- Practical acetalization and transacetalization of carbonyl compounds catalyzed by recyclable PVP-I
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A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild reaction condition, short reaction time, recyclable of catalyst and broad substrates scope with excellent yields.
- Cao, Fu-Rong,Lu, Guangying,Ren, Jiangmeng,Wang, Di,Zeng, Bu-Bing
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- Photochemical synthesis of acetals utilizing Schreiner's thiourea as the catalyst
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Acetalization of aldehydes is an area of great importance in Organic Chemistry for both synthetic and biological puproses. Herein, we report a mild, inexpensive and green photochemical protocol, where Schreiner's thiourea (N,N′-bis[3,5-bis(trifluoromethyl)-phenyl]-thiourea) is utilized as the catalyst and cheap household lamps as the light source. A variety of aromatic and aliphatic aldehydes were converted into acetals in good to high yields (23 examples, 36-96% yield) and an example of the synthesis of a cyclic acetal is provided. The reaction mechanism was also studied.
- Kokotos, Christoforos G.,Nikitas, Nikolaos F.,Spiliopoulou, Nikoleta
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supporting information
p. 3539 - 3545
(2020/06/25)
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- Photo-organocatalytic synthesis of acetals from aldehydes
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A mild and green photo-organocatalytic protocol for the highly efficient acetalization of aldehydes has been developed. Utilizing thioxanthenone as the photocatalyst and inexpensive household lamps as the light source, a variety of aromatic and aliphatic aldehydes have been converted into acyclic and cyclic acetals in high yields. The reaction mechanism was extensively studied.
- Nikitas, Nikolaos F.,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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supporting information
p. 669 - 674
(2019/02/14)
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- Synthesis of propargylic ethers by gold-mediated reaction of terminal alkynes with acetals
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A gold-catalyzed introduction of various terminal alkynes to acetals was investigated. Extensive optimization of the reaction conditions revealed that thermally stable cationic gold catalysts bearing bulky ligands such as 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene 3-1H-benzo[d][1,2,3]triazolyl gold trifluoromethanesulfonate (IPrAu(BTZ-H)OTf) were particularly suitable for the reaction. Additionally, significant solvent effects were observed. Ether solvents such as tetrahydrofuran (THF), cyclo pentyl methyl ether (CPME), and 1,4-dioxane were effective for the reaction. Studies on the scope of substrates and alkynes indicated that various alkynes and acetals were feasible to provide a wide range of propargylic ethers.
- Furuta, Miyu,Sugiyama, Kyoko,Yamaguchi, Minami,Ueda, Hirofumi,Tokuyama, Hidetoshi
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p. 872 - 876
(2019/08/20)
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- Antimony(v) catalyzed acetalisation of aldehydes: An efficient, solvent-free, and recyclable process
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A highly selective, solvent-free process for the acetalisation of aldehydes was achieved by the use of a readily accessible antimony(v) catalyst which we previously prepared in our lab as a tetraarylstibonium triflate salt ([1][OTf]). High yields of the acetals were achieved in the presence of stoichimetric amounts of either triethoxymethane or triethoxysilane. It was found that triethoxymethane reactions required longer time to reach completion when compared to triethoxysilane reactions which were completed upon mixing of the reagents. The products can be easily separated from the catalyst by distillation which enabled further use of [1][OTf] in additional calytic reactions (up to 6 cycles). Moreover, [1]+ also catalyzed the deprotection of the acetals into their corresponding aldehydes using only water as a solvent.
- Ugarte, Renzo Arias,Hudnall, Todd W.
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p. 1990 - 1998
(2017/06/09)
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- Green synthesis method of acetal-type or ketal-type compound
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The invention discloses a green synthesis method of an acetal-type or ketal-type compound. A carbonyl compound is used as a raw material, a hydrogen-loaded compound is used as a catalyst, then an alcohol substance is added, a reaction is performed to generate the acetal-type or ketal-type compound. The synthesis method is simple and convenient, is high in conversion rate and yield, is safe and stable, has low toxicity and is easy to operate; the used catalyst is simple to prepare, and is cheap and easy to obtain; the reaction process is mild and efficient; the product is easy to separate and purify; the green synthesis method has a wide substrate application range, can be used for synthesizing acetal and ketal spices, and has potential industrial application value.
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Paragraph 0063-0068
(2017/05/26)
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- A recyclable fluorous hydrazine-1,2-bis(carbothioate) with NCS as efficient catalysts for acetalization of aldehydes
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A fluorous hydrazine-carbothioate organocatalyst was prepared. Together with NCS, the catalyst showed a good activity in acetalization of aldehydes and alcohols. It could be recovered from the reaction mixture by fluorous solid-phase extraction (F-SPE) with excellent purity for direct reuse.
