26450-58-8Relevant articles and documents
Photo-organocatalytic synthesis of acetals from aldehydes
Nikitas, Nikolaos F.,Triandafillidi, Ierasia,Kokotos, Christoforos G.
supporting information, p. 669 - 674 (2019/02/14)
A mild and green photo-organocatalytic protocol for the highly efficient acetalization of aldehydes has been developed. Utilizing thioxanthenone as the photocatalyst and inexpensive household lamps as the light source, a variety of aromatic and aliphatic aldehydes have been converted into acyclic and cyclic acetals in high yields. The reaction mechanism was extensively studied.
A novel application of terminal alkynes as the homogeneous catalysts for acetalization and esterification
Sekerová, Lada,Vysko?ilová, Eli?ka,?erveny, Libor,Sedlá?ek, Jan
, p. 2877 - 2882 (2019/04/17)
The theoretical study focused on the possible use of low-molecular-weight mono-as well as multifunctional terminal alkynes as catalysts for two reactions, which are known to be typically acid catalyzed - acetalization and esterification, is presented in this study. Multifunctional terminal alkynes [(diethynylbenzenes, triethynylbenzene, and tetrakis(4-ethynylphenyl)methane]were significantly more active than the monofunctional ones (cyclopropylacetylene, phenylacetylene, 3-cyclohexylprop-1-yne, 1-ethynyl-2-fluorobenzene, 1-ethynyl-4-fluorobenzene, 4-ethynyltoluene, 4-tert-butylphenylacetylene, and 2-ethynyl-α,α,α-trifluorotoluene), this fact can be partly explained by the higher amount of ethynyl groups per alkyne molecule. We confirmed that terminal ethynyl groups in low-molecular-weight alkynes can successfully act as acid catalytic centers for acetalization as well as for esterification.
Hyper-Cross-Linked Polyacetylene-Type Microporous Networks Decorated with Terminal Ethynyl Groups as Heterogeneous Acid Catalysts for Acetalization and Esterification Reactions
Sekerová, Lada,Lhotka, Miloslav,Vysko?ilová, Eli?ka,Faukner, Tomá?,Slováková, Eva,Brus, Ji?í,?erveny, Libor,Sedlá?ek, Jan
, p. 14742 - 14749 (2018/09/25)
Heterogeneous catalysts based on materials with permanent porosity are of great interest owing to their high specific surface area, easy separation, recovery, and recycling ability. Additionally, porous polymer catalysts (PPCs) allow us to tune catalytic activity by introducing various functional centres. This study reports the preparation of PPCs with a permanent micro/mesoporous texture and a specific surface area SBET of up to 1000 m2 g?1 active in acid-catalyzed reactions, namely aldehyde and ketone acetalization and carboxylic acid esterification. These PPC-type conjugated hyper-cross-linked polyarylacetylene networks were prepared by chain-growth homopolymerization of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane. However, only some ethynyl groups of the monomers (from 58 to 80 %) were polymerized into the polyacetylene network segments while the other ethynyl groups remained unreacted. Depending on the number of ethynyl groups per monomer molecule and the covalent structure of the monomer, PPCs were decorated with unreacted ethynyl groups from 3.2 to 6.7 mmol g?1. The hydrogen atoms of the unreacted ethynyl groups served as acid catalytic centres of the aforementioned organic reactions. To the best of our knowledge, this is first study describing the high activity of hydrogen atoms of ethynyl groups in acid-catalyzed reactions.
The use of anhydrous CeCl3 as a recyclable and selective catalyst for the acetalization of aldehydes and ketones
Silveira, Claudio C.,Mendes, Samuel R.,Ziembowicz, Francieli I.,Lenarda?o, Eder J.,Perin, Gelson
scheme or table, p. 371 - 374 (2010/09/07)
An efficient, clean, chemoselective and solvent-free method for the synthesis of ketone and aldehyde dimethyl acetals was developed using trimethyl orthoformate and commercially available anhydrous CeCl3 as a recyclable catalyst. The method is general and affords the protected carbonyl compounds in good yields and under mild conditions, including aryl and alkyl ketones and activated aldehydes. The catalyst could be utilised directly for 3 cycles, without significant loss of activity.
