- Bioinspired Oxidative Cleavage of Aliphatic C–C Bonds Utilizing Aerial Oxygen by Nickel Acireductone Dioxygenase Mimics
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Bioinspired oxidative cleavage of aliphatic C–C bonds of the acireductone model substrate 2-hydroxy-3-oxo-1,3-diphenylprop-1-en-1-olate, bound to two paramagnetic nickel(II) complexes that are mimics for the nickel containing acireductone dioxygenase, has been achieved utilizing aerial oxygen under ambient conditions.
- Raje, Sakthi,Mani, Kalaikodikumaran,Kandasamy, Parameswaran,Butcher, Ray J.,Angamuthu, Raja
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- N-Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air
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Oxygenation reactions with molecular oxygen (O2) as the oxygen source provides a green and straightforward strategy for the construction of O-containing compounds. Demonstrated here is a novel N-heterocyclic carbene (NHC) catalyzed oxidative transformation of simple and readily available organic halides into valuable esters through the incorporation of O-atoms from O2. Mechanistic studies prove that the deoxy Breslow intermediate generated in situ is oxidized to a Breslow intermediate for further transformation by this oxidative protocol. This method broadens the field of NHC catalysis and promotes oxygenation reactions with O2.
- Tan, Hui,Wang, Shen-An,Yan, Zixi,Liu, Jianzhong,Wei, Jialiang,Song, Song,Jiao, Ning
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supporting information
p. 2140 - 2144
(2020/12/01)
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- Decarboxylative Oxyacyloxylation of Propiolic Acids: Construction of Alkynyl-Containing α-Acyloxy Ketones
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Novel decarboxylative oxyacyloxylation of propiolic acids has been developed. This reaction provides an efficient access to alkynyl-containing α-acyloxy ketones from readily available starting materials and exhibits significant functional group tolerance. Furthermore, oxyacyloxylation of terminal alkynes and aliphatic propiolic acids was also developed. A possible reaction mechanism is proposed based on mechanistic studies.
- Chen, Xin,Xin, Yangchun,Zhao, Zhi-Wei,Hou, Yu-Jian,Wang, Xiang-Xiang,Xia, Wen-Jin,Li, Ya-Min
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supporting information
p. 8216 - 8225
(2021/06/28)
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- 1,2-Dibromoethane and KI mediated α-acyloxylation of ketones with carboxylic acids
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The 1,2-dibromoethane- and KI-mediated α-acyloxylation of ketones is reported in moderate to good yield without the use of transition metals and strong oxidants. Various acids are well tolerated with wide functional group compatibility. An 1,2-dibromoethane- and KI-catalysed reaction mechanism is proposed based on the results of control experiments.
- Wang, Xujie,Li, Gangsheng,Yang, Yanan,Jiang, Jianshuang,Feng, Ziming,Zhang, Peicheng
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supporting information
p. 711 - 714
(2019/09/30)
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- Aerobic Photooxidative Synthesis of β-Alkoxy Monohydroperoxides Using an Organo Photoredox Catalyst Controlled by a Base
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Transition-metal-free synthesis of β-alkoxy monohydroperoxides via aerobic photooxidation using an acridinium photocatalyst was developed. This method enables the synthesis of some novel hydroperoxides. The peroxide source is molecular oxygen, which is cost-effective and atomically efficient. Magnesium oxide plays an important role as a base in the catalytic system.
- Asano, Yuya,Nagasawa, Yoshitomo,Yamaguchi, Eiji,Itoh, Akichika
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supporting information
p. 409 - 412
(2018/02/21)
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- Metal-free one-pot α-benzoxylation of benzylic alcohols with acids or aldehydes
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A metal-free strategy has been developed for α-benzoxylation of benzylic alcohols with acids or aldehydes. The reaction proceeds via sequential oxidation and α-benzoxylation in one pot. Importantly, the reactions are performed in metal-free condition and utilize cheap aqueous TBHP as an oxidant, affording α-benzoxy ketones in moderate to good yields.
- Zhu, Yefu,Zheng, Yong,Song, Weibin,Wei, Bole,Xuan, Lijiang
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supporting information
p. 368 - 371
(2018/01/04)
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- Copper-catalyzed α-C-H acyloxylation of carbonyl compounds with terminal alkynes
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Herein, a copper/TBHP catalyst system for the α-C-H acyloxylation of carbonyl compounds is developed using terminal alkynes as the acyloxy source. A variety of carbonyl compounds and terminal alkynes are tolerated in this reaction. In addition, its possible mechanism is proposed.
