- Reactivation of Boron Phosphate Catalysts for the Synthesis of Isoprene from 2-Methylbutanal Dehydration
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Boron phosphate catalysts, when used for the title reaction, are deactivated both by coke deposition and by loss of surface phosphorus; air reactivation at 800 deg C is shown to totally restore the catalyst structure and performance.
- Hutchings, Graham J.,Hudson, Ian D.,Timms, Donald G.
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Read Online
- Trifluoroacetylation of ketone O-vinyloximes
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Ketone oxime O-vinyl ethers having alkyl or phenyl radicals react with trifluoroacetic anhydride in ether in the presence of pyridine, yielding 43-54% of the corresponding ketone oxime O-(trans-4,4,4-trifluoro-3-oxo-1-butenyl) ethers with high stereoselec
- Vasil'tsov,Shmidt,Mikhaleva,Zaitsev,Tarasova,Afonin,Toryashinova,Il'icheva,Trofimov
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- Oxidation of an αβ-(epoxyalkyl) trimethylsilane with pyridine oxides in the presence of silylating agents. A facile enantioselective synthesis of glyceraldehyde derivatives
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Trimethylsilyl glycidol derivatives 1 were oxidized with pyridine N-oxides in the presence of silylating agents to give the corresponding glyceraldehyde derivatives 3. Reaction of (α,β-epoxyalkyl)silanes with N-oxides was studied.
- Raubo, Piotr,Wicha, Jerzy
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- Acid-catalyzed isomerization of pivalaldehyde to methyl isopropyl ketone via a reactive protosolvated carboxonium ion intermediate
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Quantitative rearrangement of pivalaldehyde to methyl isopropyl ketone is observed in acids such as trifluoromethanesulfonic acid, anhydrous HF, and trifluoroethyl alcohol - BF3 but not in trifluoroacetic acid. Studies in a mixture of trifluoroacetic acid and trifluoromethanesulfonic acid show that acids with Ho ≤ - 11 are able to carry out complete isomerization. These results and density functional theory calculations at the B3LYP/6-31 G* level suggest that protonated pivalaldehyde undergoes further protosolvation at higher acidities to a reactive superelectrophilic species resulting in rearrangement. A mechanism for the pivalaldehyde rearrangement to methyl isopropyl ketone in strong protic acids involving a reactive protosolvated superelectrophilic intermediate is suggested. Aspects of the related mechanism of the reaction with isobutane with CO in HF/BF3 medium leading to methyl isopropyl ketone are also discussed.
- Olah,Mathew,Marinez,Esteves,Etzkorn,Rasul,Surya Prakash
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- Oxidation of Saturated Hydrocarbons by Hydrogen Peroxide in Pyridine Solution Catalysed by Copper and Iron Perchlorates
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Oxidation of secondary C-H bonds of saturated hydrocarbons (C6H12, 2-methylbutane) by H2O2 in the presence of copper or iron perchlorates in pyridine solution yields the ketone and alcohol with alkyl radicals not being intermediates.
- Geletii, Yurii V.,Lavrushko, Valentina V.,Lubimova, Galina V.
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Read Online
- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- Hydration of Alkynes to Ketones with an Efficient and Practical Polyoxomolybdate-based Cobalt Catalyst
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Hydration of alkynes to ketones is one of the most atom economical and universal methods for the synthesis of carbonyl compounds. However, the basic reaction usually requires organic ligand catalysts or harsh reaction conditions to insert oxygen into the C≡C bond. Here, we report an inorganic ligand supported cobalt (III) catalyst, (NH4)3[CoMo6O18(OH)6], which is supported by a central cobalt (III) mononucleus and a ring-shaped pure inorganic ligand composed of six MoVIO6 octahedrons to avoid the disadvantages of expensive and unrecyclable organic ligand catalysts or noble metal catalysts. Under mild conditions, the cobalt (III) catalyst can be used for the hydration of alkynes to ketones. The catalyst is non-toxic, green, and environment friendly. The catalyst can be recycled at least six times with high activity. According to control experiments, a reasonable mechanism is provided.
- Xie, Ya,Wang, Jingjing,Wang, Yunyun,Han, Sheng,Yu, Han
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p. 4985 - 4989
(2021/10/12)
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- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
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Paragraph 0111
(2021/03/19)
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- Solvent-free, microwave assisted oxidation of alcohols with 4-hydroxypyridinium chlorochromate functionalized silica gel
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4-Hydroxypyridinium chlorochromate functionalized silica gel was found to be an efficient and reusable oxidant for the very fast oxidation of primary and secondary alcohols to the corresponding carbonyl compounds under solventfree conditions and microwave irradiation in excellent yields.
- AHMADI, Sayed Ali,GHALEHBANDI, Shermineh Sadat,GHAZANFARI, Dadkhoda,SHEIKHHOSSEINI, Enayatollah
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p. 283 - 289
(2020/10/06)
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- Base-free oxidation of alcohols enabled by nickel(ii)-catalyzed transfer dehydrogenation
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An efficient nickel(ii)-catalyzed transfer dehydrogenation oxidation of alcohols is reported that relies on cyclohexanone as the formal oxidant and does not require the use of an external base. The synthetic utility of this protocol is demonstratedviathe facile oxidation of structurally complicated natural products.