Chemoselective protection of aldehydes in the presence of ketones using rupvp complex as a heterogeneous catalyst
Kshirsagar, Siddheshwar W.,Patil, Nitin R.,Samant, Shriniwas D.
experimental part, p. 407 - 413 (2010/04/04)
Ruthenium(III)-polyvinyl pyridine (RuPVP) complex was prepared by refluxing a methanolic solution of polyvinyl pyridine and trihydrated ruthenium trichloride. RuPVP catalyst was characterized by Fourier transform-infrared and diffential scanning calorimetry-thermogravimetry (TG). The catalyst was used for chemoselective protection of aldehydes in the presence of a ketonic carbonyl group.
Microwave-assisted preparation of 1-butyl-3-methylimidazolium tetrachlorogallate and its catalytic use in acetal formation under mild conditions
Yong, Jin Kim,Varma, Rajender S.
, p. 7447 - 7449 (2007/10/03)
1-Butyl-3-methylimidazolium tetrachlorogallate, [bmim][GaCl4], prepared via microwave-assisted protocol, is found to be an active catalyst for the efficient acetalization of aldehydes under mild conditions.
Method for producing enol ethers
-
, (2008/06/13)
Enol ethers of the formula I where R1is an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical which may carry further substituents which do not react with acetylenes or allenes, and the radicals R, independently of one another, are hydrogen or aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radicals, which may be bonded to one another to form a ring, and m is 0 or 1, are prepared by reacting an acetal or ketal of the formula II with an acetylene or allene of the formula III or IV where R and R1have the abovementioned meanings, in the gas phase at elevated temperatures in the presence of a zinc- or cadmium- and silicon- and oxygen-containing heterogeneous catalyst.
Reactions of N-methyl-2-phenylindole with malondialdehyde and 4- hydroxyalkenals. Mechanistic aspects of the colorimetric assay of lipid peroxidation
Erdelmeier, Irene,Gerard-Monnier, Dominique,Yadan, Jean-Claude,Chaudiere, Jean
, p. 1184 - 1194 (2007/10/03)
Under specific acidic conditions, both malondialdehyde (1, MDA) and 4- hydroxynonenal (2, 4-HNE) react with N-methyl-2-phenylindole (3) to give the same chromophoric cyanine 4 with maximal absorbance at 586 nm. Under such conditions, the reaction of 3 with 4-HNE (2) as well as with alkanals yields a second chromophoric cyanine 10 with maximal absorbance at 505 nm. The influence of different acids, iron(III), and oxygen on the reaction of 3 with such aldehydes was studied in detail. Under anaerobic conditions, the acid- induced reaction of 4-HNE with 3 afforded three rapidly interconverting intermediates, 5-7. Their subsequent fragmentation to 4 and hexanal in the presence of iron(III) and oxygen is consistent with the tandem β- fragmentation of an indolyl radical cation. 1-Indolylalkenes were identified as essential intermediates in the acid-induced reaction of 3 with alkanals. A very mild iron(III)catalyzed fragmentation of these intermediates afforded the corresponding 3-formylindole 11 as the direct precursor of the 505 nm chromophore 10. Such reactions were markedly influenced by the nature of the acid. Contrary to the rapid chromogenic reaction of 4-HNE which was observed in the presence of methanesulfonic acid, the HCl-induced reaction of 4-HNE with 3 did not afford the 586 nm chromophore. Furthermore, hexanal did not yield the 505 nm chromophore 10 upon reaction with 3 in the presence of HCl, again in contrast with the rapid chromogenic reaction which was observed in the presence of methanesulfonic acid. Comparison of the reaction mixtures under the two assay conditions confirmed that the same intermediates were formed. We conclude that the nature of the acid plays a crucial role in the oxidative fragmentation of intermediates into chromophores, allowing the selective assay of MDA in the presence of 4-HNE, using HCl acidic conditions.
Highly effective acetalization of aldehydes and ketones with methanol on siliceous mesoporous material
Tanaka, Yasuhiro,Sawamura, Naoki,Iwamoto, Masakazu
, p. 9457 - 9460 (2007/10/03)
Aromatic and linear aldehydes as well as cyclohexanone could be converted to the corresponding dimethylacetals in yields of ca. 90-100% at ambient or refluxing temperature in the titled reaction.
Acetals by AlFe-pillared montmorillonite catalysis
Cramarossa, Maria Rita,Forti, Luca,Ghelfi, Franco
, p. 15889 - 15894 (2007/10/03)
AlFe-pillared montmorillonite is an efficient catalyst for acetals preparation in CH2Cl2 at room temperature.