- Li, Jiao,Yang, Zan,Yang, Tao,Yi, Jianmin,Zhou, Congshan
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supporting information
p. 1581 - 1584
(2018/02/09)
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- α-Acetoxyarone synthesis via iodine-catalyzed and tert-butyl hydroperoxide-mediateded self-intermolecular oxidative coupling of aryl ketones
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We present a metal-free method for α-acetoxyarone synthesis by self-intermolecular oxidative coupling of aryl ketones using I2?tert-butyl hydroperoxide (TBHP). Under the optimum conditions, various aryl ketones gave the corresponding products i
- Tan, Liquan,Chen, Cui,Liu, Weibing
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supporting information
p. 1079 - 1084
(2017/06/20)
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- Desyl and phenacyl as versatile, photocatalytically cleavable protecting groups: A classic approach in a different (visible) light
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A highly efficient, catalytic strategy for the deprotection of classical phenacyl (Pac) as well as desyl (Dsy) protection groups has been developed using visible light photoredox catalysis. The deliberate use of a neutral two-phase acetonitrile/water mixture with K3PO4 applying catalytic amounts of [Ru(bpy)3](PF6)2 in combination with ascorbic acid is the key to this truly catalytic deprotection of Pac- and Dsy-protected carboxylic acids. Our mild yet robust protocol allows for fast and selective liberation of the free carboxylic acids in very good to quantitative yields, while only low catalyst loadings (1 mol %) are required. Both Pac and Dsy, easily introduced from commercially available precursors, can be applied for the direct protection of carboxylic acids and amino acids, offering orthogonality to a great variety of other common protecting groups. We further demonstrate the general applicability and versatility of these formerly underrated protecting groups in combination with our catalytic cleavage conditions, as underscored by the gained high functional group tolerance. Moreover, this method could successfully be adapted to the requirements of solidphase synthesis. As a proof of principle for an efficient visible light, photocatalytic linker cleavage, a Boc-protected tripeptide was split off from commercially available brominated Wang resin.
- Speckmeier, Elisabeth,Zeitler, Kirsten
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p. 6821 - 6826
(2017/11/06)
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- I2/TBHP-mediated oxidative coupling of ketones and toluene derivatives: a facile method for the preparation of α-benzoyloxy ketones
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An efficient oxidative approach was developed for the α-benzoyloxylation of ketones using tert-butyl hydroperoxide (TBHP). This process provided facile access to a wide range of α-benzoyloxy ketones in good to excellent yields via the direct oxidative α-benzoyloxylation of a structurally diverse series of ketones using simple arylmethane compounds.
- Chen, Cui,Liu, Weibing,Zhou, Peng,Liu, Hailing
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p. 20394 - 20397
(2017/04/19)
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- Method for preparing alpha-acyloxy ketone compound from terminal alkyne compounds
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The invention provides a method for efficiently synthesizing an alpha-acyloxy ketone compound containing different substitute functional groups. According to the method, acetylacetone copper is taken as a reaction catalyst, t-butylhydroperoxide is taken as an antioxidant, ketone compounds and terminal alkyne compounds are taken as reaction substrates, and an organic solvent is added into a reaction system. The method has the advantages that the catalyst is cheap and easily available; reaction conditions are mild, safe and reliable; and the productivity of an obtained target product is relatively high. According to the method, the problem that a traditional alpha-acyloxylation reaction system is single is solved, and a novel acyloxylation reagent is provided; and the method has good industrial application prospects.
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Paragraph 0040
(2017/09/01)
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- Copper Acetate Mediated α-Oxysulfonylation of α-Diazo β-Ketosulfones
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Copper acetate mediated α-oxysulfonylation of α-diazo β-ketosulfones in wet nitromethane under nitrogen provides α-oxysulfonyl β-ketosulfones. The use of different copper salts is investigated for the development of a facile and efficient transformation.
- Chan, Chieh-Kai,Wang, Heui-Sin,Hsu, Ru-Ting,Chang, Meng-Yang
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p. 2423 - 2434
(2017/05/22)
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- Method for preparing alpha-acyloxy ketone compound
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The invention discloses a method for preparing an alpha-acyloxy ketone compound. According to the invention, simple and easily available alcohol and carboxylic acid are taken as the raw materials, under mediation of NBS(N-bromo-succinimide) and DBU(1,8-diazabicyclo(5.4.0)undec-7-alkene), the alpha-acyloxy ketone is prepared by a one-pot reaction. The method has the advantages of mild reaction condition, simple and easily available raw materials, wide substrate adaptation scope, no requirement of rigorous reaction conditions such as any metal catalyst, peroxy compounds, low or high temperature and water-free and oxygen-free conditions, metal pollution is avoided; and the method also has the advantages of stable technical condition, simple and safe operation, and easy purifying of the product.