- Zhu, Yi-Wei,Yi, Wen-Bin,Cai, Chun
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supporting information
p. 890 - 892
(2013/07/05)
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- Carbon nanotubes supported palladium catalysts for selective hydrogenation of cinnamaldehyde under atmospheric pressure
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Carbon nanotubes supported Pd catalysts have been prepared by an impregnation method with aqueous solution containing a Pd(II) salt. The selective hydrogenation of cinnamaldehyde with the catalysts is studied in ethanol at 30 °C under atmospheric pressure. A comparison has been made with activated carbon and graphite supported Pd catalysts. The results show that all the Pd/CNTs catalysts prepared with different Pd precursors exhibit good catalytic properties. The Pd/CNTs(a) catalyst prepared with Pd(NH 3)4Cl2 as Pd precursor shows remarkably high selectivity (90.8%) for the conversion of cinnamaldehyde (92.0%) with 18.1 mmol H 2 g-1 min-1 hydrogenation rate. The influence of the solvent polarity and promoter has been investigated. The results demonstrate that highly polar solvent is advantageous for catalytic activity of Pd/CNTs(a) catalyst, while traces of weak base is advantageous for selective hydrogenation of C=C double bond.
- Ge, Changhua,Li, Yan,Zhao, Jie,Zhou, Renxian
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scheme or table
p. 281 - 287
(2011/01/07)
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- NCS with thiourea as highly efficient catalysts for acetalization of aldehydes
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NCS/thiourea-mediated acetalization of aldehydes and alcohols has rapidly provided acetals in almost quantitative yields.
- Mei,Bentley,Du
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supporting information; experimental part
p. 4199 - 4200
(2009/10/04)
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- Gallium triiodide as a highly efficient and mild catalyst for the diethyl acetalization of carbonyl compounds
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Diethyl acetals were obtained from carbonyl compounds in good to excellent yields under mild reaction conditions in the presence of triethyl orthoformate and a catalytic amount of gallium triiodide in anhydrous ethanol.
- Ding, Jin-Chang,Xu, Rong,Liu, Miao-Chang,Chen, Xi-An,Wu, Hua-Yue
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experimental part
p. 566 - 568
(2009/07/18)
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- Tetrafluoroboric acid adsorbed on silica gel as a reusable heterogeneous dual-purpose catalyst for conversion of aldehydes/ketones into acetals/ketals and back again
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Aldehydes and ketones can be protected as acetals and ketals by treatment with trimethyl orthoformate (TMOF) or triethyl orthoformate (TEOF) under the catalytic influence of tetrafluoroboric acid adsorbed on silica gel (HBF 4-SiO2). In the case of aldehydes or ketones with highly electrophilic carbonyl group, the reactions are carried out under solvent-free conditions. Aryl alkyl ketones, aryl styryl ketones, aldehydes with weakly electrophilic carbonyl groups, and aldehydes with substituents that can coordinate with the catalyst require the presence of the corresponding alcohol as solvent. For substrates that can be converted into acetals under neat conditions, the acetal formation takes place at a faster rate when the alcohol is used as the solvent. The catalyst can be recovered and reused/recycled four times (after reactivation after each use) without any significant decrease in its catalytic efficiency. The parent aldehydes/ketones are regenerated from the corresponding acetals/ketals in high yields by the treatment with water-alcohol in the presence of HBF4-SiO2 at room temperature for short times. Excellent selectivity was observed during inter- and intramolecular competition studies involving carbonyl substrates with varying electronic and steric environments. Selective acetal formation of benzaldehyde takes place in the presence of 4-(dimethylamino)benzaldehyde, thiophene-2-carboxaldehyde, 1-naphthaldehyde, 9-anthraldehyde, or acetophenone, but 3-nitrobenzaldehyde undergoes selective acetal formation in preference to benzaldehyde. In the case of 4-acetylbenzaldehyde, exclusive acetal formation of the aldehyde carbonyl group occurs. Georg Thieme Verlag Stuttgart.
- Kumar, Dinesh,Kumar, Raj,Chakraborti, Asit K.
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p. 1249 - 1256
(2008/12/22)
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- Perchloric acid adsorbed on silica gel (HClO4-SiO2) as an inexpensive, extremely efficient, and reusable dual catalyst system for acetal/ketal formation and their deprotection to aldehydes/ketones
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Perchloric acid adsorbed on silica gel (HClO4-SiO2) is reported as extremely efficient, inexpensive, and reusable catalyst for dual role for protection of aldehydes/ketones (with trialkyl orthoformates) as acetals/ketals and deprotection (with water-alcohol) to regenerate the carbonyl compounds in high yields at room temperature and in short times. Acetalization/ketalization of electrophilic aldehydes/ketones was carried out under solvent-free conditions. Weakly electrophilic aldehydes/ketones and aldehydes having a substituent that can coordinate with the catalyst, required the corresponding alcohol as solvent. Georg Thieme Verlag Stuttgart.
