- Lithium chloride-assisted chemoselective conversion of aldehydes into geminal diacetates under solvent-free conditions
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A mixture of lithium chloride and acetic anhydride was used for converting aldehydes into geminal diacetates under solvent-free conditions in high yields. Copyright Taylor & Francis, Inc.
- Bosco, J.W. John,Purkayastha,Raju, B. Rama,Saikia, Anil K.
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- P2O5/Al2O3 as an efficient heterogeneous catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free conditions
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An efficient and chemoselective method for the preparation of acylals from different aldehydes using P2O5/Al2O3 and acetic anhydride under solvent-free conditions.
- Hajipour, Abdol R.,Zarei, Amin,Ruoho, Arnold E.
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- Conversion of aldehydes into geminal dicarboxylates (acylals) catalyzed by lithium tetrafluoroborate
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A variety of aldehydes react with acid anhydrides in the presence of a catalytic amount of lithium tetrafluoroborate to afford the corresponding geminal dicarboxylates (acylals) in good to excellent yields.
- Sumida,Nishioka,Sato
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- Preparation and deprotection of 1,1-diacetates (acylals) using zirconium sulfophenyl phosphonate as catalyst
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Layered zirconium sulfophenyl phosphonate was found to be an efficient heterogeneous catalyst for the preparation and deprotection of 1,1-diacetates.
- Curini, Massimo,Epifano, Francesco,Marcotullio, Maria Carla,Rosati, Ornelio,Nocchetti, Morena
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- An efficient method for the synthesis of acylals from aldehydes under solvent-free conditions catalyzed by antimony trichloride
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A mild and efficient method has been developed for the preparation of acylals from aldehydes catalyzed by antimony trichloride under solvent-free conditions in very good to excellent yields. The easy availability, low cost, and ease of handling of the catalyst make this procedure especially attractive for large-scale synthesis. Copyright Taylor & Francis Group, LLC.
- Bhattacharya, Asish K.,Mujahid, Mohammad,Natu, Arvind A.
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- Cerium(IV) triflate-catalyzed selective gem-diacetylation of aldehydes with acetic anhydride
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It has been observed that a catalytic amount (0.1 mol%) of cerium(IV) triflate afforded geminal diacetates from aldehydes with acetic anhydride in toluene at ambient temperature. Ketones are not affected under these reaction conditions. The reaction is rapid and mild with good to high yields. Copyright Taylor & Francis Group, LLC.
- Bosco, J. W. John,Saikia, Anil K.
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- Application of poly(Vinylbenzyltrimethylammonium tribromide) resin as an efficient polymeric catalyst in the acetalization and diacetylation of benzaldehydes
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The applications of a new supported tribromide reagent (poly(vinylbenzyltrimethylammonium tribromide) resin) were reported. This supported tribromide resin was used as a catalyst in the acetalization and diacetylation of benzaldehydes under mild conditions with high efficiency. The effects of solvents, and amount of the supported tribromide resin on the reactions were investigated. Under the optimal conditions, most of acetal and 1,1-diacetates of benzaldehydes were selectively obtained in excellent yields.
- Han, Bingbing,Hu, Junjun,Li, Xianwei,Zheng, Zubiao
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supporting information
p. 287 - 293
(2021/04/28)
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- The studies on chemoselective promiscuous activity of hydrolases on acylals transformations
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Chemoselective, mild and convenient protocol for the hydrolysis of the synthetically relevant acylals via promiscuous enzyme-catalyzed hydrolysis has been developed. It has been shown that promiscuous activity of the used hydrolases dominates their native activity related with carboxylic esters hydrolysis. The main advantage of the present methodology is that it can be conducted under neutral conditions at room temperature. Moreover, complete deprotection of acylals takes place within 10–20 min. Developed protocol can be used with compounds having a variety of hydrolytic labile groups since the cleavage is proceeded under neutral conditions and occurs exclusively on acylal moiety. Further this protocol was extended by the tandem Passerini multicomponent reaction leading to the α-acetoxy amides using acylals as the surrogates of the carbonyl components to P-MCR.
- Koszelewski, Dominik,Ostaszewski, Ryszard
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- Chemoselective synthesis of 1,1-diacetates under solvent-free condition using efficient heterogeneous ecofriendly catalyst: P2O5/kaolin
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An efficient and chemoselective method for the preparation of acylals from different aldehydes and acetic anhydride using.....kaolin supported catalyst (P2O5). under solvent-free conditions is described herein. The present protocol offers several advantages including use of inexpensive and non-toxic catalyst support i.e., natural kaolin. Preparation of the supported catalyst is easy, the process is simple in operation, maintaining solvent free conditions, with short reaction times, high yields and affording selective protection of aldehyde in presence of ketone.