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Paragraph 0025
(2017/04/28)
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- Palladium-Catalyzed Chemo- and Enantioselective C?O Bond Cleavage of α-Acyloxy Ketones by Hydrogenolysis
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A chemoselective C?O bond cleavage of the ester alkyl side-chain of α-acyloxy ketones was realized for the first time by a highly efficient palladium-catalyzed hydrogenolysis (S/C=6000, the highest catalytic efficiency by far). Furthermore, a kinetic resolution of α-acyloxy ketones was first developed by enantioselective hydrogenolysis with good yields and up to 99 % ee.
- Chen, Jianzhong,Zhang, Zhenfeng,Liu, Delong,Zhang, Wanbin
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supporting information
p. 8444 - 8447
(2016/07/19)
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- Synthesis method of 2-arylformyl-1-arylethanone derivative
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The invention discloses a synthesis method of 2-arylformyl-1-arylethanone derivative shown by the formula (I). The synthesis method comprises the following steps: in a reaction solvent and with an omega-bromoacetophenone compound shown by the formula (II)
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Paragraph 0021
(2017/03/08)
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- NBS/DBU mediated one-pot synthesis of α-acyloxyketones from benzylic secondary alcohols and carboxylic acids
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A simple and efficient one-pot NBS/DBU-mediated method has been developed for the synthesis of α-acyloxyketones from various benzylic secondary alcohols and carboxylic acids. Through this methodology, a series of α-acyloxyketones could be obtained in good to excellent yields under mild conditions. Importantly, this new reaction avoids the direct usage of toxic metal catalysts or potentially dangerous peroxide oxidants.
- Zhu, Minghui,Wei, Wei,Yang, Daoshan,Cui, Hong,Cui, Huanhuan,Sun, Xuejun,Wang, Hua
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supporting information
p. 10998 - 11001
(2016/12/06)
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- Novel and efficient transformation of enamides into α-acyloxy ketones via an acyl intramolecular migration process
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Hydrogen peroxide and anhydride mediated transformation of enamides to afford substituted α-acyloxy ketones is described. This transition-metal-free cascade reaction has a broad substrate scope and high efficiency. The acyl intramolecular migration procedure successfully achieved this acyloxylation process under mild conditions and increased the atom efficiency.
- Zhou, Xiaoqiang,Ma, Haojie,Cao, Jinhui,Liu, Xingxing,Huang, Guosheng
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supporting information
p. 10070 - 10073
(2016/11/06)
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- NBu4NI-catalyzed α-benzoxylation of ketones with terminal aryl alkenes
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A metal-free protocol for the α-benzoxylation of ketones has been developed by using terminal aryl alkenes as an arylcarboxy surrogate. Moderate to good yields were attained for a variety of propiophenones and acetophenones by using tetra-n-butylammonium iodide (TBAI) as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant under ambient reaction conditions. An efficient synthesis for the α-benzoxylation of aryl ketones has been developed by using terminal aryl alkenes as the arylcarboxy surrogate. The products were obtained in moderate to good yields for a broad scope of substrates. Tetra-n-butylammonium iodide (TBAI) and tert-butyl hydroperoxide (TBHP) were employed as the catalyst and oxidant, respectively.
- Mondal, Buddhadeb,Sahoo, Subas Chandra,Pan, Subhas Chandra
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p. 3135 - 3140
(2015/05/13)
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- I2-catalyzed regioselective oxo- and hydroxy-acyloxylation of alkenes and enol ethers: A facile access to α-acyloxyketones, esters, and diol derivatives
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I2-catalyzed oxo-acyloxylation of alkenes and enol ethers with carboxylic acids providing for the high yield synthesis of α-acyloxyketones and esters is described. This unprecedented regioselective oxidative process employs TBHP and Et3/s
- Reddi, Rambabu N.,Prasad, Pragati K.,Sudalai, Arumugam
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p. 5674 - 5677
(2015/02/19)
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- ONE STEP PROCESS FOR REGIOSELECTIVE SYNTHESIS OF α-ACYLOXY CARBONYLS
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A regioselective N-Heterocyclic Carbene (NHC) catalyzed one step process for high yield synthesis of α-acyloxy carbonyl compounds is disclosed.
