Trialkylamine Controlled Phenol–Formaldehyde Reaction over Clay Catalysts: Selective and Environmentally Benign Synthesis of Salicylic Aldehydes

Bigi, Franca; Conforti, Maria Lina; Maggi, Raimondo; Sartori, Giovanni

doi:10.1016/s0040-4020(00)00171-x

Cited by 30 publications

(11 citation statements)

References 24 publications

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“…The methodology employing paraformaldehyde and tin(IV) tetrachloride as a strong Lewis acid also failed . The methods of Sartori and co‐workers using montmorillonite KSF as a heterogeneous catalyst and of Liedholm with CuCl 2 and dimethyl sulfoxide did not give the desired results either . We also tried to protect the hydroxy group in the starting phenol 1 by reaction with diethylcarbamoyl chloride and subsequent formylation using s BuLi, but this method failed as well .…”

Section: Resultsmentioning

confidence: 99%

The Coumarin‐Dimer Spring—The Struggle between Charge Transfer and Steric Interactions

Kielesiński

Morawski

Sobolewski

et al. 2017

Chemistry A European J

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The synthesis of a weakly coupled, strongly polarized coumarin dimer has been achieved for the first time. The three-step strategy comprises the Skattebøl formylation followed by the Knoevenagel reaction and the formation of a tertiary amide by using a peptide-type procedure. The molecule consists of two different coumarin moieties: One is a classical donor-acceptor system and the second one possesses a weaker amide donor at the 7-position. The polarized coumarin dimer can form an electronically conjugated structure possessing an electric dipole larger than that of 7-(dimethylamino)coumarin-3-carboxylic acid. The limited flexibility of the inter-coumarin connection results in stable conformers of different electric dipole moments and complex photophysics. In the solid state, this compound has a strongly bent conformation with the two coumarin units forming an angle of around 74°. In solution, two conformers are in equilibrium. The existence of the molecule as two conformers in the ground state has been confirmed by optical studies, and further corroborated by molecular calculations. The fluorescence spectra possess a unique feature: A charge-transfer band (ca. 550 nm) is visible only in nonpolar or weakly polar solvents. Optical spectroscopy studies coupled with molecular calculations allowed us to rationalize this phenomenon: The large amplitude of intramolecular motions is responsible for the conformational isomerization as well as producing a conical intersection between the potential energy surfaces of the excited singlet state and the ground state, which opens an internal conversion channel that effectively competes with the fluorescence of the conformers.

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Section: Resultsmentioning

confidence: 99%

The Coumarin‐Dimer Spring—The Struggle between Charge Transfer and Steric Interactions

Kielesiński

Morawski

Sobolewski

et al. 2017

Chemistry A European J

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“…This work reported on the preparation of Fe 3 O 4 @SiO 2~u rea/MgBr 2 via functionalization of silicacoated magnetic NPs with CPTES as a linker for the immobilization of urea and then incorporation of MgBr 2 on the surface of urea by an electron interaction between Mg 2+ [20] MgCl 2 Acetonitrile, reflux 1.5-44 5-99 [21] SnCl 4 Toluene 100°C, under an argon atmosphere 8 37-62 [22] CH 3 CH 2 MgBr Toluene 90°C, HMPA 3 Up to 40 [23] Fe 3 O 4 @SiO 2~u rea/MgBr 2 Acetonitrile, 90°C 1-2.5 74-97 This work and N or NH of urea. The core-shell NPs were stable and reusable, and the non-toxic and inexpensive heterogeneous nanocatalyst prepared has great potential for applications in organic syntheses.…”

Section: Discussionmentioning

confidence: 99%

MgBr₂ supported on Fe₃O₄@SiO₂ ~ urea nanoparticle: An efficient catalyst for ortho‐formylation of phenols and oxidation of benzylic alcohols

Soleimani

Yaesoobi

Ghasempour

2017

Applied Organom Chemis

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Urea was successfully immobilized on the surface of chloropropyl‐modified Fe3O4@SiO2 core–shell magnetic nanoparticles, then supported by MgBr2 and acts as a unique catalyst for oxidation of benzylic alcohols to aldehydes and ketones, and ortho‐formylation of phenols to salicylaldehydes. The prepared catalyst was characterized by FT‐IR, transmission electron microscopy, scanning electron microscopy, X‐ray powder diffraction, dispersive X‐ray spectroscopy, CHN and TGA. It was found that Fe3O4@SiO2 ~ urea/MgBr2 showed higher catalytic activity than homogenous MgBr2, and could be reused several times without significant loss of activity.

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“…Besides the above reactions number of organic transformations have been carried out in presence of clay. Some of them are pyrrolytic eliminations 5 , oxidation-reduction reactions 6 , formylation of phenols 7 , aldol condensation reaction 8 .…”

Section: Introduction:-mentioning

confidence: 99%

An Eco-Friendly Green Route for the Synthesis of Amide From Carboxylic Acids Employing Montmorillonite as a Catalyst.

Jagtap¹,

Yadav²,

Mhaske³

et al. 2018

IJAR

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Trialkylamine Controlled Phenol–Formaldehyde Reaction over Clay Catalysts: Selective and Environmentally Benign Synthesis of Salicylic Aldehydes

Cited by 30 publications

References 24 publications

The Coumarin‐Dimer Spring—The Struggle between Charge Transfer and Steric Interactions

The Coumarin‐Dimer Spring—The Struggle between Charge Transfer and Steric Interactions

MgBr₂ supported on Fe₃O₄@SiO₂ ~ urea nanoparticle: An efficient catalyst for ortho‐formylation of phenols and oxidation of benzylic alcohols

An Eco-Friendly Green Route for the Synthesis of Amide From Carboxylic Acids Employing Montmorillonite as a Catalyst.

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Trialkylamine Controlled Phenol–Formaldehyde Reaction over Clay Catalysts: Selective and Environmentally Benign Synthesis of Salicylic Aldehydes

Cited by 30 publications

References 24 publications

The Coumarin‐Dimer Spring—The Struggle between Charge Transfer and Steric Interactions

The Coumarin‐Dimer Spring—The Struggle between Charge Transfer and Steric Interactions

MgBr2 supported on Fe3O4@SiO2 ~ urea nanoparticle: An efficient catalyst for ortho‐formylation of phenols and oxidation of benzylic alcohols

An Eco-Friendly Green Route for the Synthesis of Amide From Carboxylic Acids Employing Montmorillonite as a Catalyst.

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Product

Resources

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MgBr₂ supported on Fe₃O₄@SiO₂ ~ urea nanoparticle: An efficient catalyst for ortho‐formylation of phenols and oxidation of benzylic alcohols