- Rai, Nityanand,Sharma, Abha
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p. 340 - 344
(2019/05/21)
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- N-Propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) as a green and reusable heterogeneous nanocatalyst for the chemoselective preparation and deprotection of acylals
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Abstract: N-propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) was simply synthesized and used as a highly efficient, environmentally friendly, and chemoselective catalyst for the synthesis of 1,1-diacetates (acylals) from the one-pot condensation reaction of various aromatic aldehydes with acetic anhydride, in high yield of products (86–96%) and short reaction time (20–60?min) under solvent-free conditions at room temperature. In addition to these results, we further studied the possibility of deprotection of the resulting acylals into benzaldehyde derivatives in this catalytic system by the addition of water. More importantly, noteworthy advantages of this study are non-use of toxic organic solvents and catalysts, simple work-up procedure, short reaction time, high yield of products, and recovery and reusability of MNPs-PSA by an external magnet. Graphical Abstract: A simple and highly efficient procedure for the protection of various aldehydes with acetic anhydride in the presence of N-propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) is reported. We further studied the possibility of deprotection of the resulting acylals into benzaldehyde derivatives in this catalytic system by the addition of water as a green solvent. The catalyst was reused several times without loss of its catalytic activity.
- Sajjadifar, Sami,Nasri, Parastoo
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p. 6677 - 6689
(2017/10/06)
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- Tungstosulfonic acid as an efficient solid acid catalyst for acylal synthesis for the protection of the aldehydic carbonyl group
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Tungstosulfonic acid (TSA) has been found to be an efficient solid acid catalyst for the protection of aldehydic carbonyl groups by geminal diacetate (acylal) formation following the nucleophilic addition of acetic anhydride under neat conditions as well as in a solvent. The TSA catalyst is fully characterized by infrared spectroscopy, wide-angle X-ray scattering analysis, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The deprotection of acylals to corresponding aldehydes has also been investigated under the similar conditions. The catalyst can be reused seven times without a significant loss of activity. In addition, no chromatographic separations are needed to obtain the desired products. This method is a green approach for the chemoselective protection of aldehydes in the presence of ketones.
- Kalla, Reddi Mohan Naidu,Kim, Mi Ri,Kim, Yu Na,Kim, Il
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supporting information
p. 687 - 693
(2016/01/12)
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- Microwave-assisted green synthesis of 1,1-diacetates (acylals) using selectfluor as an environmental-friendly catalyst under solvent-free conditions
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An efficient and simple procedure has been developed for the acetylation of aldehyde by selectfluor [1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis(tetrafluoroborate)] as a chemoselective and environmentally friendly catalyst under solvent-free conditions or microwave irradiation. The application of microwave irradiation improved the yields and reduced the reaction times. In this study, selective conversion of aldehydes was observed in the presence of ketones, and the deprotection of 1,1-diacetates has also been achieved using selectfluor in water as green solvent in reflux conditions. The methodology provides synergy of microwave irradiation which offers several advantages such the simple work-up procedure, short reaction time, excellent yields and environmentally benign procedure.
- Rezayati, Sobhan,Hajinasiri, Rahimeh,Erfani, Zahra
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p. 2567 - 2576
(2016/03/16)
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- Synthesis of 1,1-diacetates catalyzed by cellulose sulfonic acid from aldehydes and acetic anhydride
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1,1-Diacetates have been synthesized in good to excellent yields via a reaction of corresponding aldehydes and acetic anhydride in the presence of cellulose sulfonic acid as a heterogeneous catalyst at room temperature. The protection of aldehydes generated an anhydrodimer as single product under similar reaction conditions. The catalysis is equally applicable for the deprotection of acylal in acetonitrile.
- Ding, Songsong,Zhang, Jiming,Shi, Wei,Zhou, Jianhua
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p. 340 - 342
(2015/02/19)
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- Preparation of 1,1-diacetates from aldehydes by LiBH4 and Ac2O in the presence of cation exchange resin
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A variety of 1,1-diacetates have been produced from the corresponding aldehydes (1 mmol) by LiBH4(1.25 mmol) and Ac2O (1 mL) in the presence of DOWEX(R)50WX4 (0.5 g) as a cation exchange resinwithin 10 min at room temperature with excellent yields of the products (93-97%).
- Rezaeekhordehforosh, Reza,Khezri, Behrooz,Setamdideh, Davood
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p. 1205 - 1209
(2015/10/28)
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- Solvent-free Chemoselective Synthesis of 1,1-diacetates Catalyzed by Iron Zirconium Phosphate
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In the present study, a mild, rapid, and efficient method for the protection of aldehydes with acetic anhydride (AA) in the presence of iron zirconium phosphate (ZPFe), at room temperature is reported. Selective conversion of aldehydes was observed in the presence of ketones. Under these conditions, different aldehydes bearing electron-withdrawing and electron-donating substituents were reacted with AA and the corresponding 1,1-diacetates (acylals) were obtained in high to excellent yields. The steric and electronic properties of the different substrates had a significant influence on the reaction conditions. Also, the deprotection of 1,1-diacetates has been achieved using this catalyst in water. The catalyst was characterized by several physico-chemical techniques. It was recovered easily from the reaction mixture, regenerated, and reused at least 7 times without significant loss in catalytic activity. This protocol has the advantages of easy availability, stability, reusability of the eco-friendly catalyst, chemoselectivity, simple experimental and work-up procedure, solvent-free conditions and only a stoichiometric amount of AA is needed.
