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Rational synthesis of palladium nanoparticles modified by phosphorous for the conversion of diphenyl ether to KA oil
Conversion of lignin-derived molecules into value-added chemicals is critical for sustainable chemistry but still challenging. Herein, phosphorus-modified palladium catalyzed the degradation of lignin-derived 4-O-5 linkage to produce KA oil (cyclohexanone-cyclohexanol oil) was reported. The reaction proceeds via a restricted partial hydrogenation-hydrolysis pathway. Phosphorus-modified palladium catalyst suppressed the full hydrogenation of diary ether, which was the key point to produce KA oil selectively. Under the optimized conditions, the 4.5 nm Pd-P NPs could catalyze the conversion of 4-O-5 linkage into KA oil in 83% selectivity with a high production rate of 32.5 mmol·g?1Pd·min?1. This study represented an original method for KA oil production.
Bai, Hong-Cun,Cao, Jing-Pei,Jiang, Wei,Wei, Yu-Lei,Xie, Jin-Xuan,Zhang, Chuang,Zhao, Liang,Zhao, Ming,Zhao, Xiao-Yan
(2021/12/23)

Hydrodeoxygenation of Lignin-Derived Aromatic Oxygenates Over Pd-Fe Bimetallic Catalyst: A Mechanistic Study of Direct C–O Bond Cleavage and Direct Ring Hydrogenation
Hydrodeoxygenation of lignin-derived phenols could be achieved generally with three reaction pathways: tautomerization, direct ring hydrogenation and direct C–O bond cleavage. The former pathway has been extensively studied over Pd/Fe catalyst in liquid-phase reaction, however, the contribution of the latter two is yet subject to further investigations. In this report, a comparative study of direct C–O bond cleavage and direct ring hydrogenation reaction pathways is presented on Pd/Fe, Fe and Pd/C catalysts using diphenyl ether as modelling compound. Despite its much higher activation energy than direct ring hydrogenation, direct C–O bond cleavage is dominant over Pd/Fe with much higher rates than the monometallic analogues due to the synergic catalysis of Pd–Fe. Based on this study and our previous results, the detailed reaction network for HDO of diphenyl ether is proposed. Graphic Abstract: [Figure not available: see fulltext.]
Zhang, Jianghao,Sudduth, Berlin,Sun, Junming,Wang, Yong
p. 932 - 939
(2020/09/02)

Selective hydrogenation of lignin-derived compounds under mild conditions
A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
supporting information
p. 3069 - 3073
(2020/06/17)

Highly Efficient and Selective N-Alkylation of Amines with Alcohols Catalyzed by in Situ Rehydrated Titanium Hydroxide
Catalytic N-alkylation of amines by alcohols to produce desired amines is an important catalytic reaction in industry. Various noble-metal-based homogeneous and heterogeneous catalysts have been reported for this process. The development of cheap non-noble-metal heterogeneous catalysts for the N-alkylation reaction would be highly desirable. Hereby, we propose the N-alkylation of amines by alcohols over a cheap and efficient heterogeneous catalyst-titanium hydroxide. This catalyst provides a selectivity higher than 90% to secondary amines for functionalized aromatic and aliphatic alcohols and amines with high catalytic activity and stability. Mild Br?nsted acidity formed by the continuous rehydration of Lewis acidity excludes the side reactions and deactivation by adsorbed species. The mechanism of the reaction involves dehydration of alcohols to ethers with subsequent C-O bond cleavage by amine with the formation of secondary amine and recovery of alcohol.
Khodakov, Andrei Y.,Kusema, Bright T.,Niu, Feng,Ordomsky, Vitaly V.,Wang, Qiyan,Yan, Zhen
p. 3404 - 3414
(2020/03/23)

Application of Yttrium Iron Garnet as a Powerful and Recyclable Nanocatalyst for One-Pot Synthesis of Pyrano[2,3-c]pyrazole Derivatives under Solvent-Free Conditions
The application of yttrium iron garnet (YIG) superparamagnetic nanoparticles as a new recyclable and highly efficient heterogeneous magnetic catalyst for one-pot synthesis of pyrano[2,3-c]pyrazole derivatives under solvent-free conditions, as well as etherification and esterification reactions are described. The advantages of the proposed method include the lack of organic solvents, clean reaction, rapid removal of the catalyst, short reaction times, excellent yields, and recyclability of the catalyst.
Sedighinia,Badri,Kiasat
p. 1755 - 1763
(2020/01/11)

Reductive Etherification of Aldehydes and Ketones with Alcohols and Triethylsilane Catalysed by Yb(OTf)3: an Efficient One-Pot Benzylation of Alcohols
The one-pot synthesis of symmetrical and unsymmetrical ethers from aldehydes and ketones can be conveniently performed using Yb(OTf)3 as catalyst and triethylsilane as reducing agent in presence of alcohols. This methodology leads to the synthesis of ether derivatives with good yields. Notably, this process resulted a useful tool to protect alcohols as benzyl ether derivatives using differently substituted benzaldehydes as protecting agents under mild conditions. A plausible mechanism was also proposed. (Figure presented.).
Pelosi, Azzurra,Lanari, Daniela,Temperini, Andrea,Curini, Massimo,Rosati, Ornelio
supporting information
p. 4527 - 4539
(2019/08/26)

Polysilane-Immobilized Rh-Pt Bimetallic Nanoparticles as Powerful Arene Hydrogenation Catalysts: Synthesis, Reactions under Batch and Flow Conditions and Reaction Mechanism
Hydrogenation of arenes is an important reaction not only for hydrogen storage and transport but also for the synthesis of functional molecules such as pharmaceuticals and biologically active compounds. Here, we describe the development of heterogeneous Rh-Pt bimetallic nanoparticle catalysts for the hydrogenation of arenes with inexpensive polysilane as support. The catalysts could be used in both batch and continuous-flow systems with high performance under mild conditions and showed wide substrate generality. In the continuous-flow system, the product could be obtained by simply passing the substrate and 1 atm H2 through a column packed with the catalyst. Remarkably, much higher catalytic performance was observed in the flow system than in the batch system, and extremely strong durability under continuous-flow conditions was demonstrated (>50 days continuous run; turnover number >3.4 × 105). Furthermore, details of the reaction mechanisms and the origin of different kinetics in batch and flow were studied, and the obtained knowledge was applied to develop completely selective arene hydrogenation of compounds containing two aromatic rings toward the synthesis of an active pharmaceutical ingredient.
Miyamura, Hiroyuki,Suzuki, Aya,Yasukawa, Tomohiro,Kobayashi, Shu
supporting information
p. 11325 - 11334
(2018/09/06)