- Ye, Danfeng,Liu, Zhiyuan,Sessler, Jonathan L.,Lei, Chuanhu
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supporting information
p. 11811 - 11814
(2020/10/13)
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- Br?nsted Acid Catalyzed Tandem Defunctionalization of Biorenewable Ferulic acid and Derivates into Bio-Catechol
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An efficient conversion of biorenewable ferulic acid into bio-catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate, that is, C?O (demethylation) and C?C (de-2-carboxyvinylation) bond cleavage, occurring in one step. The process only requires heating of ferulic acid with HCl (or H2SO4) as catalyst in pressurized hot water (250 °C, 50 bar N2). The versatility is shown on a variety of other (biorenewable) substrates yielding up to 84 % di- (catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work-up.
- Bal, Mathias,Bomon, Jeroen,Liao, Yuhe,Maes, Bert U. W.,Sels, Bert F.,Sergeyev, Sergey,Van Den Broeck, Elias,Van Speybroeck, Veronique
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supporting information
p. 3063 - 3068
(2020/02/05)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- Chemoselective Oxidation of Equatorial Alcohols with N-Ligated λ3-Iodanes
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The site-selective and chemoselective functionalization of alcohols in complex polyols remains a formidable synthetic challenge. Whereas significant advancements have been made in selective derivatization at the oxygen center, chemoselective oxidation to the corresponding carbonyls is less developed. In cyclic systems, whereas the selective oxidation of axial alcohols is well known, a complementary equatorial selective process has not yet been reported. Herein we report the utility of nitrogen-ligated (bis)cationic λ3-iodanes (N-HVIs) for alcohol oxidation and their unprecedented levels of selectivity for the oxidation of equatorial over axial alcohols. The conditions are mild, and the simple pyridine-ligated reagent (Py-HVI) is readily synthesized from commercial PhI(OAc)2 and can be either isolated or generated in situ. Conformational selectivity is demonstrated in both flexible 1,2-substituted cyclohexanols and rigid polyol scaffolds, providing chemists with a novel tool for chemoselective oxidation.
- Mikhael, Myriam,Adler, Sophia A.,Wengryniuk, Sarah E.
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supporting information
p. 5889 - 5893
(2019/08/26)
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- Transfer-dehydrogenation of secondary alcohols catalyzed by manganese NNN-pincer complexes
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Novel catalytic systems based on pentacarbonylmanganese bromide and stable NNN-pincer ligands are presented for the transfer-dehydrogenation of secondary alcohols to give the corresponding ketones in good to excellent isolated yields. Best results are obtained using di-picolylamine derivatives as ligands and acetone as an inexpensive hydrogen acceptor. Besides high activity for benzylic substrates, aliphatic alcohols, as well as steroid derivatives, are readily oxidized in the presence of the optimal phosphorus-free catalyst.
- Budweg, Svenja,Junge, Kathrin,Beller, Matthias
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supporting information
p. 14143 - 14146
(2019/12/02)
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- Method for preparing 3,4-dimethylpyrazole and phosphate and metal organic complex thereof
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The invention discloses a method for preparing 3,4-dimethylpyrazole and phosphate and metal organic complex thereof. The method for preparing the 3,4-dimethylpyrazole comprises the steps that (1) isoprene is in contact with water under the action of a catalyst to obtain methyl isopropyl ketone; (2) the methyl isopropyl ketone is in contact with hydrazine hydrate under the action of sulfuric acid and iodide to obtain the 3,4-dimethylpyrazole. The method for preparing the 3,4-dimethylpyrazole has the advantages that the isoprene is taken as a raw material, the preparation method is simple, and the yield and purity of the product are high.
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Paragraph 0091; 0092; 0093
(2019/05/02)
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- Synthesis of a Water-Soluble Ruthenium Complex and Its Catalytic Activity for Acceptorless Alcohol Dehydrogenation in Aqueous Medium
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The synthesis of a ruthenium complex bearing a PN-chelating ligand is described. The complex, in the presence of KOH, enabled the synthesis of ketones from secondary alcohols in the absence of a hydrogen acceptor in aqueous medium. This synthetic protocol, which uses water as the medium, is green and has a high atom economy as it avoids the use of an acceptor and produces hydrogen as the sole byproduct. Mechanistic investigations revealed that the catalytic cycle involves a phosphine dissociative pathway.
- Bhatia, Anita,Muthaiah, Senthilkumar
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supporting information
p. 1644 - 1648
(2018/06/26)
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- Biocatalytic Racemization Employing TeSADH: Substrate Scope and Organic Solvent Compatibility for Dynamic Kinetic Resolution
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Racemization in combination with a kinetic resolution is the base for a dynamic kinetic resolution (DKR). Biocatalytic racemization was successfully performed for a broad scope of sec-alcohols by employing a single alcohol dehydrogenase (ADH) variant from Thermoanaerobacter pseudoethanolicus (formerly T. ethanolicus; TeSADH W110A I86A C295A). The catalyst employed as a lyophilized whole cell preparation or cell free extract, which tolerated various non-water miscible organic solvents under micro-aqueous or two-phase conditions, whereby cyclohexane and n-hexane suited best. Various concepts for combining the enzymatic racemization with an enzymatic kinetic resolution to achieve overall a bis-enzymatic DKR were evaluated. A proof of concept showed a successful DKR with racemization in aqueous phase combined with acylation in the organic phase.
