- Facile hydrogenation of carbon-carbon double bonds using catalytic noble nanoparticles immobilized in microfluidic reactors
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Facile hydrogenation of carbon-carbon double bonds was achieved in a poly(dimethylsiloxane) (PDMS) microfluidic reactor with immobilized noble nanoparticles, using the conversion of 6-bromo-1-hexene to 1-bromo-hexane as a model reaction. The microreactor was used to measure the intrinsic catalytic activity and turnover frequencies (TOF) of palladium (Pd), platinum (Pt) and ruthenium (Ru) nanocatalysts. The TOF of reactions run with immobilized nanocatalysts in the microfluidic reactor were hundreds of times larger than those measured in identical reactions in batch reactors. The combination of well-defined nanocatalysts and microfluidics significantly enhances hydrogen diffusion to catalytic sites, thus eliminating mass transfer limitations and enabling evaluation of the intrinsic catalytic activity. The system provides an excellent platform for high throughput screening of catalysts, and for conducting mechanistic studies of reaction kinetics.
- Lin, Rui,Ma, Xianfeng,Fielitz, Thomas R.,Obare, Sherine O.,Ofoli, Robert Y.
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Read Online
- Synthesis of the sex pheromone of Lygus lineolaris (Heteroptera miridae)
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We propose a new synthesis of the sex pheromone of Lygus lineolaris (Heteroptera miridae) that uses a phase-transfer version of the Wittig - Horner reaction to produce a monoene synthon of the principal component of the pheromone, E-2-hexenylbutyrate.
- Shakirzyanova,Abdukakharov,Abduvakhabov
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Read Online
- Anion nucleophilicity in ionic liquids: A comparison with traditional molecular solvents of different polarity
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The nucleophilic reactivity of a homogeneous series of anions (halides, pseudohalides and organic anions) in the ionic liquids [hexmim] [ClO 4] and [hexmim] [PF6] has been measured in their reaction with n-alkyl methanesulfonates, and compared with that found in traditional molecular solvents of different polarity, that is, chlorobenzene, DMSO, and MeOH.
- Landini, Dario,Maia, Angelamaria
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Read Online
- A preparing method of diethylamino hydroxybenzoyl hexylbenzoate
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The present invention relates to a method for the preparation of diethylamino hydroxybenzoyl hexyl benzoate. Specifically, the present invention relates to a method for preparing diethylamino hydroxybenzoyl hexyl benzoate which is easy to manufacture and commercially available in mass production, and diethylamino hydroxybenzoyl hexyl benzoate crystalline particles prepared thereby. According to the present invention, diethylamino hydroxybenzoyl hexyl benzoate crystalline particles having excellent UV blocking effect can be obtained in a stable and high yield.COPYRIGHT KIPO 2020
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Paragraph 0073-0075
(2020/03/28)
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- Synthesis and mass spectra of rearrangement bio-signature metabolites of anaerobic alkane degradation via fumarate addition
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Metabolite profiling in anaerobic alkane biodegradation plays an important role in revealing activation mechanisms. Apart from alkylsuccinates, which are considered to be the usual biomarkers via fumarate addition, the downstream metabolites of C-skeleton rearrangement can also be regarded as biomarkers. However, it is difficult to detect intermediate metabolites in both environmental samples and enrichment cultures, resulting in lacking direct evidence to prove the occurrence of fumarate addition pathway. In this work, a synthetic method of rearrangement metabolites was established. Four compounds, namely, propylmalonic acid, 2-(2-methylbutyl)malonic acid, 2-(2-methylpentyl)malonic acid and 2-(2-methyloctyl)malonic acid, were synthesized and determined by four derivatization approaches. Besides, their mass spectra were obtained. Four characteristic ions were observed at m/z 133 + 14n, 160 + 28n, 173 + 28n and [M - (45 + 14n)]+ (n = 0 and 2 for ethyl and n-butyl esters, respectively). For methyl esterification, mass spectral features were m/z 132, 145 and [M - 31]+, while for silylation, fragments were m/z 73, 147, 217, 248, 261 and [M - 15]+. These data provide basis on identification of potential rearrangement metabolites in anaerobic alkane biodegradation via fumarate addition.