- Karimi, Hirbod
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p. 1000 - 1010
(2015/12/01)
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- Zinc zirconium phosphate as an efficient catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free conditions
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In the present study, a mild, rapid, and efficient method for the protection of aldehydes with acetic anhydride (AA) in the presence of zinc zirconium phosphate (ZPZn) as a nano catalyst, at room temperature is reported. Selective conversion of aldehydes was observed in the presence of ketones. Under these conditions, different aldehydes bearing electron-withdrawing and electron-donating substituents were reacted with AA and the corresponding 1,1-diacetates (acylals) were obtained in high to excellent yields. The steric and electronic properties of the different substrates had a significant influence on the reaction conditions. Also, the deprotection of 1,1-diacetates has been achieved using this catalyst in water. This nanocatalyst was characterized by several physico-chemical techniques. It was recovered easily from the reaction mixture, regenerated and reused at least 7 times without significant loss in catalytic activity. This protocol has the advantages of easy availability, stability, reusability of the eco-friendliness, chemoselectivity, simple experimental and work-up procedure, solvent-free conditions and usage of only a stoichiometric amount of AA.
- Hajipour, Abdol R,Karimi, Hirbod
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p. 1945 - 1955
(2015/12/30)
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- Synthesis of 1,1-diacetates catalysed by silica-supported boron sulfonic acid under solvent-free conditions and ambient temperature
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1,1-Diacetates derivatives were prepared using the direct condensation of aldehydes with acetic anhydride in the presence of silica-supported boron sulfonic acid (SiO2/B(SO4H)3) as a tri-functional inorganic Bronsted acid catalyst under solvent-free conditions at ambient temperature. The salient features of this methodology are: (i) cheaper process ready availability of the catalyst; (ii) versatility; (iii) high regio-selectivity of the procedure and recyclable property of the catalyst.
- Sajjadifar, Sami,Rezayati, Sobhan
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p. 531 - 539
(2014/01/17)
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- NaBH4/Ac2O/DOWEX(R)50WX4: A convenient system for fast preparation of gem-diacetates from aldehydes
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Reductive-acylalation of aldehydes has been carried out by NaBH 4/Ac2O/DOWEX(R)50WX4 system. A variety of aldehydes (1 mmol) have been reacted with Ac2O (0.5 mL) and NaBH4 (1 mmol) in the presence of DOWEX(R)50WX4 (0.5 g) for the preparation of their corresponding acylals within 1 min at room temperature with excellent yields of the products (90-95%). Ketones do not react with this system.
- Asl, Parisa Azizi,Setamdideh, Davood
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p. 940 - 944
(2014/10/16)
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- Phospho sulfonic acid as an efficient and recyclable solid acid catalyst for the solvent-free preparation of acylals
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Phospho sulfonic acid (PSA) acts as a highly effective and reusable catalyst for the chemo-selective protection of aldehydes with acetic anhydride under solvent-free conditions. The desirable features of this new catalytic methodology include its sustaina
- Kalla, Reddi Mohan Naidu,Park, Huiju,Hoang, Trinh Thi Kim,Kim, Il
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supporting information
p. 5373 - 5376
(2015/01/09)
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- Poly(4-vinylpyridinium) perchlorate as an efficient solid acid catalyst for the chemoselective preparation of 1,1-diacetates from aldehydes under solvent-free conditions
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Poly(4-vinylpyridinium) perchlorate has been used as a supported, recyclable, environmentally-benign catalyst for the formation of acylals from aliphatic and aromatic aldehydes in good to excellent yields under solvent-free conditions. Notably, the reaction conditions were tolerant of ketones. This methodology offers several distinct advantages, including its operational simplicity and high product yield, as well as being green in terms of avoiding the use of toxic catalysts and solvents. Furthermore, the catalyst can be recovered and reused several times without any loss in its activity.
- Khaligh, Nader Ghaffari
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p. 329 - 334
(2014/04/03)
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- Functionalized Poly(Amidoamine) Dendrimer as a Strong Ionic Br?nsted Acid Organocatalyst for Protection/Deprotection of Aldehydes
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Poly(amidoamine) dendrimer (PAMAM) was successfully functionalized by chlorosulfonic acid to form an strong ionic acid catalyst. The resulting polymeric catalyst was shown to be an efficient catalyst for the synthesis of 1,1-diacetyl from aldehydes under free solvent conditions at room temperature. Also, the deprotection of the resulting aldehydes was investigated under catalytic conditions. The Hammett acidity function of catalyst showed that catalyst is a strong Br?nsted acid. Due to the multi-functional nature of PAMAM, the catalyst has high loading level of acidic protons.
