- Woody species: A new bio-based material for dual Ca/Mg catalysis with remarkable Lewis acidity properties
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Advances in green catalysis have promoted the development of ecocatalysis encountered in most of the main transformations of organic chemistry. Taking advantage of the remarkable capacity of certain plants to hyperaccumulate transition metals into shoots or roots, we have addressed the direct use of metals derived from contaminated plant wastes as supported Lewis acid catalysts, coupling agents, oxidative and reducing catalysts in green chemistry. This approach constituted the first example of chemical catalyst based on phytotechnologies. Herein, we show that the concept can be extended to common and abundant plant species that are surprisingly appropriated for chemical catalysis. We present that willow, birch, plane and linden trees can be used to produce bio-based and original Lewis acid catalysts. The catalytic potential of these species will be illustrated through two representative transformations, acetalisation and oxidative esterification. Thanks to their original polymetallic composition, ecocatalysts provided better results compared to classical metal chlorides such as MgCl2, CaCl2 or ZnCl2. This illustrates the interest of the ecocatalysis and is incorporated within the green and sustainable chemistry concept.
- Deyris, Pierre-Alexandre,Adler, Pauline,Petit, Eddy,Legrand, Yves-Marie,Grison, Claude
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supporting information
p. 3133 - 3142
(2019/06/18)
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- Facile oxidative hydrolysis of acetals to esters using hypervalent iodine(III)/LiBr combination in water
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The combination of (diacetoxy)iodobenzene (PhI(OAc)2, DIB) and lithium bromide (LiBr) efficiently oxidized cyclic and acyclic acetals to the corresponding hydroxyalkyl carboxylic esters and simple esters in good to excellent yields. The merits of this reaction are that it employs commercially available and non-explosive hypervalent iodine(III) reagent, water as the solvent, a short reaction time, and mild reaction conditions.
- Panchan, Waraporn,Chiampanichayakul, Supanimit,Snyder, Deanna L.,Yodbuntung, Siriporn,Pohmakotr, Manat,Reutrakul, Vichai,Jaipetch, Thaworn,Kuhakarn, Chutima
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experimental part
p. 2732 - 2735
(2010/05/17)
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- 2-Iodoxybenzoic acid/tetraethylammonium bromide/water: An efficient combination for oxidative cleavage of acetals
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A simple and efficient procedure has been developed for the oxidation of cyclic and acyclic acetals to the corresponding hydroxyalkyl carboxylic esters and simple esters, respectively. 2-Iodoxybenzoic acid (IBX) in the presence of tetraethylammonium bromide was employed for the reaction in aqueous media. The salient features of the protocol include short reaction time, environmentally benign reagents and solvent, and moderate to high yields. Georg Thieme Verlag Stuttgart.
- Kuhakarn, Chutima,Panchan, Waraporn,Chiampanichayakul, Supanimit,Samakkanad, Natthapol,Pohmakotr, Manat,Reutrakul, Vichai,Jaipetch, Thaworn
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experimental part
p. 929 - 934
(2009/10/14)
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- A test reaction to assess the presence of Broensted and the softness/hardness of Lewis acid sites in palladium supported catalysts
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Cyclic ethylene acetal of α-bromopropiophenone gives rise to three distinctive products, each one being specific to Broensted, hard Lewis and soft Lewis sites, respectively. In the presence of Broensted sites, hydrolysis of cyclic acetal forms the corresponding α-bromophenone. Hard or soft Lewis sites promote selectively a rearrangement of the phenyl or ethylenedioxy group to form 2-phenylpropionate ester or dioxine, respectively. This test reaction has been used to assess the influence of the support on the catalytic activity of palladium in zeolites. Three series of supports including alkali-exchanged faujasite, Beta zeolites and sepiolites have been tested. It has been observed that the nature of the zeolite plays an important role on the palladium selectivity, basic supports increasing the softness of the palladium Lewis sites. The catalytic test correlates well with electrochemical data about the reduction potential of supported palladium, XPS characterization of the oxidation state of palladium supported on the surface and activity in the Suzuki reaction.
