. SG-[C3ImC3SO3H][OTf] was observed to have the highest catalytic performance and durability during ecofriendly acetal synthesis, with the highest selectivity for 1,3-dioxane. Parametric studies of the acetalization reaction were carried out, and the catalyst showed noteworthy performance at 90 °C, showing 94% conversion in an equimolar reactant mixture under solvent-free conditions with 0.03 wt% catalyst loading in a short time span of 75 min. In addition, kinetics modelling was performed using reversible second-order kinetics to calculate the forward rate constants at various temperatures. The activation energy of the reaction was determined using the Arrhenius equation, and the overall activation energy was 69.33 kJ mol-1. These investigations have demonstrated the excellent potential of SG@BAIL catalysts for practical application in the glycerol acetalization process.
- Shashni, Shalini,Singh, Vasundhara,Toor, Amrit Pal
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p. 21807 - 21823
(2021/12/09)
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- Structure–Activity Relationships of WOx-Promoted TiO2–ZrO2 Solid Acid Catalyst for Acetalization and Ketalization of Glycerol towards Biofuel Additives
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Abstract: WOx-promoted TiO2–ZrO2 solid acid catalyst was prepared and applied in the catalytic acetalization and ketalization of glycerol with carbonyl compounds to produce biofuel additives. The presence of WOx promoter and TiO2 remarkably improved the catalytic activity of ZrO2. Approximately, 100% glycerol conversion was evidenced with non-bulky aliphatic aldehydes and ketones like, propanol and cyclohexanone. The physical characterization of WOx-promoted TiO2–ZrO2, revealed a higher formation of tetragonal crystalline phase of ZrO2, over monoclinic. The total surface acidity and the ratio of Br?nsted to Lewis acidic site concentrations were determined by NH3-TPD and pyridine-chemisorbed FTIR spectroscopy, respectively. A considerably higher concentration of Lewis acidic sites, ~ 213.29?μmol/gm, was evidenced on the WOx-promoted TiO2–ZrO2 catalyst surface. Catalytic activity study revealed a direct correlation between the surface Lewis acidic site concentration and the activity of catalyst. This significant observation indicated the key role of Lewis acidic sites in this catalytic process. The WOx-promoted TiO2–ZrO2 catalyst was also considerably stable and showed good performance in the acetalization/ketalization of glycerol with other substituted carbonyl compounds. Graphic Abstract: The WOx-promoted TiO2–ZrO2 solid acid catalyst exhibits superior catalytic performance for acetalization and ketalization of glycerol with carbonyl compounds to produce biofuel additives. [Figure not available: see fulltext.].
- Baithy, Mallesham,Mukherjee, Deboshree,Rangaswamy, Agolu,Reddy, Benjaram M.
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- A green approach for the preparation of a surfactant embedded sulfonated carbon catalyst towards glycerol acetalization reactions
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The green synthesis of heterogeneous catalysts often requires a solid-state reaction pathway. In this work, a cationic surfactant (CTAB) embedded sulfonated carbon catalyst was prepared via a sustainable route with the aim of having controlled surface hydrophobicity and acidity for glycerol acetalization reactions. The main objective of this study was to tune the hydrophobicity and acidic site density, either via adding a cationic surfactant or changing the carbon to sulphur ratio. The as-synthesized catalyst was characterized via XRD, N2 adsorption/desorption, SAXS, FESEM, FTIR, pyridine-IR, high-temperature DR-FTIR, TGA, 13C-NMR, Raman, and XPS techniques. The incorporation of a cationic surfactant (CTAB) reduces the surface area but increases the acidic site density to a greater extent. The bonding between the surfactant (CTAB) and surface hydroxyl groups was elucidated via XPS analysis. DR-FTIR studies implied that the -SO3H groups are strongly bonded to the carbon network, while the lower amount of water mass loss seen from TGA studies showed the substantial improvement in surface hydrophobicity after modification with the surfactant. Moreover, the combination of acidic site density and hydrophobicity played a key role in attaining around 90% glycerol conversion and 98% solketal selectivity under ambient conditions. Notably, characterization of the used catalyst revealed that the loss of activity is mainly related to a drop in hydrophobicity, which occurs due to the loss of surfactant during washing with methanol.