- Pourjavadi, Ali,Hosseini, Seyed Hassan
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p. 1794 - 1801
(2015/10/29)
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- An efficient method for synthesis of acylals from aldehydes using multi-walled carbon nanotubes functionalized with phosphonic acid (MWCNTs-C-PO3H2)
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MWCNTs-C-PO3H2 has been used as an efficient, heterogeneous and reusable nanocatalyst for synthesis of acylals from aldehydes under solvent-free conditions at room temperature. A wide range of aldehydes was studied and corresponding products were obtained in good to excellent yields in short reaction times. Nanocatalyst can be easily recovered by centrifuge and reused for subsequent reactions for at least five times without deterioration in catalytic activity. The major advantages of the present method are high yields, short reaction time, recyclable catalyst and solvent-free reaction conditions at room temperature.
- Dehghani, Farzaneh,Sardarian, Ali Reza,Doroodmand, Mohammad Mehdi
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p. 1630 - 1634
(2015/01/09)
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- Chemoselective synthesis of geminal diacetates (acylals) using eco-friendly reusable propylsulfonic acid based nanosilica (SBA-15-Ph-PrSO3H) under solvent-free conditions
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An expeditious method for the acetylation of aldehydes by mesoporous solid sulfonic acid (SBA-15-Ph-PrSO3H) under solvent-free reaction conditions was described. The route furnished selectively and in excellent yields the corresponding 1,1-diacetates starting from aldehydes and acetic anhydride using the environmentally friendly catalyst. The catalyst was found to be highly active and selective and could be recycled several times.
- Zareyee, Daryoush,Moosavi, Sayed M.,Alaminezhad, Alireza
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p. 227 - 231
(2013/08/23)
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- PEG-SO3H as an efficient and reusable catalyst for chemoselective synthesis of 1,1-diacetates
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An efficient and convenient procedure of the synthesis of 1,1-diacetates from aromatic aldehydes and acetic anhydride under mild and solvent-free conditions at room temperature, in the presence of PEG-SO3H is reported. PEG-SO3H acts as a catalyst and can be recovered and reused eight times without apparent loss of its catalytic activity.
- Zong, Ying-Xiao,Wang, Jun-Ke,Niu, Yu-Ying,Li, Zheng-Liang,Song, Zheng-En,Quan, Zheng-Jun,Wang, Xi-Cun,Yue, Guo-Ren,Pan, Yi
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p. 140 - 142
(2013/06/26)
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- Solvent-free catalytic preparation of 1,1-diacetates using a silica-supported functional ionic liquid as catalyst
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An efficient and convenient preparation of acylals from aldehydes and acetic anhydride, under solvent-free conditions, in the presence of a silica-supported functional ionic liquid, Si-[SbSipim][PF6], is reported. Si-[SbSipim][PF6] acts as a catalyst and can be recovered and reused four times without apparent loss of its catalytic activity.
- Kang, Li Q.,Cai, Yue Q.,Cheng, Lin
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p. 247 - 249
(2013/07/27)
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- Ultrasound assisted the chemoselective 1,1-diacetate protection and deprotection of aldehydes catalyzed by poly(4-vinylpyridinium)hydrogen sulfate salt as a eco-benign, efficient and reusable solid acid catalyst
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Poly(4-vinylpyridinium) hydrogen sulfate solid acid was found to be efficient catalyst for preparation of 1,1-diacetate using ultrasound irradiation at ambient temperature and neat condition. Deprotection of the resulting 1,1-diacetates were achieved using the same catalyst in methanol solvent under ultrasound irradiation at room temperature. This new method consistently has the advantage of excellent yields and short reaction times. Utilization of solvent free, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective. Further, the catalyst can be reused and recovered for several times.
- Khaligh, Nader Ghaffari,Shirini, Farhad
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- A succinimide-N-sulfonic acid catalyst for acetylation reactions in absence of a solvent
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A small amount of succinimide-N-sulfonic acid efficiently catalyzed the acetylation of a variety alcohols, phenols, thiols, amines and aldehydes with acetic anhydride at room temperature under solvent free conditions. This catalyst has the advantages of excellent yields and short reaction times and the reaction can be carried out on a large scale, which makes it potentially useful for industrial applications.
- Shirini, Farhad,Khaligh, Nader Ghaffari
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p. 695 - 703
(2013/08/25)
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- Sulfonated rice husk ash (RHA-SO3H): A highly powerful and efficient solid acid catalyst for the chemoselective preparation and deprotection of 1,1-diacetates
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Rice husk ash (RHA), as a source of amorphous silica, was treated with chlorosulfonic acid and sulfonated rice husk ash (RHA-SO3H) as a highly powerful solid acid catalyst was obtained and characterized with a variety of techniques including IR, TGA, SEM, XRD, pH analysis, Hammett acidity function and BET method. This solid acid showed excellent catalytic activity for the protection and deprotection of aldehydes with Ac2O at room temperature under solvent free conditions. The procedure gave the products in excellent yields in very short reaction times and good to high yields. Also this catalyst can be reused for several times without loss of its catalytic activity.