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Page/Page column 8; 9; 14
(2015/01/06)
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- Optimizing P,N-bidentate ligands for oxidative gold catalysis: Efficient intermolecular trapping of α-oxo gold carbenes by carboxylic acids
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Control confirmed: Optimization of P,N-bidentate ligands (L) reveals the importance of conformation control for intermolecular trapping of reactive α-oxo gold carbene intermediates. As a result, the highly efficient and broadly applicable synthesis of car
- Ji, Kegong,Zhao, Yulong,Zhang, Liming
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supporting information
p. 6508 - 6512
(2013/07/27)
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- Palladium-catalyzed asymmetric hydrogenation of α-acyloxy-1- arylethanones
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First hand: The first example of a palladium-catalyzed asymmetric hydrogenation of α-acyloxy ketones (1) was accomplished to give the hydrogenated products 2 with by far the highest catalytic efficiency in up to quantitative conversions and excellent enantioselectivities. The hydrogenated products could serve as important intermediates for the preparation of many drug candidates. TFE=2,2,2-trifluoroethanol. Copyright
- Chen, Jianzhong,Liu, Delong,Butt, Nicholas,Li, Chao,Fan, Dongyang,Liu, Yangang,Zhang, Wanbin
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p. 11632 - 11636
(2013/11/06)
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- On the configurational stability of chiral heteroatom-substituted [D 1]Methylpalladium complexes as intermediates of stille and suzuki-miyaura cross-coupling reactions
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Enantiomerically pure (S)-tributylstannyl[D1]methanol and (R)- and (S)-tributylstannyl[D1]methyl benzoates were Stille-coupled with bromobenzene and benzoyl chloride in 1,4-dioxane and toluene using [(Ph 3P)4Pd] or [(Ph3P)2PdCl2] either alone or in combination with CuCN as cocatalyst at temperatures up to 80 °C. The products were found to be enantiomerically pure. (R)- and (S)-N-(tributylstannyl[D1]methyl)phthalimides gave enantiomerically pure products with benzoyl chloride, but with bromobenzene protected phenyl[D1]methylamines gave products of only 52-69 % ee depending on the solvent used. Tributyl(thio[D1]methyl)stannanes could not be Stille-coupled with benzoyl chloride or with bromobenzene. Similarly, dimethyl phenyl[D1]methylboronate underwent a Suzuki-Miyaura coupling with bromobenzene to give phenyl[D1]methylsilane with 99 % ee. All couplings followed a retentive course and, except in one case, the intermediate [XCHDPdLn] complexes were found to be microscopically configurationally stable. Stille coupling of enantiomerically pure tributylstannyl[D1]methanol, its benzoate, and the N-(tributylstannyl[D1]methyl)phthalimide with bromobenzene and benzoyl chloride furnished products containing a chiral XCHD group. Overall net retention of configuration was found in all cases.
- Malova Krizkova, Petra,Hammerschmidt, Friedrich
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p. 5143 - 5148
(2013/11/06)
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- Regioselective aliphatic carbon-carbon bond cleavage by a model system of relevance to iron-containing acireductone dioxygenase
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Mononuclear Fe(II) complexes ([(6-Ph2TPA)Fe(PhC(O)C(R)C(O)Ph)]X (3-X: R = OH, X = ClO4 or OTf; 4: R = H, X = ClO4)) supported by the 6-Ph2TPA chelate ligand (6-Ph2TPA = N,N-bis((6-phenyl-2-pyridyl)methyl)-N-(2-pyridylmethyl)amine) and containing a β-diketonate ligand bound via a six-membered chelate ring have been synthesized. The complexes have all been characterized by 1H NMR, UV-vis, and infrared spectroscopy and variably by elemental analysis, mass spectrometry, and X-ray crystallography. Treatment of dry CH3CN solutions of 3-OTf with O2 leads to oxidative cleavage of the C(1)-C(2) and C(2)-C(3) bonds of the acireductone via a dioxygenase reaction, leading to formation of carbon monoxide and 2 equiv of benzoic acid as well as two other products not derived from dioxygenase reactivity: 2-oxo-2- phenylethylbenzoate and benzil. Treatment of CH3CN/H2O solutions of 3-X with O2 leads to the formation of an additional product, benzoylformic acid, indicative of the operation of a new reaction pathway in which only the C(1)-C(2) bond is cleaved. Mechanistic studies show that the change in regioselectivity is due to the hydration of a vicinal triketone intermediate in the presence of both an iron center and water. This is the first structural and functional model of relevance to iron-containing acireductone dioxygenase (Fe-ARD′), an enzyme in the methionine salvage pathway that catalyzes the regiospecific oxidation of 1,2-dihydroxy-3-oxo-(S)- methylthiopentene to form 2-oxo-4-methylthiobutyrate. Importantly, this model system is found to control the regioselectivity of aliphatic carbon-carbon bond cleavage by changes involving an intermediate in the reaction pathway, rather than by the binding mode of the substrate, as had been proposed in studies of acireductone enzymes.
- Allpress, Caleb J.,Grubel, Katarzyna,Szajna-Fuller, Ewa,Arif, Atta M.,Berreau, Lisa M.
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p. 659 - 668
(2013/03/14)
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- Straightforward and highly efficient synthesis of α-acetoxy ketones through gold-catalyzed intermolecular oxidation of terminal alkynes
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A variety of terminal alkynes were efficiently converted into the corresponding α-acetoxy ketones through gold-catalyzed intermolecular oxidation in the presence of 8-methylquinoline 1-oxide as the oxidant. The reaction probably proceeds through an α-oxo gold carbene intermolecular O-H insertion.
