A novel approach for selective cross aldol condensation using reusable NaOH-cationic micellar systems

Vashishtha, Manu; Mishra, Manish; Shah, Dinesh O.

doi:10.1016/j.apcata.2013.06.015

Cited by 35 publications

(10 citation statements)

References 37 publications

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“…As can be seen in Figure 2, the intense peaks at ca. 2q of 2.5° (101), 4.5° (110) and 5.2° (200) were corresponded to the diffraction peaks of MCM-41 prepared from different surfactants which were DTAB with a carbon number of 15 (Figure 2(a)), CTAB with a carbon number of 18 (Figure 2(b)) and STAB with a carbon number 21 (Figure 2(c)) [27][28][29]. Based on the XRD patterns, the degree of crystallinity of MCM-41 decreased from 76.3 to 32.8% with an increasing number of the carbon chain.…”

Section: Resultsmentioning

confidence: 98%

Properties and Photocatalytic Behaviour of Vanadia Loaded Titania Supported on MCM-41 Synthesized using Different Surfactants for Degradation of Methylene Blue

Ooi¹,

Hatta²,

Lee³

2020

J. Idn. Chem. Soc.

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An attempt has been carried out to prepare vanadia loaded TiO2 supported on MCM-41(V-TiO2/MCM-41) nanostructured photocatalysts using different surfactants. The surfactants used in the photocatalysts synthesis were dodecyl-trimethyl-ammonium bromide (DTAB), hexadecyl-trimethyl-ammonium bromide (CTAB) and octadecyl-trimethyl-ammonium bromide (STAB) which have varied carbon chains. The effect of crystallinity, surface area and porosity of the MCM-41 support on the physical-chemical properties of synthesized photocatalysts of vanadia loaded TiO2/MCM-41 and their photocatalytic performance were investigated. X-ray diffraction (XRD) patterns showed that the crystallinity of vanadia-TiO2/MCM-41 decreased with increasing of carbon-chain number of the surfactant used. Both surface area and pore volume of V-TiO2 increased significantly from 16.2 m2/g and 0.034 cm3/g to 864.3 m2/g and 0.618 cm3/g, respectively, after being loaded on MCM-41 support which was prepared using CTAB. It was demonstrated that all the V loaded TiO2/MCM-41 materials exhibited remarkable improvement in photocatalytic degradation of methylene blue (MB) under the irradiation of visible light as compared to that of bare TiO2 and V-TiO2. Among these materials, V-TiO2/MCM-41 which was synthesized using CTAB appeared to be the best photocatalyst with 57% of MB removal under visible light irradiation.

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Section: Resultsmentioning

confidence: 98%

Properties and Photocatalytic Behaviour of Vanadia Loaded Titania Supported on MCM-41 Synthesized using Different Surfactants for Degradation of Methylene Blue

Ooi¹,

Hatta²,

Lee³

2020

J. Idn. Chem. Soc.

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“…Micellar catalysis (both chemical and enzymatic) for many years is demonstrated as a very effective tool for a number of diverse reactions. Formed micellar aggregates showed tremendous catalytic potential, also in carbohydrate chemistry . In the scientific literature only a few examples of the use of micellar catalysis for the synthesis of alkyl glucosides can be found.…”

Section: Methodsmentioning

confidence: 99%

Micellar Catalysis in Fischer Glycosidation: En Route to Diverse Functional Glycosides

et al. 2019

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We have demonstrated that direct Fischer glycosidation of carbohydrates with selected alcohols, glycols and chloroalcohols to corresponding glucosides in micellar reaction system can be a promising and effective route for the selective synthesis of a number of functional glucosides. The use of specific catalyst combining both surfactant and acid catalyst functions enables formation of the reactive micellar system. The formation of corresponding glucosides with spectacular high selectivity to monoglucosides is one of the most important phenomena of the application of micellar catalysis to functional glucosides synthesis.