- Corma, Avelino,Garcia, Hermenegildo,Primo, Ana,Domenech, Antonio
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p. 361 - 365
(2007/10/03)
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- Soft and Hard Acidity in Ion-exchanged Y Zeolites: Rearrangement of 2-Bromopropiophenone Ethylene Acetal to 2-Hydroxyethyl 2-Phenylpropanoate
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The rearrangement of the cyclic ethylene acetal of 2-bromopropiophenone to 2-hydroxyethyl 2-phenylpropanoate is catalysed by zinc exchanged Y zeolites with higher activity than the conventional ZnCl2; hydrolysis of the acetal moiety owing to the Broensted acid sites is one of the major side reactions, while the competitive formation of 5-methyl-6-phenyl-2,3-dihydro-1,4-dioxine increases with the softness of the Lewis acid centres.
- Baldovi, Maria V.,Corma, Avelino,Fornes, Vicente,Garcia, Hermenegildo,Martinez, Agustin,Primo, Jaime
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p. 949 - 951
(2007/10/02)
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- Application of Oxidative Aryl Migration in Organo-selenium and -tellurium Compounds to the Synthesis of 2-Arylpropanoic Acids
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The ethylene acetals of aryl α-phenylseleno- and α-phenyltelluro-ethyl ketones i, Ph, Br) and 5-bromo-6-methoxy-2-naphthyl> have been prepared in 12-83percent yields by treating the corresponding α-bromo compounds with diphenyl diselenide-sodium or diphenyl ditelluride-sodium, respectively, in tetrahydrofuran-dimethylformamide under reflux for 6-10 h, during which the bromine is substituted by the PhSe or PhTe group.This substitution is not observed when the (PhM)2-NaBH4-EtOH (M=Se, Te) system which is known as a source of PhM- anion is used.Oxidation of the acetals thus formed with an excess of meta-chloroperbenzoic acid at 20-25 deg C for 1 h affords hydroxy-ethyl 2-arylpropanoates in 56-86percent yields via aryl group migration which are hydrolysed to 2-arylpropanoic acids, some of which are pharmaceutically important compounds.Overall isolated yields of 2-arylpropanoic acids are around 30-42percent based on the starting propiophenones over 5 steps.
- Uemura, Sakae,Fukuzawa, Shin-ichi,Yamauchi, Takayoshi,Hattori, Kaneaki,Mizutaki, Shoichi,Tamaki, Kentaro
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p. 1983 - 1987
(2007/10/02)
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- New Preparative Method for 2-Arylpropanoic Acids by Oxidative Aryl Migration in Aryl α-Seleno- and Aryl α-Telluro-ethyl Ketones
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Oxidation with m-chloroperbenzoic acid of the ethylene acetals of aryl α-phenylseleno- or aryl α-phenyltelluro-ethyl ketones prepared by treating the corresponding α-bromo compounds with diphenyl diselenide-sodium or diphenyl ditelluride-sodium, respectively, affords hydroxyethyl 2-arylpropanoates in moderate to good yields via aryl group migration.
- Uemura, Sakae,Fukuzawa, Shin-ichi,Yamauchi, Takayoshi,Hattori, Kaneaki,Mizutaki, Shoichi,Tamaki, Kentaro
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p. 426 - 427
(2007/10/02)
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- A Simple and Efficient Conversion of Aldehyde Acetals into Esters
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The reaction of aldehydic acetals with hypochlorous acid in acetic acid-acetone afforded the corresponding esters in excellent yields.From cyclic acetals, only the corresponding hydroxyalkyl esters were obtained.Keywords - acetal; hypochlorite; hypochlorous acid; conversion; ester; hydroxyalkyl ester; regioselectivity
- Sugai, Saburo,Kodama, Takashi,Akaboshi, Sanya,Ikegami, Shiro
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