- Chen, Jing,Zhou, Lei,Liu, Yi-Fan,Hou, Zhao-Wei,Li, Wei,Mbadinga, Serge Maurice,Zhou, Jing,Yang, Tao,Liu, Jin-Feng,Yang, Shi-Zhong,Wu, Xiao-Lin,Gu, Ji-Dong,Mu, Bo-Zhong
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- Synthesis of Branched Biolubricant Base Oil from Oleic Acid
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The mature manufacturing of synthetic lubricants (poly-α-olefins, PAO) proceeds through oligomerization, polymerization, and hydrogenation reactions of petrochemical ethylene. In this work, we utilize the inexpensive bio-derived oleic acid as raw material to synthesize a crotch-type C45 biolubricant base oil via a full-carbon chain synthesis without carbon loss. It contains several cascade chemical processes: oxidation of oleic acid to azelaic acid (further esterification to dimethyl azelate) and nonanoic acid (both C9 chains). The latter is then selectively hydrogenated to nonanol and brominated to the bromo-Grignard reagent. In a next step, a C45 biolubricant base oil is formed by nucleophilic addition (NPA) of excessive C9 bromo-Grignard reagent with dimethyl azelate, followed by subsequent hydrodeoxygenation. The specific properties of the prepared biolubricant base oil are almost equivalent to those of the commercial lubricant PAO6 (ExxonMobil). This process provides a new promising route for the production of value-added biolubricant base oils.
- Chen, Shuang,Wu, Tingting,Zhao, Chen
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p. 5516 - 5522
(2020/09/07)
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- An efficient conversion of alcohols to alkyl bromides using pyridinium based ionic liquids: A green alternative to appel reaction
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Pyridinium based ionic liquids namely 4-alkylpyridinium bromides were prepared and used for the conversion of alcohols to alkyl bromides in the presence of p-toluenesulphonic acid in the absence of volatile organic compounds. This solvent free procedure promises to be a much improved and environmentally benign alternative to the Appel reaction.
- Das, Pranab J.,Das, Jupitara,Das, Dimpee
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p. 651 - 654
(2018/02/09)
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- Facile continuous process for gas phase halogen exchange over supported alkyl phosphonium salts
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Chloride-bromide halogen exchange was realized when a mixture of an alkyl chloride and an alkyl bromide were reacted over a supported molten alkyl phosphonium catalyst. Conversion was found to be near equilibrium in a tubular flow reactor at 150 °C and 1500 GHSV. The catalyst was prepared by impregnation of alumina or silica support and found to be highly stable for relatively long periods of time. A pathway for the catalytic cycle is proposed.
- Sharma, Priti,Sasson, Yoel
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p. 2824 - 2828
(2018/02/06)
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- B(C6F5)3-Catalyzed Chemoselective Defunctionalization of Ether-Containing Primary Alkyl Tosylates with Hydrosilanes
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Catalytic C(sp3)?O bond cleavage promoted by B(C6F5)3 /Et3SiH proceeds preferentially with primary tosylates in the presence of primary and secondary silyl ethers and aryl ethers. This reactivity difference enables the chemoselective defunctionalization of several 1,n-diols, and the efficiency of the new procedure is highlighted by the selective deoxygenation of the hydroxymethyl group of an orthogonally protected carbohydrate. Tosylates with an adjacent phenyl group are cleaved with anchimeric assistance.