- Shirini, Farhad,Mamaghani, Manouchehr,Seddighi, Mohadeseh
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- Rice husk supported FeCl3 nanoparticles as an efficient and reusable catalyst for the chemoselective 1,1-diacetate protection and deprotection of aldehydes
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1,1-Diacetates were produced from a variety of aromatic aldehydes using rice husk supported FeCl3 nanoparticles as a catalyst. The procedure generally resulted in good yields (98%) of aromatic aldehydes including those carrying electron donating- or withdrawing-substituents. Deprotection of the resulting 1,1-diacetates was also achieved using the same catalyst in ethanol. This new method consistently has the advantages of excellent yields and relatively short reaction times. Further, the catalyst can be reused and recovered for several times.
- Shirini, Farhad,Akbari-Dadamahaleh, Somayeh,Mohammad-Khah, Ali
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- Ultrasound-assisted synthesis of acylals from aldehydes using Mg(CH 3SO3)2-HOAC
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An efficient method for the synthesis of acylals from different aldehydes and acetic anhydride in the presence of magnesium methanesulfonate-acetic acid under ultrasound irradiation at room temperature is achieved. Only 1.5mol% of magnesium methanesulfonate and a small quantity of acetic acid are needed to effect the reaction. Selective conversion of aldehydes is observed in the presence of ketones. The catalyst remains active and exhibits no substantial loss of activity or selectivity in up to three reaction cycles.
- Liu, Qing,Ai, Hong-Mei,Feng, Shuai
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experimental part
p. 122 - 127
(2011/11/01)
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- ZSM-5-SO3H as a novel, efficient, and reusable catalyst for the chemoselective synthesis and deprotection of 1,1-diacetates under eco-friendly conditions
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ZSM-5 has been modified as supported sulfuric acid (ZSM-5-SO3H) and introduced for the first time as a mild, convenient, reusable, and heterogeneous catalyst. Various types of aldehydes were efficiently converted to their 1,1-diacetates using a catalytic amount of ZSM-5- SO3H in excellent yields under solvent-free and heterogeneous conditions at room temperature. The deprotection of 1,1-diacetates has also been achieved using this novel catalyst in ethanol. The procedure is operationally simple, environmentally benign, and only a stoichiometric amount of anhydride is used. Springer-Verlag 2011.
- Massah, Ahmad Reza,Kalbasi, Roozbeh Javad,Shafiei, Anahita
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experimental part
p. 643 - 652
(2012/07/14)
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- Ultrasound-assisted synthesis of acylals catalyzed by stannum (IV) phosphomolybdate under solvent-free condition
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An efficient method for the synthesis of acylals from different aldehydes and acetic anhydride in the presence of Keggin-type stannum (IV) phosphomolybdate under ultrasound irradiation at room temperature was achieved. This method provides a new and efficient protocol in terms of cost effective of catalyst, a wide scope of substrates, and simple work-up procedure.
- Ai, Hong Mei,Liu, Qing
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experimental part
p. 299 - 301
(2012/07/17)
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- Schiff base complex of metal ions supported on superparamagnetic Fe 3O4@SiO2 nanoparticles: An efficient, selective and recyclable catalyst for synthesis of 1,1-diacetates from aldehydes under solvent-free conditions
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We report a new multistep method for preparing functionalized superparamagnetic Fe3O4@SiO2 possessing high saturation magnetization. During the first step, Fe3O 4@SiO2 nanosphere core-shell is synthesized using nano-Fe3O4 as the core, TEOS as the silica source and PVA as the surfactant. Then, Schiff base complex of metal is synthesized from the reaction between Schiff base and metal acetates [Co(OAc)2, Mn(OAc)2, Ni(OAc)2, Cu(OAc)2, Hg(OAc) 2, Cr(OAc)3 and Cd(OAc)2] on the Fe 3O4@SiO2 surface. The structural and magnetic properties of functionalized magnetic silica are identified by transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) instruments. Moreover, functionalized Fe3O4@SiO2 possessed a superparamagnetic characteristic with saturation magnetization value of about 34 emu/g. NMR, FT-IR, elemental analysis and XRD were also used for the identification of these structures. The catalytic ability of Fe 3O4@SiO2/Schiff base complex of metal ions was found to be an efficient nanocatalyst for the conversion of aldehydes to their corresponding 1,1-diacetates compounds under mild and solvent-free conditions at room temperature. This method gives notable advantages such as excellent chemoselectivity, mild reaction condition, short reaction times and excellent yields. Also, the aforementioned nanocatalyst can be easily recovered by a magnetic field and reused for subsequent reactions for at least 5 times without noticeable deterioration in catalytic activity.
- Esmaeilpour, Mohsen,Sardarian, Ali Reza,Javidi, Jaber
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p. 359 - 367
(2013/02/21)
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- A rapid, convenient and chemoselective synthesis of acylals from aldehydes catalyzed by reusable nano-ordered MCM-41-SO3H
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Acylals were prepared by direct condensation of aldehydes with acetic anhydride using nano-ordered MCM-41-SO3H as a heterogeneous catalyst under solvent-free conditions at room temperature in a very short reaction time and excellent yields. The catalyst is recyclable, non-toxic, neither air nor moisture sensitive, and easy to handle. High chemoselectivity toward aldehydes in the presence of ketones is another advantage of the present method which provides selective protection of aldehydes in their mixtures with ketones.
