122-00-9Relevant articles and documents
Formal asymmetric hydration of non-activated alkenes in aqueous medium through a "chemoenzymatic catalytic system"
Schnapperelle, Ingo,Hummel, Werner,Groeger, Harald
, p. 1073 - 1076 (2012)
A direct one-pot conversion of (substituted) styrene(s) into the corresponding (substituted) (R)-phenylethan-1-ol(s) in a highly enantioselective manner has been achieved by using a "chemoenzymatic catalytic system", comprising a palladium-catalyzed Wacker-Tsuji oxidation and subsequent enantioselective enzymatic reduction of the in situ formed (substituted) acetophenone(s) (see scheme). Copyright
Structural effects on the β-scission reaction of alkoxyl radicals. Direct measurement of the absolute rate constants for ring opening of benzocycloalken-1-oxyl radicals
Bietti, Massimo,Lanzalunga, Osvaldo,Salamone, Michela
, p. 1417 - 1422 (2005)
(Chemical Equation Presented) The absolute rate constants for β-scission of a series of benzocycloalken-1-oxyl radicals and of the 2-(4-methylphenyl)-2-butoxyl radical have been measured directly by laser flash photolysis. The benzocycloalken-1-oxyl radicals undergo ring opening with rates which parallel the ring strain of the corresponding cycloalkanes. In the 1-X-indan-1-oxyl radical series, ring opening is observed when X = H, Me, whereas exclusive C-X bond cleavage occurs when X = Et. The factors governing the fragmentation regioselectivity are discussed.
Copper(I) Catalyzed Differential Peroxidation of Terminal and Internal Alkenes Using TBHP
Mir, Bilal Ahmad,Rajamanickam, Suresh,Begum, Pakiza,Patel, Bhisma K.
, p. 252 - 261 (2020)
Terminal and internal alkenes react contrarily with tert-butyl hydroperoxide (TBHP) giving various products. A Cu(I) catalyzed decarbonylative C–C bond formation followed by a carbonylation–peroxidation of vinyl arenes has been achieved using tert-butyl hydroperoxide (TBHP) as the oxidant in acetonitrile. Whereas, α-methyl styrenes yielded aryl methyl ketones and the α-substituted unsymmetrical internal alkenes afforded selective α-peroxidation under the identical reaction conditions. Concurrent peroxidation–carbonylation–cycloalkylation/cycloetherifiction of internal cyclic alkene such as indene is achieved by switching the solvent system from acetonitrile to cycloalkanes/cyclic ether. All these reactions proceed via radical paths generating interesting peroxo-compounds.
Continuous liquid phase acylation of toluene over HBEA zeolite: Solvent effects and origin of the deactivation
Chen, Zhihua,Chen, Wenqi,Tong, Tianxia,Zeng, Aiwu
, p. 231 - 238 (2014)
The continuous liquid phase Friedel-Crafts acylation of toluene (T) by acetic anhydride (AA) over HBEA zeolite was carried out in a fixed bed reactor, with acetic acid (AC) as a solvent. 4-Methylacetophenone (4-MAP) was selectively formed in the initial reaction stage. However, a rapid catalyst deactivation occurred with a sharp decrease of the conversion of acetic anhydride, and this was mainly caused by 4-MAP and heavy compounds ('coke') existing in the zeolite pore, which poisoned the active sites of the catalyst. The use of excess toluene and moderate acetic acid enhanced catalyst activity and stability to some extent as it limited both the retention of 4-MAP and the formation of 'coke'. Moreover, a considerable reduction of Broensted acid sites after deactivation revealed that the toluene acylation is primarily a Broensted acid catalyzed reaction.
PENTACOORDINATE ORGANOSILICATE AS AN ALKYLATING REAGENT: PALLADIUM CATALYZED METHYLATION OF ARYL HALIDES
Hatanaka, Yasou,Hiyama, Tamejiro
, p. 97 - 98 (1988)
Under the influence of palladium catalyst, tris(diethylamino)sulfonium difluorotrimethylsilicate is found to deliver the methyl group to aryl halides highly chemoselectively, and the corresponding methylated aromatic compounds are produced in moderate to high yields.
