- The synthesis of butene glycol ethers with aluminium triflate
-
The use of aluminium triflate as a ring-opening catalyst for butene oxide (BuO) was evaluated in the presence of different alcohols such as methanol, ethanol, n-propanol, n-butanol, 2-propanol, 2-methyl-1-propanol, and 2-methyl-2-propanol. The reaction with methanol was studied kinetically by varying the temperature, catalyst concentration, and methanol - butene oxide molar ratio. These reactions yielded two major products (2-methoxy-1-butanol and 1-methoxy-2-butanol) in a approximate ratio of 1:1. It was noted that at low catalyst concentrations (5 ppm), low temperatures (90 °C), and a MeOH-BuO molar ratio of 8:1, the selectivity of the reaction could be kinetically manipulated to shift the product ratio towards 1-methoxy-2-butanol, the α-alkoxyalcohol. This result was confirmed by an experimental design program. Statistical calculations using the data from the experimental design identified a feasible region in which reactions with methanol could be carried out, which would lead to slightly higher selectivities to 1-methoxy-2-butanol. This region shows that the methanol - butene oxide ratio should be 8:1, the temperature between 80 and 85 °C, and the catalyst concentration between 3.9 and 5 ppm. These reaction conditions were used to carry out a test reaction with methanol and an extended series of alcohols. All the alcohols, except for 2-methyl-2-propanol, reacted with butene oxide under these conditions, with the selectivity to the α-alkoxyalcohol higher than to the β- alkoxyalcohol. To obtain a ring-opening reaction with 2-methyl-2-propanol, it was found that a higher catalyst concentration (approximately 10 ppm) and a lower alcohol - butene oxide ratio (6:1) at a temperature of 80 °C were necessary. This reaction led to a mixture of 1-tert-butoxy-2-butanol and 2-tert-butoxy-1-butanol with the selectivity to the α-alkoxyalcohol being somewhat higher because of the steric influence of the bulky tert-butoxy group.
- Terblans, Yvette M.,Huyser, Michelle,Young, Desmond A.,Green, Michael J.
-
-
Read Online
- Encapsulating Copper Nanocrystals into Metal–Organic Frameworks for Cascade Reactions by Photothermal Catalysis
-
Composite materials with multifunctional properties usually possess synergetic effects in catalysis toward cascade reactions. In this work, a facile strategy to the encapsulation of octahedral Cu2O nanocrystals (NCs) by metal–organic frameworks (MOFs) is reported, and an oriented growth of MOF enclosures (namely, HKUST-1) around Cu2O NCs with desired feedstock ratio is achieved. The strategy defines the parameter range that precisely controls the etching rate of metal oxide and the MOF crystallization rate. Finally, the Cu@HKUST-1 composites with uniform morphology and controlled MOF thickness have been successfully fabricated after the reduction of Cu2O to Cu NCs in HKUST-1. The integration of Cu NCs properties with MOF advantages helps to create a multifunctional catalyst, which exhibits cooperative catalytic activity and improved recyclability toward the one-pot cascade reactions under mild conditions involving visible-light irradiation. The superior performance can be attributed to the plasmonic photothermal effect of Cu NCs, while HKUST-1 shell provides Lewis acid sites, substrates and H2 enrichment, and stabilizes the Cu cores.
- Wang, Lin,Li, Shu-Rong,Chen, Yu-Zhen,Jiang, Hai-Long
-
-
Read Online
- Polyoxometalate-modified reduced graphene oxide foam as a monolith reactor for efficient flow catalysis of epoxide ring-opening reactions
-
Continuous flow catalysis has been attracting significant interest due to its remarkable advantages over traditional batch reactions. In this work, a facile and broad-spectrum hydrothermal approach has been developed to construct polyoxometalate-modified reduced graphene oxide (POM@rGO) foam, which worked as a monolith reactor for efficient continuous flow catalysis of epoxide ring-opening reactions. The porous structures of rGO foam allow the high dispersion of the POM catalyst onto the substrate through electrostatic interactions. Specifically, a phosphotungstic acid (H3PW12O40, denoted as PW12)-modified rGO (PW12@rGO) monolith reactor exhibits remarkable catalytic activity and durability towards epoxide ring-opening reactions with alcohols, achieving 99% conversion and 92% selectivity for the methanolysis product in 10 min under ambient conditions without stirring. Notably, while coupling with a micro-injection pump, such PW12@rGO foam can work as an efficient continuous flow reactor towards methanolysis of styrene oxide for 38 h with 99% conversion and over 90% selectivity, reaching a turnover number (TON) as high as 28?044.