- Kumar, Raj,Kumar, Dinesh,Chakraborti, Asit K.
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p. 299 - 303
(2007/10/03)
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- Characterization and catalytic-hydrogenation behavior of SiO 2-embedded nanoscopic Pd, Au, and Pd-Au alloy colloids
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Colloids embedded in a silica sol-gel matrix were prepared by using fully alloyed Pd-Au colloids, and pure Pd and Au colloids stabilized with tetraalkylammonium bromide following a modified sol-gel procedure with tetrahydrofuran (THF) as the solvent. Tetraethoxysilicate (TEOS) was used as the precursor for the silica support. The molar composition of the sol was TEOS/THF/H2O/HCl = 1:3.5:4:0.05 for the bimetallic Pd-Au and TEOS/THF/H2O/HCl = 1:4.5:4:0.02 for Pd and Au monometallic systems. After refluxing. the colloid was added as a 4.5 wt % solution in THF for Pd-Au. 10.2 wt % solution in THF for Pd and 8.4 wt % solution in THF for Au at room temperature. The gelation was carried out with vigorous stirring (4 days) under an Ar atmosphere. Following these procedures, bimetallic Pd-Au-SiCK catalysts with 0.6 and 1 wt % metal, and monometallic Pd- and Au-SiO2 catalysts with 1 wt% metal were prepared. These materials were further treated following four different routes: 1) by simple drying, 2) in which the dried catalysts were calcined in air at 723 K and then reduced at the same temperature, 3) in which they were directly reduced in hydrogen at 723 K, and 4) in which the surfactant was extracted using an ethanol-heptane azeotropic mixture. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K, H2 chemisorption measurements, solid-state 1H, 13C 29SiCP/MAS-NMR spectroscopy, powder X-ray diffraction (XRD), small angle X-ray scattering (SAXS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and 197Au M?ssbauer spectroscopy. The physical characterization by a combination of these techniques has shown that the size and the structural characteristics of the Pd-Au colloid precursor are preserved when embedded in an SiO2 matrix. Catalytic tests were carried out in selective hydrogenation of 3-hexyn-1-ol, cinnamaldehyde, and styrene. These data showed evidence that alloying Pd with Au in bimetallic colloids leads to enhanced activity and most importantly to improved selectivity. Also, the combination of the two metals resulted in catalysts that were very stable against poisoning, as was evidenced for the hydrogenation of styrene in the presence of thiophene.
- Parvulescu, Vasile I.,Parvulescu, Viorica,Endruschat, Uwe,Filoti, George,Wagner, Friedrich E.,Kübel, Christian,Richards, Ryan
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p. 2343 - 2357
(2008/02/03)
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- Copper(II) tetrafluoroborate as a novel and highly efficient catalyst for acetal formation
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Commercially available copper(II) tetrafluoroborate hydrate has been found to be a highly efficient catalyst for dimethyl/diethyl acetal formation in high yields from aldehydes and ketones by reaction with trimethyl/triethyl orthoformate at room temperature and in short period. Acetalisation was carried out under solvent-free conditions with electrophilic aldehydes/ketones. For weakly electrophilic aldehydes/ketones (e.g., benzaldehyde, cinnamaldehyde and acetophenone) and for aldehydes having a substituent that can coordinate with the catalyst, the corresponding alcohol was used as solvent.
- Kumar, Raj,Chakraborti, Asit K.
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p. 8319 - 8323
(2007/10/03)
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- Iron(III) chloride catalysis of the acetal-ene reaction
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Iron(III) chloride was found to act as a very efficient catalyst in the acetal-ene reaction involving 1,1-disubstituted alkenes.
- Lade?pe?che, Arnaud,Tam, Eric,Ancel, Jean-Erick,Ghosez, Le?on
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p. 1375 - 1380
(2007/10/03)
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- An efficient and versatile procedure for the synthesis of acetals from aldehydes and ketones catalyzed by lithium tetrafluoroborate
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Acetals are obtained in good to excellent yields by treatment of aldehydes and ketones with trialkyl orthoformate and the corresponding alcohol in the presence of a catalytic amount of lithium tetrafluoroborate. Due to the mild reaction conditions, this method is compatible with acid-sensitive substrates.
- Hamada, Nao,Kazahaya, Kiyoshi,Shimizu, Hisashi,Sato, Tsuneo
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p. 1074 - 1076
(2015/10/07)
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- Palladium-catalyzed coupling of alkyl chlorides and Grignard reagents
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Chloroalkanes refined: A simple catalyst system renders the palladium-catalyzed coupling reaction of functionalized alkyl chlorides and Grignard reagents at room temperature (see example in scheme; PCy3 = tricyclohexylphosphane, NMP = N-methylpyrrolidinone).
