- Robust acidic pseudo-ionic liquid catalyst with self-separation ability for esterification and acetalization
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The novel acidic pseudo-ionic liquid catalyst with self-separation ability has been synthesized through the quaternization of triphenylphosphine and the acidification with silicotungstic acid. The pseudo-IL showed high activities for the esterification with average conversions over 90%. The pseudo-IL showed even higher activities for acetalization than traditional sulfuric acid. The homogeneous catalytic process benefited the mass transfer efficiency. The pseudo-IL separated from the reaction mixture automatically after reactions, which was superior to other IL catalysts. The high catalytic activities, easy reusability and high stability were the key properties of the novel catalyst, which hold great potential for green chemical processes.
- Shi, Yingxia,Liang, Xuezheng
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p. 1413 - 1421
(2019/05/04)
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- Combination of NH2OH·HCl and NaIO4: an effective reagent for molecular iodine-free regioselective 1,2-difunctionalization of olefins and easy access of terminal acetals
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We have demonstrated a new application of our oxidizing reagent, a combination of NH2OH·HCl and NaIO4, in the first generalized regioselective 1,2-difunctionalization of olefins. It is a general method for the preparation of β-iodo-β′-hydroxy ethers, β-iodo ethers, β-iodohydrin, and β-iodo acetoxy compounds using different reaction media. The reactions are highly regioselective, always affording Markovnikov's type addition products. The methodology is also applicable for the easy access of terminal acetals. Molecular iodine-free synthesis, room temperature reaction conditions, high yields, use of less expensive reagents, mild reaction conditions, broad applicability of nucleophiles, and applicability for gram-scale synthesis are the notable advantages of this present protocol.
- Chakraborty, Nirnita,Santra, Sougata,Kundu, Shrishnu Kumar,Hajra, Alakananda,Zyryanov, Grigory V.,Majee, Adinath
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p. 56780 - 56788
(2015/07/15)
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- Acetalization of aldehydes and ketones over H4[SiW 12O40] and H4[SiW12O 40]/SiO2
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H4[SiW12O40] (H-SiW12) is demonstrated to be able to efficiently catalyze the acetalization of aldehydes and ketones with ethylene glycol and 1,3-propanediol. Nevertheless, the possible leaching and the recycling of H-SiW12 are two major disadvantages that largely restrict its further application in industry. Moreover, H 4[SiW12O40] tends to deactivate strong proton sites due to the small surface area of 10 m2 g-1. Due to interactions with surface silanol groups, the proton sites of polyoxometalates (POMs) on SiO2 are less susceptible to deactivation. As such, immobilization of H4[SiW12O40] onto SiO 2 leads to the heterogeneous catalyst H4[SiW 12O40]/SiO2 (H-SiW12/SiO 2), which can catalyze the acetalization of aldehydes and ketones with ethylene glycol and 1,3-propanediol selectively and efficiently without the need of a drying agent. The acetalization process can proceed smoothly at a relatively low temperature under solvent-free conditions. The catalyst of H 4[SiW12O40]/SiO2 can be recycled at least ten times without an obvious decrease in its catalytic activity. As far as we know, the TONs of the H-SiW12/SiO2-catalyzed acetalization of cyclohexanone with ethylene glycol, and benzaldehyde with 1,3-propanediol are the highest reported so far.
- Zhao, Shen,Jia, Yueqing,Song, Yu-Fei
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p. 2618 - 2625
(2014/07/22)
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- Driving an equilibrium acetalization to completion in the presence of water
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Formation of an acetal from a carbonyl substrate by condensation with an alcohol is a classical reversible equilibrium reaction in which the water formed must be removed to drive the reaction to completion. A new method has been developed for acetalization of carbonyl substrates by diols in the presence of water. Complexation of poly(4-styrenesulfonic acid) with poly(4-vinylpyridine) generates a catalytic membrane of polymeric acid at the interface between two parallel laminar flows in a microchannel of a microflow reactor. The catalytic membrane provides a permeable barrier between the organic layer and water-containing layer in the reaction, and permits discharge of water to the outlet of the microreactor to complete the acetalization. Condensation of a variety of carbonyl substrates with diols proceeded in the presence of water in the microflow device to give the corresponding acetals in yields of up to 97% for residence times of 19 to 38 s. the Partner Organisations 2014.
- Minakawa, Maki,Yamada, Yoichi M. A.,Uozumi, Yasuhiro
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p. 36864 - 36867
(2014/11/08)
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- Acid-free, organocatalytic acetalization
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The acid-free, organocatalytic acetalization of various aldehydes and ketones with N,N′-bis[3,5-bis(trifluoromethyl)phenyl]thiourea is presented. The neutral, double hydrogen bonding thiourea catalyst can be used at very low loadings of 0.01-1 mol% at room temperature to furnish the respective acetals in 65-99% yield at turnover frequencies around 600 h-1. Acid-labile TBDMS-protected as well as unsaturated aldehydes can be converted efficiently into their acetals utilizing this very mild and highly practical method.
- Kotke, Mike,Schreiner, Peter R.
