3453-99-4Relevant articles and documents
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.
PROCESS OF PRODUCTION OF SPECIFIC ACETALS AND KETALS
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Page/Page column 28, (2016/08/10)
The present invention relates to a method to produce specific acetals and ketals. The acetals and ketals, which are produced by the process according to the present invention are the ones of formula (I) wherein R is H or C1-, -C4 -alkyl, and R1 is C1-, -C4 -alkyl, and R2 is C1-, -C6 -alkyl. Surprisingly, it was found that the use of the specific ionic liquids and the use of a low reaction temperature (below room temperature) allows producing acetals and ketals of formula (I) in excellent yield in the absence of HCI as well as in the absence of any anhydrous calcium sulfate (or compounds having the same purpose).
Bis(perfluorooctanesulfonyl)imide supported on fluorous silica gel: Application to protection of carbonyls
Hong, Mei,Xiao, Guomin
experimental part, p. 121 - 126 (2012/08/28)
The immobilization of bis(perfluorooctanesulfonyl)imide (HNPf2) on fluorous silica gel (FSG) and its utilization in protection of carbonyls have been investigated. This system is reasonably general and can be applied to converting several carbonyls to the corresponding acetals and ketals in good to excellent yields. There is no need for the use of anhydrous solvents or inert atmosphere. Recycling studies have shown that the FSG-supported HNPf2 catalyst can be readily recovered and reused several times without significant loss of activity.
Trifluoroacetylation of unsymmetrical ketone acetals. A convenient route to obtain alkyl side chain trifluoromethylated heterocycles
Bonacorso, Helio G.,Martins, Marcos A.P.,Bittencourt, Sandra R.T.,Lourega, Rogerio V.,Zanatta, Nilo,Flores, Alex F.C.
, p. 177 - 182 (2007/10/03)
A convenient method to obtain β-alkyl-β-methoxyvinyl trifluoromethyl ketones [CF3COCHC(OMe)R, where R = Et, n-Pr, i-Pr, i-Bu, t-Bu, -(CH2)2OMe] from the regiospecific acylation of kinetic enol ether generated in situ is reported. The unsymmetrical ketone dimethyl acetals react with trifluoroacetic anhydride in the presence of pyridine using dry chloroform as solvent with a temperature range of 25-60°C. These acetals [R-C(OMe)2Me] are obtained from the reaction of alkyl methyl ketones with trimethyl orthoformate in the presence of p-toluenesulfonic acid as catalyst in pure methanol as solvent. The new acetylated enol ethers proved to be versatile building blocks for the construction of interesting alkyl trifluoromethyl substituted heterocycles. Thus, examples of isoxazoline, pyrazoline, pyrazole and pyrimidinone have been obtained in good yields (62-79%).
Investigation of the Effectiveness of Various 1-Dialkylamino-1-methoxycarbenium-Methyl Sulfates in the Course of Acetalization
Kantlehner, Willi,Gutbrod, Heinz-Dieter,Funke, Bernd
, p. 246 - 252 (2007/10/02)
The rate of dimethyl ketal formation from acetone and methanol in the presence of several 1-dialkylamino-1-methoxycarbenium methyl sulfates 1a, 5a-g is studied.The fastest rate was observed in the case of 5c.In the presence of 5c, the reaction of carbonyl compounds with either methanol or 1,2-diols gave the dimethyl ketals 6 and 1,3-dioxolanes 7, respectively.