- Chatterjee, Indranil,Porwal, Digvijay,Oestreich, Martin
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supporting information
p. 3389 - 3391
(2017/03/17)
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- Mild partial deoxygenation of esters catalyzed by an oxazolinylborate-coordinated rhodium silylene
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An electrophilic, coordinatively unsaturated rhodium complex supported by borate-linked oxazoline, oxazoline-coordinated silylene, and N-heterocyclic carbene donors [{κ3-N,Si,C-PhB(OxMe2)(OxMe2SiHPh)ImMes}Rh(H)CO][HB(C6F5)3] (2, OxMe2 = 4,4-dimethyl-2-oxazoline; ImMes = 1-mesitylimidazole) is synthesized from the neutral rhodium silyl {PhB(OxMe2)2ImMes}RhH(SiH2Ph)CO (1) and B(C6F5)3. The unusual oxazoline-coordinated silylene structure in 2 is proposed to form by rearrangement of an unobserved isomeric cationic rhodium silylene species [{PhB(OxMe2)2ImMes}RhH(SiHPh)CO][HB(C6F5)3] generated by H abstraction. Complex 2 catalyzes reductions of organic carbonyl compounds with silanes to give hydrosilylation products or deoxygenation products. The pathway to these reactions is primarily influenced by the degree of substitution of the organosilane. Reactions with primary silanes give deoxygenation of esters to ethers, amides to amines, and ketones and aldehydes to hydrocarbons, whereas tertiary silanes react to give 1,2-hydrosilylation of the carbonyl functionality. In contrast, the strong Lewis acid B(C6F5)3 catalyzes the complete deoxygenation of carbonyl compounds to hydrocarbons with PhSiH3 as the reducing agent.
- Xu, Songchen,Boschen, Jeffery S.,Biswas, Abhranil,Kobayashi, Takeshi,Pruski, Marek,Windus, Theresa L.,Sadow, Aaron D.
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p. 15897 - 15904
(2015/09/15)
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- Site-selective aliphatic C-H bromination using N -bromoamides and visible light
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Transformations that selectively functionalize aliphatic C-H bonds hold significant promise to streamline complex molecule synthesis. Despite the potential for site-selective C-H functionalization, few intermolecular processes of preparative value exist. Herein, we report an approach to unactivated, aliphatic C-H bromination using readily available N-bromoamide reagents and visible light. These halogenations proceed in useful chemical yields, with substrate as the limiting reagent. The site selectivities of these radical-mediated C-H functionalizations are comparable (or superior) to the most selective intermolecular C-H functionalizations known. With the broad utility of alkyl bromides as synthetic intermediates, this convenient approach will find general use in chemical synthesis.
- Schmidt, Valerie A.,Quinn, Ryan K.,Brusoe, Andrew T.,Alexanian, Erik J.
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supporting information
p. 14389 - 14392
(2014/12/10)
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- Bromination of hydrocarbons with CBr4, initiated by light-emitting diode irradiation
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The bromination of hydrocarbons with CBr4 as a bromine source, induced by light-emitting diode (LED) irradiation, has been developed. Monobromides were synthesized with high efficiency without the need for any additives, catalysts, heating, or inert conditions. Action and absorption spectra suggest that CBr4 absorbs light to give active species for the bromination. The generation of CHBr3 was confirmed by NMR spectroscopy and GC-MS spectrometry analysis, indicating that the present bromination involves the homolytic cleavage of a C-Br bond in CBr4 followed by radical abstraction of a hydrogen atom from a hydrocarbon.
- Nishina, Yuta,Ohtani, Bunsho,Kikushima, Kotaro
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p. 1663 - 1667
(2013/10/22)
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- Loss of benzene to generate an enolate anion by a site-specific double-hydrogen transfer during CID fragmentation of o-alkyl ethers of ortho-hydroxybenzoic acids
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Collision-induced dissociation of anions derived from orffco- alkyloxybenzoic acids provides a facile way of producing gaseous enolate anions. The alkyloxyphenyl anion produced after an initial loss of CO2 undergoes elimination of a benzene molecule by a double-hydrogen transfer mechanism, unique to the ortho isomer, to form an enolate anion. Deuterium labeling studies confirmed that the two hydrogen atoms transferred in the benzene loss originate from positions 1 and 2 of the alkyl chain. An initial transfer of a hydrogen atom from the C-l position forms a phenyl anion and a carbonyl compound, both of which remain closely associated as an ion/neutral complex. The complex breaks either directly to give the phenyl anion by eliminating the neutral carbonyl compound, or to form an enolate anion by transferring a hydrogen atom from the C-2 position and eliminating a benzene molecule in the process. The pronounced