A Systematic Study on Knoevenagel Reaction and Nazarov Cyclization of Less Reactive Carbonyl Compounds Using Rare Earth Triflates and Its Applications

Ilangovan, A.; Muralidharan, S.; Maruthamuthu, S.

doi:10.5012/jkcs.2011.55.6.1000

Cited by 18 publications

(5 citation statements)

References 39 publications

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“…Thus the Knoevenagel reaction between vanillin (1) and barbituric acid (2) yielding 5-(4-hydroxy-3-methoxybenzylidene)pyrimidine-2,4,6(1H,3H,5H)-trione 3 (Scheme 1) was chosen as the two-component model reaction. 24,[32][33][34][35] All criteria with respect to chemical parameters are fullled and processing in both types of intended ball mills -PBM and SBMwill be possible.…”

Section: Resultsmentioning

confidence: 99%

Scale-up of organic reactions in ball mills: process intensification with regard to energy efficiency and economy of scale

2014

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The scale-up of the Knoevenagel-condensation between vanillin and barbituric acid carried out in planetary ball mills is investigated from an engineering perspective. Generally, the reaction proceeded in the solid state without intermediate melting and afforded selectively only one product. The reaction has been used as a model to analyze the influence and relationship of different parameters related to operation in planetary ball mills. From the viewpoint of technological parameters the milling ball diameter, dMB, the filling degree with respect to the milling balls' packing, ΦMB,packing, and the filling degree of the substrates with respect to the void volume of the milling balls' packing, ΦGS, have been investigated at different reaction scales. It was found that milling balls with small dMB lead to higher yields within shorter reaction time, treaction, or lower rotation frequency, rpm. Thus, the lower limit is set considering the technology which is available for the separation of the milling balls from the product after the reaction. Regarding ΦMB,packing, results indicate that the optimal value is roughly 50% of the total milling beakers' volume, VB,total, independent of the reaction scale or reaction conditions. Thus, 30% of VB,total are taken by the milling balls. Increase of the initial batch sizes changes ΦGS significantly. However, within the investigated parameter range no negative influence on the yield was observed. Up to 50% of VB,total can be taken over by the substrates in addition to 30% for the total milling ball volume. Scale-up factors of 15 and 11 were realized considering the amount of substrates and the reactor volume, respectively. Beside technological parameters, variables which influence the process itself, treaction and rpm, were investigated also. Variation of those allowed to fine-tune the reaction conditions in order to maximize the yield and minimize the energy intensity.

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Section: Resultsmentioning

confidence: 99%

Scale-up of organic reactions in ball mills: process intensification with regard to energy efficiency and economy of scale

2014

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“…However, ab initio calculations on the geometrical adducts were introduced to enhance understanding of the interactions between Lewis acids and bases . A number of concrete examples (e.g., Diels–Alder (DA), Friedel–Crafts acylation, alkylation, cycloaddition reactions, hydrosilylation of alkynes, decomposition of ethers) have already been described in the literature, and others are summarized in Table …”

Section: Reactions Catalyzed By Conventional Homogenous Lewis Acidsmentioning

confidence: 99%

“…A good alternative is the utilization of surfactants, such as sodium dodecylsulfate, dodecane sulfonate, cerium(III) trislaurylsulfonate, or a mixture of sodium dodecylsulfate with trisdodecylsulfate, in combination with the Lewis acids (LASCs: Lewis acid–surfactant combined catalysts). These surfactants are usually used to solubilize organic compounds or form emulsions with them in water; this was realized previously in Michael, Mannich, or Mukaiyama aldol reactions, for example …”

Section: Reactions Catalyzed By Conventional Homogenous Lewis Acidsmentioning

confidence: 99%

From Conventional Lewis Acids to Heterogeneous Montmorillonite K10: Eco‐Friendly Plant‐Based Catalysts Used as Green Lewis Acids

et al. 2018

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The concept of green chemistry began in the USA in the 1990s. Since the publication of the 12 principles of this concept, many reactions in organic chemistry have been developed, and chemical products have been synthesized under environmentally friendly conditions. Lewis acid mediated synthetic transformations are by far the most numerous and best studied. However, the use of certain Lewis acids may cause risks to environmental and human health. This Review discusses the evolution of Lewis acid catalyzed reactions from a homogeneous liquid phase to the solid phase to yield the expected organic molecules under green, safe conditions. In particular, recent developments and applications of biosourced catalysts from plants are highlighted.

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“…In addition, poly(4-methyl vinylpyridinium hydroxide)/ SBA-15, a novel basic polymeric composite was applied as a recyclable catalyst for the Knoevenagel condensation reaction of aromatic aldehydes with ethyl cyanoacetate in water at 95˚C [339]. Furthermore, they were prepared via heating a mixture of aldehyde and ethyl cyanoacetate at 80˚C -85˚C in an oil bath and in the presence of rare earth triflates as Yb(OTf) 3 [340]. The same reaction was performed in distilled water and in the presence of hydroxyapatite supported caesium carbonate as a recyclable solid base catalyst (HAP-Cs 2 CO 3 ) [278] or under microwave irradiation [341].…”

Section: Synthesis Of Ethyl Arylidenecyanoacetate Derivativesmentioning

confidence: 99%

Arylidene Derivatives as Synthons in Heterocyclic Synthesis

El‐Gohary¹

2014

OALib

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This review describes the synthetic procedures for the preparation of arylideneacetophenones, arylidenecycloalkanones, 2-arylidene-1-indanones, 2-arylidene-1-tetralones, 2-arylidene-1-benzosuberones, aurones, 1-thioaurones, 3-arylidene-4-chromanones, 3-arylidene-1-thio-4-chromanones, 3-arylideneflavanones, 3-arylidene-1-thioflavanones, arylideneanilines, arylidenemalononitriles, diethyl arylidenemalonates, ethyl arylidenecyanoacetates, arylidenecyanoacetamides, 5arylidene derivatives of barbituric and thiobarbituric acids, arylidene derivatives of Meldrum's acid and arylidene derivatives of dimedone. Also, it demonstrates the reactivity of these arylidene derivatives in heterocyclic synthesis with emphasis on the most recent findings. Some of these are the α,β-enones, víz. aurones and 3-arylidene-4-chromanones belong to the natural products. The others are synthetic substances which are convenient and important intermediates for the synthesis of a variety of useful and novel heterocyclic systems.

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A Systematic Study on Knoevenagel Reaction and Nazarov Cyclization of Less Reactive Carbonyl Compounds Using Rare Earth Triflates and Its Applications

Cited by 18 publications

References 39 publications

Scale-up of organic reactions in ball mills: process intensification with regard to energy efficiency and economy of scale

Scale-up of organic reactions in ball mills: process intensification with regard to energy efficiency and economy of scale

From Conventional Lewis Acids to Heterogeneous Montmorillonite K10: Eco‐Friendly Plant‐Based Catalysts Used as Green Lewis Acids

Arylidene Derivatives as Synthons in Heterocyclic Synthesis

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