Effect of the Crystallographic Phase of Ruthenium Nanosponges on Arene and Substituted-Arene Hydrogenation Activity
Identifying crystal structure sensitivity of a catalyst for a particular reaction is an important issue in heterogeneous catalysis. In this context, the activity of different phases of ruthenium catalysts for benzene hydrogenation has not yet been investigated. The synthesis of hcp and fcc phases of ruthenium nanosponges by chemical reduction method has been described. Reduction of ruthenium chloride using ammonia borane (AB) and tert-butylamine borane (TBAB) as reducing agents gave ruthenium nanosponge in its hcp phase. On the other hand, reduction using sodium borohydride (SB) afforded ruthenium nanosponge in its fcc phase. The as prepared hcp ruthenium nanosponge was found to be catalytically more active compared to the as prepared fcc ruthenium nanosponge for hydrogenation of benzene. The hcp ruthenium nanosponge was found to be thermally stable and recyclable over several cycles. This self-supported hcp ruthenium nanosponge shows excellent catalytic activity towards hydrogenation of various substituted benzenes. Moreover, the ruthenium nanosponge catalyst was found to bring about selective hydrogenation of aromatic cores of phenols and aryl ethers to the respective alicyclic products without hydrogenolysis of the C?O bond.
Ghosh, Sourav,Jagirdar, Balaji R.
p. 3086 - 3095
(2018/05/29)

Formal Cross-Coupling of Diaryl Ethers with Ammonia by Dual C(Ar)-O Bond Cleavages
The conversion of renewable resources and inexpensive inorganic chemicals directly into higher value-added organic chemicals is becoming more and more important for our society's future sustainable development. Lignin, being the second most abundant organic carbon renewable resource on Earth, has been treated as waste in the pulp and paper industry. The 4-O-5 linkage diaryl ether bond is the strongest among the three types of ether linkages in lignins. Selective cleavage of this linkage can potentially generate smaller processable bio-based aromatic polymeric materials and compounds. Furthermore, there has been a long synthetic interest in coupling reactions with aryl ethers via C(Ar)-O bond cleavage, for example, for polyphenylene oxide (PPO) waste recycling. On the other hand, ammonia is a very inexpensive industrial inorganic chemical. Herein, we report a direct conversion of diaryl ethers and ammonia into aniline derivatives and arenes, providing a model for selective lignin 4-O-5 linkage modification and PPO recycling with inexpensive ammonia. Both symmetrical and unsymmetrical diaryl ethers were successfully cross-coupled with ammonia via dual C(Ar)-O bond cleavages, generating the corresponding cyclohexylanilines and arenes.
Cao, Dawei,Zeng, Huiying,Li, Chao-Jun
p. 8873 - 8878
(2018/09/12)

Rh(CAAC)-Catalyzed Arene Hydrogenation: Evidence for Nanocatalysis and Sterically Controlled Site-Selective Hydrogenation
We report the arene hydrogenation of ethers, amides, and esters at room temperature and low hydrogen pressure, starting from [(CAAC)Rh(COD)Cl] (CAAC = cyclic alkyl amino carbene). Kinetic, mechanistic, and Rh K-edge XAFS studies showed formation of Rh nanoparticles from [(CAAC)Rh(COD)Cl], in contrast to a previous report of [(CAAC)Rh(COD)Cl] functioning as a homogeneous catalyst for arene hydrogenation. We determined that the site-selective arene hydrogenation catalyzed by this system is under steric control, as shown by detailed competition experiments with derivatives of ethers, amides, and esters bearing different aromatic rings of varying electronic and steric influence. This work illustrates the potential of CAAC ligands in the formation and stabilization of a colloidal dispersion of stable nanoparticle catalysts.
Tran, Ba L.,Fulton, John L.,Linehan, John C.,Lercher, Johannes A.,Bullock, R. Morris
p. 8441 - 8449
(2018/08/17)

Cobalt-Catalyzed Secondary Alkylation of Arenes and Olefins with Alkyl Ethers through the Cleavage of C(sp2)-H and C(sp3)-O Bonds
A novel cobalt-catalyzed C-H alkylation of arenes and olefins is achieved with (pyridin-2-yl)isopropyl amine as an N,N-bidentate directing group. Different linear, branched, and cyclic alkyl ethers were used as practical secondary alkylating reagents through cleavage of C(sp3)-O bond, providing an efficient approach to the synthesis of verstile o-alkylated arylamides and tetrasubstituted acrylamides. Mechanistic studies indicate that cleavage of the inert C(sp3)-O bond involves a cobalt-promoted radical process and that cleavage of the inert C(sp2)-H bond by a cobalt catalyst is a rate-limiting step.
Dong, Xunqing,Li, Qun,Li, Guigen,Lu, Hongjian
p. 13402 - 13413
(2018/11/20)

HYDROSILANE/LEWIS ACID ADDUCT, PARTICULARLY ALUMINUM, IRON, AND ZINC, METHOD FOR PREPARING SAME, AND USE OF SAID SAME IN REACTIONS FOR REDUCING CARBONYL DERIVATIVES
Disclosed is an adduct between a Lewis acid, preferably aluminum trichloride, iron trichloride, or zinc dichloride, and a hydrosilane;—a method for preparing same; and a method for for reducing, particularly, an aldehyde, a ketone, an α,β-unsaturated ketone, an imine, or an α,β-unsaturated imine.
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Paragraph 0203; 0204

(2018/02/28)

Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.
Bayguzina,Gimaletdinova,Khusnutdinov
p. 1148 - 1155
(2018/10/24)

