- Role of peroxy compounds in oxidation of crotonaldehyde with molecular oxygen
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Oxidation of crotonaldehyde with molecular oxygen and the role of percrotonic acid accumulating in the process were studied.
- Fedevich,Levush,Fedevich,Kit
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Read Online
- Flower-like Au/Ni-Al hydrotalcite with hierarchical pore structure as a multifunctional catalyst for catalytic oxidation of alcohol
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Flower-like hierarchical Au/NiAl-LDH catalysts were synthesized for selective oxidation of alcohols. The abundant hydrogen vacancies at the edge of the flowers as nucleation centers contributed to the uniform dispersion of Au NPs. The confinement effect of the hierarchical pores promoted 60% higher activity than the common Au/NiAl-LDH nanoparticle catalyst in the oxidation of benzyl alcohol by heightening the effective collisions between substrates and active sites. The evolution process of the hierarchical pores in the support was further proposed. Moreover, the reaction mechanism of the cooperation among Bronsted base sites, NiIII coordinatively unsaturated metal sites and isolated gold cations was concretely proved. In the oxidation of other typical alcoholic substrates, the flower-like catalyst showed higher activity than the common nanoparticle one except for linear alcohols, which could be attributed to the shape selectivity of straight macropores.
- Du,Jin,Feng,Zhang,He,Li
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Read Online
- Synthesis of α,β- and β-Unsaturated Acids and Hydroxy Acids by Tandem Oxidation, Epoxidation, and Hydrolysis/Hydrogenation of Bioethanol Derivatives
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We report a reaction platform for the synthesis of three different high-value specialty chemical building blocks starting from bio-ethanol, which might have an important impact in the implementation of biorefineries. First, oxidative dehydrogenation of ethanol to acetaldehyde generates an aldehyde-containing stream active for the production of C4 aldehydes via base-catalyzed aldol-condensation. Then, the resulting C4 adduct is selectively converted into crotonic acid via catalytic aerobic oxidation (62 % yield). Using a sequential epoxidation and hydrogenation of crotonic acid leads to 29 % yield of β-hydroxy acid (3-hydroxybutanoic acid). By controlling the pH of the reaction media, it is possible to hydrolyze the oxirane moiety leading to 21 % yield of α,β-dihydroxy acid (2,3-dihydroxybutanoic acid). Crotonic acid, 3-hydroxybutanoic acid, and 2,3-dihydroxybutanoic acid are archetypal specialty chemicals used in the synthesis of polyvinyl-co-unsaturated acids resins, pharmaceutics, and bio-degradable/ -compatible polymers, respectively.
- Faria, Jimmy,Komarneni, Mallik R.,Li, Gengnan,Pham, Tu,Resasco, Daniel E.,Ruiz, Maria P.,Santhanaraj, Daniel
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supporting information
p. 7456 - 7460
(2020/03/23)
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- Integrated photocatalytic-biological treatment of triazine-containing pollutants
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The degradation of triazine-containing pollutants including simazine, Irgarol 1051 and Reactive Brilliant Red K-2G (K-2G) by photocatalytic treatment was investigated. The effects of titanium dioxide (TiO2) concentration, initial pH of reaction mixture, irradiation time and ultraviolet (UV) intensity on photocatalytic treatment efficiency were examined. Complete decolorization of K-2G was observed at 60 min photodegradation while only 15 min were required to completely degrade simazine and Irgarol 1051 under respective optimized conditions. High-performance liquid chromatography (HPLC), gas chromatography/mass spectrometry (GC/MS) and ion chromatography (IC) were employed to identify the photocatalytic degradation intermediates and products. Dealkylated intermediates of simazine, deisopropylatrazine and deethyldeisopropylatrazine, and Irgarol 1051 were detected by GC/MS in the initial phase of degradation. Complete mineralization could not be achieved for all triazine-containing pollutants even after prolonged (>72 h) UV irradiation due to the presence of a photocatalysis-resistant end product, cyanuric acid (CA). The toxicities of different compounds before and after photocatalytic treatment were also monitored by three bioassays. To further treat the photocatalysis-resistant end product, a CA-degrading bacterium was isolated from polluted marine sediment and further identified as Klebsiella pneumoniae by comparing the substrate utilization pattern (Biolog microplate), fatty acid composition and 16S rRNA gene sequencing. K. pneumoniae efficiently utilized CA from 1 to 2000 mg/L as a good nitrogen source and complete mineralization of CA was observed within 24 h of incubation. This study demonstrates that the biodegradability of triazine-containing pollutants was significantly improved by the photocatalytic pre-treatment, and this proposed photocatalytic-biological integrated system can effectively treat various classes of triazine-containing pollutants.