- Auroux, Aline,Chowdhury, Biswajit,Das, Avik,Ghosh, Anindya,Sen, Debasis,Singha, Aniruddha
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p. 4827 - 4844
(2020/08/21)
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- Glycerol conversion to high-value chemicals: The implication of unnatural α-amino acid syntheses using natural resources
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Glycerol derivatives are an important class of compounds, which have great applications as basic structural building blocks in organic synthesis. O-Benzylglycerol was oxidised to produce a high-value compound in high yield using a NaOtBu-O2 system. Furthermore, the synthetic utility of the resulting product was demonstrated by its transformation into unnatural α-amino acids, thus showing the valorisation of glycerol biomass.
- Park, Yun Ji,Yang, Jung Woon
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supporting information
p. 2615 - 2620
(2019/06/03)
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- Method for industrially producing benzaldehyde glyceryl acetal
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The invention discloses a method for industrially producing benzaldehyde glyceryl acetal. The benzaldehyde glyceryl acetal is synthesized by using a strong acid cation exchange resin and a Lewis acidas catalysts, and the addition of the Lewis acid activates the aldehydic carbonyl group of benzaldehyde. The method has the advantages of low reaction temperature, high activity of the catalysts, no introduction of new water-carrying agents, short reaction time, high glycerin conversion rate reaching 92% or above, and realization of the product yield being 85% or above.
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Paragraph 0029-0034
(2019/05/15)
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- Acetalization of glycerol with ketones and aldehydes catalyzed by high silica Hβ zeolite
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In this work, proton-exchanged *BEA zeolite with a high Si/Al ratio of 75 (Hβ-75), was demonstrated as an effective catalyst for the acetalization of glycerol with carbonyl compounds. This catalyst system was applicable to various substrates and reusable for at least 4 times with slight decrease in activity. The turnover frequency, based on acid site concentration, increased as a function of Hβ Si/Al ratio, indicating the importance of the zeolite hydrophobic surface properties. The origin of the high efficiency exhibited by Hβ-75 is quantitatively discussed based on kinetic studies, hydrophobicity, and acid site concentration.
- Poly, Sharmin Sultana,Jamil, Md.A.R.,Touchy, Abeda S.,Yasumura, Shunsaku,Siddiki, S.M.A. Hakim,Toyao, Takashi,Maeno, Zen,Shimizu, Ken-ichi
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- Mesoporous tin oxide: An efficient catalyst with versatile applications in acid and oxidation catalysis
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Mesoporous tin oxide was prepared by template assisted and template-free methods. As-prepared materials were calcined at various temperatures to generate different nature (Br?nsted and Lewis), amount and strength of acidic sites. The physico-chemical properties of the catalysts were studied by XRD, N2 sorption, pyridine-FTIR, NH3-TPD, DRS UV-vis, TGA, SEM, TEM, 1H MAS and 119Sn MAS NMR analyses. The catalytic behavior of mesoporous tin oxide catalysts was evaluated for acetalization and ketalization of glycerol with benzaldehyde and acetone respectively under solvent free conditions. The catalytic performance of mesoporous tin oxide was compared with that of other conventional solid acid catalysts namely H-ZSM-5, H-mordenite, H-beta, Al-MCM-41, Al-SBA-15 and Al-TUD-1. The efficiency of mesoporous tin oxide was also tested for cyclohexene epoxidation reaction. The catalyst prepared by template assisted method showed excellent catalytic performance compared to other catalysts due the difference in nature and amount of acidic sites in the catalyst. Meso-SnO2-T-350 was stable and reusable catalyst for four cycles without any appreciable loss in activity, and therefore it offers a good catalyst for potentially wide applications.
- Manjunathan, Pandian,Marakatti, Vijaykumar S.,Chandra, Prakash,Kulal, Atul B.,Umbarkar, Shubhangi B.,Ravishankar, Raman,Shanbhag, Ganapati V.
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- Stable Zero-Valent Nickel Nanoparticles in Glycerol: Synthesis and Applications in Selective Hydrogenations
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Small (mean diameter, ca. 1.2 nm) and well-dispersed zero-valent nickel nanoparticles (NiNPs) stabilized by cinchona-based alkaloids and TPPTS (tris(3-sulfophenyl)phosphine trisodium salt), were synthesized from the organometallic precursor [Ni(cod)2] in neat glycerol under hydrogen pressure. NiNPs were fully characterized ((HR)-TEM, EDX, XPS, XRD, IR, magnetization), both at solid state and directly from the corresponding colloidal solutions in glycerol due to its negligible vapour pressure. NiNPs dispersed in glycerol were applied in hydrogenation reactions, in particular in semihydrogenation of alkynes to give (Z)-alkenes under satisfactory conditions (3 bar H2, 1 mol% Ni, 100 °C), showing remarkable activity and selectivity. The catalytic phase was recycled at least ten times without loss of activity, affording in each case metal-free organic products. Other functional groups such as nitro, nitrile and formyl groups were efficiently hydrogenated to the corresponding anilines, benzylamines and benzylalcohols respectively (77–95% yields). (Figure presented.).