Efficient cleavage of aryl ether C-O linkages by Rh-Ni and Ru-Ni nanoscale catalysts operating in water
Bimetallic Ru-Ni and Rh-Ni nanocatalysts coated with a phase transfer agent efficiently cleave aryl ether C-O linkages in water in the presence of hydrogen. For dimeric substrates with weaker C-O linkages, i.e. α-O-4 and β-O-4 bonds, low loadings of the precious metal (Rh or Ru) in the nanocatalysts quantitatively afford monomers, whereas for the stronger 4-O-5 linkage higher amounts of the precious metal are required to achieve complete conversion. Under the optimized, relatively mild operating conditions, the C-O bonds in a range of substituted ether compounds are efficiently cleaved, and mechanistic insights into the reaction pathways are provided. This work paves the way to sustainable approaches for the hydrogenolysis of C-O bonds.
Bulut, Safak,Siankevich, Sviatlana,Van Muyden, Antoine P.,Alexander, Duncan T. L.,Savoglidis, Georgios,Zhang, Jiaguang,Hatzimanikatis, Vassily,Yan, Ning,Dyson, Paul J.
p. 5530 - 5535
(2018/07/06)

Palladium-Catalyzed Formal Cross-Coupling of Diaryl Ethers with Amines: Slicing the 4-O-5 Linkage in Lignin Models
Lignin is the second most abundant organic matter on Earth, and is an underutilized renewable source for valuable aromatic chemicals. For future sustainable production of aromatic compounds, it is highly desirable to convert lignin into value-added platform chemicals instead of using fossil-based resources. Lignins are aromatic polymers linked by three types of ether bonds (α-O-4, β-O-4, and 4-O-5 linkages) and other C?C bonds. Among the ether bonds, the bond dissociation energy of the 4-O-5 linkage is the highest and the most challenging to cleave. To date, 4-O-5 ether linkage model compounds have been cleaved to obtain phenol, cyclohexane, cyclohexanone, and cyclohexanol. The first example of direct formal cross-coupling of diaryl ether 4-O-5 linkage models with amines is reported, in which dual C(Ar)?O bond cleavages form valuable nitrogen-containing derivatives.
Zeng, Huiying,Cao, Dawei,Qiu, Zihang,Li, Chao-Jun
supporting information
p. 3752 - 3757
(2018/03/13)

Palladium-Catalyzed Reductive Insertion of Alcohols into Aryl Ether Bonds
Palladium on carbon catalyzes C?O bond cleavage of aryl ethers (diphenyl ether and cyclohexyl phenyl ether) by alcohols (R?OH) in H2. The aromatic C?O bond is cleaved by reductive solvolysis, which is initiated by Pd-catalyzed partial hydrogenation of one phenyl ring to form an enol ether. The enol ether reacts rapidly with alcohols to form a ketal, which generates 1-cyclohexenyl?O?R by eliminating phenol or an alkanol. Subsequent hydrogenation leads to cyclohexyl?O?R.
Wang, Meng,Gutiérrez, Oliver Y.,Camaioni, Donald M.,Lercher, Johannes A.
p. 3747 - 3751
(2018/03/21)

Hydrogenolysis/hydrogenation of diphenyl ether as a model decomposition reaction of lignin from biomass in pressurized CO2/water condition
Catalytic hydrogenolysis of the C[sbnd]O bond of diphenyl ether (a lignin model compound) was investigated as a function of hydrogen pressure in scCO2 medium in the presence of water. Using commercially available Rh/C catalyst, the C[sbnd]O bond cleavage of diphenyl ether mainly results phenolic monomer at 80 °C. Hydrogen pressure is one of the key parameters because (i) C[sbnd]O bond cleavage and the hydrogenation of aromatic rings are two competitive reactions; very sensitive to hydrogen pressure and (ii) hydrogen has complete solubility in scCO2. Therefore, a critical control of hydrogen pressure was essential to reach the targeted cleavage of the C[sbnd]O bond when the reaction was conducted in scCO2 medium under pressurized condition. Depending on the hydrogen pressure, a significant change in the ratio of monocyclic:bicyclic products from 91:9 (0.2 MPa) to 58:42 (2 MPa) was revealed in the shortest reaction time of 5 min. Thus, low hydrogen pressure was the effective choice for the scission of the C[sbnd]O bond, whereas higher hydrogen pressure hydrogenate the aromatic ring due to the higher coverage of hydrogen on the catalytic surface. Amount of the catalyst (catalyst:substrate ratio) displayed a subtle effect on the breakage of the C[sbnd]O bond. A threshold ratio of 1:5 was preferred under the present reaction condition as the increased amount hampered the substrate:water ratio and hydrogenation of the aromatic ring occurred. In addition, as the change in temperature is associated with the change in the physical properties of scCO2, hence, the effect on the transformation of DPE was complicated and difficult to explain. Furthermore, different organic solvents as neat, along with CO2 and with water also has substantial impact on the rapture of C[sbnd]O bond. The obtained results from the solvent studies again proved that scCO2 along with water was the best choice for C[sbnd]O bond breakage and water is the driving force to mediate the reaction. In addition, a combination catalyst (Ni+Rh) was also tested for the same reaction under the similar working condition. Preliminary results suggested a synergistic effect in terms of the selectivity of monocyclic compounds.
Chatterjee, Maya,Ishizaka, Takayuki,Kawanami, Hajime
p. 402 - 409
(2016/12/14)

One-Pot Process for Hydrodeoxygenation of Lignin to Alkanes Using Ru-Based Bimetallic and Bifunctional Catalysts Supported on Zeolite Y
The synthesis of high-efficiency and low-cost catalysts for hydrodeoxygenation (HDO) of waste lignin to advanced biofuels is crucial for enhancing current biorefinery processes. Inexpensive transition metals, including Fe, Ni, Cu, and Zn, were severally co-loaded with Ru on HY zeolite to form bimetallic and bifunctional catalysts. These catalysts were subsequently tested for HDO conversion of softwood lignin and several lignin model compounds. Results indicated that the inexpensive earth-abundant metals could modulate the hydrogenolysis activity of Ru and decrease the yield of low-molecular-weight gaseous products. Among these catalysts, Ru-Cu/HY showed the best HDO performance, affording the highest selectivity to hydrocarbon products. The improved catalytic performance of Ru-Cu/HY was probably a result of the following three factors: (1) high total and strong acid sites, (2) good dispersion of metal species and limited segregation, and (3) high adsorption capacity for polar fractions, including hydroxyl groups and ether bonds. Moreover, all bifunctional catalysts proved to be superior over the combination catalysts of Ru/Al2O3 and HY zeolite.
Wang, Hongliang,Ruan, Hao,Feng, Maoqi,Qin, Yuling,Job, Heather,Luo, Langli,Wang, Chongmin,Engelhard, Mark H.,Kuhn, Erik,Chen, Xiaowen,Tucker, Melvin P.,Yang, Bin
p. 1846 - 1856
(2017/04/27)