primary kinetic isotope effect observed when a deuterium atom is transferred from the C-l position, compared to the weak effect seen for the transfer from the C-2 position, indicates that the first transfer is the rate determining step. Quantum mechanical calculations showed that the neutral loss of benzene is a thermodynamically favorable process. Under the conditions used, only the spectra from ortho isomers showed peaks at mlz 77 for the phenyl anion and mlz 93 for the phenoxyl anion, in addition to that for the ortho-specific enolate anion. Under high collision energy, the ortho isomers also produce a peak at mlz 137 for an alkene loss. The spectra of meta and para compounds show a peak at mlz 92 for the distonic anion produced by the homolysis of the O-C bond. Moreover, a small peak at mlz 136 for a distonic anion originating from an alkyl radical loss allows the differentiation of para compounds from meta isomers. Copyright
- Attygalle, Athula B.,Bialecki, Jason B.,Nishshanka, Upul,Weisbecker, Carl S.,Ruzicka, Josef
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experimental part
p. 1224 - 1234
(2009/09/29)
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- Reactivity of anionic nucleophiles in ionic liquids and molecular solvents
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The nucleophilic reactivity of a representative series of anions has been measured in [hmim][ClO4] 3i, [hm2im][ClO4] 3′i, and [hmim][PF6] 3l ILs in the reaction with n-alkyl methanesulfonates and compared with that found in common molecular solvents (MeOH, DMSO, PhCl). The reactivity is found to depend on both the imidazolium cation-anion interaction and the specific solvation by water present in the IL, the water playing the main effect, in particular with hydrophilic anions. Removal of the largest quantity of water remarkably increases the ion pair reactivity in the IL up to rate constant value k comparable with those obtained in DMSO and in low polarity media (PhCl).
- Betti, Cecilia,Landini, Dario,Maia, Angelamaria
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p. 1689 - 1695
(2008/09/18)
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- PROCESS FOR PRODUCING 2-ALKOXYETHYL BROMIDE
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A process for 2-alkoxyethyl bromide production which comprises reacting a 2-alkoxyethanol with thionyl bromide in the presence of one or more compounds having an amide or urea bond in the molecule, the one or more compounds being used in an amount of at least 0.8 mole equivalents per mole of the 2-alkoxyethanol. By the process, a high-purity 2-alkoxyethyl bromide can be produced in a high yield while inhibiting the generation of impurities as by-products.
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Page/Page column 9-10
(2008/06/13)
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- Direct bromination and iodination of non-activated alkanes by hypohalite reagents
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The direct functionalisation of alkanes through bromination and iodination has been successfully achieved. The combination of stoichiometric mixtures of elemental halogen and sodium alkoxides leads to the formation of alkyl hypobromites and hypoiodites as reagents. The halogenation occurs without external photostimulation under thermal reaction conditions. Georg Thieme Verlag Stuttgart.
- Montoro, Raul,Wirth, Thomas
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p. 1473 - 1478
(2007/10/03)
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- Process to convert alkanes into primary alcohols
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This invention provides a process to convert alkanes to primary alcohols of the same carbon number. Carbon numbers of particular interest are C8 to C18. The process comprises the steps of: a) halogenating a linear or branched (or mixture of linear and branched) alkane to produce a mixture of primary mono-haloalkanes, internal mono-haloalkanes, unreacted alkanes, hydrogen halide, and possibly multi-haloalkanes in the presence of a catalyst and/or by heating the reaction mixture; b) separating the hydrogen halide from the mixture and optionally neutralizing it with a metal oxide to produce a partially halogenated metal oxide and/or metal halide which may be regenerated; c) separating the primary mono-haloalkanes from the mixture; d) reacting the separated primary mono-haloalkanes in a reactor with a metal oxide or combination of metal oxides and water to convert the aforesaid primary mono-haloalkane to a mixture of products that contains primary alcohols, unconverted primary mono-haloalkanes, and possibly other reaction products, and a partially halogenated metal oxide and/or metal halide which may be regenerated; e) regenerating the partially halogenated metal oxide and/or metal halide to halogen (such as Cl2) and/or acid and a metal oxide for recycle by reaction with air or oxygen; and f) removing the unreacted primary mono-haloalkane from the reaction mixture and then purifying the primary alcohol.