- Wu, Chao,Liang, Zhiwu,Yan, Dong,He, Weimin,Xiang, Jiannan
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p. 2605 - 2611
(2013/09/24)
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- N-Heterocyclic carbene catalyzed regioselective oxo-acyloxylation of alkenes with aromatic aldehydes: A high yield synthesis of α-acyloxy ketones and esters
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An N-heterocyclic carbene (NHC)-catalyzed reaction of alkenes with aromatic aldehydes providing for a high yield synthesis of α-acyloxy ketones and esters has been described. This unprecedented regioselective oxidative process employs NBS and Et3N in stoichiometric amounts and O2 (1 atm) as an oxidant under ambient conditions in DMSO as a solvent.
- Reddi, Rambabu N.,Malekar, Pushpa V.,Sudalai, Arumugam
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supporting information
p. 6477 - 6482
(2013/09/24)
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- In situ generated (Hypo)iodite catalysts for the direct α-oxyacylation of carbonyl compounds with carboxylic acids
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It′s the iodine: The intra- and intermolecular title reaction is catalyzed by an in situ generated ammonium (hypo)iodite species. Either H 2O2 or tert-butyl hydroperoxide (TBHP) can be used as an environmentally benign oxidant and a wide range of substrates react to give the corresponding α-acyloxycarbonyl compounds in good to excellent yields.
- Uyanik, Muhammet,Suzuki, Daisuke,Yasui, Takeshi,Ishihara, Kazuaki
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supporting information; experimental part
p. 5331 - 5334
(2011/07/08)
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- Influence of water on the formation of O2-reactive divalent metal enolate complexes of relevance to acireductone dioxygenases
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Reaction conditions were evaluated for the preparation of [(6-PhTPA)Ni(PhC(O)C(OH)C(O)Ph)]ClO4 (3) and [(6-Ph 2TPA)Co(PhC(O)C(OH)C(O)Ph)]ClO4 (7), two complexes of structural relevance to the enzyme/substrate (ES) adduct in Ni(ii)- and Co(ii)-containing forms of acireductone dioxygenase. The presence of water in reactions directed at the preparation of 3 and 7 was found to result in isomerization of the enolate precursor 2-hydroxy-1,3-diphenylpropane-1,3-dione to give the ester 2-oxo-2-phenylethylbenzoate. Performing synthetic procedures under dryer conditions reduced the amount of ester production and enabled the isolation of 3 in high yield. This complex was comprehensively characterized, including by X-ray crystallography. Using similar conditions for the 6-Ph 2TPACo-containing system, the amount of ester generated was only modestly affected, but the formation of a benzoate complex ([(6-Ph 2TPA)Co(O2CPh)]ClO4, 10) resulting from ester hydrolysis was prevented. The best preparation of 7 was found to involve dry conditions and short reaction times. The approach outlined herein toward determining appropriate reaction conditions for the preparation of 3 and 7 involved the preparation and characterization of several air-stable (6-PhTPA)Ni- and (6-Ph2TPA)Co-containing analog complexes having enolate, solvent, and benzoate ligands. These complexes were used as paramagnetic 1H NMR standards for evaluation of reaction mixtures containing 3 and 7.
- Grubel, Katarzyna,Ingle, Gajendrasingh K.,Fuller, Amy L.,Arif, Atta M.,Berreau, Lisa M.