- Chan, Cho Yin,Chan, Ho Shing,Wong, Po Keung
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p. 371 - 380
(2019/02/07)
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- Enantioselective Synthesis of N?H-Free 1,5-Benzothiazepines
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An enantioselective sulfa-Michael-cyclization reaction was developed for the synthesis of 1,5-benzothiazepines with versatile pharmacological activities. The reaction between 2-aminothiophenol and α,β-unsaturated pyrazoleamides gave direct access to N?H-free 1,5-benzothiazepines in the presence of a chiral N,N′-dioxide/Yb(OTf)3complex. Excellent enantioselectivities (up to 96 % ee) and high yields (up to 99 %) were obtained for a broad range of substrates under mild reaction conditions. This method provided a facile approach to the antidepressant drug (R)-(?)-Thiazesim.
- Wang, Guojin,Tang, Yu,Zhang, Yu,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information
p. 554 - 557
(2017/01/18)
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- Carbene-catalyzed LUMO activation of alkyne esters for access to functional pyridines
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A carbene-catalyzed LUMO activation of α,β-unsaturated alkyne esters is reported. This catalytic process allows for effective reactions of alkyne esters with enamides to synthesize functional pyridines via simple protocols. A previously unexplored unsaturated alkyne acyl azolium intermediate is involved in the key step of the reaction.
- Mou, Chengli,Wu, Jichang,Huang, Zhijian,Sun, Jun,Jin, Zhichao,Chi, Yonggui Robin
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p. 13359 - 13362
(2017/12/26)
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- Method for synthesizing muscone by utilizing beta-monomethyl methylglutarate
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The invention discloses a method for synthesizing muscone by utilizing beta-monomethyl methylglutarate. According to the method, beta-monomethyl methylglutarate and alpha,omega-dodecanedioic acid monomethyl ester respectively prepared through a heteropoly acid catalytic transesterification method are used as raw materials, and Kolbe electrolysis, acyloin condensation and reduction reaction are performed to prepare the muscone. The method of the present invention has advantages of high raw material utilization rate, mold condition, easy control and environmental protection, and is suitable for industrial production .
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Paragraph 0021; 0022
(2017/12/05)
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- PROCESS FOR PREPARING MONO AND DICARBOXYLIC ACIDS
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The present application relates to a process for preparing a dicarboxylic acid or dicarboxylic ester according to general formula (IV) R1OOC-(CH2)m-CH2CH2-(CH2)y-COOR4 (IV), comprising the steps of subjecting alkenoic acid or alkenoate of formula (II) R1OOC-(CH2)m-CH=CH-(CH2)x-H (II) to a metathesis reaction in the presence of a metathesis catalyst to form a longer-chain alkenoic acid or alkenoate of formula (III) R1OOC-(CH2)m-CH=CH-(CH2)y-H (III) where xa carbonylation reaction in the presence of a carbonylation catalyst and a carbonyl source to form said compound of Formula (IV). Alternative embodiments provide: a process for preparing an alkenoic acid or alkenoate comprising the step of subjecting a lactone to a ring opening reaction; a process for preparing a monocarboxylic acid or monocarboxylic ester according to general formula (XI) R1OOC-(CH2)m-CH2-(CH2)y-CH3 (XI) by subjecting an alkenoic acid or alkenoate to alkene hydrogenation; and a process for preparing an alcohol or ether according to general formula (XII) R1O-CH2-(CH2)m-CH2-(CH2)y-CH3 (XII) by subjecting an alkenoic acid or alkenoate to hydrogenation. The use of the respective mono/dicarboxylic acid, mono/dicarboxylic ester, ethers or alcohols in a variety of applications is also disclosed.