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Page/Page column 4
(2008/06/13)
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- Process to convert linear alkanes into alpha olefins
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This invention provides for a process to convert branched or linear alkanes to branched or linear alpha olefins (AO) of the same carbon number. The process comprises the steps of: a) halogenating linear alkanes, branched alkanes, or a mixture of linear and branched alkane to produce a mixture containing primary mono-haloalkanes and hydrogen halide; b) separating the hydrogen halide from the mixture and optionally neutralizing it with a metal oxide to produce a partially halogenated metal oxide and/or metal halide which may be regenerated; c) separating the primary mono-haloalkanes from the mixture; d) reacting the separated primary mono-haloalkanes with a metal oxide to produce a mixture of products that contains alpha olefins, unconverted primary mono-haloalkanes, possibly other reaction products, and a partially halogenated metal oxide and/or metal halide which may be regenerated; e) regenerating the partially halogenated metal oxide and/or metal halide to halogen and/or acid and a metal oxide (such as Cl2) for recycle by reaction with air or oxygen ; and f) removing the unreacted primary mono-haloalkane from the reaction mixture and then purifying the alpha olefin.
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Page/Page column 4
(2008/06/13)
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- Cyclic amino acid compounds pharmaceutical compositions comprising same and methods for inhibiting β-amyloid peptide release and/or its synthesis by use of such compounds
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Disclosed are compounds which inhibit β-amyloid peptide release and/or its synthesis, and, accordingly, have utility in treating Alzheimer's disease. Also disclosed are pharmaceutical compositions comprising a compound which inhibits β-amyloid peptide release and/or its synthesis as well as methods for treating Alzheimer's disease both prophylactically and therapeutically with such pharmaceutical compositions.
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- Study of activation energy and order of reaction of some liquid crystals
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Liquid crystals of the type p-phenylene-di-p-n-alkoxy benzoate have been prepared. Kissinger isothermal decomposition method has been used for determination of activation energy values of liquid crystals. Kissinger's assessment for shape index of DTA peaks is used to find the order of reaction. There is no direct relationship between the carbon atoms in terminal methylene groups and Ea values. Order of reaction value decreases with increase in heating rate upto carbon atoms 10 in the terminal methylene group but beyond this the order increases or decreases.
- Mundhe
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p. 246 - 249
(2007/10/03)
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- Esterification of carboxylic acid salts
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Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
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- Alkyl radical generation using cyclohexa-1,4-diene-3-carboxylates and 2,5-dihydrofuran-2-carboxylates
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3-Methylcyclohexa-1,4-diene-3-carboxylic acid and 2-methyl-2,5-dihydrofuran-2-carboxylic acid were prepared by Birch reduction and alkylation of benzoic and furoic acid respectively and converted to alkyl esters. Cyclohexadienyl and 2,5-dihydrofuranyl radicals were generated by hydrogen abstraction and characterised by EPR spectroscopy. The esters decomposed thermally in the presence of a radical initiator to generate alkyl radicals which could be trapped with moderate efficiency by halogen donors or alkenes. Loss of methyl to afford an alkyl benzoate was an important side reaction at higher temperatures. From the thermal reaction of hex-5-enyl 3-methylcyclohexa-1,4-diene-3-carboxylate the rate constant for hydrogen abstraction from the ester by hexenyl radicals was determined to be 0.82 × 105 dm3 mol-1 s-1 at 140°C.
- Binmore, Gavin,Cardellini, Liberato,Walton, John C.
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p. 757 - 762
(2007/10/03)
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- Radical-chain Decomposition of Cyclohexa-1,4-diene-3-carboxylates and 2,5-Dihydrofuran-2-carboxylates
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3-Methylcyclohexa-1,4-diene-3-carboxylates and 2-methyl-2,5-dihydrofuran-2-carboxylates decompose to generate free alkyl radicals which have been incorporated into chain reactions producing alkyl bromides, alkene adducts and ring-closure products.
- Binmore, Gavin,Walton, John C.,Cardellini, Liberato
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- Preparation of 6-0-alkylelsamicin A derivatives
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This invention relates to novel elsamicin A derivatives having 6-O-alkyl substitutent, a process for producing said elsamicin A derivatives, antitumor compositions containing the same as the active ingredient, and a method for therapy using said compositions.
