- Ethyl acetate as an acetyl surrogate for the iodine catalyzed acetylation of alcohols
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The use of readily available ethyl acetate in the presence of iodine as an alternative acetylating agent is reported. Amines and phenols were unreactive under the examined reaction conditions, indicating that the method is highly chemoselective.
- Basumatary, Grace,Bez, Ghanashyam
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supporting information
p. 4312 - 4315
(2017/10/13)
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- Enzymatic kinetic resolution of aliphatic sec-alcohols by LipG9, a metagenomic lipase
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Bioprospection for new enantioselective enzymes for application in organic synthesis is a prominent area of investigation in biocatalysis. In this context, here we present the evaluation of an immobilized lipase isolated from a metagenomic library (LipG9) for the enzymatic kinetic resolution (EKR) of aliphatic sec-alcohols, which are still challenging substrates, since low enantioselectivity values are usually observed for these resolutions. LipG9 was successfully employed in EKR of aliphatic alcohols, which were resolved with satisfactory conversions (19-59%) and enantiomeric excesses for alcohols (26-88%) and esters (30-96%) by transesterification reactions, demonstrating that its performance is equal to or better than commercially available enzymes for the same reaction.
- Bandeira, Pamela T.,Alnoch, Robson C.,De Oliveira, Alfredo R.M.,De Souza, Emanuel M.,De O.P., Fábio,Krieger, Nadia,Piovan, Leandro
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- Fractional distribution of graphene oxide and its potential as an efficient and reusable solid catalyst for esterification reactions
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Graphene oxide (GrO) prepared by the Hummers method was separated into three different fractions (GrO5000, GrO2000, and GrOres) on the basis of their dispersion stability in the water. Infrared, nuclear magnetic resonance, X-ray photoelectron spectroscopy, and elemental analyses revealed that GrO5000 possesses a high degree of oxygen functionalities including phenolic, carboxylic, and -OSO2H groups, compared with the other fractions. The GrO5000 was found to be a highly efficient and reusable solid catalyst for the esterification of various carboxylic acids with a variety of alcohols to furnish corresponding esters in high to excellent yields. The catalytic activity of the GrO5000 was attributed to the ability of highly polar GrO5000 scaffold to adsorb/attract reactants, where the acid functionalities of GrO5000 facilitated the esterification process efficiently. The chemical and structural features of GrO5000 were discussed to understand the improved catalytic activity compared with GrO2000 and conventional solid acid catalysts.
- Mungse, Harshal P.,Bhakuni, Niharika,Tripathi, Deependra,Sharma, Om P.,Sain, Bir,Khatri, Om P.
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p. 944 - 951
(2015/02/02)
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- Fractional distribution of graphene oxide and its potential as an efficient and reusable solid catalyst for esterification reactions
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Graphene oxide (GrO) prepared by the Hummers method was separated into three different fractions (GrO5000, GrO2000, and GrOres) on the basis of their dispersion stability in the water. Infrared, nuclear magnetic resonance, X-ray photoelectron spectroscopy, and elemental analyses revealed that GrO5000 possesses a high degree of oxygen functionalities including phenolic, carboxylic, and -OSO2H groups, compared with the other fractions. The GrO5000 was found to be a highly efficient and reusable solid catalyst for the esterification of various carboxylic acids with a variety of alcohols to furnish corresponding esters in high to excellent yields. The catalytic activity of the GrO5000 was attributed to the ability of highly polar GrO5000 scaffold to adsorb/attract reactants, where the acid functionalities of GrO5000 facilitated the esterification process efficiently. The chemical and structural features of GrO5000 were discussed to understand the improved catalytic activity compared with GrO2000 and conventional solid acid catalysts.
- Mungse, Harshal P.,Bhakuni, Niharika,Tripathi, Deependra,Sharma, Om P.,Sain, Bir,Khatri, Om P.
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p. 944 - 951
(2015/08/25)
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- Solvent-free acetylation and tetrahydropyranylation of alcohols catalyzed by recyclable sulfonated ordered nanostructured carbon
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Rapid and practical green acetylation and tetrahydropyranylation routes of structurally diverse alcohols and phenols were applied under solvent-free reaction conditions providing excellent yields, using catalytic amounts of environmentally friendly sulfonated ordered nanoporous carbon (CMK-5-SO 3H). Non-toxic nature of the catalyst, its easy handling, recovery and reusability, and the absence of any solvent characterize the presented procedures as efficient methods. These procedures provide methods for the separation of the product by simple filtration.