- Pop?oński, Jaros?aw,Reiter, Tamara,Kroutil, Wolfgang
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p. 763 - 768
(2018/02/27)
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- Catalytic Radical-Polar Crossover Reactions of Allylic Alcohols
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Radical-polar crossover hydrofunctionalizations of tertiary allylic alcohols are described. Depending on the structure of the catalyst, corresponding epoxides or semipinacol rearrangement products are selectively obtained in good yields. Experimental evidence points to the participation of alkylcobalt complexes as electrophilic intermediates.
- Touney, Eric E.,Foy, Nicholas J.,Pronin, Sergey V.
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supporting information
p. 16982 - 16987
(2018/12/14)
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- Catalytic Coupling of Carbon Dioxide with Terpene Scaffolds: Access to Challenging Bio-Based Organic Carbonates
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The challenging coupling of highly substituted terpene oxides and carbon dioxide into bio-based cyclic organic carbonates catalyzed by Al(aminotriphenolate) complexes is reported. Both acyclic as well as cyclic terpene oxides were used as coupling partners, showing distinct reactivity/selectivity behavior. Whereas cyclic terpene oxides showed excellent chemoselectivity towards the organic carbonate product, acyclic substrates exhibited poorer selectivities owing to concomitant epoxide rearrangement reactions and the formation of undesired oligo/polyether side products. Considering the challenging nature of these coupling reactions, the isolated yields of the targeted bio-carbonates are reasonable and in most cases in the range 5060 %. The first crystal structures of tri-substituted terpene based cyclic carbonates are reported and their stereoconnectivity suggests that their formation proceeds through a double inversion pathway.
- Fiorani, Giulia,Stuck, Moritz,Martn, Carmen,Belmonte, Marta Martnez,Martin, Eddy,Escudero-Adn, Eduardo C.,Kleij, Arjan W.
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p. 1304 - 1311
(2016/07/09)
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- PROCESSES FOR CONVERSION OF BIOLOGICALLY DERIVED MEVALONIC ACID
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The invention relates to a process comprising reacting mevalonic acid, or a solution comprising mevalonic acid, to yield a first product or first product mixture, optionally in the presence of a solid catalyst and/or at elevated temperature and/or pressure. The invention further relates to a process comprising: (a) providing a microbial organism that expresses a biosynthetic mevalonic acid pathway; (b) growing the microbial organism in fermentation medium comprising suitable carbon substrates, whereby biobased mevalonic acid is produced; and (c) reacting said biobased mevalonic acid to yield a first product or first product mixture.
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Paragraph 0107-0111
(2016/06/13)
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- Synthesis of a-Alkylated Ketones via Tandem Acceptorless Dehydrogenation/a-Alkylation from Secondary and Primary Alcohols Catalyzed by Metal-Ligand Bifunctional Iridium Complex [CpIr(2,2′-bpyO)(H2O)]
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A new strategy for the synthesis of α-alkylated ketones via tandem acceptorless dehydrogenation/α-alkylation from secondary and primary alcohols was proposed and accomplished. In the presence of metal-ligand bifunctional iridium complex [CpIr(2,2′-bpyO)(H2O)], various desirable products were obtained in high yields. Compared with previous methods for the direct dehydrogenative coupling of secondary alcohols with primary alcohols to α-alkylated ketones, this protocol has obvious advantages including complete selectivity for α-alkylated ketones and more environmentally benign conditions. Notably, the study also exhibited the potential to develop tandem reactions catalyzed using a metal-ligand bifunctional iridium complex.
- Wang, Rongzhou,Ma, Juan,Li, Feng
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p. 10769 - 10776
(2015/11/18)
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- Selective isomerization of epoxides using magnetically recyclable ZSM-5 zeolite catalyst
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The application of magnetically recyclable ZSM-5 zeolite (MZZ) for epoxide isomerization reaction was presented. This catalyst exhibited a high catalytic efficiency for liquid phase rearrangement of 2-methyl-2,3-epoxybutane and styrene oxide, as well as high efficiency in separation, recycling with long lifetime and no significant loss of catalytic activity. The influences of reaction conditions such as solvent, reaction time, catalyst loading and temperature on the efficiency of epoxide isomerization were also investigated. Moreover, it was noticeable that for the epoxides investigated the high catalytic activity observed over the MZZ catalyst (conversion over 98% after 2 h reaction for both of two epoxides) was accompanied by the achievement of high selectivities, typically 79% and 82% for 2-methyl-2,3-epoxybutane and styrene oxide respectively, towards desired products with commercial applications.
- Hoang, Phan Huy,Nguyen Xuan, Bach
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p. 78441 - 78447
(2015/10/05)
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- Decarboxylation and simultaneous reduction of silver(I) β-ketocarboxylates with three types of coordinations
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A series of silver(I) β-ketocarboxylates were prepared by reaction of β-ketocarboxylic acids with silver nitrate in the presence of diethanolamine. The silver(I) β-ketocarboxylates decomposed over a narrow temperature range to form metallic silver, CO2, and the corresponding ketones. In addition, products derived from radical intermediates were detected by mass spectroscopic analysis for some silver(I) β-ketocarboxylates. Infrared and solid state 13C-NMR spectra of silver(I) β-ketocarboxylates suggested the presence of two types of structures involving a carbonyl group in addition to the dimeric eight-membered ring structure as in the structure of silver(I) stearate. The silver(I) β-ketocarboxylate model compound used was HCOCH2COOAg and its structures were determined using density functional theory (DFT) and atoms-in-molecules (AIM) methods. Three types of coordinations around the Ag ion differing significantly in Ag-O bond strengths were found. Based on the calculated structures and experimental results, the relationships between the structures and decomposition temperatures are discussed in terms of the thermal decomposition process.