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- Cyclic azaaliphatic compounds with a nitroxy function, processes for the preparation thereof and pharmaceutical compositions containing them
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The present invention provides anti-angina pharmaceutical compositions containing at least one compound of the formula: STR1 wherein n is 1 or 2, R is a hydrogen atom or an H-(C1 -C8)-alkylene, hydroxy-(C1 -C8)-alkylene, R1 R2 N-(C1 -C8)-alkylene, R1 R2 N-(C1 -C8)-alkylene-CO--, R1 R2 N-CO-NR3 -(C1 -C8)-alkylene or R1 R2 N-CO-- radical, A is a valency bond or an --NR4 --CO-- or --CO--NR4 -- radical, R4 is a hydrogen atom or a straight-chained or branched, saturated or unsaturated of cyclic alkyl radical containing up to 6 carbon atoms and B is a valency bond or a straight-chained or branched alkylene chain containing up to 8 carbon atoms, in which a --CH2 -- group can be replaced by a cycloalkylene radical containing 3 to 7 carbon atoms.
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- DESIGN AND REACTIVITY OF ORGANIC FUNCTIONAL GROUPS - 2-PYRIDYLSULFONATES AS NUCLEOFUGAL ESTERS: REMARKABLY MILD TRANSFORMATIONS INTO HALIDES AND OLEFINS
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The novel 2-pyridylsulfonate esters are excellent leaving groups for the preparation of bromides and olefins under very mild reaction conditions.Displacements occur with inversion of configuration.
- Hanessian, Stephen,Kagotani, Masahiro,Komaglou, Kossi
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p. 1115 - 1120
(2007/10/02)
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- Electron Spin Resonance Spectra and Structure of the Radical Cations of Dibromoalkanes and Monobromoalkanes
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The radical cations of dibromoalkanes containing two bromines separated by an alkyl chain, have been generated by exposing dilute solutions of the dibromoalkanes in freon to X-rays at 77 K.Two types of e.s.r. spectra were observed for these cations.The spectra obtained for Br(CH2)nBr, n = 1-7, show septet features characteristic of two equivalent Br nuclei.The coupling constant of the septet increases and reaches a plateau, with increased n in these dibromoalkanes.This indicates that a positive hole in these cations is shared, not by the two Br nuclei connected through ?-delocalization over the chain, but by the two Br nuclei directly bonded to each other, in accordance with conclusions recently drawn from e.s.r. studies of dichloroalkane cations.In contrast, the e.s.r. spectra obtained for Br(CH2)nBr, n > 7, are more complicated.When similar experiments were carried out with H(CH2)nBr, n > 7, analogous spectra were obtained, indicating that the spectra observed for these dibromoalkanes can be interpreted in terms of hyperfine interactions to only one of the two Br nuclei and to two nuclei with nuclear spins of 1/2.This result, considered together with the fact that similar cationic centres were detected for H(CH2)nBr, n > 3, and with the spectral change observed for Br(CH2)nBr and H(CH2)nBr cations in different matrices (CCl2FCClF2, CCl3F, and CCl4) indicates that cyclization also occurs for these cations, the positive hole being occupied in a three-centre bond comprising a Br nucleus, a C nucleus (four atoms away from the Br nucleus), and an H nucleus bonded to the C nucleus.
- Hasegawa, Akinori,Symons, Martyn C. R.,Shiotani, Masaru
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p. 657 - 666
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS. 10. THE BASE-INDUCED REACTION OF BROMINE WITH ORGANOBORNES. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO ALKYL BROMIDES VIA HYDROBORATION
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The reaction of trialkylboranes with bromine is greatly accelerated by base.Bromination in the presence of sodium hydroxide provides alkyl bromide along with a large amount of the corresponding alcohol.The use of sodium methoxide as a base eliminates this undesirable side reaction and provides an improved yield of alkyl bromide.Consequently, hydroboration, followed by bromination in the presence of sodium methoxide, provides a convenient new procedure for the conversion of alkenes into alkyl bromides.The organoboranes, obtained via hydroboration of terminal alkenes, react with the utilization of all three alkyl groups attached to boron, providing nearly quantitative yields of alkyl bromides. This procedure also accommodates common organic functional groups, as demonstrated by the preparation of methyl 11-bromoundecanoate and 11-bromoundecyl acetate from the corresponding functionally substituted alkenes.Under these conditions, secondary and bulky primary alkyl groups react more sluggishly.However, a procedure involving simultaneous addition of bromine and methanolic sodium methoxide provides improved results for such derivatives.Surprisingly, the base-induced bromination of tri-exo-nobornylborane results in an inversion of configuration at the reaction center to give predominantly endo-2-bromonorbornane.A mechanism is proposed to account for this remarkable inversion.