Nitrogen-doped carbon nanotubes encapsulate cobalt nanoparticles as efficient catalysts for aerobic and solvent-free selective oxidation of hydrocarbons
Lin, Xiu,Nie, Zhenzhen,Zhang, Liyun,Mei, Shuchuan,Chen, Yuan,Zhang, Bingsen,Zhu, Runliang,Liu, Zhigang
, p. 2164 - 2173 (2017)
The selective oxidation of hydrocarbons to the corresponding ketones with solvent-free and molecular oxygen as an oxidant is of great importance in academic and industrial fields in view of economy and environment. In this respect, we present the facile synthesis and characterization of excellent catalysts comprising cobalt nanoparticles encapsulated into graphitic nitrogen-doped carbon nanotubes (Co@GCNs) via one-pot pyrolysis of a chelate compound containing citric acid, melamine, and CoCl2·6H2O. The selective oxidation of ethylbenzene under molecular oxygen and solvent-free conditions is employed as a probe reaction to investigate the catalytic performance; the optimized catalyst shows the best conversion (68%) and selectivity for acetophenone (93%). Combination of the catalytic results of the control group and the different characterization methods demonstrates that high catalytic activity is due to the synergistic effect between metallic cobalt and nitrogen-doped carbon nanotubes. Moreover, the catalyst has high catalytic activity for the aerobic and solvent-free oxidation of other arylalkane substrates. The proposed mechanistic study illustrates that the reaction is a free radical reaction progressing through superoxide radical anions (?O2-).
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Dermer et al.
, p. 2881 (1941)
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Friedel-Crafts acylation of toluene using superacid catalysts in a solvent-free medium
El-Sharkawy,Al-Shihry, Shar S.
, p. 259 - 267 (2010)
Sulfated tin oxide and sulfated zirconia containing different amounts of sulfate and Al2O3-sulfated zirconia catalysts were prepared. The materials were characterized by DTA/TGA/DTG, XRD, FT-IR, and BET surface-area techniques. Surface acidity was determined using TGA of pyridine-pretreated samples, and acid strength was determined by potentiometric titration of the solid catalysts with n-butylamine in non-aqueous media. The catalytic activity of prepared samples was tested by Friedel-Crafts acylation of toluene with acetic acid anhydride. Incorporation of sulfate into SnO 2 impedes sintering and is associated with a decrease of surface area. Sulfated tin oxide has greater acidity and higher acid strength than Al3+-impregnated sulfated zirconia, giving, therefore, a higher yield of acylation products. Sulfated tin oxide was found to pass through maxima of higher acidity and higher efficiency for the acylation reaction when sulfate loading is 10 wt%. A good relationship between structural characteristics, acidity, and catalytic activity is observed.
Hierarchical zeolite Beta: An efficient and eco-friendly nanocatalyst for the Friedel-Crafts acylation of toluene
Selvin, Rosilda,Roselin, L. Selva,Khayyat, Suzan A.,Umar, Ahmad
, p. 4415 - 4420 (2013)
P-Methyacetophenone, the acylated product of toluene finds a wide range of applications in the flavors and fragrance industry. It is typically produced on an industrial scale by Friedel-Crafts acylation of toluene with acetic anhydride using homogeneous, corrosive and polluting acid catalysts such as aluminium chloride. The pollution problems related to this process such as the disposal of catalyst and treatment of acidic effluent needs to be replaced by a green process. The current work reports on the activity of hierarchical zeolite Beta in the liquid phase acylation of toluene with acetic anhydride. The liquid phase reactions were carried out in the temperature range of 60-140 °C in an autoclave. The effect of various reaction parameters such as time-on-stream (TOS), mole ratio of reactants, catalyst loading, and reaction temperature on the rates of reaction has been investigated. Under the optimum reaction conditions the performance of hierarchical zeolite Beta was compared with nanocrystalline zeolite Beta. It was found that hierarchical zeolite Beta catalyst exhibit higher activity, which is due to the hierarchical porosity and to the nano size of the Beta zeolite catalyst particles allows faster diffusion of the products out of the catalyst. Copyright