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Page/Page column 33; 34
(2018/02/03)
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- Enantioselective Palladium-Catalyzed Oxidative Cascade Cyclization of Aliphatic Alkenyl Amides
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The catalyst system of Pd(TFA)2/(S,S)-diPh-pyrox is reported to promote the highly efficient enantioselective oxidative cascade cyclization of alkene-tethered aliphatic acrylamides under mild aerobic conditions. A series of pyrrolizidine derivatives have been synthesized in good yield and excellent enantioselectivity. Deuterium-labeling experiments have revealed that the reaction proceeded through an anti-aminopalladation (anti-AP) pathway with high selectivity. The transition states for the anti-AP step have been calculated to account for the observed enantioselectivity.
- Du, Wei,Gu, Qiangshuai,Li, Yang,Lin, Zhenyang,Yang, Dan
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supporting information
p. 316 - 319
(2017/04/21)
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- Facile synthesis of supported RuO2·: X H2O nanoparticles on Co-Al hydrotalcite for the catalytic oxidation of alcohol: Effect of temperature pretreatment
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RuO2·xH2O supported on a CoAl-LDH catalyst was synthesized by the co-precipitation (CP) method and the deposition-precipitation (DP) method for the selective oxidation of alcohols. The catalyst prepared by the CP method exhibited higher activity compared with that obtained by the DP method due to stronger interaction between RuO2 and the CoAl-LDH support as well as the slightly smaller particle size of the RuO2 nanoparticles. The influence of the temperature pretreatment on catalytic performance was then investigated. Among the catalysts pretreated at different temperature, RuO2/CoAl-LDH treated at 200 °C showed the highest activity with a TOF of 142 h-1, which was nearly 55% higher than that of the untreated catalyst. It could be related to not only the suitable amount of RuO2·xH2O for β-H cleavage, but also the presence of Co3+ species for the activation of O2 molecules and storage of the resulting active O? species. Furthermore, the strong interaction between RuO2 and the support was revealed to promote the adsorption and activation of benzyl alcohol and thus enhance the catalytic performance. Significantly, RuO2/CoAl-LDH treated at 200 °C was found to selectively oxidize various alcohols to the corresponding aldehydes and ketones with respectable activity and had greater advantage comparable to that of some Ru catalysts.
- Zhang, Na,Du, Yiyun,Yin, Min,Guan, Chaoyang,Feng, Junting,Li, Dianqing
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p. 49588 - 49596
(2016/06/15)
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- Iron-catalyzed selective oxidation of α,β-unsaturated aldehydes to α,β-unsaturated carboxylic acids by molecular oxygen
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Selective oxidation of α,β-unsaturated aldehydes to α,β-unsaturated carboxylic acids was performed using O2 as the oxidant in the presence of a simple iron catalyst. The addition of an alkali metal carboxylate as a cocatalyst enhanced the selectivity for the desired product. Redox tuning of the iron catalyst via association with the alkali metal led to a controlled radical generation during the catalytic O2 oxidation.
- Tanaka, Shinji,Kon, Yoshihiro,Uesaka, Yumiko,Morioka, Ryo,Tamura, Masanori,Sato, Kazuhiko
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supporting information
p. 188 - 190
(2016/03/01)
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- A Metal-Free Approach to Carboxylic Acids by Oxidation of Alkyl, Aryl, or Heteroaryl Alkyl Ketones or Arylalkynes
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The metal-free oxidation of dialkyl, alkyl aryl, or alkyl heteroaryl ketones or arylalkynes to the corresponding carboxylic acids is achieved using an oxidative mixture of Oxone and trifluoroacetic acid. This green method is a simple and mild protocol to obtain carboxylic derivatives in excellent yields.
- Aravinda Kumar,Venkateswarlu, Vunnam,Vishwakarma, Ram A.,Sawant, Sanghapal D.
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p. 3161 - 3168
(2015/10/19)
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- Polymer supported rhodium carbonyl complex catalyzed carbonylation of glycerol for the synthesis of carboxylic acids
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A new polymer anchored Rh(I) complex has been synthesized and characterized. The catalytic performance of the complex has been tested for the carbonylation of glycerol under carbon monoxide atmosphere to give butyric and isobutyric acids. The effects of temperature, CO pressure, reaction time and the catalyst amount are reported. This catalyst showed excellent activity and recyclability being easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.