- Brown, Herbert C.,Lane, Clinton F.
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p. 2763 - 2772
(2007/10/02)
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- Reactions of Alkylmercurials with Heteroatom-Centered Acceptor Radicals
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The relative reactivities of alkylmercury halides toward PhS., PhSe., or I. decrease drastically from R = tert-butyl to R = sec-alkyl to R = n-butyl, indicative that R. is formed in the rate-determining step in the attack of these radicals upon RHgCl.The alkyl radicals thus formed will enter into chain reactions in which a heteroatom-centered radical (A.) is regenerated from substrates such as RS-SR, ArSe-SeAr, ArTe-TeAr, PhSe-SO2Ar, Cl-SO2Ph; ZCH=CHA (A = Cl, I, SPh, SO2Ph); or PhCCHA (A = I, SPh, SO2Ph). β-Styrenyl (PhCH=CHA, Ph2C=CHA) and β-phenethynyl (PhCCA) systems with A = I, Br, SO2Ph also enter into chain reactions with mercury(II) salts with the ligands PhS, PhSe, PhSO2, or (EtO)2PO.The relative reactivities of a series of reagents toward t-Bu. and of PhCH=CHA, Ph2C=CHA, and PhCCA toward c-C6H11. are reported as well as the regioselectivity of t-Bu. attack observed for 1,2-disubstituted ethylenes (ZCH=CHA) with Z and A from the group Ph, Cl, Br, I, SO2Ph, SPh, Bu3Sn.Reactions of (E)- and (Z)-PhCH=CHI or MeO2CCH=CHI with t-Bu. or c-C6H11. occurred in a regioselective and stereospecific (retention) manner.Reactions of (E)- and (Z)-ClCH=CHCl occurred in a nonstereospecific manner in which the E/Z product ratio increased with the bulk of the attacking radical.A similar effect on the E/Z product ratios was observed for (Z)-MeO2CCH=CHCl.
- Russell, Glen A.,Ngoviwatchai, Preecha,Tashtoush, Hasan I.,Pla-Dalmau, Anna,Khanna, Rajive K.
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p. 3530 - 3538
(2007/10/02)
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- New Reagents, XXXII, Alkyldiphenylbismutanes: Synthesis, Properties, and Halogenolysis
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Alkyldiphenylbismutanes 1 have been synthesized for the first time (61-92 percent).These compounds are air sensitive, not spontaneously inflammable liquids which decompose not below ca. 170 deg C.The diphenylbismutino group is very good equivalent for Cl- or Br-substituents at aliphatic residues since halogenolysis of the Bi-Alk bond with SO2Cl2 or Br2 already occurs at -40 to 0 deg C (corresponding fissions of As-Alk and Sb-Alk bonds afford heating to ca. 130 or ca. 220 deg C).
- Kauffmann, Thomas,Steinseifer, Fritz
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p. 1031 - 1038
(2007/10/02)
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- Biphasic hydrogenation of olefins, dienes, and α,β-unsaturated carbonyl compounds catalyzed by the dimer of chloro(1,5-hexadiene)rhodium
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Olefins, dienes, and trienes can be hydrogenated in an aqueous-organic two-phase medium using the dimer of chloro(1,5-hexadiene)rhodium as the catalyst.Selective reduction of the double bond of α,β-unsaturated carbonyls occurs in high yields.These reactions occur at room temperatures and atmospheric pressure, and are simple to work up.