Palladium-Catalyzed Hydrolytic Cleavage of Aromatic C?O Bonds
Metallic palladium surfaces are highly selective in promoting the reductive hydrolysis of aromatic ethers in aqueous phase at relatively mild temperatures and pressures of H2. At quantitative conversions, the selectivity to hydrolysis products of PhOR ethers was observed to range from 50 % (R=Ph) to greater than 90 % (R=n-C4H9, cyclohexyl, and PhCH2CH2). By analysis of the evolution of products with and without incorporation of H218O, the pathway was concluded to be initiated by palladium metal catalyzed partial hydrogenation of the phenyl group to an enol ether. Water then rapidly adds to the enol ether to form a hemiacetal, which then undergoes elimination to cyclohexanone and phenol/alkanol products. A remarkable feature of the reaction is that the stronger Ph?O bond is cleaved rather than the weaker aliphatic O?R bond.
Wang, Meng,Shi, Hui,Camaioni, Donald M.,Lercher, Johannes A.
supporting information
p. 2110 - 2114
(2017/02/15)

An efficient Pt nanoparticle-ionic liquid system for the hydrodeoxygenation of bio-derived phenols under mild conditions
Platinum nanoparticles (NPs) were synthesized in situ in the ionic liquid (IL) [Emim]NTf2 (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) as well as in mixtures of [Emim]NTf2 with a second IL, Lewis acid or Br?nsted acid, but in the absence of additional stabilizers. The resulting NP/IL systems catalyze the hydrodeoxygenation of a phenol under mild conditions (60 °C, 1.0 MPa H2), achieving full substrate conversion and a high deoxygenation rate (over 95%) to cyclohexane and cyclohexene. The combination of [Emim]NTf2 and [Bmim]PF6 results in the best catalytic performance. Also the transformation of other substituted phenols and dimers such as catechol, guaiacol and diphenyl ether was studied in the Pt NP/[Emim]NTf2-[Bmim]PF6 system and in most cases afforded cyclohexane in good yield.
Chen, Lu,Fink, Cornel,Fei, Zhaofu,Dyson, Paul J.,Laurenczy, Gabor
supporting information
p. 5435 - 5441
(2017/11/24)

Bifunctional Ni catalysts for the one-pot conversion of Organosolv lignin into cycloalkanes
In this report, Ni/ZrO2, Ni/Al2O3, Ni/Al2O3-KF, Ni/SBA-15, and Ni/Al-SBA-15 were examined as catalysts for the hydrodeoxygenation of diphenyl ether. Adopting the degree of deoxygenation and yield of monocyclic products as the criteria for the catalyst selection, Ni/Al-SBA-15 was identified as the best catalyst for HDO of diphenyl ether. In fact, in the presence of Ni/Al-SBA-15, full conversion of the model compound into cyclohexane was achieved with high selectivity (98%). Most strikingly, Ni/Al-SBA-15 is capable of hydrodeoxygenating Organosolv lignin with selectivity to cycloalkanes higher than 99%. Owing to the similarities to hydrocarbons derived from petroleum, the lignin-derived alkanes could well be refined into drop-in fuels by conventional oil refinery processes. Moreover, in a broader perspective, the current results also highlight the importance of Al-SBA-15, as an acidic support alternative to zeolites or other acidic materials, for the HDO of phenolic streams.
Wang, Xingyu,Rinaldi, Roberto
p. 48 - 55
(2016/05/10)

Hydrogenation of lignin-derived phenolic compounds over step by step precipitated Ni/SiO2
The harsh reaction conditions for the valorization of lignin-derived phenolic compounds considerably limit the efficient utilization of the lignin derivatives. Here, we put forward a high efficient and selective hydrogenation process for phenolic compounds at a mild condition over step by step precipitated Ni/SiO2 catalyst. The properties of the Ni/SiO2 catalysts by different preparation methods were detailedly compared using various characterization measurements. Catalytic activity of the catalysts was tested by the hydrogenation of guaiacol, and the results showed that guaiacol could be completely converted into cyclohexanol with 99.9% selectivity at 120 °C, 2 MPa H2 atmosphere for 2 h. Other typical lignin-derived phenolic compounds also had excellent hydrogenation performance and great energy efficiency. Catalyst characterization results demonstrated that the high catalytic activity of the step by step precipitated Ni/SiO2 was mainly ascribed to its polyporous spherical structure, which led to the large specific surface area and high nickel dispersion. The appropriate acidity of the catalyst also promoted the catalytic performance significantly. Furthermore, the catalyst exhibited an excellent recyclability, where no significant loss of the catalytic activity was showed out after 3 runs.
Shu, Riyang,Zhang, Qi,Xu, Ying,Long, Jinxing,Ma, Longlong,Wang, Tiejun,Chen, Pengru,Wu, Qingyun
p. 5214 - 5222
(2016/02/05)

Continuous-Flow Multistep Synthesis of Cinnarizine, Cyclizine, and a Buclizine Derivative from Bulk Alcohols
Cinnarizine, cyclizine, buclizine, and meclizine belong to a family of antihistamines that resemble each other in terms of a 1-diphenylmethylpiperazine moiety. We present the development of a four-step continuous process to generate the final antihistamines from bulk alcohols as the starting compounds. HCl is used to synthesize the intermediate chlorides in a short reaction time and excellent yields. This methodology offers an excellent way to synthesize intermediates to be used in drug synthesis. Inline separation allows the collection of pure products and their immediate consumption in the following steps. Overall isolated yields for cinnarizine, cyclizine, and a buclizine derivative are 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1. The incredible bulk: Bulk alcohols are converted continuously into chlorides using HCl in a microflow. A reaction network that consists of four steps and two inline separations leads to the continuous preparation of cinnarizine, cyclizine, and a buclizine derivative with yields of 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1.
Borukhova, Svetlana,Nol, Timothy,Hessel, Volker
p. 67 - 74
(2016/01/16)

