- SiO2@FeSO4 nano composite as nanocatalyst for the green synthesis 1,1-diacetates from aldehydes under solvent-free conditions
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Aldehydes compounds selective converted to 1,1-diacetates as protective reagent with SiO2@FeSO4 nano composite as effective nano catalyst at room temperature under solvent-free condition and acetic anhydride (Ac2O) as acet
- KarimKoshteh, Mostafa,Bagheri, Marziyeh,Zeynizadeh, Behzad
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p. 2780 - 2783
(2016/07/12)
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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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- Study of reaction of isomeric acetoxytoluenes with ozone in liquid phase in the presence of manganese bromide catalyst
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The kinetics of the ozone reaction with isomeric acetoxytoluenes in acetic anhydride in the presence of sulfuric acid and mixed manganese bromide catalyst was studied. Under these conditions it is possible to stop the oxidation process at the stage of formation of hydroxybenzaldehydes in the form of the respective acetoxybenzylidendiacetates (63-70%). The reaction products contain also acetoxybenzyl acetate (16-18%) and a small amount of acetoxybenzyl bromide (2%). The mechanism of oxidation-reduction catalysis with manganese bromide complex explaining the experimental data was considered. Pleiades Publishing, Ltd., 2010.
- Galstyan,Sedykh
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scheme or table
p. 948 - 952
(2011/01/07)
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- Liquid-phase reactions of isomeric methylphenols with ozone
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Ozonation of isomeric methylphenols in acetic anhydride was studied. Here, acetic anhydride acts simultaneously as solvent and acylating agent. In the presence of a mineral acid methylphenols were converted into methylphenyl acetates during preparation of solutions for ozonation. The major products in the oxidation of isomeric methylphenyl acetates with ozone were aliphatic peroxides (80-90%); oxidation of the methyl group gave rise to the corresponding acetoxybenzyl acetates (7-14%) and acetoxybenzylidene diacetates (3-6%). A probable scheme for the liquid-phase oxidation of methylphenyl acetates with ozone in acetic anhydride was proposed.
- Galstyan
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scheme or table
p. 15 - 19
(2010/05/01)
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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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scheme or table
p. 4065 - 4078
(2010/03/01)
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- Silica-bonded S-sulfonic acid as a recyclable catalyst for chemoselective synthesis of 1,1-diacetates
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A simple and efficient procedure for the preparation of silica-bonded S-sulfonic acid (SBSSA) by reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in chloroform is described. This solid acid is employed as a recyclable catalyst for the synthesis of 1,1-diacetates from aromatic aldehydes and acetic anhydride under mild and solvent-free conditions at room temperature.
- Niknam, Khodabakhsh,Saberi, Dariush,Sefat, Maryam Nouri
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scheme or table
p. 4058 - 4062
(2009/10/11)
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- Solvent-free catalytic preparation of 1,1-diacetates from aldehydes using a Wells-Dawson acid (H6P2W18O62·24H 2O)
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Aromatic and aliphatic aldehydes are transformed in 1,1-diacetates (acylals) in mild conditions, by a treatment with acetic anhydride and a Wells-Dawson acid (H6P2W18O62·24H 2O). gem-Diacetylation proceeds in Ac2O with a little as 1% mol Wells-Dawson acid at room temperature and under solventless conditions, obtaining very good to excellent yields (88-98%) of 1,1-diacetates (19 examples). Neither 4-dimethylaminobenzaldehyde nor ketones react under the same conditions.
- Romanelli, Gustavo P.,Thomas, Horacio J.,Baronetti, Graciela T.,Autino, Juan C.
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p. 1301 - 1303
(2007/10/03)
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- A facile method for the preparation and cleavage of 1,1-diacetates of aldehydes
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A convenient method for the preparation and cleavage of 1,1-diacetates of aldehydes is reported using AlCl3 as catalyst.
- Sabitha, Gowravaram,Abraham, Sunny,Ramalingam,Yadav
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p. 144 - 146
(2007/10/03)
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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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p. 2709 - 2711
(2007/10/03)
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- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
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The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
- Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
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p. 5518 - 5523
(2007/10/02)
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