- Tourani, Hesam,Naimi-Jamal, Mohammad Reza,Dekamin, Mohammad Ghorban,Amirnejad, Meysam
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p. 1072 - 1076
(2013/02/22)
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- Polystyrene-supported, Al(OTf)3-catalyzed chemoselective synthesis of acylals from aldehydes
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Cross-linked polystyrene-supported aluminium triflate [Ps-Al(OTf)3] has been shown to be a mild, efficient, and chemoselective heterogeneous Lewis acid catalyst for acetylation of aldehydes with acetic anhydride. The catalyst can be recovered simply and reused efficiently at least five times without any noticeable loss of catalytic activity. Copyright Taylor & Francis Group, LLC.
- Boroujeni, Kaveh Parvanak
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scheme or table
p. 277 - 284
(2011/03/20)
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- [HSO3-pmim][CH3SO3] as an efficient catalyst for chemoselective synthesis of 1,1-diacetates under ultrasound irradiation
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A mild and efficient method for the chemoselective preparation of 1,1-diacetates catalyzed by 1-methyl-3-(3- sulfopropyl)-imidazolium methyl sulfate under ultrasound irradiation has been developed. The yields are ranged in 90%-98%. This protocol offered several advantages including low catalyst loading, high yields, short reaction time and environmentally benign approach.
- Li, Chao,Guo, Tao,Zhou, Xin,Wang, Chun,Ma, Jing-Jun,Li, Jin-Bin
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experimental part
p. 484 - 487
(2012/04/11)
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- Chromic(III) sulfamate as a versatile catalyst for organic synthesis
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Chromic sulfamate was synthesized and used as catalyst for the first time in various organic reactions such as the transformation of aldehydes or ketones and indole to bis(indolyl)methanes, the transformation of aldehydes and acetic anhydride to 1,1-diacetates and Biginelli reaction. The advantages of the chromic sulfamate are ease of preparation, easy handling, simple work-up and versatility.
- Liu, Qing,Li, Zhen
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experimental part
p. 3208 - 3210
(2012/02/03)
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- Chemoselective protection and deprotection of aldehydes using solid supported reagent (Silica Chloride) under solvent-free conditions
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Silica chloride, a heterogeneous catalyst, has been found to be an efficient catalyst for the protection of aldehydes as acylals under solvent-free conditions, and deprotection of acylals to aldehydes in methanol as a solvent occurred. The reaction takes a shorter time and ensures good to excellent yield of the products.
- Datta, Bandita,Pasha
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experimental part
p. 1160 - 1166
(2011/05/06)
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- Amorphous carbon-silica composites bearing sulfonic acid as solid acid catalysts for the chemoselective protection of aldehydes as 1,1-diacetates and for N-, O- and S-acylations
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Amorphous carbon-silica composites bearing sulfonic acid derived from inexpensive natural organic compounds (glucose, maltose, cellulose, chitosan and starch) were prepared by partial carbonization followed by sulfonation and their catalytic activity was evaluated for the protection of aldehydes as 1,1-diacetates and for N-, O- and S-acylations under solvent-free conditions. Different biomaterials have been chosen, with a view to select the most active solid acid catalyst. Carbon-silica composites were characterized by FTIR, XRD and elemental analysis. Sulfonated carbon-silica composite derived from starch was found to be the most active and could be recycled for several runs without loss of significant activity. It was also characterized by TGA, SEM and TEM.
- Gupta, Princy,Paul, Satya
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experimental part
p. 2365 - 2372
(2011/10/31)
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- A convenient and efficient protocol for the synthesis of acylals catalyzed by Br?nsted acidic ionic liquids under ultrasonic irradiation
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The synthesis of acylals (1,1-diacetates) via the reactions of aldehydes with acetic anhydride was carried out in 85-97% yields at room temperature under ultrasound irradiation catalyzed by the Br?nsted acidic ionic liquid [bmpy]HSO4. This method provides several advantages, such as solvent-free conditions, operational simplicity, higher yields, and reduced environmental consequences. The ionic liquid was recovered and reused.
- Borikar, Sanjay P.,Daniel, Thomas
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experimental part
p. 928 - 931
(2012/03/08)
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- Conjugate polymer-supported acid catalysts: An efficient and reusable catalyst for the synthesis of geminal diacetates (acylals) under solvent-free conditions
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A comparative study on the catalytic activity of conducting polyaniline (PANI), polypyrrole (PPY), and poly-(3,4-ethylenedioxythiophene) (PEDOT) salts as solid acid catalysts for the synthesis of 1,1-diacetates (acylals) under solvent-free conditions has been presented. Use of the polypyrrole and poly-(3,4-ethylenedioxythiophene) salts as solid acid catalysts is reported for the first time. Preparation, recovery, and reusability of the catalysts were found to be good. Copyright Taylor & Francis Group, LLC.