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“…Although acetone self‐condensation is often studied in the gas phase, most aldol condensations are performed in the aqueous phase, at low pressure, and mild temperatures, and it leads to sustainable and environmentally benign biorefinery processes. Despite the fact that the first references about these reactions propose homogeneous catalysts such as NaOH and KOH, there have been important advances in the development of active, selective, and stable solid basic catalysts, such as mixed oxides, aluminophosphate, and carbon materials …”

Section: Methodsmentioning

confidence: 99%

Base‐Catalyzed Condensation of Levulinic Acid: A New Biorefinery Upgrading Approach

2016

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The base-catalyzedc ondensation of levulinic acid (LA) under mild conditions (0.1 MPa, 323 K, 0.45 mol L À1 aq solution of levulinic acid, catalyst/reactant = 1:24 wt.)w as proposed as an ew approachf or the upgrading of this molecule by using mixed oxides as catalysts. Three products were identified: a-angelica lactone (AL) and two aldol condensation adducts,L A-LA and AL-LA. These last ones (obtainedw ith selectivities higher than 90 %a t3 0% conversion upon using MgZr)p resenth igh value as fuel and chemical precursors. The distribution of basic and acidic sites on the catalyst governs the performance and selectivity of the catalyst, whereas the stability of the catalyst in the reactionm edia determines the deactivation behavior.B ulk MgZr oxidespresent agood balance of these properties.Transformation of biomass into highly valuable products and liquid fuels has received much attention in the last years. Levulinic acid (4-oxopentanoic acid, LA) is nowadays considered one of the most promisingb ioplatformm olecules. This keto acid is obtained in significant yields (> 80 %) by the aqueousphase hydrolysis of cellulosic feedstock if the hydrolytic conditions are acidic enough to yield levulinic acid and formic acid by fragmentation of dehydrated sugars.[1] These conditions are industrially implemented by the BIOFINE process.[2] LA has been proposed asareactant in different processesf or the productiono fa dvanced biofuels, monomers, as well as other molecules with industriali nterest.[3] Most of these processes involve the transformation of levulinic acid into g-valerolactone. [4,5] However,t his reactionr equires the presence of molecular hydrogen and severe conditions (473 Ka nd 3MPa), which hinder both energy trade-off and process sustainability.C onsequently,d ifferent improvements, such as using formic acida s the hydrogen source,h ave been explored.[6] Other acid-catalyzed reactions are proposed, including esterification with different alcohols catalyzedb yh omogeneous acids such as HCl, H 2 SO 4 ,a nd H 3 PO 4 [7] or basic salts such as K 2 CO 3 at temperatures over 450 K, [8] not fulfilling the "green chemistry" principles.Most of these previously studied reactions are focused on the reactivity of the carboxyl group of the levulinic acid;r eferences dealing with the reactivity of the carbonyl group are very scarce. In this framework, aldol condensation is one of the most common reactions involving this functional group.T his reactioni ncreases the length of the carbon chain by ab asecatalyzed mechanism that beginsw ith abstraction of ap roton a to the carbonyl functional group. This reaction has already been proposed to upgrade bioplatform molecules,s uch as acetone, 5-hydroxymethylfurfural, and furfural.[9-12] Although acetones elf-condensation is often studied in the gas phase, [9,13] most aldol condensations are performed in the aqueous phase, at low pressure, and mild temperatures, [10][11][12] and it leads to sustainable and environmentally benignb iorefinery processes. Despitet he fact that the fir...

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A novel approach for selective cross aldol condensation using reusable NaOH-cationic micellar systems

Cited by 35 publications

References 37 publications

Properties and Photocatalytic Behaviour of Vanadia Loaded Titania Supported on MCM-41 Synthesized using Different Surfactants for Degradation of Methylene Blue

Properties and Photocatalytic Behaviour of Vanadia Loaded Titania Supported on MCM-41 Synthesized using Different Surfactants for Degradation of Methylene Blue

Micellar Catalysis in Fischer Glycosidation: En Route to Diverse Functional Glycosides

Base‐Catalyzed Condensation of Levulinic Acid: A New Biorefinery Upgrading Approach

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