- Reina, Antonio,Favier, Isabelle,Pradel, Christian,Gómez, Montserrat
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supporting information
p. 3544 - 3552
(2018/08/01)
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- New technology for synthesizing 1,3-propylene glycol from glycerin through dehydroxylation method
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The invention discloses a new technology for synthesizing 1,3-propylene glycol from glycerin through a dehydroxylation method. The technology comprises the following steps: protecting two hydroxyl groups at the head end and the tail end of a glycerin molecule through using a group protection process, converting a hydroxyl group in the middle of the molecule into a group easy to eliminate, that is a sulfonyloxy group, removing hydroxyl group protection groups, and reducing the sulfonyloxy in the presence of a catalyst in order to obtain the 1,3-propylene glycol product. The technology has the characteristics of few byproducts, easiness in separation, and low cost, is a route with environmentally-friendly and economic dual values, and has wide development prospect.
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Paragraph 0017; 0018
(2017/05/12)
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- Graphene-promoted acetalisation of glycerol under acid-free conditions
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Serendipity led us to unveil unexpected and uncovered properties of graphene for the acetalisation of glycerol with both aldehydes and ketones, furnishing an acid-free process for fuel bio-additive candidates. Mechanistic studies ruled out the intervention of residual acidic species or metallic cations at the surface of graphene, and therefore, the peculiar electronic properties of graphene are most probably responsible for this unforeseen reactivity. Recycling studies revealed the robustness of graphene under the experimental conditions since only a marginal erosion of the reaction yield was observed after six cycles.
- Oger, Nicolas,Lin, Yuting F.,Le Grognec, Erwan,Rataboul, Franck,Felpin, Fran?ois-Xavier
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p. 1531 - 1537
(2016/04/04)
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- Clay catalysed rapid valorization of glycerol towards cyclic acetals and ketals
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Biodiesel production usually results in a huge amount of glycerol, raising a critical need to transform it into high value products. The present study highlights that solvent-free, conventional thermal activation, and non-conventional microwave/ultrasonic activation in the liquid phase are able to selectively transform glycerol into cyclic acetals and ketals using an optimised acid activated clay catalyst. Several parameters for the acid activation of bentonite clay were optimized under mild reaction conditions with a high concentration of clay (6%) and varying the acid concentration in the range of 6 to 15 N. The acid-activated clay samples were characterized by XRD, FT-IR, BET, and XRF analysis. The active sites of the catalyst were examined by volumetric titration and confirmed by pyridine adsorbed FT-IR and advanced NH3-TPD analyses. The activation performed at relatively mild conditions, i.e.; 6 N H2SO4 and 6% w/v clay, reproducibly resulted in an improved surface area (180 m2 g-1) and surface acidity (23 mg KOH g-1), with superior quantitative Br?nsted and Lewis acidic sites. Moreover, the eco-friendly process involving a catalyst, microwave, or ultra-sonication were successfully utilized to achieve a commercially valuable hyacinth fragrance, in addition to furan-based fuel additive precursors exhibiting a high conversion of glycerol and excellent selectivity within much less activation time (2 min).
- Pawar, Radheshyam R.,Gosai, Kalpeshgiri A.,Bhatt, Adarsh S.,Kumaresan,Lee, Seung Mok,Bajaj, Hari C.
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p. 83985 - 83996
(2015/10/28)
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- Room temperature acetalization of glycerol to cyclic acetals over anchored silicotungstates under solvent free conditions
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Heterogeneous catalysts comprising of parent Keggin type silicotungstate as well as monolacunary silicotungstate anchored to MCM-41 were synthesized and characterized by several physicochemical methods. A solvent free green route towards valorisation of glycerol via acetalization with benzaldehyde has been proposed. Both the catalysts showed very good activity as well as selectivity towards dioxolane derivatives within a short reaction time and at room temperature. The tuning of the acidity of the parent silicotungstate leads to an increase in the selectivity towards 1,3-dioxolane. The catalysts were also recycled up to four times without any significant loss in the conversion. The excellent performance of these mesoporous catalysts is attributed to their combination of acidity, wide pores and large specific surface area. the Partner Organisations 2014.