- Hatamura, Mariko,Yamaguchi, Shunro,Takane, Shin-Ya,Chen, Yu,Suganuma, Katuaki
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p. 8993 - 9003
(2015/05/20)
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- Expanding Substrate Specificity of ω-Transaminase by Rational Remodeling of a Large Substrate-Binding Pocket
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Production of structurally diverse chiral amines via biocatalytic transamination is challenged by severe steric interference in a small active site pocket of ω-transaminase (ω-TA). Herein, we demonstrated that structure-guided remodeling of a large pocket by a single point mutation, instead of excavating the small pocket, afforded desirable alleviation of the steric constraint without deteriorating parental activities toward native substrates. Molecular modeling suggested that the L57 residue of the ω-TA from Ochrobactrum anthropi acted as a latch that forced bulky substrates to undergo steric interference with the small pocket. Removal of the latch by a L57A substitution allowed relocation of the small pocket and dramatically improved activities toward various arylalkylamines and alkylamines (e.g., 1100-fold increase in kcat/KM for α-propylbenzylamine). This approach may provide a facile strategy to broaden the substrate specificity of ω-TAs.
- Han, Sang-Woo,Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
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p. 2712 - 2720
(2015/09/01)
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- Aluminum oxide-induced gas-phase ring-opening in methyl substituted gem-difluorocyclopropanes, leading to 2-fluorobuta-1,3-dienes and vinylacetylenes
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A gas-phase pyrolysis of methyl-substituted gem-difluorocyclopropanes in a flow-tube reactor in the presence of Al2O3 at 185 - 250 °C gives 2-fluorobuta-1,3-dienes and vinylacetylenes.
- Volchkov,Lipkind,Novikov,Nefedov
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p. 658 - 663
(2015/11/27)
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- Electroorganic synthesis of esters and ketones at the platinum anode in aqueous medium
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Elcctroorganic synthesis of esters from the saturated primary aliphatic alcohols and ketones from the secondary aliphatic alcohols have been carried out in electrooxidation at the platinum anode in aqueous medium. This is an important reaction because of high oxidation potential of alcohols. Electrochemical oxidation has been carried out under controlled potential electrolysis at room temperature in a three electrode cell assembly containing two platinum electrodes In the form of square plates as working as well as counter electrode and saturated calomel electrode was used as a reference electrode. The structures of compounds were confirmed from the IR, NMR, inass spectral and microanalyses. The products formed during the electrooxidation of ethanol, propanol, 1-butanol, 1-pentanol, 2-butanol and sec-butyl alcohol are reported here.
- Kumar, Sanjeev
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p. 739 - 744
(2013/08/23)
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- An efficient and scalable room temperature aerobic alcohol oxidation catalyzed by iron chloride hexahydrate/mesoporous silica supported TEMPO
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An efficient room temperature catalytic system FeCl3· 6H2O/SBA-15-TEMPO/NaNO2 for the oxidation of alcohols with dioxygen or air as terminal oxidant has been developed. Various alcohols were oxidized at a low catalyst loading (0.1-1 mol %) to the corresponding carbonyl compounds in good to excellent yields. For the oxidation of benzyl alcohol, the excellent turn-over frequency (TOF) of 81.4 h-1 was achieved (turn-over number (TON) up to 9770). The catalyst SBA-15-TEMPO can be reused for 10 reaction runs without significant loss of catalytic activity. In addition, the two components FeCl3·6H2O and SBA-15-TEMPO can also be reused for at least four reaction runs without appreciable loss of catalytic activity. In the case of large-scale experiment for the oxidation of benzyl alcohol, the desired product benzaldehyde was obtained in 94.5% yield.
- Wang, Lianyue,Li, Jun,Zhao, Xiaoping,Lv, Ying,Zhang, Hengyun,Gao, Shuang
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p. 6041 - 6045
(2013/07/27)
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- Tunneling control of chemical reactions: C-H insertion versus H-tunneling in tert-butylhydroxycarbene
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Elusive tert-butylhydroxycarbene was generated in the gas phase via high-vacuum flash pyrolysis of tert-butylglyoxylic acid at 960 °C. The pyrolysis products were subsequently matrix isolated in solid Ar at 11 K and characterized by means of IR spectroscopy. While still being exposed to the harsh pyrolysis conditions, the hydroxycarbene undergoes CH-insertion to dimethylcyclopropanol, as well as a CC-insertion to novel methylbutenol, with activation barriers of 23.8 and 31.0 kcal mol-1, respectively. Once embedded in the cold Ar matrix, the carbene transforms to its isomer pivaldehyde not only by photolysis, but it also cuts through the barrier of 27.3 kcal mol-1 by quantum mechanical tunneling. The temperature independent half-life is measured as 1.7 h; the tunneling pathway was entirely blocked upon O-deuteration. The experimental half-life of tert-butylhydroxycarbene was verified by tunneling computations applying the Wentzel-Kramers-Brillouin formalism on the minimum energy path evaluated at the computationally feasible M06-2X/6-311++G(d,p) level of theory. Our experimental findings are supported by relative energy computations at the CCSD(T)/cc-pVDZ level of theory. The Royal Society of Chemistry 2013.
- Ley, David,Gerbig, Dennis,Schreiner, Peter R.