Efficient photodecarboxylation of 3- and 4-acetylphenylacetic acids in aqueous solution
Huck, Lawrence A.,Xu, Musheng,Forest, Kaya,Wan, Peter
, p. 1760 - 1768 (2004)
The photochemistry of 3- and 4-acetylphenylacetic acids (6 and 7) has been studied in aqueous solution. This work is a continuation of research efforts aimed at understanding the structural effects on the efficacy for benzyl carbanion photogeneration via photodecarboxylation. The nitro group (at the 3- and 4-positions) is known to be an exceptionally good activating group on the benzene ring - because of its enhanced electron-withdrawing effect in the excited triplet state - for photodecarboxylation and the related photo-retro-aldol type process. It is shown in this work that the acetyl group is an equally good activating group for the photodecarboxylation. Thus, the photochemistry of 6 and 7 parallels much of what was observed for the corresponding nitrophenylacetic acids 1 and 2. Both 6 and 7 photodecarboxylate efficiently (Φd = 0.60 and 0.22, respectively, at pH 7) via the carboxylate form, to give observable (by laser flash photolysis) benzyl carbanion or related intermediates. The meta isomer 6 displays an acid-catalyzed pathway for photodecarboxylation at pH 3 and along with its enhanced overall reactivity, is consistent with a meta effect of the acetyl group. Triplet state reactivity is inferred from sensitization and laser flash photolysis experiments. Based on the results of this work, the acetyl group may now be viewed as an "enhanced" electron-withdrawing group (in the excited state) when attached to a benzene ring (i.e., in acetophenone derivatives) that is capable of inducing ionic reactions, which is not the traditional photochemistry that is expected from such compounds.
Surface Coordination of Multiple Ligands Endows N-Heterocyclic Carbene-Stabilized Gold Nanoclusters with High Robustness and Surface Reactivity
Shen, Hui,Xu, Zhen,Hazer, Maryam Sabooni Asre,Wu, Qingyuan,Peng, Jian,Qin, Ruixuan,Malola, Sami,Teo, Boon K.,H?kkinen, Hannu,Zheng, Nanfeng
, p. 3752 - 3758 (2021)
Deciphering the molecular pictures of the multi-component and non-periodic organic-inorganic interlayer is a grand technical challenge. Here we show that the atomic arrangement of hybrid surface ligands on metal nanoparticles can be precisely quantified through comprehensive characterization of a novel gold cluster, Au44(iPr2-bimy)9(PA)6Br8 (1), which features three types of ligands, namely, carbene (1,3-diisopropylbenzimidazolin-2-ylidene, iPr2-bimy), alkynyl (phenylacetylide, PA), and halide (Br), respectively. The delicately balanced stereochemical effects and bonding capabilities of the three ligands give rise to peculiar geometrical and electronic structures. Remarkably, despite its complex and highly distorted surface structure, cluster 1 exhibits unusual catalytic properties and yet it is highly stable, both chemically and thermally. Moreover, rich reactive sites on the cluster surface raise the prospect of bio-compatibility (as it can be functionalized to yield water-soluble derivatives) and bio-applications.
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Heine,Cottle,Van Mater
, p. 524 (1946)
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NOVEL TYPES OF TRANSFORMATIONS OF α-AZIDOSTYRENE DERIVATIVES AND 3-ARYL-2H-AZIRINES IN THE PRESENCE OF HEXACARBONYLMOLYBDENUM
Nitta, Makoto,Kobayashi, Tomoshige
, p. 1715 - 1718 (1983)
The reaction of α-azidostyrene derivatives with hexacarbonylmolybdenum was found to give 2,5-diarylpyrroles and acetophenone derivatives via a complexed 1-arylvinylnitrene intermediate, while that of 3-aryl-2H-azirines gave 2,4-diarylpyrroles in addition to acetophenone derivatives and 2,5-diarylpyrazines.
An efficient oxidation of alcohols by aqueous H2O2 with 1,3-dibromo-5,5-dimethylhydantoin
Lee, Jieun,Lee, Jong Chan
, p. 895 - 898 (2018)
An efficient protocol is described for the oxidation of alcohols to the corresponding aldehydes or ketones with 1,3-dibromo-5,5-dimethylhydantoin in the presence of aqueous H2O2.