- Narkhede, Nilesh,Patel, Anjali
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p. 19294 - 19301
(2014/05/20)
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- Al-SBA-15 catalysed cross-esterification and acetalisation of biomass-derived platform chemicals
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Al-SBA-15 exhibited excellent catalytic activities in acid-catalysed glycerol transformation including esterification and acetalisation reactions. Quantitative conversion and good selectivities to mono- and diacetylglycerides could be obtained in the esterification of glycerol with levulinic acid. The catalyst also proved to be very effective in the acetalisation of glycerol with aldehydes and acetone, with an interesting selectivity switch from the 6-membered acetal (using paraformaldehyde as an aldehyde source) to a 5-membered acetal (when benzaldehyde or furfural was employed). Al-SBA-15 materials were also proved to be highly stable and reusable in most glycerol transformations under the investigated reaction conditions.
- Gonzalez-Arellano, Camino,Arancon, Rick A. D.,Luque, Rafael
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p. 4985 - 4993
(2015/01/08)
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- Selective glycerol transformations to high value-added products catalysed by aluminosilicate-supported iron oxide nanoparticles
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Conversion of glycerol to cyclic acetals (with paraformaldehyde, benzaldehyde, furfural and acetone) and to mono-, di- and triacetylglycerides (with levulinic acid) was investigated using a supported iron oxide nanoparticle system of a mesoporous aluminosilicate heterogeneous catalyst (Fe/Al-SBA-15). The effect of various parameters on the reaction, temperature, mol% of catalyst or ratio of glycerol:substrate were studied. An optimization of the reaction conditions carried out with glycerol by means of experimental design methodology showed that a very high glycerol conversion (99%) and high combined selectivity toward di- and triacetylglycerides could be obtained under optimized conditions. All of the acetalisation reactions carried out at 100 °C also gave good to excellent conversions and selectivities to target products, illustrating the potential of Fe/Al-SBA-15 as a highly active, stable and reusable heterogeneous catalyst in glycerol acid-catalysed transformations.
- Gonzalez-Arellano, Camino,De, Sudipta,Luque, Rafael
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p. 4242 - 4249
(2015/01/09)
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- Highly mesoporous single-crystalline zeolite beta synthesized using a nonsurfactant cationic polymer as a dual-function template
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Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules.
- Zhu, Jie,Zhu, Yihan,Zhu, Liangkui,Rigutto, Marcello,Van Der Made, Alexander,Yang, Chengguang,Pan, Shuxiang,Wang, Liang,Zhu, Longfeng,Jin, Yinying,Sun, Qi,Wu, Qinming,Meng, Xiangju,Zhang, Daliang,Han, Yu,Li, Jixue,Chu, Yueying,Zheng, Anmin,Qiu, Shilun,Zheng, Xiaoming,Xiao, Feng-Shou
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supporting information
p. 2503 - 2510
(2014/03/21)
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- Synthesis and characterization of chrysanthemic acid esters
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A short and convenient synthesis for a series of novel chrysanthemic acid esters from aldehyde and chrysanthemic acid is reported.
- Ding, Qingwei,Li, Yonghong,Zhang, Mingang
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experimental part
p. 2881 - 2883
(2012/08/29)
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- Rapid access to structured triacylglycerols acylated with n-3 polyunsaturated fatty acids for nutritional applications
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In order to better understand the metabolic fate of n-3 polyunsaturated fatty acids (PUFAs), an efficient access to symmetrical and unsymmetrical triacylglycerols (TGs), esterified with PUFAs, with known high purity, is required. In this context, we optimized the esterification of a mixture of glycerols protected as dioxane and dioxolane with PUFAs. The kinetics of this reaction depends on various factors, such as the fatty acid chain length and the stereochemistry of the dioxane. Then, one-pot acetal hydrolysis and esterification of hydroxyl groups led to the desired structured TGs without either double bond isomerization or acyl migration (except when symmetrical TGs are acylated with long-chain saturated fatty acids in external positions). PUFAs location on the glycerol backbone was assayed by NMR, HPLC and pancreatic lipase hydrolysis.