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p. 677 - 684
(2013/04/10)
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- Room-Temperature oxidation of secondary alcohols by bromate-bromide coupling in acidic water
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The use of environmentally benign reactions is currently an important topic in the field of synthetic chemistry. Here we report a high-yielding method to oxidize aliphatic or aromatic secondary alcohols into corresponding ketones using nonhazardous and inexpensive BrOH reagent at room temperature in water. BrOH reagent was derived from NaBr and NaBrO3 in aqueous acid. Based on the presented results, a mechanism was proposed for this oxidation. The reported method offers a facile, efficient procedure to produce various ketones with a low amount of side products. Taylor & Francis Group, LLC.
- Paeaekkoenen, Sanna,Pursiainen, Jouni,Lajunen, Marja
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experimental part
p. 534 - 540
(2011/12/04)
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- Tetraflic acid (1,1,2,2-Tetrafluoroethanesulfonic acid, HC 2F4SO3H) and gallium tetraflate as effective catalysts in organic synthesis
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Tetraflic acid offers ample acidity for various organic reactions that require high acidity. Its gallium(III) salt is an efficient catalyst under mild condtions for synthetic transformations such as the ketonic Strecker reaction for the synthesis of fluorinated α-amino nitriles and condensation- cyclzation reactions using suitable fluoro ketones and 1,2-disubstituted benzenes for the direct preparation of 5-membered or 6-membered fluorinated heterocycles. Copyright
- Prakash, G. K. Surya,Mathew, Thomas,Panja, Chiradeep,Kulkarni, Aditya,Olah, George A.,Harmer, Mark A.
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p. 2163 - 2171
(2012/11/07)
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- Polymer-mediated pinacol rearrangements
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Both poly(3,4-ethylenedioxythiophene) and poly(pyrrole) mediate a pinacol rearrangement of 1,2-diols. The yields of ketone or aldehyde products are comparable to those observed for treatment with mineral acids or Lewis acids. The advantage of this protocol is a two-phase reaction medium in hydrocarbon solvents that allows facile recovery of the products by simple filtration of the polymer and removal of solvents. Both the polymer and the hydrocarbon solvent may be recovered and used in subsequent reactions. Georg Thieme Verlag Stuttgart · New York.
- Pavlik, Christopher,Morton, Martha D.,Smith, Michael B.
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p. 2191 - 2194
(2011/11/06)
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- FUEL COMPOSITIONS COMPRISING ISOPRENE DERIVATIVES
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The invention provides for methods, compositions and systems using isoprene from a bioisoprene composition derived from renewable carbon for production of a variety of hydrocarbon fuels, fuel additives, and additives for fine chemistry and other uses.
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Page/Page column 79
(2012/01/06)
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- Structure-reactivity relationship for alcohol oxidations via hydride transfer to a carbocationic oxidizing agent
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Second-order rate constants were determined for the oxidation of 27 alcohols (R1R2CHOH) by a carbocationic oxidizing agent, 9-phenylxanthylium ion, in acetontrile at 60°C. Alcohols include open-chain alkyl, cycloalkyl, and unsaturated alcohols. Kinetic isotope effects for the reaction of 1-phenylethanol were determined at three H/D positions of the alcohol (KIEα-D=3.9, KIEβ-D3=1.03, KIE OD=1.10). These KIE results are consistent with those we previously reported for the 2-propanol reaction, suggesting that these reactions follow a hydride-proton sequential transfer mechanism that involves a rate-limiting formation of the α-hydroxy carbocation intermediate. Structure-reactivity relationship for alcohol oxidations was deeply discussed on the basis of the observed structural effects on the formation of the carbocationic transition state (Cδ+-OH). Efficiencies of alcohol oxidations are largely dependent upon the alcohol structures. Steric hindrance effect and ring strain relief effect win over the electronic effect in determining the rates of the oxidations of open-chain alkyl and cycloalkyl alcohols. Unhindered secondary alkyl alcohols would be selectively oxidized in the presence of primary and hindered secondary alkyl alcohols. Strained C7-C11 cycloalkyl alcohols react faster than cyclohexyl alcohol, whereas the strained C5 and C12 alcohols react slower. Aromatic alcohols would be efficiently and selectively oxidized in the presence of aliphatic alcohols of comparable steric requirements. This structure-reactivity relationship for alcohol oxidations via hydride-transfer mechanism is hoped to provide a useful guidance for the selective oxidation of certain alcohol functional groups in organic synthesis. Copyright
- Lu, Yun,Bradshaw, Joshua,Zhao, Yu,Kuester, William,Kabotso, Daniel
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p. 1172 - 1178
(2013/01/12)
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- Fast oxidation of secondary alcohols by the bromate-bromide system using cyclic microwave heating in acidic water
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We report an improved, gentle, cyclic microwave activation technique for the oxidation of secondary alcohols using nonhazardous hypobromous acid (BrOH) as the reagent in acidic water. Several aliphatic and aromatic secondary alcohols were successfully oxidized to the corresponding ketones using this technique in high yields and with only minor amounts of side products.