- Jing, Xiaoting,Li, Zhen,Geng, Weijie,Lv, Hongjin,Chi, Yingnan,Hu, Changwen
-
p. 8480 - 8488
(2021/04/12)
-
- Epoxide ring opening with alcohols using heterogeneous Lewis acid catalysts: Regioselectivity and mechanism
-
Lewis acidic catalytic materials are investigated for the regioselective ring opening of epoxides with alcohols. For ring opening epichlorohydrin with methanol, the catalytic activity shows a strong dependence on the type of support and Lewis acidic species used. While Sn-SBA-15 is catalytically active, significantly higher catalytic activity can be achieved with hydrothermally synthesized zeolites of which Sn-Beta is 6 and 7 times more active than Zr-Beta or Hf-Beta, respectively. Sn-Beta is determined to be more active and more regioselective for epoxide ring opening of epichlorohydrin with methanol than Al-Beta. For Sn-Beta, the activation energy for the reaction between epichlorohydrin and methanol is determined to be 53 ± 7 kJ mol?1. For epichlorohydrin, the activation energy barrier and experimentally observed regioselectivity are found using DFT to be consistent with a concerted reaction mechanism involving activation of the epoxide on an alcohol adsorbed on the catalytic site and nucleophilic attack by a second alcohol. The epoxide is shown to impact the regioselectivity and the mechanism since isobutylene oxide is selectively ring opened by methanol to form the terminal alcohol. DFT calculations indicate the mechanism for isobutylene ring opening involves epoxide activation and ring opening on an alcohol adsorbed onto the catalytic site. Finally, catalyst reuse testing indicates that Sn-Beta can be used for multiple reactions with no decrease in activity and limited to no leaching of the tin site, demonstrating Sn-Beta is a promising catalytic material for epoxide ring opening reactions with alcohols.
- Deshpande, Nitish,Parulkar, Aamena,Joshi, Rutuja,Diep, Brian,Kulkarni, Ambarish,Brunelli, Nicholas A.
-
-
- Graphite oxide: A simple and efficient solid acid catalyst for the ring-opening of epoxides by alcohols
-
A simple, efficient, and general procedure for the ring-opening of epoxides with various alcohols to give the corresponding β-alkoxy alcohols using graphite oxide (GO) as the catalyst, under very mild reaction conditions is described. The method proceeds in good to excellent yields and in short reaction times at room temperature under metal-free conditions.
- Mirza-Aghayan, Maryam,Alizadeh, Mahdi,Molaee Tavana, Mahdieh,Boukherroub, Rabah
-
p. 6694 - 6697
(2014/12/11)
-
- COMPOSITIONS, SYNTHESIS, AND METHODS OF USING PHENYLCYCLOALKYLMETHYLAMINE DERIVATIVES
-
The present invention provides novel phenylcycloalkylmethylamme derivatives, and methods of preparing phenylcycloalkylmethylamme derivatives. The present invention also provides methods of using phenylcycloalkylmethylamme derivatives and compositions of phenylcycloalkylmethylamme derivatives. The pharmaceutical compositions of the compounds of the present invention can be used for treating and/or preventing obesity and obesity related co- morbid indications and depression and depression related co-morbid indications.
- -
-
Page/Page column 54-55
(2013/07/19)
-
- Aluminium triflate as catalyst for epoxide ring-opening and esterification reactions - Mechanistic aspects
-
A1(CF3SO3)3 is a highly effective catalyst for the ring opening of epoxides with methanol, as well as for the esterification of carboxylic acids with alcohols. Factors that influence the rate of the ring opening of butene oxide with methanol and the esterification of acetic acid with n-propanol and ethanol were investigated. It was found that low concentrations (e.g., ~5 ppm) of Al(CF3SO3) 3 catalyze the ring-opening reactions, whereas considerably higher concentrations are required for esterification reactions. Molecular modeling studies suggest that these differences can be rationalized in terms of the formation energies of the active intermediates of these reactions.
- Terblans, Yvette M.,Huyser, Johannes J.,Huyser, Michelle,Green, Michael J.,Young, Desmond A.,Sibiya, Mike S.
-
p. 854 - 861
(2007/10/03)
-
- Aluminium triflate: A remarkable Lewis acid catalyst for the ring opening of epoxides by alcohols
-
Al(OTf)3 was found to be an extremely effective catalyst (at ppm levels) for ring opening reactions of epoxides using a range of alcohols. The Royal Society of Chemistry 2005.
- Bradley,Williams,Lawton, Michelle
-
p. 3269 - 3272
(2007/10/03)
-