- Zareyee, Daryoush,Alizadeh, Parastoo,Ghandali, Mohammad S.,Khalilzadeh, Mohammad A.
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p. 713 - 721
(2013/07/26)
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- Highly efficient solvent-free acetylation of alcohols with acetic anhydride catalyzed by recyclable sulfonic acid catalyst (SBA-15-Ph-Pr-SO3H)- An environmentally benign method
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The catalytic activity of highly thermal stable, hydrophobic, and complete heterogeneous propylsulfonic acid functionalized nanostructured SBA-15 for excellent acetylation of alcohols and phenols with acetic anhydride at ambient temperature in solvent-free conditions was examined under environmentally benign reaction conditions. The salient features of this protocol are the absence of solvent, a green experimental procedure, and simple reusability of the catalyst (at least five reaction cycles).
- Zareyee, Daryoush,Ghadikolaee, Abdollah Razaghi,Khalilzadeh, Mohammad A.
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experimental part
p. 464 - 468
(2012/06/16)
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- Hydroacetoxylation of olefins with acetic acid genetated in situ from vinyl acetate in the presence of ruthenium complexes
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Ruthenium complexes catalyze the decomposition of vinyl acetate releasing the acetic acid and its subsequent addition to linear and cyclic olefins.
- Khusnutdinov,Shchadneva,Khisamova,Dzhemilev
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experimental part
p. 155 - 160
(2011/05/03)
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- Novel sol-gel lipases by designed bioimprinting for continuous-flow kinetic resolutions
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The bioimprinting effect in sol-gel immobilization of lipases was studied to develop efficient novel immobilized biocatalysts with significantly improved properties for biotransformations in continuous-flow systems. The bioimprinting candidates were selected systematically among the substrate mimics already found in the active site of experimental lipase structures. Four lipases (Lipase AK, Lipase PS, CaLB and CrL) were immobilized by a sol-gel process with nine bioimprinting candidates using various combinations of tetraethoxysilane (TEOS), phenyltriethoxysilane (PhTEOS), octyltriethoxysilane (OcTEOS) and dimethyldiethylsilane (DMDEOS) as silica precursors. The biocatalytic properties of the immobilized lipases were characterized by enantiomer selective acylation of various racemic secondary alcohols in two different multisubstrate systems (mixture A: a series of alkan-2-ols rac-1a-e and mixture B: heptan-2-ol rac-1f and 1-phenylethanol rac-1g). Except with Lipase AK, the most significant activity enhancement was found with the imprinting molecules already found as substrate mimics in X-ray structures of various lipases. The synthetic usefulness of the best biocatalysts was demonstrated by the kinetic resolution of racemic 1-(thiophen-2-yl)ethanol (rac-1h) in batch and continuous-flow systems. Copyright
- Hellner, Gabriella,Boros, Zoltan,Tomin, Anna,Poppe, Laszlo
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supporting information; experimental part
p. 2481 - 2491
(2011/11/06)
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- P-Toluenesulfonyl chloride as a new and effective catalyst for acetylation and formylation of hydroxyl compounds under mild conditions
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The catalytic application of p-toluenesulfonyl chloride for efficient acetylation of various types of alcohols and phenols with acetic anhydride in solvent-free conditions is reported. Also structurally diverse alcohols were formylated using formic acid based on the use of catalytic amount of p-toluenesulfonyl chloride under solvent-free condition. The reactions were carried out in short reaction time and in good to excellent yields at room temperature.
- Khazaei, Ardeshir,Rostami, Amin,Mantashlo, Fatemeh
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experimental part
p. 1430 - 1434
(2011/10/08)
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- N,N′-dibromo-N,N′-1,2-ethanediylbis(benzene sulfonamide) as an efficient catalyst for acetylation and formylation of alcohols under mild conditions
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An efficient method for the acylation and formylation of alcohols and phenols by using an acylating/formylating agent (acetic anhydride and formic acid) in the presence of a catalytic amount of N,N′-dibromo-N,N′-1, 2-ethanediylbis(benzene sulfonamide) under mild and solvent-free conditions at room temperature in good to excellent yields is described. The use of protic acids and metal Lewis acids is avoided.