- P??kk?nen, Sanna,Pursiainen, Jouni,Lajunen, Marja
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scheme or table
p. 6695 - 6699
(2011/02/23)
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- Nanocrystalline ZSM-5: A catalyst with high activity and selectivity for epoxide rearrangement reactions
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Nanocrystalline ZSM-5 (~20-50 nm) has been tested as a catalyst in the liquid phase rearrangement of 1,2-epoxyoctane, 2-methyl-2,3-epoxybutane and isophorone oxide together with a microcrystalline ZSM-5 sample (~5 μm) employed as a reference. Whereas this last material shows a low activity for the three epoxide rearrangement reactions considered, nanocrystalline ZSM-5 leads in all cases to high epoxide conversion. This different catalytic performance is attributed to the differences in the accessibility of the reactant molecules to the catalyst active sites. The smallest crystal size of the nanocrystalline zeolite contributes favourably to both the formation of a high external surface area, with no steric constraints, and to a faster intracrystalline diffusion of the epoxide molecules towards the acid sites located within the zeolite micropores. When sterically hindered epoxides are tested, the catalytic rearrangement occurs mainly on the external surface of the nanocrystalline zeolite. Moreover, it is remarkable that for the three epoxides investigated the high catalytic activity observed over nanocrystalline ZSM-5 is accompanied by the attainment of high selectivities, typically around or over 80%, towards products with commercial applications.
- Serrano, David P.,van Grieken, Rafael,Melero, Juan Antonio,García, Alicia,Vargas, Carolina
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scheme or table
p. 68 - 74
(2010/06/16)
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- Mechanistic origin of the stereodivergence in decarboxylative allylation
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A stereochemical test has been used to probe the mechanism of decarboxylative allylation. This probe suggests that the mechanism of DcA reactions can change based on the substitution pattern at the α-carbon of the nucleophile; however, reaction via stabilized malonate nucleophiles is the lower energy pathway. Lastly, this mechanistic proposal has predictive power and can be used to explain chemoselectivities in decarboxylative reactions that were previously confounding.
- Chattopadhyay, Kalicharan,Jana, Ranjan,Day, Victor W.,Douglas, Justin T.,Tunge, Jon A.
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supporting information; experimental part
p. 3042 - 3045
(2010/08/20)
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- CATALYSTS SELECTIVE FOR THE PREPARATION OF MIXED KETONES FROM A MIXTURE OF CARBOXYLIC ACIDS
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Mixed ketones are prepared from a mixture of carboxylic acids in a process with high selectivity by using an improved catalyst. The catalyst contains zirconium dioxide or zirconium dioxide and titanium dioxide, and a Group 1 or 2 metal silicate or phosphate salt. The new catalyst is more selective toward the formation of the mixed ketone, as opposed to a symmetrical ketone.
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Page/Page column 14-16
(2008/06/13)
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- Catalyst and process for the preparation of unsymmetrical ketones
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Carboxylic acid mixtures form unsymmetrical ketones in yields approaching statistical using zirconia catalysts promoted with Group IA and IIA elements. Active catalysts exist in their monoclinic or tetragonal but not cubic form. And the level of promoter loading is generally less than ten percent. The advantages of this catalyst over other ketonization catalysts include its high selectivity to ketones, its low formation of dehydrogenated byproducts, and its stability. The catalyst stability permits its regeneration to remove carbon accumulations by air oxidation. This regeneration restores full catalytic activity.
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Page/Page column 7
(2008/06/13)
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- Relative and absolute kinetic studies of 2-butanol and related alcohols with tropospheric Cl atoms
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A newly constructed chamber/Fourier transform infrared system was used to determine the relative rate coefficient, ki, for the gas-phase reaction of Cl atoms with 2-butanol (k1), 2-methyl-2-butanol (k 2), 3-methyl-2-butanol (k3), 2,3-dimethyl-2-butanol (k4) and 2-pentanol (k5). Experiments were performed at (298 ± 2) K, in 740 Torr total pressure of synthetic air, and the measured rate coefficients were, in cm3 molecule-1 s -1 units (±2σ): k1 = (1.32 ± 0.14) × 10-10, k2 = (7.0 ± 2.2) × 10 -11, k3 = (1.17 ± 0.14) × 10-10, k4 = (1.03 ± 0.17) × 10-10 and k5 = (2.18 ± 0.36) × 10-10, respectively. Also, all the above rate coefficients (except for 2-pentanol) were investigated as a function of temperature (267-384 K) by pulsed laser photolysis-resonance fluorescence (PLP-RF). The obtained kinetic data were used to derive the Arrhenius expressions: k1(T) = (6.16 ± 0.58) × 10 -11exp[(174 ± 58)/T], k2(T) = (2.48 ± 0.17) × 10-11exp[(328 ± 42)/T], k3(T) = (6.29 ± 0.57) × 10-11exp[(192 ± 56)/T], and k 4(T) = (4.80 ± 0.43) × 10-11exp[(221 ± 56)/T] (in units of cm3 molecule-1 s-1 and ±σ). Results and mechanism are discussed and compared with the reported reactivity with OH radicals. Some atmospheric implications derived from this study are also reported. This journal is the Owner Societies.
- Ballesteros, Bernabe,Garzon, Andres,Jimenez, Elena,Notario, Alberto,Albaladejo, Jose
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p. 1210 - 1218
(2008/04/05)
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- CATALYST FOR THE PRODUCTION OF METHYL ISOPROPYL KETONE
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A catalyst for the production of methyl isopropyl ketone containing aluminum and titanium oxides, treated with Group 1 or 2 metal hydroxides, or their salts.
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Page/Page column 9-10
(2008/06/13)
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- Catalyst for the preparation of ketones from carboxylic acids
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A catalyst for the preparation of ketones from carboxylic acids is described. The catalyst comprises a mixture of zirconium dioxide, titanium dioxide, and one or more metal oxides from Group 1 or 2 of the Periodic Table of Elements. The catalyst can operate at a lower temperature, reduce coke formation, and provide longer lifetime.