- Vaique, Emilie,Guy, Alexandre,Couedelo, Leslie,Gosse, Isabelle,Durand, Thierry,Cansell, Maud,Pinet, Sandra
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supporting information; body text
p. 8872 - 8879
(2011/01/04)
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- Metal organic frameworks as solid acid catalysts for acetalization of aldehydes with methanol
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Room temperature acetalization of aldehydes with methanol has been carried out using metal organic frameworks (MOFs) as solid heterogeneous catalysts. Of the MOFs tested, a copper-containing MOF [Cu3(BTC)2] (BTC=1,3,5-benzenetricarboxylate) showed better catalytic activity than an iron-containing MOF [Fe(BTC)] and an aluminium containing MOF [Al 2(BDC)3] (BDC=1,4-benzenedicarboxylate). The protocol was validated for a series of aromatic and aliphatic aldehydes and used to protect various aldehydes into commercially important acetals in good yields without the need of water removal. In addition, the reusability and heterogeneity of this catalytic system was demonstrated. The structural stability of MOF was further studied by characterization with powder X-ray diffraction, Brunauer-Emmett- Teller surface area measurements and Fourier-transformed infrared spectroscopic analysis of a deactivated catalyst used to convert a large amount of benzaldehyde. The performance of copper MOF as acetalization catalyst compares favourably with those of other conventional homogeneous and heterogeneous catalysts such as zinc chloride, zeolite and clay. Copyright
- Dhakshinamoorthy, Amarajothi,Alvaro, Mercedes,Garcia, Hermenegildo
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scheme or table
p. 3022 - 3030
(2011/02/24)
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- Dehydrogenation of glycerol to dihydroxyacetone catalyzed by iridium complexes with P-N ligands
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The chemoselective dehydrogenation of glycerol was catalyzed by organoiridium derivatives of the type [HIr(cod)L] (cod = 1,5-cyclooctadiene; L = Prn-N(CH2CH2PPh2)2, Et2NCH2CH2N(CH2CH 2PPh2)2, o-Me2NC6H 4PPh2) using hydrogen acceptors such as acetophenone, cyclohexanone, styrene and benzaldehyde. The catalytic reactions were performed in the absence of a basic cocatalyst in order to avoid decomposition of the desired product, i.e. dihydroxyacetone. Acceptor-less dehydrogenation was also observed either in the absence of a hydrogen acceptor, or as a parallel route, when the reaction was performed in the presence of acetophenone. The Royal Society of Chemistry 2010.
- Crotti, Corrado,Kaspar, Jan,Farnetti, Erica
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experimental part
p. 1295 - 1300
(2010/10/05)
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- Investigations on heterogeneously catalysed condensations of glycerol to cyclic acetals
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The acid-catalysed condensation of glycerol, a chemical from renewable materials, with benzaldehyde, formaldehyde, acetone (acetalisation), and their dimethyl acetals (transacetalisation) to mixtures of [1,3]dioxan-5-ols and [1,3]dioxolan-4-yl-methanols was investigated. Various solid acids were evaluated as heterogeneous catalysts for the desired glycerol conversion into these potential novel platform chemicals. [1,3]dioxan-5-ols are of particular interest as precursors for 1,3-propanediol derivatives. Therefore, the reported investigations were focused on the identification of reaction conditions that promote the formation of [1,3]dioxan-5-ols and suppress the formation of [1,3]dioxolan-4-yl-methanols.
- Deutsch,Martin,Lieske
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p. 428 - 435
(2007/10/03)
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- Intermolecular reactions of chlorohydrine anions: Acetalization of carbonyl compounds under basic conditions
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Nonenolizable aldehydes and ketones react with 2-chloroethanol and 3-chloropropanol under basic conditions (t-BuOK, DMF/THF) with formation of 2-substituted 1,3-dioxolanes and 1,3-dioxanes, respectively. Conversion of the two-step addition-alkylation process depends on the electrophilicity of the carbonyl group that governs the equilibrium of addition of chloroalkoxides. This method of protection of carbonyl groups in the form of cyclic acetals under kinetically controlled conditions is complementary to the acid-catalyzed reaction with diols.