Ruthenium Nanoparticles Stabilized in Cross-Linked Dendrimer Matrices: Hydrogenation of Phenols in Aqueous Media
Novel catalysts consisting of ruthenium nanoparticles encapsulated in cross-linked matrices based on the poly(propylene imine) dendrimers of the 1st and 3rd generations have been synthesized with a narrow particle size distribution (3.8 and 1.0 nm, respectively). The resulting materials showed high activity for the hydrogenation of phenols in aqueous media (specific catalytic activity reached turnover frequencies of 2975h-1 with respect to hydrogen uptake). It has been shown that the use of water as a solvent leads to a 1.5 to 50-fold increase in the reaction rate depending upon the nature of the substrate. It has been established that unlike the traditional heterogeneous catalysts based on ruthenium, during the hydrogenation of dihydroxybenzenes, the hydrogenation rate decreases in the order: resorcinol>hydroquinoneacatechol. The maximum specific activity for resorcinol was a turnover frequency of 243150h-1 with respect to hydrogen uptake. The catalyst based on the dendrimer of the 3rd generation containing finer particles has significantly inferior activity to the catalyst based on the dendrimer of the 1st generation by virtue of steric factors, as well as the need for prereduction of the ruthenium oxide contained on the surface. These catalysts showed resistance to metal leaching and may be reused several times without loss of activity.
Maximov, Anton,Zolotukhina, Anna,Murzin, Vadim,Karakhanov, Edward,Rosenberg, Edward
p. 1197 - 1210
(2015/04/14)

Synthesis of ethers from carbonyl compounds by reductive etherification catalyzed by iron(III) and silyl chloride
A simple iron- and silyl chloride catalyzed method for the preparation of symmetrical and nonsymmetrical ethers is presented. Various aldehydes and ketones were reductively etherified by using triethylsilane as a reducing agent in the presence of 2 mol% of iron(III) oxo acetate and 8 mol% of chloro(trimethyl)silane. The reactions can be carried out at ambient temperatures and pressures with ethyl acetate as the solvent.
Savela, Risto,Leino, Reko
p. 1749 - 1760
(2015/06/16)

Mechanisms of selective cleavage of C-O bonds in di-aryl ethers in aqueous phase
A route for cleaving the C-O aryl ether bonds of p-substituted H-, CH 3-, and OH- diphenyl ethers has been explored over Ni/SiO2 catalyst at very mild conditions (393 K, 0.6 MPa). The C-O bond of diphenyl ether is cleaved by parallel hydrogenolysis and hydrolysis (hydrogenolysis combined with HO* addition) on Ni. The rates as a function of H2 pressure from 0 to 10 MPa indicate that the rate-determining step is the C-O bond cleavage on Ni surface. H* atoms compete with the organic reactant for adsorption leading to a maximum in the rate with increasing H2 pressure. In contrast to diphenyl ether, hydrogenolysis is the exclusive route for cleaving a C-O bond of di-p-tolyl ether to form p-cresol and toluene. 4,4′-Dihydroxydiphenyl ether undergoes sequential surface hydrogenolysis, first to phenol and OC6H4OH * (adsorbed), which is then cleaved to phenol (C 6H4OH* with added H*) and H2O (O* with two added H*) in a second step. Density function theory supports the operation of this pathway. Notably, addition of H* to OC6H4OH * is less favorable than a further hydrogenolytic C-O bond cleavage. The TOFs of three diaryl ethers with Ni/SiO2 in water follow the order 4,4′-dihydroxydiphenyl ether 69molmolNi Surf-1h -1 > diphenyl ether 26molmolNi Surf-1h-1 > di-p-tolyl ether 1.3molmolNi Surf-1h-1, in line with the increasing apparent activation energies, ranging from 4,4′-dihydroxydiphenyl ether (93 kJ mol-1) -1) -1).
He, Jiayue,Zhao, Chen,Mei, Donghai,Lercher, Johannes A.
p. 280 - 290
(2014/04/03)

Catalytic hydrodeoxygenation of anisole as lignin model compound over supported nickel catalysts
Catalytic hydrodeoxygenation (HDO) of anisole, a methoxy-rich lignin model compound, has been investigated over a series of Ni-containing (10 wt% loading) catalysts with activated carbon, SBA-15, SiO2, and γ-Al 2O3 supports, in order to understand their ability for removal of OCH3 from anisole. This catalytic reaction had been carried out in an autoclave at 180-220 °C and 0.5-3.0 MPa H2 pressure. Nickel-catalyzed aromatic ring-hydrogenation compared with the subsequent demethylation and deoxygenation is the fastest step in HDO of anisole under the present reaction conditions. Among these catalysts, the aromatic ring-saturated cyclohexyl methyl ether is mainly obtained over Ni/AC, while the Ni/SiO2 displayed the highest activity in HDO of anisole (selectivity to deoxygenated products >95%). Differences in HDO efficiency among the catalysts are attributed not only to variations in the dispersion of the active phase, but also to the acid sites which may contribute to the cleavage of CO bonds. It has also been shown that the activity toward oxygen-removal strongly depended on reaction temperature and the conversion of anisole favors the production of oxygen-free aromatics by the direct demethoxylation pathway at the relatively low H2 pressure.
Jin, Shaohua,Xiao, Zihui,Li, Chuang,Chen, Xiao,Wang, Lei,Xing, Jiacheng,Li, Wenzhen,Liang, Changhai
p. 125 - 132
(2014/07/07)

Reduction of aromatic compounds with Al powder using noble metal catalysts in water under mild reaction conditions
In water, Al powder becomes a powerful reducing agent, transforming in cyclohexyl either one or both benzene rings of aromatic compounds such as biphenyl, fluorene and 9,10-dihydroanthracene under mild reaction conditions in the presence of noble metal catalysts, such as Pd/C, Rh/C, Pt/C, or Ru/C. The reaction is carried out in a sealed tube, without the use of any organic solvent, at low temperature. Partial aromatic ring reduction was observed when using Pd/C, the reaction conditions being 24 h and 60 °C. The complete reduction process of both aromatic rings required 12 h and 80 °C with Al powder in the presence of Pt/C.
Rayhan, Ummey,Kwon, Hyeokmi,Yamato, Takehiko
p. 952 - 957
(2014/08/18)