- Khazaei, Ardeshir,Rostami, Amin,Rosta, Zahra,Alavi, Ali
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experimental part
p. 181 - 186
(2010/04/05)
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- Polymer-supported gadolinium triflate as a convenient and efficient Lewis acid catalyst for acetylation of alcohols and phenols
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A polymer-supported gadolinium triflate (CMPS-IM-Gd) catalyst was prepared from chloromethyl polystyrene (CMPS) resin using a simple and convenient procedure. This polymeric catalyst was used as an efficient Lewis acid catalyst for the acetylation of various alcohols and phenols with acetic anhydride, affording high yields under mild conditions. The reaction was completed in a short period of time with small amounts of the catalyst. The catalyst was reused over 10 times without any significant loss of its catalytic activity.
- Yoon, Hyo-Jin,Lee, Sang-Myung,Kim, Jong-Ho,Cho, Hong-Jun,Choi, Jung-Woo,Lee, Sang-Hyeup,Lee, Yoon-Sik
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p. 3165 - 3171
(2008/09/20)
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- Enantioselective analysis of secondary alcohols and their esters in purple and yellow passion fruits
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The enantiomeric compositions of the acetates, butanoates, hexanoates, and octanoates of the secondary alcohols 2-pentanol, 2-heptanol, and 2-nonanol were determined in yellow (Passiflora edulis f. flavicarpa) and purple (Passiflora edulis Sims) passion fruits. The compounds were isolated by means of simultaneous distillation-extraction. Enantiodifferentiation was performed via multidimensional gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert- butyldimethylsilyl)-β-cyclodextrin as chiral stationary phase. The series of homologous 2-alkyl esters, which are typical constituents of purple passion fruits, were shown to be present as nearly optically pure (R)-enantiomers. The proportions of the (S)-enantiomers varied in different batches and were dependent on the alcohol moieties of the esters. For minor amounts of esters detected in yellow fruits, the (R)-enantiomers were also dominating. However, the enantiomeric excesses were significantly lower than in the purple variety. Enantioselective analysis of the free alcohols revealed that 2-heptanol exhibited opposite configurations in purple and yellow passion fruits. A similar phenomenon was observed for 2-pentanol, which was present in the yellow fruits as a nearly racemic mixture. Data determined in extracts obtained by other techniques (liquid-liquid extraction, vacuum headspace technique) showed that the isolation procedure had no significant impact on the enantiomeric ratios.
- Strohalm, Hedwig,Dregus, Marta,Wahl, Astrid,Engel, Karl-Heinz
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experimental part
p. 10339 - 10344
(2009/09/25)
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- New free-radical halogenations of alkanes, catalysed by N-hydroxyphthalimide. Polar and enthalpic effects on the chemo- and regioselectivity
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Reactions of alkanes with different halogenating systems are compared in order to explore the reactivity of phthalimido-N-oxyl radical in hydrogen abstraction; the importance of polar effects is emphasised.
- Minisci, Francesco,Porta, Ombretta,Recupero, Francesco,Gambarotti, Cristian,Paganelli, Roberto,Pedulli, Gian Franco,Fontana, Francesca
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p. 1607 - 1609
(2007/10/03)
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- Iodine as an extremely powerful catalyst for the acetylation of alcohols under solvent-free conditions
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Iodine was found to promote quantitative acetylation of alcohols in a very short time with an equimolar amount of acetic anhydride under solvent-free conditions at room temperature.
- Phukan, Prodeep
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p. 4785 - 4787
(2007/10/03)
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- Iron perchlorate on silica gel as multi-purpose reagent for catalysis of closure and rupture of carbon-oxygen bond in epoxides, alcohols, and esters
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Aliphatic alcohols and water in the presence of catalytic amounts of Fe3+ ion introduced as iron(III) perchlorate on silica gel carrier perform efficient regiospecific opening of an epoxy ring. Carbon acids esterification with various type alcohols was carried out using the system Fe(ClO4)3-silica gel in dichloromethane under conditions excluding solvolysis. Acetylation and formylation of alcohols was performed by efficient transesterification with ethyl acetate and ethyl formate.