Palladium-catalyzed cross-methylation of haloarenes possessing active hydrogen atoms by intramolecularly stabilized dimethylindium and dimethylaluminum reagents
Jaber, Nimer,Gelman, Dmitri,Schumann, Herbert,Dechert, Sebastian,Blum, Jochanan
, p. 1628 - 1632 (2002)
While the intramolecularly stabilized aluminum complex [(CH3)2AlOCH2CH2 N(CH3)2]2 (2a) reacts readily with 4-bromophenol to give methane and [(4-BrC6H4O)su
Synthesis of ketones with alkyl phosphonates and nitriles as acyl cation equivalent: Application of dephosphonylation reaction of β-functionalized phosphonate with hydride
Jang, Won Bum,Shin, Won Suk,Hong, Jong Eun,Lee, Shi Yong,Oh, Dong Young
, p. 3333 - 3339 (1997)
The preparation of several α-substituted ketones is performed in a one-pot procedure with alkyl phosphonates and aromatic nitriles by subsequent treatment of LiAlH4. A new method for nitriles used as an acyl cation equivalent is described.
Nanocrystalline magnesium oxide-stabilized molybdenum: An efficient heterogeneous catalyst for the aerobic oxidation of alcohols to carbonyl compounds
Kantam, M. Lakshmi,Yadav, Jagjit,Laha, Soumi,Sreedhar, Bojja,Bhargava, Suresh
, p. 2575 - 2582 (2008)
A nanocrystalline magnesium oxide-stabilized molybdenum(VI) complex catalyzed the oxidation of primary and secondary alcohols to carbonyl compounds in excellent yields using molecular oxygen as stoichiometric oxidant. The nanomaterials with their three-dimensional structure and defined size and shape act as suitable supports for metal complexes. The catalyst can be reused for four runs without any significant loss of activity.
Friedel-crafts acylation reactions in pyridinium based ionic liquids
Xiao, Ying,Malhotra, Sanjay V.
, p. 3609 - 3613 (2005)
The Friedel-Crafts acylations of representative aromatic compounds with acetic anhydride in pyridinium based ionic liquids (ILs) were investigated. The effect of factors such as reactant composition, catalyst-IL composition, catalyst dosage and reaction temperature were studied. The reactions were found to proceed under relatively mild conditions with excellent conversions; and a simple product isolation procedure was achieved. ILs could also be recycled and reused effectively, thus rendering green characteristic to this reaction.
ESI-MS detection of proposed reaction intermediates in the air-promoted and ligand-modulated oxidative heck reaction
Enquist, Per-Anders,Nilsson, Peter,Sjoeberg, Per,Larhed, Mats
, p. 8779 - 8786 (2006)
Electrospray ionization mass spectrometry (ESI-MS) and subsequent MS/MS analyses were used to directly detect palladium-containing cationic reaction intermediates in a ligand controlled palladium(II)-catalyzed oxidative Heck arylation. All potential intermediates were observed as dmphen-ligated palladium(II) species, suggesting that the dmphen bidentate ligand is attached to the metal center during the entire catalytic cycle. The study supports previous mechanistic propositions and provides new information regarding the composition of aryl-containing Pd(II) complexes in an ongoing oxidative Heck reaction. In addition, sodium acetate was found to be a useful base alternative to previously used tertiary amines.
Temperature dependent solvent effects in photochemistry of 1-phenylpentan-1-ones
Klan, Petr,Literak, Jaromir
, p. 2007 - 2018 (1999)
Temperature dependent solvent effects have been investigated on the Norrish Type II reaction of 1-phenylpentan-1-one and its p-methyl derivative. Efficiencies of the photoreaction were studied in terms of solvent polarity and base addition as a function of temperature. Such a small structure change as the p-methyl substitution in 1-phenylpentan-1-one altered the temperature dependent photoreactivity in presence of weak bases. The experimental results suggest that the hydrogen bonding between the Type II biradical intermediate OH group and the solvent is weaker for 1-(4-methylphenyl)pentan-1-one than that for 1-phenylpentan-1-one at 20°C but the interactions probably vanish in both cases at 80°C.