- Frisch, Anja C.,Shaikh, Nadim,Zapf, Alexander,Belier, Matthias
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p. 4056 - 4059
(2007/10/03)
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- Solvent free protection of carbonyl group under microwave irradiation
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Protection of aldehydes and ketones as acetals or dioxolanes catalysed by PTSA or KSF clay was readily achieved from orthoformates, 1,2-ethanediol or 2,2-dimethyl-1,3-dioxolane without solvent under microwave irradiation.
- Perio, Bertrand,Dozias, Marie-Joelle,Jacquault, Patrick,Hamelin, Jack
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p. 7867 - 7870
(2007/10/03)
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- Synthesis of acetals from alkenes by one-pot hydroformylation-transacetalization reactions catalysed by rhodium complexes and pyridinium p-toluenesulphonate
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Efficient conversion of alkenes to acetals has been achieved by consecutive hydroformylation-acetalization reactions catalyzed by rhodium complexes and pyridinium p-toluenesulphonate or by a zwitterionic rhodium catalyst.
- Fernandez, Elena,Castillon, Sergio
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p. 2361 - 2364
(2007/10/02)
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- Alkylation of 2-Oxy-Substituted 1-Sulfonylallyl and 1-Sulfonylvinyl Anions. New Routes to Functionalized Carbocycles and Dihydrofurans
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Alkylation of the anion derived from 2-phenoxy-3-(phenylsulfonyl)-1-propene proceeds α to the phenylsulfonyl group and affords cyclic products from 1,ω-dihalides.Reaction of the monoalkylated products, in which a suitably positioned olefinic or acetylenic unit is present, with sodium benzenesulfinate-acetic acid gives functionalized acetylcyclopentenes and cyclohexenes via C-C bond formation from the allyl cation-sulfinate ion pair.In the vinyl sulfone series, deprotonation of (E)- or (Z)-2-alkoxyvinyl phenyl sulfones rapidly affords the more stable (E)-lithio derivative, an acetaldehyde anion equivalent which reacts normally with aldehydes, ketones, alkyl halides, and epoxides.The latter process may be effected in an intramolecular fashion.Thus, (E)-(2-phenylsulfonyl)vinyl ethers of 2,3-epoxy alcohols cyclize on treatment with amide bases to afford dihydrofurans whose stereochemistry is fully defined by that of the starting epoxy alcohol.
- Padwa, Albert,Bullock, William H.,Dyszlewski, Andrew D.,McCombie, S. W.,Shankar, B. B.,Ganguly, A. K.
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p. 3556 - 3564
(2007/10/02)
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- Asymmetric Hydroformylation Catalyzed by Homogeneous and Polymer-Supported Platinum Complexes Containing Chiral Phosphine Ligands
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A complex of Pt(II) containing the chiral ligand (2S,4S)-N-(tert-butoxycarbonyl)-4-(diphenylphosphino)-2-pirrolidine in the presence of stannous chloride catalyzed the hydroformylation of a variety of prochiral olefins.Although the branched/normal (b/n) ratios were low (ca. 0.5), high ee's were achieved in the hydroformylation of styrene (70-80percent), p-isobutylstyrene (80percent), 2-vinylnaphthalene (77percent), 2-ethenyl-6-methoxynaphthalene (81percent), 4-(2-thienylcarbonyl)styrene (78percent), vinyl acetate(82percent), N-vinylphthalimide (73percent), methyl methacrylate (60percent), and norbornene (60percent).When the hydroformylation of styrene, 2-ethenyl-6-methoxynaphthalene, and vinyl acetate with PtCl2/SnCl2 was carried out in the presence of triethyl orthoformate, enantiomerically pure acetals were obtained.The hydroformylation in the presence of ethyl orthoformate also could be carried out by using a catalyst containing the PtCl2/SnCl2 complex bound to 60-μm beads composed of cross-linked polystyrene.
- Parrinello, Giovanni,Stille, J. K.
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p. 7122 - 7127
(2007/10/02)
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- A Simple and Efficient Conversion of Aldehyde Acetals into Esters
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The reaction of aldehydic acetals with hypochlorous acid in acetic acid-acetone afforded the corresponding esters in excellent yields.From cyclic acetals, only the corresponding hydroxyalkyl esters were obtained.Keywords - acetal; hypochlorite; hypochlorous acid; conversion; ester; hydroxyalkyl ester; regioselectivity
- Sugai, Saburo,Kodama, Takashi,Akaboshi, Sanya,Ikegami, Shiro
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