- Molla, Rostam Ali,Ghosh, Kajari,Roy, Anupam Singha,Islam, Sk. Manirul
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p. 268 - 274
(2015/02/18)
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- Application of chiral ligands: Carbohydrates, nucleoside-lanthanides and other Lewis acid complexes to control regio- and stereoselectivity of the dipolar cycloaddition reactions of nitrile oxides and esters
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Chiral Lewis acid mediated 1,3-dipolar cycloaddition reactions of 4-trifluoromethylbenzonitrile oxide to methyl crotonate as well to β-substituted acrylates and (Z)-pent-2-en-1-yl esters were examined. Excellent enantioselectivities with moderate to good regioselectivities were achieved for crotonates with complexes of BiBr3 with (+)-(4,6-benzylidene)methyl-α-d-glucopyranoside C, with the l-ascorbic acid I-FeCl3 system, and with lipase Candida antarctica. High enantiomeric excess was observed for isopropyl ester and benzyl ester. The outstanding ee values were achieved for acrylates with β-t-butyl, cyclohexyl, and 1,3-benzodioxol-5-yl groups in cycloadditions catalyzed by C-Yb(OTf)3 and the (+)-2-hydroxy-3-pinanone N-TiCl4 system. High enantioselectivities were found in reactions of (Z)-pent-2-en-1-yl esters mediated by complexes N-Mg(OTf)2 and N-TiCl4.
- Gucma, Miroslaw,Golbiewski, W. Marek,Krawczyk, Maria
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p. 13112 - 13124
(2015/02/19)
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- Polymer supported rhodium carbonyl complex catalyzed carbonylation of glycerol for the synthesis of carboxylic acids
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A new polymer anchored Rh(I) complex has been synthesized and characterized. The catalytic performance of the complex has been tested for the carbonylation of glycerol under carbon monoxide atmosphere to give butyric and isobutyric acids. The effects of temperature, CO pressure, reaction time and the catalyst amount are reported. This catalyst showed excellent activity and recyclability being easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.
- Molla, Rostam Ali,Ghosh, Kajari,Roy, Anupam Singha,Islam, Sk. Manirul
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p. 268 - 274
(2015/02/18)
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- Controlling the selectivity of the manganese/bicarbonate/hydrogen peroxide catalytic system by a biphasic pyrrolidinium ionic liquid/n-heptane medium
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The Mn2+/HCO3-/H2O2 catalytic system exhibits excellent aldehyde selectivity in the oxidation of various benzylic and allyic alcohols under mild conditions and short reaction time when the reactions are carried out in a biphasic dicationic pyrrolidinium ionic liquid/n-heptane medium. The dicationic pyrrolidinium ionic liquid shows differential solubility towards alcohols and their aldehydes whereas the immiscible n-heptane instantaneously extracted and separated aldehydes from the reaction phase. This design of biphasic ionic liquid/n-heptane catalytic system prevents the over-oxidation of aldehydes to carboxylic acids effectively. Separation and recycling can also be easily done by decantation of the n-heptane layer after reaction. With the biphasic system, high conversion of benzyl alcohol to benzaldehyde was achieved with very low loadings of H 2O2 and Mn(OAc)2 catalyst at room temperature and within short reaction time. Throughout 10 reaction cycles, a total turnover number (TON) of 37,600 was achieved and excellent catalytic reactivity and selectivity were maintained with an average yield of 94%.
- Wong, Wing-Leung,Ho, Kam-Piu,Lee, Lawrence Yoon Suk,So, Ming-Him,Chan, Tak Hang,Wong, Kwok-Yin
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p. 244 - 249
(2013/03/28)
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- Design, synthesis and biological evaluation of benzothiazepinones (BTZs) as novel non-ATP competitive inhibitors of glycogen synthase kinase-3β (GSK-3β)
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Glycogen synthase kinase-3β (GSK-3β) plays a key role in type II diabetes and Alzheimer's diseases, to which non-ATP competitive inhibitors represent an effectively therapeutical approach due to their good specificity. Herein, a series of small molecules benzothiazepinones (BTZs) as novel non-ATP competitive inhibitors of GSK-3β have been designed and synthesized. The in vitro evaluation performed by luminescent assay showed most BTZ derivatives have inhibitory effects in micromolar scale. Among them compounds 6l, 6t and 6v have the IC50 values of 25.0 μM, 27.8 μM and 23.0 μM, respectively. Moreover 6v is devoid of any inhibitory activity in the assays to other thirteen protein kinases. Besides, SAR is analyzed and a hypothetical enzymatic binding mode is proposed by molecular docking study, which would be useful for new candidates design.