- Nabid, Mohammad Reza,Rezaei, Seyed Jamal Tabatabaei,Abedi, Mahvash
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experimental part
p. 191 - 199
(2011/03/18)
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- Host (nanocavity of zeolite-Y)-guest (molybdophosphoric acid) nanocomposite materials: An efficient catalyst for solvent-free synthesis and deprotection of 1,l-diacetates
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In the present work, a mild and efficient method has been developed for the synthesis of acylals from aldehydes with acetic anhydride in the presence of molybdophosphoric acid encapsulated into dealuminated zeolite Y (MPA-DAZY) as a catalyst under solvent-free conditions at 45-55 °C in good to excellent yield. The deprotection of acylals has also been attained using this catalyst in acetonitrile. The catalyst was reused several times without efficient loss of its catalytic activity.
- Moosavifar, Maryam,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 953 - 956
(2012/05/04)
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- Synthesis and characterization of BEA-SO3H as an efficient and chemoselective acid catalyst
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BEA zeolite was synthesized under hydrothermal condition and modified with various amounts of chlorosulphonic acid. It was characterized by XRD, XRF, FT-IR, BET, thermogravimetric analysis and SEM techniques. Catalytic activity of BEA-SO3H was tested for the synthesis of 1,1-diacetates from a variety of aromatic and aliphatic aldehydes including those carrying electron donating or withdrawing substituents by acetic anhydride. At optimized conditions, The BEA-SO3H (28 wt.%) catalyst showed good yield at very short time for the synthesis and deprotection of 1,1-diacetates. Furthermore, BEA-SO3H was found to be recyclable for the protection of aldehydes with acetic anhydride under solvent-free and room temperature conditions. This method is a green approach for the protection of aldehydes in the presence of ketones.
- Kalbasi, Roozbeh Javad,Massah, Ahmad Reza,Shafiei, Anahita
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experimental part
p. 51 - 59
(2011/04/15)
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- Mild and chemoselective synthesis and deprotection of geminal diacetates catalyzed by titanium(IV) halides
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A novel, mild, and chemoselective method was developed for the preparation of gem-diacetates from aldehydes and acetic anhydride in the presence of titanium(IV) fluoride (1-5 mol%) under solvent-free conditions at room temperature. The reaction showed a high chemoselectivity toward aldehydes in the presence of ketones. Moreover, titanium(IV) fluoride also catalyzed the deprotection of gem-diacetates to the corresponding aldehydes in water. This efficient and simple method has several benefits, including the use of an inexpensive catalyst, solvent-free conditions, mild reaction temperatures, and high yields, which make it both cost-effective and environmentally friendly. Georg Thieme Verlag Stuttgart.
- Jung, Misuk,Yoon, Jieun,Kim, Hak Sung,Ryu, Jae-Sang
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experimental part
p. 2713 - 2720
(2010/10/02)
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- Chemoselective synthesis of 1,1-diacetates from aldehydes using anhydrous cobalt(II) bromide under solvent-free conditions
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A mild and efficient method has been developed for the chemoselective preparation of 1,1-diacetates (acylals) from aldehydes catalyzed in the presence of a catalytic amount (0.1mmol) of anhydrous cobalt(II) bromide under solvent-free conditions. The remarkable selectivity under mild and neutral conditions, excellent yields, short reaction time, and easily available and inexpensive catalyst are important features of this method.
- Meshram, Gangadhar A.,Patil, Vishvanath D.
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experimental part
p. 442 - 449
(2010/04/02)
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- Silica phosphoric acid: An efficient and recyclable catalyst for the solvent-free synthesis of acylals and their deprotection in MeOH
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Silica phosphoric acid was used as an efficient, mild, and recyclable solid catalyst for the synthesis of acylals from various structurally diverse aldehydes and acetic anhydride under solvent-free conditions. The acylation of aldehydes was highly chemoselective, and no ketone was acylated, which provided a method for the synthesis of acylals from aldehydes in the presence of ketones. Silica phosphoric acid-catalyzed deprotection of acylals to the corresponding aldehydes in MeOH has also been developed with excellent yield. The deprotection of the acylals of aromatic aldehydes took priority over those of aliphatic aldehydes. Copyright Taylor & Francis Group, LLC.
- Zhang, Fuyi,Liu, Hong,Zhang, Qing-Ju,Zhao, Yu-Fen,Yang, Feng-Ling
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scheme or table
p. 3240 - 3250
(2010/12/24)
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- An efficient and chemoselective procedure for acylal synthesis
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A novel heterogeneous efficient procedure has been developed for the chemoselective synthesis of acylals (1,1-diacetates) under solvent-free conditions. A novel catalyst prepared by the sulfuric acid catalyzed copolymerization of p-toluenesulfonic acid and paraformaldehyde displays extremely high activities for the title reactions, affording average yields over 90% within several minutes. A comparative study showed that the novel catalyst has much higher activity than other catalysts used for this purpose. Besides, the novel catalyst displays chemoselectivity for the protection of aldehydes in the presence of ketones. In addition the high acidity (4.0 mmol/g), thermal stability (200 °C) and easy reusability make the novel catalyst one of the best choices for the process.