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experimental part
p. 10609 - 10620
(2011/12/22)
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- O2-dependent aliphatic carbon-carbon bond cleavage reactivity in a Ni(II) enolate complex having a hydrogen bond donor microenvironment; comparison with a hydrophobic analogue
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A mononuclear Ni(II) complex having an acireductone type ligand, and supported by the bnpapa (N,N-bis((6-neopentylamino-2-pyhdyl)methyl)-N-((2- pyridyl)methyl)amine) ligand, [(bnpapa)Ni(PhC(O)C(OH)C(O)Ph)]ClO4 (14), has been prepared and characterized by elemental analysis, 1H NMR, FTIR, and UV-vis. To gain insight into the1H NMR features of 14, the air stable analogue complexes [(bnpapa)Ni(CH3C(O)CHC(O)CH 3)]ClO4 (16) and [(bnpapa)Ni(ONHC(O)CH3)] ClO4 (17) were prepared and characterized by X-ray crystallography, 1H NMR, FTIR, UV - vis, mass spectrometry, and solution conductivity measurements. Compounds 16 and 17 are 1:1 electrolyte species in CH 3CN. 1H and 2H NMR studies of 14, 16, and 17 and deuterated analogues revealed that the complexes having six-membered chelate rings for the exogenous ligand (14 and 16) do not have a plane of symmetry within the solvated cation and thus exhibit more complicated 1H NMR spectra. Compound 17, as well as other simple Ni(II) complexes of the bnpapa ligand (e.g., [(bnpapa)Ni(ClO4)(CH3CN)]ClO4 (18) and [(bnpapaNi)2(μ-Cl)2](ClO4)2 (19)), exhibit 1H NMR spectra consistent with the presence of a plane of symmetry within the cation. Treatment of [(bnpapa)Ni(PhC(O)C(OH)C(O)Ph)] ClO4 (14) with O2 results in aliphatic carbon-carbon bond cleavage within the acireductone-type ligand and the formation of [(bnpapa)Ni(O2CPh)]ClO4 (9), benzoic acid, benzil, and CO. Use of 18O2 in the reaction gives high levels of incorporation (>80%) of one labeled oxygen atom into 9 and benzoic acid. The product mixture and level of 18O incorporation in this reaction is different than that exhibited by the analogue supported the hydrophobic 6-Ph2TPA ligand, [(6-Ph2TPA)Ni(PhC(O)C(OH)C(O)Ph)]ClO 4 (2). We propose that this difference is due to variations in the reactivity of bnpapa- and 6-Ph2TPA-ligated Ni(II) complexes with triketone and/or peroxide species produced in the reaction pathway.
- Grubel, Katarzyna,Fuller, Amy L.,Chambers, Bonnie M.,Arlf, Atta M.,Berreau, Lisa M.
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experimental part
p. 1071 - 1081
(2010/05/15)
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- A rapid and facile esterification of na-carboxylates with alkyl halides promoted by the synergy of the combined use of DMSO and an ionic liquid under ambient conditions
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The synergy of the combined use of DMSO and an ionic liquid viz. (bbim) has brought about a rapid and efficient esterification of sodium carboxylates with acyl and alkyl halides under ambient conditions in excellent isolated yields (90-95%) in short reaction times (12-40min). Copyright Taylor & Francis Group, LLC.
- Dighe, Satish N.,Bhattad, Ravindra V.,Kulkarni, Raghunath R.,Jain, Kishor S.,Srinivasan, Kumar V.
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experimental part
p. 3522 - 3527
(2011/02/22)
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- The reaction of terminal alkynes with PhI(OAc)2: a convenient procedure for the preparation of α-acyloxy ketones
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Treatment of terminal alkynes with PhI(OAc)2 in different acids at 70 °C provided the corresponding α-acyloxy ketones in good to excellent yields. A plausible mechanism has been proposed based on the experimental results.
- Mo, Dong-Liang,Dai, Li-Xin,Hou, Xue-Long
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supporting information; experimental part
p. 5578 - 5581
(2011/02/22)
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- Darzens reaction of acyl phosphonates with α-bromo ketones: Selective synthesis of cis- and trans-epoxyphosphonates
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(Chemical Equation Presented) Acyl phosphonates with α-halo ketones in the presence of bases at room temperature afford cis- and trans-epoxyphosphonates in good chemical yields and high selectivities using different bases. The diastereoselectivity of this reaction is easily controlled by changing the base. Changing the base from Cs2CO3 to DBU changed the diastereomeric ratio (transieis) from 3/2 to 9/1. Moreover, the treatment of the trans isomer with DBU showed a complete conversion to the corresponding cis isomer.
- Demir, Ayhan S.,Emrullahoglu, Mustafa,Pirkin, Eser,Akca, Nazmiye
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scheme or table
p. 8992 - 8997
(2009/04/06)
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- Enantioselective synthesis of α-tertiary hydroxyaldehydes by palladium-catalyzed asymmetric allylic alkylation of enolates
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Chiral α-tertiary hydroxyaldehydes are very versatile building blocks in synthetic chemistry. Herein, we report the first examples of a catalytic asymmetric protocol for the synthesis of such compounds from readily available α-halo or α-hydroxy ketones or enol silyl ethers with excellent yields and enantioselectivity. Its synthetic utility is demonstrated in the short, efficient formal synthesis of (S)-oxybutynin. In this process, the chiral ligand controls the regioselectivity as well as the enantioselectivity. Copyright
- Trost, Barry M.,Xu, Jiayi,Reichle, Markus
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p. 282 - 283
(2007/10/03)
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- Organic reactions in water: Synthesis of phenacyl esters from phenacyl bromide and potassium salts of aromatic acids in the presence of β-cyclodextrin
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A convenient and facile synthesis of phenacyl esters is reported by the reaction of phenacyl bromide with potassium salts of aromatic acids in the presence of β-cyclodextrin in water under neutral conditions. Copyright Taylor & Francis, Inc.