- Zhang, Peng,Hu, Hai-Rong,Bian, Shi-Hui,Huang, Zhao-Hui,Chu, Yong,Ye, De-Yong
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- Carbodeoxygenation of biomass: The carbonylation of glycerol and higher polyols to monocarboxylic acids
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Glycerol is converted to a mixture of butyric and isobutyric acid by rhodium- or iridium-catalysed carbonylation using HI as the co-catalyst. The initial reaction of glycerol with HI results in several intermediates that lead to isopropyl iodide, which upon carbonylation forms butyric and isobutyric acid. At low HI concentration, the intermediate allyl iodide undergoes carbonylation to give vinyl acetic acid and crotonic acid. Higher polyols CnH n+2(OH)n are carbonylated to the corresponding C n+1 mono-carboxylic acids. Copyright
- Coskun, Timur,Conifer, Christopher M.,Stevenson, Laura C.,Britovsek, George J. P.
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supporting information
p. 6840 - 6844
(2013/07/05)
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- Solvent-free oxidation of aldehydes to acids by TBHP using environmental-friendly MnO-14-exchanged Mg-Al hydrotalcite catalyst
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A number of hydrotalcite (Mg-Al, Mn-Al, Co-Al, Ni-Al, Mg-Fe, Mg-Cr and Cu-Al) catalysts, with or without MnO-14-exchange, were evaluated for their performance in the solvent-free oxidation of benzaldehyde to benzoic acid by tert-butyl hydroperoxide under reflux in the absence of any solvent. The MnO-14 - exchanged Mg-Al-hydrotalcite (Mg/Al = 10) showed high activity in the oxidation of different aromatic and aliphatic aldehydes to their corresponding acids and also showed excellent reusability in the oxidation process which is environmental-friendly. Indian Academy of Sciences.
- Choudhary, Vasant R.,Dumbre, Deepa K.,Narkhede, Vijay S.
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p. 835 - 839
(2012/11/13)
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- Ceric ammonium nitrate catalyzed oxidation of aldehydes and alcohols
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A variety of aromatic, aliphatic and conjugated aldehydes and alcohols were transformed to the corresponding carboxylic acids and ketones with a quantitative conversion in high yields with 70% t-BuOOH solution in water in the presence of catalytic amounts of ceric ammonium nitrate [Ce(NH 4)2(NO3)6] (CAN) under room temperature conditions. The scope of our catalytic system is applicable for a wide range of aromatic, conjugated and aliphatic substrates. These aldehydes were converted to the corresponding carboxylic acids in good isolated yields in reasonable times. This method possesses a wide range of capabilities since it can be used with other functional groups which may not tolerate oxidative conditions, involves fairly simple method for work-up, exhibits chemoselectivity and proceeds under ambient conditions. The resulting products are obtained in good yields within reasonable time.
- Gowda, Ravikumar R.,Chakraborty, Debashis
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experimental part
p. 2379 - 2384
(2012/02/15)
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- Cu(II) bromide catalyzed oxidation of aldehydes and alcohols
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A variety of aromatic, aliphatic and conjugated aldehydes and alcohols were transformed to the corresponding carboxylic acids and ketones with a quantitative conversion in high yields with 70% t-BuOOH solution in water in the presence of catalytic (5 mol%) amounts of CuBr2 under room temperature conditions. The conversion of 4-methoxybenzaldehyde to 4-methoxybenzoic acid is extremely facile in MeCN at ambient temperature in the presence of 5 mol% CuBr2 and 2 equiv. 70% t-BuOOH (water) as the oxidant. Oxidation with t-BuOOH (water) alone in MeCN was found to be negligible. The scope of our catalytic system is applicable for a wide range of aromatic, conjugated and aliphatic substrates. These aldehydes were converted to the corresponding carboxylic acids in good isolated yields in reasonable times. It is pertinent to mention here that mild halogenic oxidants like hypochlorites, chlorites and NBS are not suitable for substrates with electron-rich aromatic rings, olefinic bonds and secondary hydroxyl groups. Substitutions at different positions on the phenyl ring do not hinder the reaction, although the reaction time is affected. Oxidation of α,β unsaturated derivatives resulted in the formation of the expected acid in good yield. In addition, the transformation of secondary alcohols to ketones is extremely facile. No recemization was observed for menthone. This method possesses a wide range of capabilities since it can be used with other functional groups which may not tolerate oxidative conditions, involves fairly simple method for work-up, exhibits chemoselectivity and proceeds under ambient conditions. The resulting products are obtained in good yields within reasonable time.