- Salechi,Khodaei,Ghareghani,Motlagh
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p. 794 - 796
(2007/10/03)
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- Esterification of alkene with cerium(IV) sulfate in carboxylic acid
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Reaction of alkenes [cyclohexene (1), cycloheptene (2), cyclooctene (3), 1-heptene (4), 1-octene (5), styrene (6), 1,7-octadiene (7), indene (8), and 1,2-dihydronaphthalene (9)] with cerium(IV) sulfate (CS) in carboxylic acids [formic acid, acetic acid, and propionic acid] readily yielded the corresponding carboxylic esters. This addition reaction follows the Markovnikov rule. This reaction provides a new simple method for preparing carboxylic esters from alkenes. It was also found that this method is useful for formylation.
- Horiuchi, C. Akira,Fukushima, Tomoaki,Furuta, Noriyuki,Chai, Wen,Ji, Shun-Jun,Saito, Yoshikazu,Hashimoto, Chikao,Takahashi, T. Tomoyoshi,Sugiyama, Takashi,Muto, Akinori,Sakata, Yusaku,Nozaki, Sukekatsu
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p. 270 - 272
(2007/10/03)
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- Desilylation-acetylation of trimethylsilyl ethers with acetic anhydride catalysed by montmorillonite K-10
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Two mild and simple one-step desilylation-acetylations of a variety of alkyl- and aryl-trimethylsilyl ethers, Me3SiOR(Ar), with acetic anhydride in the presence of montmorillonite K-10 clay are described.
- Movassagh,Lakouraj,Fasihi
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p. 348 - 349
(2007/10/03)
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- Enzymatic resolution of racemic secondary alcohols by lipase B from Candida antarctica
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Chiral intermediates S-(+)-2-pentanol and S-(+)-2-heptanol were prepared by a lipase-catalyzed enzymatic resolution process. Among various lipases evaluated for the stereoselective acylation of racemic alcohols, lipase B from Candida antarctica catalyzed the acylation of the undesired enantiomer of racemic alcohols leaving the desired S-(+)-alcohols unreacted. A reaction yield of 43-45% and an enantiomeric excess (e.e.) of >99% were obtained for S-(+)-2-pentanol or S-(+)-2-heptanol when the reaction was carried out using vinyl acetate or succinic anhydride as acylating agent. In an alternative process, an enantioselective hydrolysis of 2-pentyl acetate was demonstrated using lipase B giving S-(+)-2-pentyl acetate and R-(-)-2-pentanol. A reaction yield of 45% and an e.e. of 98.6% were obtained for S-(+)-2-pentyl acetate.
- Patel, Ramesh N.,Banerjee, Amit,Nanduri, Venkata,Goswami, Animesh,Comezoglu
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p. 1015 - 1019
(2007/10/03)
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- Alkane reaction with a mixture of nitric acid and acetic anhydride
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Alkanes C6-C10 at 15-20°C react with a mixture of concentrated HNO3 and acetic anhydride to afford nitrates of secondary alcohols in the yield up to 70%. Acetates of secondary alcohols, acetates and nitrates of β-nitroalcohols form in small quantity. Isooctane reacts under milder conditions to give a nitrate of β-nitroalcohol.
- Svetlakov
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p. 1081 - 1084
(2007/10/03)
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- Nucleophilic Displacement with Heterocycles as Leaving Groups. Part 16. Reactions of Secondary Alkyl Primary Amines with 5,6,8,9-Tetrahydro-7-phenyldibenzoxanthylium Trifluoromethanesulphonate to give Intermediates Solvolysing without Rearrangement
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Representative secondary alkyl primary amines R1R2CHNH2 react with the title pyrylium cation in acetic acid, alcohols, phenols, and NN-dimethylaniline acting as nucleophilic solvents to give O- and C-(secondary alkyl) products.Absence of carbenium ion rearrangements is consistent with reaction via intimate ion-molecule pairs formed rapidly from the corresponding pyridinium cations.
- Katritzky, Alan R.,Lopez-Rodriguez, Maria L.,Keay, James G.,King, Roy W.
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p. 165 - 170
(2007/10/02)
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- SELECTIVE OXIDATION OF n-ALKANES WITH LEAD TETRAACETATE
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Alkanes, when treated with lead tetraacetate under thermal or photochemical conditions, undergo a slow but highly selective oxidation to form secondary acetates.
- Bestre, R. D.,Cole, E. R.,Crank, G.
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p. 3891 - 3892
(2007/10/02)
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