- Narender,Somi Reddy,Pavan Kumar,Rama Rao
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p. 1681 - 1686
(2007/10/03)
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- Organic Reactions in Ionic Liquids: Ionic Liquid-Accelerated Nucleophilic Substitution Reaction of α-Tosyloxyketones with Potassium Salts of Aromatic Acids
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The room temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) is used as a 'green' recyclable alternative to classical molecular solvents for the nucleophilic substitution reaction of α-tosyloxy ketones with pota
- Liu, Zhi,Chen, Zhen-Chu,Zheng, Qin-Guo
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- Photolysis of phenacyl esters in a two-phase system
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Phenacyl esters are useful photoremovable protecting groups for carboxylic acids in organic synthesis and biochemistry. In this work, simple one-pot arrangements of the phenacyl and 2,5-dimethylphenacyl ester photolysis are proposed. The reactions were performed in both the benzene/water two-phase system and in water. Cetyltrimethylammonium bromide was found to increase substantially the efficiency of the deprotection as well as the purity of the products by lowering the interfacial tension between the phases. Utilizing water as a medium significantly reduced the necessity to use environmentally malign organic solvents. The overall yields varied from 72 to 98% depending on the reaction conditions.
- Ruzicka, Radovan,Zabadal, Miroslav,Klan, Petr
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p. 2581 - 2590
(2007/10/03)
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- Protecting Groups that can be Removed through Photochemical Electron Transfer: Mechanistic and Product Studies on Photosensitized Release of Carboxylates from Phenacyl Esters
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Photolysis of electron-donating photosensitizers in the presence of various phenacyl esters (PhCOCH2-OCOR) results in C-O bond scission leading to the formation of acetophenone (PhCOCH3) and the corresponding carboxylic acid (RCO2H). Preparative experiments showed that the carboxylic acids are generated in high or quantitative isolated yields. It is argued that this reaction is initiated by a photoinduced electron transfer from the excited state sensitizer to the phenacyl ester. The latter process forms the anion radical of the phenacyl ester which in turn undergoes rapid C-O bond scission leading to the phenacyl radical and the corresponding carboxylate anion. This mechanism is supported by the following observations. (1) The phenacyl esters quench fluorescence from the sensitizers. (2) Analysis of the redox potentials of the sensitizer excited states and the substrates shows that the proposed electron transfer step is exergonic by 15-20 kcal/mol. (3) The byproducts are indicative of the proposed ion radical intermediates. In particular N-methylaniline is detected when N4Y-dimethylaniline is used as a sensitizer. (4) Competing processes are observed in phenacyl esters whose acid components are themselves labile to single-electron transfer. For example, phenacyl 4-bromophenylacetate showed bromide elimination in competition with deprotection.
- Banerjee, Anamitro,Falvey, Daniel E.
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p. 6245 - 6251
(2007/10/03)
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- Synthesis of phenacyl esters by using PTC and dibenzo-[18)-crown-6
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In view of the importance of phenacyl esters as a protecting groups, a simple and efficient method is now reported here for synthesis of phenacyl esters in quantitative yield and high purity under mild reaction condition by using phase transfer catalyst a
- Jugdale,Patil,Salunkhe
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p. 1747 - 1752
(2007/10/03)
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- A novel improved procedure for the synthesis of oxazoles
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In the present work a novel improved and convenient procedure for the synthesis of oxazoles has been developed. Acetamide, instead of ammonium acetate, was used to react with phenacyl benzoates in boiling xylene in the presence of BF3/Et2
- Huang, Wei,Pei, Jian,Chen, Bingzi,Pei, Weiwei,Ye, Xiulin
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p. 10131 - 10136
(2007/10/03)
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- Fragmentation of substituted acetophenone and halobenzophenone ketyls. Calibration of a mechanistic probe
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Disubstituted acetophenones, XC4H4COCH2Y, and benzophenoncs, XC4H4COC6H4Y, are used to measure the cleavage rate constants, kfY, of a series of α-substituted acetophenone ketyls and ring-substituted benzophenone ketyls. The cleavage rate constants can be determined from the competitive rates of fragmentation, kfY/kfX, of a series of ketyls, [XC6H4COCH2Y]- and [XC6H4COC6H4Y]-, since the rate constants, kfX, for a number of ketyl fragmentations have been electrochemically determined. Ring fragmentation is not significantly affected by substitution at the α-position of the acetophenone nor on the opposite ring of the benzophenone. The ketyls are formed by the reaction of 1,3-dimethyl-2-phenylbenzimidazoline (DMBI) with the disubstituted ketones. Ketyl fragmentation can be used as a diagnostic chemical probe for reactions of ketones suspected of having ketyl intermediates.