- Fan, Da-He,Wang, Hui,Mao, Xing-Xing,Shen, Yong-Miao
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experimental part
p. 6493 - 6501
(2010/11/04)
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- Sulphated zirconia as an eco-friendly catalyst in acylal preparation under solvent-free conditions, acylal deprotection assisted by microwaves, and the synthesis of anhydro-dimers of o-hydroxybenzaldehydes
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A solvent-free approach is described for the regioselective synthesis of acylals (1,1-diacetates) in shorter reaction times and higher yields, compared to conventional methodology using solvents. In the protection reaction of the o-hydroxybenzaldehyde the formation of acetyl compounds and anhydro-dimers was observed. The deprotection reaction involves microwave (MW) exposure of diluted reactants in the presence of solid sulphated zirconia (SZ) catalyst that can be easily recovered and reused. The sulphated zirconia was recycled several times without any loss of activity.
- Palacios-Grijalva, Laura Nadxieli,Cruz-Gonzalez, Deysi Y.,Lomas-Romero, Leticia,Gonzalez-Zamora, Eduardo,Ulibarri, Gerardo,Negron-Silva, Guillermo E.
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experimental part
p. 4065 - 4078
(2010/03/01)
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- NbCl5 as an efficient catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free conditions
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A mild and efficient method for the chemoselective preparation of 1,1-diacetates catalyzed by NbCl5(5mmol%) under solvent-free conditions has been developed. The yields are in the range of 93-98%. This protocol offered several advantages, including low catalyst loading, good yields, short reaction times, and environmentally friendliness.
- Gao, Shu-Tao,Zhao, Ying,Li, Chao,Ma, Jing-Jun,Wang, Chun
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experimental part
p. 2221 - 2229
(2009/10/17)
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- An efficient and green procedure for the preparation of acylals from aldehydes catalyzed by alum [KAl(SO4)212H2O]
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Alum [KAl(SO4)2-12H2O] is an inexpensive, efficient, non-toxic and mild catalyst for the preparation of acylals from aromatic and heteroaryl aldehydes with acetic anhydride at room temperature under solvent-free conditions
- Shelke, Kiran,Sapkal, Suryakant,Kategaonkar, Amol,Shingate, Bapurao,Shingare, Murlidhar S.
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experimental part
p. 109 - 112
(2010/08/06)
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- Chloroferrate(III) ionic liquid as recyclable catalyst for the acetylation of alcohols and phenols and for 1,1-Diacylation of aldehydes
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A Lewis acidic ionic liquid, [bmim][FeCl4], was employed to catalyze acetylation of alcohols and phenols, and the conversion of aldehydes to corresponding 1,1-diacetates without conventional organic solvents. The catalyst is easily available, water-tolerant, recoverable and easy to handle.
- Wanga, Dong-Sheng,Lib, Gui-Yun,Pengb, Yan-Qing
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experimental part
p. 834 - 838
(2010/08/13)
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- RuCl3·xH2O: A new efficient catalyst for facile preparation of 1,1-diacetates from aldehydes
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An efficient, facile preparation of aldehyde 1,1-diacetates (acylals) in excellent yields catalyzed by RuCl3·xH2O is described. Ketones do not react under these conditions. Copyright Taylor & Francis Group, LLC.
- Saini, Anil,Kumar, Sanjay,Sandhu, Jagir S.
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p. 106 - 113
(2008/03/14)
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- Synthesis of 1,1-diacetates using a new combined catalytic system: Copper p-toluenesulfonate/HOAc
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Copper p-toluenesulfonate acetic acid has been established as an efficient combined catalytic system for chemoselective conversion of aldehydes to diacetates in high yields at ambient temperature in short reaction times. For the catalytic system, the amount of copper p-toluenesulfonate reduced to 0.3 mol%. After the reaction, copper p-toluenesulfonate can be easily recovered and reused for at least 10 runs. Copyright Taylor & Francis Group, LLC.
- Wang, Min,Song, Zhiguo,Gong, Hong,Jiang, Heng
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p. 961 - 966
(2008/09/17)
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- Thallium(III) chloride: A mild and efficient catalyst for acylation of alcohols, phenols and thiols, and for geminal diacylation of aldehydes under solvent-free conditions
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Thallium(III) chloride is a simple and efficient catalyst for acylation of alcohols, phenols and thiols. It is also very effective for geminal diacylation of aldehydes. The acylation reaction using acetic anhydride proceeds in excellent yield in the presence of catalytic amounts of thallium(III) chloride (1 mol%) at room temperature within relatively short reaction times (20 min). Structurally diverse alcohols, phenols, thiols and aldehydes undergo acylation under solvent-free conditions.
- Kadam, Santosh T.,Kim, Sung Soo
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experimental part
p. 3307 - 3313
(2009/05/07)
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