Hydrodeoxygenation of mono- and dimeric lignin model compounds on noble metal catalysts
The influence of reaction conditions (temperature, acidity) on the catalytic performance of supported Pt, Pd and Ru catalysts for the aqueous phase hydrodeoxygenation (HDO) of lignin model compounds was systematically investigated. Phenol conversion proceeds via hydrogenation of the aromatic ring resulting in cyclohexanone, which is subsequently converted to cyclohexanol and cyclohexane. Although aromatic ring hydrogenation has a higher rate for Pt and Pd-based catalysts, the rate of hydrogenation of the polar C=O moiety in cyclohexanone is faster for Ru/C. The complete HDO of phenol to cyclohexane on noble-metal catalysts can only be achieved in the presence of a Br?nsted acid co-catalyst. In guaiacol conversion, efficient demethoxylation and ring hydrogenation can be achieved within 0.5 h on Pt/C. Under acidic conditions, selectivity of nearly 90% to cyclohexane at a conversion of 75% was achieved in 4 h. To get an insight into the possibility to cleave covalent linkages between aromatic units in lignin under HDO conditions, the reactivity of dimeric model substances such as diphenyl ether, benzyl phenyl ether, diphenyl methane and biphenyl was investigated. Although dimeric oxygen-bridged model compounds such as benzylphenyl ether and diphenyl ether can be readily converted to monomeric species in the presence of noble metal catalysts, cleavage of C-C bonds in diphenyl methane and biphenyl was not observed. Plausible reaction mechanisms are proposed.
Güvenatam, Burcu,Kur?un, Osman,Heeres, Erik H.J.,Pidko, Evgeny A.,Hensen, Emiel J.M.
p. 83 - 91
(2014/07/07)

Titanium nitride-nickel nanocomposite as heterogeneous catalyst for the hydrogenolysis of aryl ethers
Lignin from biomass can become a sustainable source of aromatic compounds. Its depolymerization can be accomplished through hydrogenolysis, although the development of catalysts based on cheap and abundant metals is lacking. Herein, a sustainable composite based on titanium nitride and nickel is synthesized and employed as catalyst for the hydrogenolysis of aryl ethers as models for lignin. The catalytic activity of the new material during hydrogenation reactions is proven to be superior to that of either component alone. In particular, different aryl ethers could be efficiently converted under relatively mild conditions into aromatic compounds and cycloalkanes within minutes.
Molinari, Valerio,Giordano, Cristina,Antonietti, Markus,Esposito, Davide
supporting information
p. 1758 - 1761
(2014/03/21)

Mesoporous nickel-aluminosilicate nanocomposite: A solid acid catalyst for ether synthesis
Mesoporous nickel aluminosilicate, a solid acid catalyst prepared by sol-gel technique was utilized as a heterogeneous catalyst for the synthesis of symmetrical ethers by dehydro-condensation of alcohols. The prepared catalysts were characterized by Fourier-transform infra red spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), N2 adsorption-desorption analysis, temperature programmed desorption of ammonia (TPD) and X-ray photoelectron spectroscopic techniques. The presence of the catalyst assisted the etherification reaction in 30 minutes. Ethers formed in these reactions were quantified by gas chromatography (GC) and the identities of few of them were confirmed by nuclear magnetic resonance spectral data (NMR). Copyright
Neelakandeswari,Karvembu,Dharmaraj
p. 2853 - 2863
(2013/08/25)

An efficient cleavage of the aryl ether C-O bond in supercritical carbon dioxide-water
A simple and highly efficient Rh/C catalyzed route for the cleavage of the C-O bond of aromatic ether at 80 °C in the presence of 0.5 MPa of H 2 in the scCO2-water medium is reported; CO2 pressure and water play a key role under the tested conditions.
Chatterjee, Maya,Ishizaka, Takayuki,Suzuki, Akira,Kawanami, Hajime
supporting information
p. 4567 - 4569
(2013/06/04)

Hydrogenation of phenols in ionic liquids on rhodium nanoparticles
A new catalyst system based on rhodium nanoparticles stabilized by polyacrylic acid have been suggested for the hydrogenation of phenols in ionic liquids. It has been shown that high near-quantitative yields of reaction products are achieved in ionic liquids containing a tetraalkylammonium cation. By the TEM and XPS techniques it has been revealed that the use of ionic liquids substantially decreases the particle size and reduces the aggregation of nanoparticles through the inclusion of the ionic liquid cations into the surface layer along with polyacrylic acid.
Maksimov,Kuklin,Kardasheva,Karakhanov
p. 157 - 163
(2013/07/27)

CATALYTIC C-H BOND ACTIVATION FOR THE SYNTHESIS OF ETHERS AND THIOETHERS
Disclosed is a method for the transition metal-mediated oxidation of C-H bonds to form C-0 or C-S bonds. The methods are useful for the formation of ethers (R-OR') from alcohols, R'OH, and sp3 -hybridized C-H bonds in substrates, R-H. Aryl or heteroaryl acetates may also be used for C-H to C-OAr bond formation. The methods are also useful in the preparation of C-S bonds from acetyl-protected thiols, MeC(0)SR, and disulfides, RSSR. Advantageously, the methods minimize reaction steps, the handling of oxidized intermediates, and environmental impact.
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(2014/01/08)

Screening of catalysts for hydrodeoxygenation of phenol as a model compound for bio-oil
Four groups of catalysts have been tested for hydrodeoxygenation (HDO) of phenol as a model compound of bio-oil, including oxide catalysts, methanol synthesis catalysts, reduced noble metal catalysts, and reduced non-noble metal catalysts. In total, 23 different catalysts were tested at 100 bar H2 and 275 C in a batch reactor. The experiments showed that none of the tested oxides or methanol synthesis catalysts had any significant activity for phenol HDO under the given conditions, which were linked to their inability to hydrogenate the aromatic ring of phenol. HDO of phenol over reduced metal catalysts could effectively be described by a kinetic model involving a two-step reaction in which phenol initially was hydrogenated to cyclohexanol and then subsequently deoxygenated to cyclohexane. Among reduced noble metal catalysts, ruthenium, palladium, and platinum were all found to be active, with activity decreasing in that order. Nickel was the only active non-noble metal catalyst. For nickel, the effect of support was also investigated and ZrO2 was found to perform best. Pt/C, Ni/CeO2, and Ni/CeO2-ZrO 2 were the most active catalysts for the initial hydrogenation of phenol to cyclohexanol but were not very active for the subsequent deoxygenation step. Overall, the order of activity of the best performing HDO catalysts was as follows: Ni/ZrO2 > Ni-V2O5/ZrO 2 > Ni-V2O5/SiO2 > Ru/C > Ni/Al2O3 > Ni/SiO2 Pd/C > Pt/C. The choice of support influenced the activity significantly. Nickel was found to be practically inactive for HDO of phenol on a carbon support but more active than the carbon-supported noble metal catalysts when supported on ZrO2. This observation indicates that the nickel-based catalysts require a metal oxide as a carrier on which the activation of the phenol for the hydrogenation can take place through heterolytic dissociation of the O-H bond to facilitate the reaction.
Mortensen, Peter M.,Grunwaldt, Jan-Dierk,Jensen, Peter A.,Jensen, Anker D.
p. 1774 - 1785
(2013/09/02)