- Tanner, Dennis D.,Chen, Jian Jeffrey,Chen, Lucia,Luelo, Christine
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p. 8074 - 8081
(2007/10/02)
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- Oxidation of Aryl Alkyl Ketones to α-Acyloxy, α-(Camphorsulfonyloxy), or α-Hydroxy Derivatives Using Manganese(III) Acetate in Combination with Carboxylic Acids or (1S)-(+)-10-Camphorsulfonic Acid
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The α-oxidation of aryl alkyl ketones using manganese(III) acetate in the presence of various carboxylic acids and (1S)-(+)-10-camphorsulfonic acid provided a convenient synthesis of α-acyloxy, α-(10-camphorsulfonyloxy), and α-hydroxy derivatives in good yield.
- Demir, Ayhan S.,Camkerten, Nurettin,Akgun, Hulya,Tanyeli, Cihangir,Mahasneh, Ali S.,Watt, David S.
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p. 2279 - 2289
(2007/10/02)
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- CONVENIENT SYNTHESIS AND FACILE CLEAVAGE OF PHENACYL ESTERS
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A convenient synthesis of phenacyl esters and a facile cleavage of them with sodium hydrogen telluride are described.
- Huang, Zhizhen,Xie, Linghong,Huang, Xian
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p. 1167 - 1170
(2007/10/02)
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- Structure-Reactivity Relationships in Nucleophilic Substitution Reactions of Phenacyl Bromide with Aliphatic Carboxylate Ions
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The second order rate constants for the reactions of phenacyl bromide with various substituted aliphatic carboxylate ions (XCOO(-); X = H, Me, Pr, Et, ClCH2, BrCH2, HOOCCH2, Ph, PhCH2, PhCH=CH, PhSCH2, PhOCH2 and PhSO2CH2) have been measured in 90percent
- Shunmugasundaram, A.,Rajkumar, M.
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- O-ACYLATION OF 1,3-DICARBONYL COMPOUNDS
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Previously unknown 5-acyl-substituted 1,3-dioxolanium salts were obtained by the action of benzoyl hexachloroantimonate on 1,3-ketoaldehydes and 1,3-diketones with a quaternary meso-carbon atom.The acyloxycarbocations formed in the reaction can either rearrange with 1,2-acyl migration or undergo fragmentation with the elimination of the acyl cation to the enol acyloxy compound, depending on the structure of the 1,3-dicarbonyl compound.
- Zhdanov, Yu. A.,Luk'yanov, S. M.,Borodaev, S. V.,Borodaeva, S. V.
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p. 2135 - 2139
(2007/10/02)
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- Kinetics of the Reactions of Phenacyl Bromide and of para-Substituted Phenacyl Bromides with Benzoate and Substituted trans-Cinnamate Ions
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The second-order rate constants for the reactions of various para-substituted phenacyl bromides with benzoate ion and with several substituted trans-cinnamate ions have been measured in 90 percent acetone - 10 percent water (v/v) mixture.Electron-releasin
- Srinavasan, Chockalingam,Shunmugasundaram, Arunachalam,Arumugam, Natesan
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- Separation of Polar and Steric Effects in Reactions of ortho-Substituted Benzoate Ions with para-Substituted Phenacyl Bromides
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The second order rate constants for SN2 reactions of several ortho-substituted benzoate ions with several para-substituted phenacyl bromides have been measured in 90percent acetone - 10percent water (v/v) mixture at 35 deg C.Satisfactory correl
- Srinivasan, C.,Shunmugasundaram, A.,Roja, M.,Arumugam, N.
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p. 555 - 557
(2007/10/02)
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- KINETICS OF REACTION OF TRIETHYLAMMONIUM CARBOXYLATES WITH α-HALOGENOCARBONYL COMPOUNDS IN ORGANIC SOLVENTS. REACTION OF BENZOATES AND PHENOXYACETATES WITH PHENACYL BROMIDE IN ACETONE
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The kinetics of the reaction of phenacyl bromide with triethylammonium p-substituted benzoates and phenoxyacetates at 25 deg C, 30 deg C and 35 deg C in acetone suggest a rigid cyclic transition state involving a hydrogen bonded ion-pair as the active nuc
- Pillay, M. Krishna,Kannan, K.,Ramasubramanian, P.
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p. 3899 - 3908
(2007/10/02)
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- Influence of Anionic Surfactant Aggregates in the Reaction of Benzoate Ion and Phenacyl Bromide
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The reaction between phenacyl bromide and benzoate ion has been followed in aqueous methanol and aqueous acetone solvent systems in the presence of anionic surfactant aggregates of sodium dodecyl sulphate (NaLS).Electrostatic and hydrophobic effects both
- Behera, G. B.,Mishra, S. S.,Panda, D. S.,Sutar, S.
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p. 465 - 467
(2007/10/02)
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