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Page/Page column 3-4
(2008/06/13)
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- Polymeric DABCO-bromine complex: a mild oxidant for the preparation of ketones and aldehydes
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A stable, shelf-ready polymeric oxidant was prepared from the addition of Br2 to DABCO in CCl4. This material was used to convert simple primary and secondary alcohols to the corresponding aldehydes and ketones in biphasic CH2Cl2/H2O.
- Struss, John A.,Barnhart, William D.,Velasco, Maria R.,Bronley-DeLancey, Apryl
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p. 6635 - 6636
(2007/10/03)
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- BF3·2CF3CH2OH (BF 3·2TFE), an efficient superacidic catalyst for some organic synthetic transformations
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BF3 · 2CF3CH2OH complex was found to be a very effective superacidic catalyst comparable in acid strength to at least that of 100% anhydrous sulfuric acid for various acid-catalyzed organic transformations such as isomerizations, rearrangements, ionic hydrogenation of various ketones, and aromatics with triethylsilane and nitration of aromatics with metal nitrate. Studies of the pivalaldehyde-methyl isopropyl ketone rearrangement and the benzopinacol to phenanthrene transformation suggest that the complex has an acidity comparable to that of 100% anhydrous sulfuric acid. The structure and properties of the 1:2 boron trifluoride-trifluoroethanol complex have been further studied using NMR (1H, 13C, 19F, 11B) and DFT calculations at the B3LYP/6- 311++G**//B3LYP/6-31G* level.
- Prakash, G. K. Surya,Mathew, Thomas,Marinez, Eric R.,Esteves, Pierre M.,Rasul, Golam,Olah, George A.
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p. 3952 - 3958
(2007/10/03)
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- Kinetics and mechanism of oxidation of alcohols by butyltriphenylphosphonium dichromate
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Butyltriphenylphosphonium dichromate (BTPPD) oxidizes aliphatic alcohols to the corresponding carbonyl compounds. The reaction is first order in BTPPD. The reaction exhibits a second order dependence each on the alcohol and hydrogen ions. The oxidation of deuteriated ethanol and 2-propanol indicates the presence of a substantial primary kinetic isotope effect. The reaction has been studied in nineteen organic solvents and the solvent effect was analyzed using multiparametric equations. It is observed that the cation-solvating power plays a major role in the reaction. The rate of oxidation shows excellent correlation with the polar and steric substituent constants. Suitable mechanisms have been proposed.
- Kothari, Anita,Kothari, Seema,Banerji, Kalyan K.
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p. 2039 - 2043
(2007/10/03)
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- Kinetics and mechanism of the liquid-phase rearrangement of 2-Methyl-2,3-epoxybutane in the presence of a magnesium bromide complex
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The mechanism of intramolecular rearrangement of epoxides in the presence of the MgBr2 · 2H2O · 4DMF catalytic complex was proposed on the basis of a kinetic study of the liquid-phase isomerization of 2-methyl-2,3-epoxybutane and data on the influence of the ligand environment of the catalyst, solvent nature, and the epoxide structure. Copyright
- Mel'nik,Khvatova,Moskvichev,Srednev
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p. 275 - 278
(2007/10/03)
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- GaCl3-catalyzed skeletal rearrangement of α,α, α-trisubstituted aldehydes
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(Chemical Equation Presented) GaCl3 is found to be a superior catalyst for the skeletal rearrangement of α,α,α- trisubstituted aldehydes to ketones. The rearrangement can proceed smoothly in the presence of a catalytic amount of GaCl3, and even substrates having no heteroatoms α to the carbonyl group or without steric strains can be used. Double activation of a carbonyl group by two molecules of GaCl 3 was supported on the basis of experimental data and a DFT study.
- Oshita, Masayuki,Okazaki, Takao,Ohe, Kouichi,Chatani, Naoto
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p. 331 - 334
(2007/10/03)
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- Thermal isomerization of isoborneols and dehydroisoborneols to new chiral building blocks in terpenoid synthesis
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The substituted isoborneols 1a-1g and 5,6-dehydroisoborneols 6a-6c, readily prepared in excellent yields from (+)-camphor and (+)-5,6-dehydrocamphor (2) by aryl, vinyl, or alkyl Grignard addition in the presence of stoichiometric amounts of CeCl3, were thermally isomerized in a flow reactor system under DGPTI (dynamic gas-phase thermo-isomerization) conditions at temperatures between 480 and 630° to give the enantiomerically pure monocyclic carbonyl compounds 7a-7d, 19a,b, 23, and 24. In all cases, product formation proceeded highly regio- as well as stereoselectively. The absolute configurations of the new stereogenic centers were determined by 1H-NOE measurements. DGPTI of the aryl substrates 1a-1d is proposed to effect initial cleavage of the weakest single bond in the molecule under formation of a diradical intermediate state followed by intramolecular H-abstraction to afford the acetophenone derivatives 7a-7d. This reaction path was further supported by a 2H-labeling study showing the OH group to be the exclusive H-source. In contrast, DGPTI of the vinyl substrates 1e and 6b allowed concerted retro-ene and oxy-Cope rearrangements. In the case of 5,6-dehydro-2-phenylisoborneol (6a), concomitant diradical and retro-Diels-Alder reaction pathways could be observed. In addition, a new route to (+)-rrans-a-campholanic acid (9) and (+)-trans-a-dihydrocampholytic acid (14) is presented by regioselective Baeyer-Villiger oxidation and subsequent hydrolysis of 7c and 7d, respectively.