Solvent effects on the hydrogenolysis of diphenyl ether with raney nickel and their implications for the conversion of lignin
The conversion of lignin, the most recalcitrant of the biopolymers, is necessary for a carbon-efficient utilization of lignocellulosic materials. In this context, hydrogenolysis of lignin is a process receiving increasing attention. In this report, the solvent effects on the hydrogenolysis of diphenyl ether and lignin with Raney Ni are addressed. The Lewis basicity of the solvent very much affects the catalytic activity, so Raney Ni in nonbasic solvents is an extremely active catalyst for hydrogenolysis and hydrogenation. In basic solvents, however, Raney Ni is a less active, but much more selective catalyst for hydrogenolysis while preserving the aromatic products. With regard to the reactions with lignin, assessing the complexity of the product mixtures by two-dimensional GC×GC-MS revealed solvent effects on the product distribution. Reaction in methylcyclohexane resulted in cyclic alcohols and cyclic alkanes, whereas reaction in 2-propanol led to cyclic alcohols, cyclic ketones, and unsaturated products. The hydrogenolysis of lignin in methanol, however, produced mostly phenols. Overall, these results demonstrate that the solvent plays a key role in directing the selectivity and, thus, it must be taken into consideration in the design of catalytic systems for conversion of lignin by hydrogenolysis of C-O ether bonds. Copyright
Wang, Xingyu,Rinaldi, Roberto
scheme or table
p. 1455 - 1466
(2012/10/07)

Intermolecular dehydration of alcohols by the action of copper compounds activated with carbon tetrabromide. synthesis of ethers
Copper compounds of the general formula CuXn (X = Cl, Br, I, acac, OAc, C7H4O3, C7H 5O2; n = 1, 2) activated by carbon tetrabromide catalyzed intermolecular dehydration of primary and secondary alcohols with formation of the corresponding ethers.
Khusnutdinov, R. I.,Bayguzina, A. R.,Gimaletdinova, L. I.,Dzhemilev, U. M.
p. 1191 - 1196,6
(2020/10/15)

Ni-catalyzed cleavage of aryl ethers in the aqueous phase
A novel Ni/SiO2-catalyzed route for selective cleavage of ether bonds of (lignin-derived) aromatic ethers and hydrogenation of the oxygen-containing intermediates at 120 C in presence of 6 bar H2 in the aqueous phase is reported. The C-O bonds of α-O-4 and β-O-4 linkages are cleaved by hydrogenolysis on Ni, while the C-O bond of the 4-O-5 linkage is cleaved via parallel hydrogenolysis and hydrolysis. The difference is attributed to the fact that the Caliphatic-OH fragments generated from hydrolysis of α-O-4 and β-O-4 linkages can undergo further hydrogenolysis, while phenol (produced by hydrolysis of the 4-O-5 linkage) is hydrogenated to produce cyclohexanol under conditions investigated. The apparent activation energies, Ea(α-O-4) a(β-O-4) a(4-O-5), vary proportionally with the bond dissociation energies. In the conversion of β-O-4 and 4-O-5 ether bonds, C-O bond cleavage is the rate-determining step, with the reactants competing with hydrogen for active sites, leading to a maximum reaction rate as a function of the H2 pressure. For the very fast C-O bond cleavage of the α-O-4 linkage, increasing the H2 pressure increases the rate-determining product desorption under the conditions tested.
He, Jiayue,Zhao, Chen,Lercher, Johannes A.
supporting information
p. 20768 - 20775
(2013/02/22)

Copper(II) triflate-catalyzed reduction of carboxylic acids to alcohols and reductive etherification of carbonyl compounds
A protocol is described for the reduction of carboxylic acids to primary alcohols using 1,1,3,3-tetramethyldisiloxane (TMDS) and a catalytic amount of Cu(OTf)2. Aliphatic as well as aromatic carboxylic acids are reduced in high selectivity and good yields. TMDS/Cu(OTf)2 has also been found to be an efficient catalytic reducing system for the preparation of symmetrical ethers from carbonyl compounds under mild conditions.
Zhang, Yin-Jie,Dayoub, Wissam,Chen, Guo-Rong,Lemaire, Marc
experimental part
p. 7400 - 7407
(2012/09/10)

Silica chloride and boron sulfonic acid as solid acid catalysts in preparation of ethers and esters under solvent-free condition
Boron sulfonic acid was easily prepared from the reaction of boric acid and chlorosulfonic acid under solvent free condition. The prepared solid acid was supported on silica gel by simple grinding and used as efficient solid acid catalyst in the preparation of ethers from the aliphatic and aromatic alcohols. The ethers were prepared in high isolated yields and in lesser times. Silica chloride was prepared by refluxing of silica gel in thionyl chloride. The obtained solid acid was efficiently used for the conditions of alcohols to the corresponding ethers and acetyl esters in less reaction time and in high isolated yields.
Elham, Sedighinia,Mozhgan, Zahed Sargoli
supporting information; experimental part
p. 1456 - 1458
(2012/01/06)

Triflic acid catalyzed reductive coupling reactions of carbonyl compounds with O-, S-, and N-nucleophiles
Highly efficient metal-free reductive coupling reactions of aldehydes and ketones with a range of nucleophiles in the presence of triflic acid (1-5 mol %) as the catalyst are presented. The reactions can be performed at ambient temperature without exclusion of moisture or air. A range of symmetrical and unsymmetrical ethers were obtained by this method in high yields and short reaction times. For the first time, the influence of additional functionalization has been studied. Furthermore, the formation of thioethers from ketones (by addition of unmodified thiols) and of sulfonamides from either aldehydes or ketones has been achieved under catalytic conditions.
Gellert, Beate A.,Kahlcke, Nils,Feurer, Markus,Roth, Stefanie
supporting information; experimental part
p. 12203 - 12209
(2011/11/07)