- Barbasiewicz, Michal,Makosza, Mieczyslaw
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p. 3745 - 3748
(2007/10/03)
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- Binding of tetramethylammonium to polyether side-chained aromatic hosts. Evaluation of the binding contribution from ether oxygen donors
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A set of macrocyclic and open-chain aromatic ligands endowed with polyether side chains has been prepared to assess the contribution of ether oxygen donors to the binding of tetramethylammonium (TMA), a cation believed incapable of interacting with oxygen donors. The open-chain hosts consisted of an aromatic binding site and side chains possessing a variable number of ether oxygen donors; the macrocyclic ligands were based on the structure of a previously investigated host, the dimeric cyclophane 1,4-xylylene-1,4-phenylene diacetate (DXPDA), implemented with polyether-type side chains in the backbone. Association to tetramethylammonium picrate (TMAP) was measured in CDCl 3 at T = 296 K by 1H NMR titrations. Results confirm that the main contribution to the binding of TMA comes from the cation - π interaction established with the aromatic binding sites, but they unequivocally show that polyether chains participate with cooperative contributions, although of markedly smaller entity. Water is also bound, but the two guests interact with aromatic rings and oxygen donors in an essentially noncompetitive way. An improved procedure for the preparation of cyclophanic tetraester derivatives has been developed that conveniently recycles the oligomeric ester byproducts formed in the one-pot cyclization reaction. An alternative entry to benzylic diketones has also been provided that makes use of a low-order cyanocuprate reagent to prepare in fair yields a class of compounds otherwise uneasily accessible.
- Bartoli, Sandra,De Nicola, Gina,Roelens, Stefano
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p. 8149 - 8156
(2007/10/03)
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- Novel oxepane formation by TiCl4-catalyzed nucleophilic cleavage of 1- alkoxymethyl-6,8-dioxabicyclo[3.2.1]octanes
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Introduction of an alkoxymethyl group at the C1 position in the 6,8- dioxabicyclo[3.2.1]octane system enabled novel formation of oxepane compounds in TiCl-4-catalyzed acetal cleavage reactions. (C) 2000 Elsevier Science Ltd.
- Fujiwara, Kenshu,Amano, Arika,Tokiwano, Tetsuo,Murai, Akio
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p. 1065 - 1080
(2007/10/03)
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- Synthesis and lipase-catalyzed enantiotope selective acetylation of 2- benzoyloxy-1,3-propanediol
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Preparation and porcine pancreatic lipase (PPL)-catalyzed enantiotope selective acetylation of the prochiral 2-benzoyloxy-1,3-propanediol (1a) is described. The reaction with PPL and vinyl acetate gave monoacetate (2a) of 96 % e.e.
- Bódai, Viktória,Novák, Lajos,Poppe, László
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p. 759 - 761
(2007/10/03)
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- New synthesis of sn-1,2- and sn-2,3-O-diacylglycerols application to the synthesis of enantiopure phosphonates analogous to triglycerides: A new class of inhibitors of lipases
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Phosphonate compounds mimic the first transition state occurring during enzymatic carboxyester hydrolysis of natural substrates by forming a covalent bond with the catalytic serine. However, until now the organophosphorus compounds used in the inhibition studies more or less resembled a natural triglyceride substrate. In order to elucidate the interfacial activation and the mechanism of action of lipases, specific inhibitors need to be prepared. To achieve this goal, enantiomerically pure sn-1,2- and sn-2,3O- didecanoylglycerol compounds were prepared - starting from a C-4 chiral synthon, 3-buten-1,2-diol - and treated with n-pentylphosphonic dichloride and p-nitrophenol to afford the corresponding diastereomeric phosphonates, which were acylglycerol analogs. Subsequent separation of each of the phosphonate diastereomers A/B or ent-A/ent-B, performed by HPLC, led to four enantiopure stereoisomers that will be investigated as inhibitors of Human Pancreatic Lipase (HPL) and Human Gastric Lipase (HGL) using the monomolecular film technique.
- Marguet, Frank,Cavalier, Jean-Francois,Verger, Robert,Buono, Gerard
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p. 1671 - 1678
(2007/10/03)
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- A FACILE CLEAVAGE OF BENZYLIDENE ACETALS WITH DIISOBUTYLALUMINUM HYDRIDE
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Benzylidene acetals of 1,2- and 1,3-glycols are easily cleft by diisobutylaluminum hydride in a toluene solution at 0 deg C - room temperature to give the corresponding monobenzyl ethers of the glycols.In general the reaction proceeds excellently in regioselective manner depending on the stereochemical environment.
- Takano, Seiichi,Akiyama, Masashi,Sato, Seiji,Ogasawara, Kunio
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p. 1593 - 1596
(2007/10/02)
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