- Rueedi, Georg,Hansen, Hans-Juergen
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p. 1968 - 1989
(2007/10/03)
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- Products and mechanism of the reaction of OH radicals with 2,3,4-trimethylpentane in the presence of NO
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Alkanes are important constituents of gasoline fuel and vehicle exhaust, with branched alkanes comprising a significant fraction of the total alkanes observed in urban areas. Using a relative rate method, a rate constant for the reaction of OH radicals with 2,3,4-trimethylpentane of (6.84 ± 0.12) × 10-12 cm3 molecule-1 s-1 at 298 ± 2 K was measured, where the indicated error is two least-squares standard deviations and does not include the uncertainty in the rate constant for the n-octane reference compound. Products of the gas-phase reaction of OH radicals with 2,3,4-trimethylpentane in the presence of NO at 298 ± 2 K and atmospheric pressure of air have been investigated using gas chromatography with flame ionization detection (GC-FID), combined gas chromatography-mass spectrometry (GC-MS), and in situ atmospheric pressure ionization tandem mass spectrometry (API-MS). Products identified and quantified by GC-FID and GC-MS were (molar yields given in parentheses): acetaldehyde (47 ± 6%), acetone (76 ± 11%), 3-methyl-2-butanone (41 ± 5%), 3-methyl-2-butyl nitrate (1.6 ± 0.2%), and 2-propyl nitrate (6.2 ± 0.8%). These compounds account for 69 ± 6% of the reaction products, as carbon. Additional products observed by API-MS analyses using positive and negative ion modes were C5- and C8-hydroxynitrates and a C 8-hydroxycarbonyl, which, together with the predicted formation of octyl nitrates, account for some or all of the remaining products. The product distribution is compared to those for the linear and branched C 8-alkanes n-octane and 2,2,4-trimethylpentane.
- Aschmann, Sara M.,Arey, Janet,Atkinson, Roger
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p. 5038 - 5045
(2008/04/18)
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- Ion exchange catalysis in oxidation of organic compounds with KMnO4
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The oxidation of organic compounds under ion exchange resin (IER) catalysis by KMnO4 has been studied in CH2Cl2 under reflux conditions. Secondary aliphatic and aromatic alcohols are converted to ketones, alkyl arenes and sulfides oxidized to corresponding ketones and sulfones, respectively, and thiols undergo oxidative coupling reactions to give disulfides. The experimental procedure is simple and products are easily isolated in good yields.
- Shaabani, Ahmad,Teimouri, Fatemeh,Lee, Donald G.
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p. 1057 - 1065
(2007/10/03)
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- Liquid-phase isomerization of saturated and unsaturated epoxides
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The liquid-phase isomerization of a variety of epoxides was studied using a complex catalyst system based on magnesium bromide and dimethylformamide. The data obtained elucidate the mechanism of the liquid-phase isomerization and show the range of oxygen-containing compounds which can be prepared through this reaction.
- Mel'nik,Khvatova,Moskvichev,Srednev,Egorova
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p. 167 - 169
(2007/10/03)
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- Synthesis of olivacene, a constituent of Archilejeunea olivacea
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A simple synthesis of olivacene 1, a naturally occurring sesquiterpenoid hydrocarbon isolated from Archilejeunea olivacea has been described.
- Kamat, Shrivallabh P.,D'Souza, Asha M.,Paknikar, Shashikumar K.
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p. 2662 - 2664
(2007/10/03)
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- Hexamethylenetetramine-bromine complex (HMTAB) on wet silica: Oxidation of alcohols and sulfides
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Secondary or benzylic alcohols and sulfides are converted into their corresponding carbonyl and sulfoxide compounds efficiently using wet silica supported HMTAB complex at room temperature.
- Shaabani, Ahmad,Teimouri, Mohammad Bagher,Bazgir, Ayoob
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p. 1975 - 1977
(2007/10/03)
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- Direct carbonylation of paraffins using solid strong acid catalyst
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A process for the direct carbonylation of saturated hydrocarbons has been developed. The process involves contacting the saturated hydrocarbons, which contain at least one primary, secondary or tertiary carbon atom, with carbon monoxide in the presence of a solid strong acid catalyst to produce an oxygenated saturated hydrocarbon. In a specific embodiment isobutane is reacted with carbon monoxide using sulfated zirconia as the catalyst to produce methylisopropyl ketone. The oxygenated hydrocarbon can subsequently be hydrogenated to give a reduced oxygenated saturated hydrocarbon. The hydrogenation can also be done simultaneously with the carbonylation, i.e., reductive carbonylation.
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Page column 6
(2010/01/31)
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- The effect of solvent on the liquid-phase catalytic isomerization reaction of 2-methyl-2,3-epoxybutane
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The effect of solvent on the rate and direction of the liquid-phase isomerization reaction of 2-methyl-2,3-epoxybutane was studied. The solvent effect was found to be due to a change in the stability of the transition state and its influence on the conformational equilibrium. A possibility was shown for controlling the chemical process by varying the character of the reaction medium.
- Mel'nik,Khvatova,Moskvichev,Srednev,Egorova
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p. 277 - 280
(2007/10/03)
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