- Das, Rima,Chakraborty, Debashis
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experimental part
p. 437 - 442
(2012/01/30)
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- Mohr's salt catalyzed oxidation of aldehydes with t-BuOOH
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Various aromatic, aliphatic and conjugated aldehydes were transformed to the corresponding carboxylic acids with 70% t-BuOOH solution (water) in the presence of catalytic amounts (10 mol%) of Mohr's salt. This method possesses functional group compatibility, does not involve cumbersome work-up, exhibits chemoselectivity since other functional groups remain intact and proceeds under mild conditions. The resulting products are obtained in good yields within reasonable times. Copyright
- Chakraborty, Debashis,Majumder, Chandrima,Malik, Payal
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experimental part
p. 487 - 490
(2012/04/04)
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- Silver nitrate-catalyzed oxidation of aldehydes to carboxylic acids by H2O2
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A variety of aromatic, aliphatic and conjugated aldehydes were converted to the corresponding carboxylic acid derivatives with 30% H2O 2 as the oxidant in the presence of catalytic amounts of AgNO 3. The method described has wide range of applicabilities, does not involve cumbersome work-up, exhibits chemoselectivity and proceeds under mild reaction conditions, and the resulting products are obtained in good yields within reasonable time.
- Chakraborty, Debashis,Gowda, Ravikumar R.,Malik, Payal
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experimental part
p. 6553 - 6556
(2011/02/21)
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- A simple method for the alkaline hydrolysis of esters
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A very mild and rapid procedure for the efficient alkaline hydrolysis of esters in non-aqueous conditions has been developed, by the use of dichloromethane/methanol (9:1) as solvent. This method conveniently provides both carboxylic acids and alcohols from the corresponding esters and sodium hydroxide in a few minutes at room temperature. A plausible reaction mechanism is proposed.
- Theodorou, Vassiliki,Skobridis, Konstantinos,Tzakos, Andreas G.,Ragoussis, Valentine
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p. 8230 - 8233
(2008/03/14)
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- Exploring the synthetic applicability of a cyanobacterium nitrilase as catalyst for nitrile hydrolysis
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The substrate specificity and synthetic applicability of the nitrilase from cyanobacterium Synechocystis sp. strain PCC 6803 have been examined. This nitrilase catalyzed the hydrolysis of both aromatic and aliphatic nitriles to the corresponding acids in high yields. Furthermore, the stereoselective hydrolysis of phenyl-substituted β-hydroxy nitriles to (S)-enriched β-hydroxy carboxylic acids and selective hydrolysis of α,ω- dinitriles with five or less methylene groups to ω-cyano carboxylic acids have been achieved. This suggested that nitrilase from Synechocystis sp. PCC 6803 could be a useful enzyme catalyst for the "green" nitrile hydrolysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Hua, Ling
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p. 5238 - 5242
(2007/10/03)
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- Enzymatic nitrile hydrolysis catalyzed by nitrilase ZmNIT2 from maize. An unprecedented β-hydroxy functionality enhanced amide formation
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To explore the synthetic potential of nitrilase ZmNIT2 from maize, the substrate specificity of this nitrilase was studied with a diverse collection of nitriles. The nitrilase ZmNIT2 showed high activity for all the tested nitriles except benzonitrile, producing both acids and amides. For the hydrolysis of aliphatic, aromatic nitriles, phenylacetonitrile derivatives and dinitriles, carboxylic acids were the major products. Unexpectedly, amides were found to be the major products in nitrilase ZmNIT2-catalyzed hydrolysis of β-hydroxy nitriles. The hydrogen bonding between the hydroxyl group and nitrogen in the enzyme-substrate complex intermediates that disfavors the loss of ammonia and formation of acyl-enzyme intermediate, which was further hydrolyzed to acid, was proposed to be responsible for the unprecedented β-hydroxy functionality assisted high yield of amide formation.
- Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Parmar, Rajiv R.,Hua, Ling
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p. 6150 - 6154
(2007/10/03)
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- Kinetics of oxidation of α,β-unsaturated aldehydes by quinolinium dichromate
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A series of α,β-unsaturated aldehydes (crotonaldehyde, cinnamaldehyde, acrylaldehyde, and methacrylaldehyde) were oxidized by quinolinium dichromate in sulfuric acid to the corresponding acids in 50% (v/v) acetic acid water medium. The kinetic data have been discussed with reference to the aldehyde hydration equilibria. The kinetic results support a mechanistic pathway proceeding via a rate-determining oxidative decomposition of the chromate ester of the aldehyde hydrate.
- Chaubey, Girija S.,Das, Simi,Mahanti, Mahendra K.
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p. 204 - 208
(2007/10/03)
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- Oxidation kinetics of crotonaldehyde (2-butenal) at elevated oxygen pressure
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Liquid-phase oxidation of crotonaldehyde in ethyl acetate at 285-309 K and oxygen pressure of 1-16 atm was studied. Kinetic equations satisfactorily describing the oxidation kinetics of crotonaldehyde were obtained.
- Fedevich,Levush,Fedevich,Kit
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p. 1123 - 1127
(2007/10/03)
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- Kinetics and mechanism of oxidation of allyl, crotyl and propargyl alcohols by diperiodato cuprate(III) in alkaline medium
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The kinetics and mechanism of oxidation of α, β-unsaturated alcohols (UA) such as allyl, crotyl and propargyl alcohols by periodate complex of trivalent copper in aqueous alkaline medium has been studied spectrophotometrically at 416 nm.The order in and is found to be unity each.The rate decreases with increase in and increases with increase in ->.There is no effect of addition of salts like Na2SO4 and KNO3.The primary kinetic isotopic effect kH/kD is 3.87 at 313 K.The solvent isotopic effect kH2O/kD2O is 0.912 at 313 K.The product of oxidation has been identified as the corresponding aldehyde.Participation of double bond in the oxidation reaction has not been observed.Under the experimental conditions monoperiodato cuprate(III) species has been assumed to be the active species.The results are discussed in terms of +I effect of methyl group and resonance stabilisation of free radical.The observed results are explained in terms of an outersphere electron transfer mechanism.
- Padmaja, S.,Rao, K. Nageshwar,Sethuram, B.
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p. 685 - 688
(2007/10/02)
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- Preparation of stereoisomers of 3-sulfinylbutyric acid from (R)- and (S)-4-methyl-2-oxetanone
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The β-lactone ((S) and (R)-4-methyl-2-oxetanone, 1, ent-1), readily available from (R)- and (S)-3-hydroxybutyric acid, is opened by sodium hydrosulfide, sodium alkane- and arenethiolates, respectively, with inversion of configuration. The resulting 3-(alkylthio)-2f, 2g, and 3-(arylthio)butyric acids, 2b-2e, ent-2h-2k (Table 1), oxidized with hydrogen peroxide in acetone to give the corresponding 3-(alkylsulfinyl)- and 3-(arylsulfinyl)butyric acids as mixtures of diastereoisomers 3b-3k and 4b-4k. These are separated and the pure like and unlike diastereoisomers isolated and fully characterized (Table 4). Configurational assignments rest upon a crystal structure analysis and comparison of properties in the two series.
- Breitschuh,Seebach
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- Lactonization of Unsaturated Alcohols Catalyzed by Palladium Complexes under Neutral Conditions
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Secondary and tertiary allylic alcohols react with carbon monoxide in the presence of catalytic quantities of bis(dibenzylideneacetone)palladium (0) and 1,4-bis(diphenylphosphino)butane affording lactones in 45-92percent isolated yields. α,β-Unsaturated acids are formed by isomerization and carbonylation of primary allylic alcohols. 2-(5H)-Furanones were isolated in yields of 60-80percent when alkynols were employed as substrates for the cyclocarbonylation process.