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Simons,Randall,Archer
, p. 1796 (1939)
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Ester Cleavage in Superacid Media Involving Diprotonated Gitonic Carboxonium Dications
Olah, George A.,Hartz, Nikolai,Rasul, Golam,Burrichter, Arwed,Prakash, G. K. Surya
, p. 6421 - 6427 (1995)
The reactivity of protonated and methylated methyl ester in superacidic media was investigated by experiment and theory.Protonated methyl acetate was found to undergo slow acyl oxygen cleavage at -78 deg C in FSO3H/SbF5/SO2 solution to give acetyl cation and methyloxonium ion. 1,1-Dimethoxyethyl cation (methylated methyl acetate) was found to undergo slow methyl exchange in CD3SO3F/SbF5 solution.The reaction of 1,1-dimethoxyethyl cation with toluene in the presence of trifluoromethanesulfonic acid at -78 deg C gave acylation in 4percent yield.Theoretical calculations at the MP4(SDTQ)/6-31G*//MP2/6-31G* level of theory were performed to find stationary points on the potential energy surface of the mono- and diactivated ester system.Based on the available evidence a new mechanism for the acid-catalyzed ester cleavage in superacidic media is proposed.
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Groggins,Nagel
, p. 1313,1314 (1934)
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Synthesis of a 2,7-dioxatricyclo[4.2.1.03,8]nonane: A model study for possible application in a synthesis of dictyoxetane
Marshall,Mapp,Heathcock
, p. 9135 - 9145 (1996)
A method for the synthesis of the 2,7-dioxatricyclo[4.2.1.03,8]nonane ring system characteristic of the marine diterpene dictyoxetane has been developed. This method utilizes a dipolar cycloaddition of a 3-oxidopyrylium salt to create the carbon skeleton and employs an intramolecular S(N)2 displacement to form the oxetane ring. The route described could easily be adapted to incorporate additional functionality, making it potentially useful in a total synthesis of dictyoxetane.
Acylation of Toluene with Acetic Anhydride over Beta Zeolites: Influence of Reaction Conditions and Physicochemical Properties of the Catalyst
Botella,Corma,Lopez-Nieto,Valencia,Jacquot
, p. 161 - 168 (2000)
Acylation of toluene with acetic anhydride was carried out over Beta-type zeolites in a stainless steel autoclave. At low temperature, i.e., 150°C, and an arene/anhydride molar ratio 10-20, high yields of 4-methylacetophenone were obtained with selectivity close to 100%. The reaction is limited by the poisoning of the active sites by adsorption of the product and pore blockage due to coke -type products. Acid site accessibility is of paramount importance for this reaction, and the use of a nanocrystalline Beta zeolite as catalyst minimizes catalyst decay. This, combined with an optimum framework composition, allows the preparation of active and selective acylation catalysts based on Beta zeolite.
Visible light-mediated, high-efficiency oxidation of benzyl to acetophenone catalyzed by fluorescein
Geng, Haoxing,Liu, Xin,Zhu, Qing
supporting information, (2021/12/20)
An environmentally friendly aerobic oxidation of benzyl C(sp3)-H bonds to ketones via selective oxidation catalysis was developed. Fluorescein is an efficient photocatalyst with excellent chemical selectivity. The reaction has a wide substrate scope, and a successful gram-scale experiment demonstrated its potential industrial utility.
Selective Activation of Unstrained C(O)-C Bond in Ketone Suzuki-Miyaura Coupling Reaction Enabled by Hydride-Transfer Strategy
Zhong, Jing,Zhou, Wuxin,Yan, Xufei,Xia, Ying,Xiang, Haifeng,Zhou, Xiangge
supporting information, p. 1372 - 1377 (2022/02/23)
A Rh(I)-catalyzed ketone Suzuki-Miyaura coupling reaction of benzylacetone with arylboronic acid is developed. Selective C(O)-C bond activation, which employs aminopyridine as a temporary directing group and ethyl vinyl ketone as a hydride acceptor, occurs on the alkyl chain containing a β-position hydrogen. A series of acetophenone products were obtained in yields up to 75%.
Electrochemical Aerobic Oxidative Cleavage of (sp3)C-C(sp3)/H Bonds in Alkylarenes
Liu, Shuai,Liu, Zhong-Quan,Shen, Tong,Shen, Xu,Wang, Nengyong,Wu, Jintao,Yang, Le,Zhao, Jianyou
, p. 3286 - 3295 (2022/03/14)
An electrochemistry-promoted oxidative cleavage of (sp3)C-C(sp3)/H bonds in alkylarenes was developed. Various aryl alkanes can be smoothly converted into ketones/aldehydes under aerobic conditions using a user-friendly undivided cell setup. The features of air as oxidant, scalability, and mild conditions make them attractive in synthetic organic chemistry.