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p. 434 - 439
(2007/10/03)
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- Acidic properties of sulfonic acid-functionalized FSM-16 mesoporous silica and its catalytic efficiency for acetalization of carbonyl compounds
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Propyl-sulfonic acid-functionalized FSM-16 mesoporous silica (SO 3H-FSM) is prepared by a conventional post-modification method. For the acetalization of carbonyl compounds with ethylene glycol, SO 3H-FSM shows a higher rate and 1,3-dioxolane yield than conventional heterogeneous solid acids such as zeolites, montmorillonite K10 clay, silica-alumina, and the sulfonic resin. SO3H-FSM is stable during the reaction, with no leaching and deactivation of sulfonic acid groups, and is reusable without loss of its activity. The acidity and hydrophilicity of SO 3H-FSM are well characterized by the microcalorimetry of NH 3 adsorption, NH3-TPD, and H2O-TPD, and the result is compared with those for various aluminosilicate zeolites (HZSM5, HBEA, HY) and K10 clay. It is found that NH3-TPD is not suitable for characterizing the acidity of SO3H-FSM, because the decomposition of SO3H groups on SO3H-FSM begins above 200°C. An NH 3 adsorption microcalorimetric experiment at 150°C shows that, compared with HZSM5, SO3H-FSM has a smaller number of acid sites but has a similar number of strong acid sites with ammonia adsorption heat above 140 kJ mol-1. Comparison of the structural properties and catalytic results shows that a large pore diameter and low hydrophilicity are required to obtain high activity. Bronsted acid sites with a relatively strong acid strength are more suitable for this reaction, but the high acid concentration is not indispensable. The high activity of SO3H-FSM should be caused by the presence of the strong Bronsted acid sites in the mesopore with a relatively low hydrophilicity, where both reactants can smoothly access the acid sites.
- Shimizu, Ken-Ichi,Hayashi, Eidai,Hatamachi, Tsuyoshi,Kodama, Tatsuya,Higuchi, Tomoya,Satsuma, Atsushi,Kitayama, Yoshie
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p. 131 - 138
(2007/10/03)
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- Highly shape-selective, biomimetic, and efficient deprotection of carbonyl compounds masked as ethylene acetals or dioxolanes produced from 1,2-ethanediol
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A simple, mild, efficient, and organic solvent-free biochemical approach for the deprotection of carbonyl compounds protected as 1,3-dioxolanes through the use of cyclodextrins as catalysts has been developed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Ji, Hong-Bing
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p. 3659 - 3662
(2007/10/03)
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- Highly efficient heterogeneous acetalization of carbonyl compounds catalyzed by a titanium cation-exchanged montmorillonite
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The titanium cation-exchanged montmorillonite efficiently catalyzed the selective acetalization of various carbonyl compounds as a recyclable solid acid. This heterogeneous catalyst has an advantage of a strikingly simple workup procedure over conventional homogeneous acids.
- Kawabata, Tomonori,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 8329 - 8332
(2007/10/03)
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- Microwave-assisted acetalization of carbonyl compounds catalyzed by reusable Envirocat supported reagents
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Envirocat supported reagents (EPZG, EPZ10, and EPIC) are found to efficiently catalyze the acetalization of carbonyl compounds with 1,2-ethanediol under microwave irradiation under solvent-free conditions. The reagents can be used in repeated experiments to perform the reaction with the same activity.
- Beregszaszi, Timea,Molnar, Arpad
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p. 3705 - 3709
(2007/10/03)
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- Percutaneous absorption enhancers, compositions containing same and method of use
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Novel 1,3-dioxolanes (1,3-dioxyacyclopentanes) are provided along with new 1,3-dioxolanes (1,3-dioxacyclopentanes) compositions which are useful in enhancing the absorption of therapeutic agents through the skin of humans and animals. The method for enhancing skin penetration of therapeutic agents using 1,3-dioxacycloalkanes is also described. The preferred compounds are 1,3-dioxolanes (1,3-dioxacyclopentanes) and 1,3-dioxanes (1,3-dioxacyclohexanes). The preferred compounds have the formula: STR1 wherein R, R0, R1, R2, R3, R4, R5 and R6 are each independently selected from hydrogen and C1 to C18 aliphatic groups, preferably alkyl, alkenyl, and the halo, hydroxy, carboxy, carboxamide and carboalkoxy substituted forms thereof, with at least one of said R's an alkyl or alkenyl group of C4 to C18 and n=0 or 1; the total number of carbon atoms in all of said R groups being no more than 40, and preferably less than 20 and not more than 1 thereof containing 18 or more carbon atoms.
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- A New Ready, High-Yielding, General Procedure for Acetalization of Carbonyl Compounds
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Carbonyl compounds are smoothly and rapidly acetalized by treatment with alcohols, in anhydrous acetonitrile, in the presence of polystyryl diphenyl phosphine - iodine complex as catalyst.Open and cyclic acetals, including 1,3-dioxolanes, 1,3-oxathiolanes, and 1,3-dithiolanes, of miscellaneous aldehydes and ketones have been successfully prepared in this way.The isolation of the product is very easily performed, by simple filtration of the polymer-linked phosphine oxide which is formed in the reaction.
- Caputo, Romualdo,Ferreri, Carla,Palumbo, Giovanni
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p. 386 - 389
(2007/10/02)
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