DEHYDROGENATION OF CYCLOHEXANONE TO PRODUCE PHENOL
In a process for the dehydrogenation of cyclohexanone to produce phenol, a feed comprising cyclohexanone is contacted with a dehydrogenation catalyst under dehydrogenation conditions comprising a temperature of less than 4000C and a pressure of less than 690 kPa, gauge, such 0.1 to 50 wt% of the cyclohexanone in said feed is converted to phenol and the dehydrogenation product contains less than 100 ppm by weight of alkylbenzenes.
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(2011/09/14)

InBr3-catalyzed reduction of ketones with a hydrosilane: Deoxygenation of aromatic ketones and selective synthesis of secondary alcohols and symmetrical ethers from aliphatic ketones
An InBr3-Et3SiH reducing system was developed to selectively convert aliphatic ketones to a variety of secondary alcohols in moderate to good yields. An initial mixing of InBr3 and PhSiH 3 was followed by the addition of aliphatic ketones and a solvent to afford the symmetrical ether derivatives.
Sakai, Norio,Nagasawa, Ken,Ikeda, Reiko,Nakaike, Yumi,Konakahara, Takeo
experimental part
p. 3133 - 3136
(2011/06/26)

Hydrodeoxygenation of lignin-derived phenols into alkanes by using nanoparticle catalysts combined with Brensted acidic ionic liquids
Oxy-gone in a tandem: A catalytic system composed of metal nanoparticles (NPs) and a functionalized Brensted acidic ionic liquid (IL), both of which are immobilized in a nonfunctionalized IL, is highly efficient in upgrading lignin-derived phenolic compounds into alkanes; the hydrogenation and dehydration reactions take place in tandem. Figure Presented
Yan, Ning,Yuan,Dykeman, Ryan,Kou, Yuan,Dyson, Paul J.
supporting information; experimental part
p. 5549 - 5553
(2010/10/03)

The reductive etherification of carbonyl compounds using polymethylhydrosiloxane activated by molecular iodine
Aldehydes and ketones undergo a smooth reductive etherification by polymethylhydrosiloxane (PMHS) in the presence of a catalytic amount of molecular iodine under mild conditions to afford the corresponding symmetrical ethers in excellent yields. This new reagent system (PMHS/I2) provides a simple and convenient route for the preparation of symmetrical ethers from carbonyl compounds.
Yadav,Subba Reddy,Shiva Shankar,Swamy
experimental part
p. 46 - 48
(2010/03/24)

Chlorine borrowing: An efficient method for an easier use of alcohols as alkylation agents
Chlorine functionalised tin dioxide nanoparticles proved able to partially convert alcohols into the corresponding chlorides, which act as alkylation agents with an increased electrophilicity, as evidenced on ether formation and Friedel-Crafts reactions.
Makowski, Philippe,Rothe, Regina,Thomas, Arne,Niederberger, Markus,Goettmann, Frederic
scheme or table
p. 34 - 37
(2010/04/22)

Rhodium/graphite-catalyzed hydrogenation of carbocyclic and heterocyclic aromatic compounds
Rhodium on graphite (Rh/Gr, C24Rh) was prepared by reaction of anhydrous rhodium trichloride with potassium graphite (C8K, 3 equivalents) and used as a heterogeneous catalyst for the hydrogenation of carbocyclic and heterocyclic aromatic compounds at room temperature and 1 atm of hydrogen pressure. The effect of substitution on the benzene ring was examined in a variety of derivatives, including those with alkyl, hydroxy, alkoxy, aryloxy, carboxy, amino, nitro, acyl, chloro, or functionalized alkyl groups. Reduction of carbonyl functions of aromatic aldehydes and ketones occurred with complete or partial cleavage of the benzylic C-O bond; this cleavage also occurred in the hydrogenation of benzylic alcohols and esters. Georg Thieme Verlag Stuttgart.
Falini, Giuseppe,Gualandi, Andrea,Savoia, Diego
experimental part
p. 2440 - 2446
(2010/02/27)

Near-monodisperse tetrahedral rhodium nanoparticles on charcoal: The shape-dependent catalytic hydrogenation of arenes
The shape of things to come? Monodisperse (4.9±0.4)-nm tetrahedral rhodium nanoparticles on charcoal (/C) are compared to (4.8±0.4)-nm spherical rhodium nanoparticles on charcoal(?/C) and commercial Rh/C as a catalyst for the hydrogenation of anthracene (see picture). The former is 5.8- and 109-times more active than the latter two, respectively. It also shows a higher selectivity and excellent activity in the hydrogenation of several other arenes. (Graph Presented).
Park, Kang Hyun,Jang, Kwonho,Kim, Hae Jin,Son, Seung Uk
p. 1152 - 1155
(2008/03/15)

Catalytic reductive etherification of ketones with alcohols at ambient hydrogen pressure: A practical, waste-minimized synthesis of dialkyl ethers
A heterogeneous platinum catalyst was found to efficiently mediate the reductive etherification of ketones at ambient hydrogen pressure. In this environmentally benign transformation, water is released as the only by-product, and this is trapped with molecular sieves. The preparative utility of the new reaction protocol is demonstrated by the synthesis of ten unsymmetrical ethers from the corresponding ketones and primary or secondary alcohols. Georg Thieme Verlag Stuttgart.
Goo?en, Lukas J.,Linder, Christophe
p. 3489 - 3491
(2007/10/03)

High selectivity of MCM-22 for cyclopentanol formation in liquid-phase cyclopentene hydration
Highly effective formation of cyclopentanol through the liquid-phase hydration of cyclopentene has been attempted on various zeolites catalysts. MCM-22 zeolite was the most selective catalyst, which actively converted cyclopentene to cyclopentanol with a selectivity up to 99%. The effects on the hydration of catalyst preparation method, reaction atmosphere and temperature have been investigated for the MCM-22 catalysts. On the basis of the effect of reaction atmosphere, the mechanism of liquid-phase cyclopentene hydration was proposed. The thermodynamic equilibrium between cyclopentene and cyclopentanol was suggested to control greatly the cyclopentene conversion. The cyclopentene conversion was increased to 10% by increasing the water/cyclopentene ratio. Poisoning using organic amines with different molecular sizes revealed that the hydration occurred mainly in the 10-membered ring channels of MWW structure, which had an elliptic aperture smaller than that of MFI structure, exhibiting a significant shape selectivity by suppressing the etherification cyclopentanol.
Nuntasri, Duangamol,Wu, Peng,Tatsumi, Takashi
p. 272 - 280
(2007/10/03)