- El Ali, Bassam,Alper, Howard
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p. 5357 - 5360
(2007/10/02)
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- A MILD AND SELECTIVE METHOD OF ESTER HYDROLYSIS
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Carboxylic esters, when refluxed in an aqueous suspension of Dowex-50, furnish the corresponding carboxylic acids in excellent yields.Tertiary esters and nitriles remain unaffected under this condition and β-keto esters undergo smooth decarboxylation.
- Basu, Manas K.,Sarkar, Dipak C.,Ranu, Brindaban C.
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p. 627 - 632
(2007/10/02)
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- Electrochemical Oxidation of Primary Alcohols to Aldehydes at the Nickel Hydroxide Electrode
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Primary alcohols were oxidized to aldehydes at the nickel hydroxide electrode in an emulsion of water and a nonpolar organic solvent.Benzylic and allylic primary alcohols afforded good yields, whereas the oxidation of saturated primary alcohols was less satisfactory.
- Schneider, Roy,Schaefer, Hans-J.
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p. 742 - 743
(2007/10/02)
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- Formation of Acrylic Acid from Lactic Acid in Supercritical Water
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Supercritical (SC) water is an unusual medium in which fast and specific heterolytic reactions can be conducted at temperatures as high as 400 deg C.In supercritical water, lactic acid decomposes into gaseous and liquid products via three primary reaction pathways.Products of the acid-catalyzed heterolytic decarbonylation pathway are carbon monoxide, water, and acetaldehyde.Products of the homolytic, decarboxylation pathway are carbon dioxide, hydrogen, and acetaldehyde.Products of the heterolytic, dehydration pathway are acrylic acid and water.The intramolecular nucleophilic displacement of the α-hydroxyl by the carbonyl group of lactic acid, producing α-propiolactone as an unstable intermediate which subsequently rearranges to become the unsaturated acid, is a likely mechanism for acrylic acid formation, although an intramolecular E2 elimination initiated by attack of the carbonyl oxygen on a methyl hydrogen cannot be ruled out.Support for the former mechanism comes in part from the observed 100percent relative yield of acrylic acid from β-propiolactone in SC water.
- Mok, William Shu-Lai,Antal, Michael Jerry,Jones, Maitland
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p. 4596 - 4602
(2007/10/02)
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- Palladium-Catalyzed, Atmospheric Pressure Carbonylation of Allylic Chlorides in Two-Phase Aqueous Sodium Hydroxide-Organic Solvent Media
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The palladium-catalyzed, atmospheric pressure carbonylation of allylic chlorides is realized in aqueous NaOH/benzene.Phosphine complexes PdCl2L2 (I) (a, L=Ph2P(m-C6H4SO3Na; b, L=Ph3P), or Na2PdCl4 can be used as the catalyst.
- Kiji, Jitsuo,Okano, Tamon,Nishiumi, Wataru,Konishi, Hisatoshi
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p. 957 - 960
(2007/10/02)
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- RUTHENATE ION CATALYSED OXIDATION OF SOME UNSATURATED ALCOHOLS BY ALKALINE HEXACYANOFERRATE(III) ION
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The kinetics of ruthenate ion catalysed oxidation of allyl alcohol, crotyl alcohol, cinnamyl alcohol and propargyl alcohol by hexacyanoferrate(III) ion in aqueous alkaline media at constant ionic strength indicate no dependence of rate on alkali concentration or ionic strength.The reaction shows first order dependence on ruthenate ion and zero order in hexacyanoferrate(III) ion.The rate of the reaction increases with increase in substrate concentration and shows Michaelis-Menten type of behaviour.The data suggests that the oxidation proceeds via the formation of a complex between an alcohol molecule and ruthenate ion yielding corresponding acids.The reaction has been studied at four different temperatures and thermodynamic parameters have been computed.A plausible mechanism consistent with the experimental results is proposed.
- Dwivedi, R. K.,Verma, Meena,Kumar, Pradeep,Behari, K.
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p. 815 - 818
(2007/10/02)
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- CATALYTIC DEBROMINATION OF VICINAL DIBROMIDES
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A number of vicinal dibromides were debrominated using sodium borohydride and a catalytic amount of bis(2-thienyl)ditelluride.
- Engman, Lars
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p. 3601 - 3602
(2007/10/02)
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