- Januszkiewicz, Krzysztof R.,Alper, Howard
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p. 1031 - 1033
(2007/10/02)
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- Antibiotics and derivatives thereof having β-lactamase inhibitory activity and production thereof
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A novel antibiotic substance of the formula STR1 wherein R1 is CH3 and R2 is --CH2 --CH2 -- or R1 is H and R2 is --CH=CH--; and R3 represents hydrogen, lower alkyl or triphenylmethyl, and including the salts of the compound of formula (I) wherein R3 is hydrogen, said antibiotic substance having strong antibiotic activity and β-lactamase inhibiting effect, and a method for producing the same by aerobic cultivation of Streptomyces A271.
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- LIQUID CRYSTALLINE PROPERTIES OF 4-N-ALKOXYPHENYL 4-NITROBENZOATES.
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Twelve 4-alkoxyphenyl esters of 4-nitrobenzoic acid were synthesized. The mesophases were identified and the transition temperatures and enthalpies determined. The above series shows considerable similarity to the reverse analogues, i. e. , the 4-nitro-phenyl 4-n-alkoxybenzoates.
- Galewski,Sobczyk
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- FREE-RADICAL TRANSFORMATIONS OF TRIALKOXYMETHANES IN POLYHALOGENOALKANE MEDIA
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The free-radical transformations of trialkoxymethanes in chloroform, bromoform, and carbon tetrachloride lead to the formation of the corresponding dialkyl carbonates, alkyl formates, alkanes, alkanals, halogenoalkanes, and α-halogeno ortho esters.A mechanism for the transformations is proposed, and the reactivity of the various C-H bonds in the trialkoxymethane molecules is evaluated; the bond adjacent to the three oxygen atoms is most active.
- Rol'nik, L. Z.,Kalashnikov, S. M.,Pastushenko, E. V.,Zlot-skii, S. S.,Rakhmankulov, D. L.
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p. 2246 - 2249
(2007/10/02)
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- Selectivity in the Halogenation of Hexane by Tertiary Aminium Radicals from the Photodecomposition of N-Halogenoammonium Perchlorates
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The photochlorination of hexane with tertiary N-chloroammonium perchlorates in trifluoroacetic acid gives monochlorohexanes in high yield and with a striking preference for the 2-isomer.It is shown that free-radical chains are involved in which hydrogen-atom abstraction is by tertiary aminium radicals.The marked preference for 2- compared with 3-chlorination is attributed mainly to the bulky aminium radical attacking the relatively more accessible 2-position; an alternative explanation involving a reversible hydrogen-atom abstraction is ruled out.The magnitude of the primary deuterium kinetic isotope effect in these photochlorinations gives information about the dependence of the extent of C-H bond breakage in the transition state on the structure of the abstracting aminium radical.
- Fuller, Steven E.,Smith, John R. Lindsay,Norman, Richard O. C.,Higgins, Raymond
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p. 545 - 552
(2007/10/02)
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- DEALUMINOXYLATION OF ALUMINUM ALLYL OR BENZYL ALKOXIDES AND DEOXYGENATION OF ALLYL ETHERS BY LITHIUM ALUMINUM HYDRIDE IN THE PRESENCE OF TITANIUM CATALYST
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Various aluminum allyl and benzyl alkoxides and allyl ethers undergo hydrogenolysis by LiAlH4 in the presence of catalytic amount of TiCl4 or Cp2TiCl2.Thus, the present reaction provides a convenient method for replacing oxygen-containing functional groups at the allylic or benzylic position by hydrogen.
- Sato, Fumie,Tomuro, Yasuji,Ishikawa, Hiroaki,Oikawa, Takeshi
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p. 103 - 106
(2007/10/02)
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- Preparation of aliphatic perchlorates and of trifluoromethane sulfonates
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The formation of predominantly primary aliphatic perchlorates and trifluoethanesulfonates by reacting the corresponding silver salt with primary aliphatic halides in benzene at a temperature from about 5° C. to about 50° C. Primary aliphatic perchlorates and trifluoromethanesulfonates are excellent alkylating agents for amines, alcohols, and nitroalcohols.
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- 1-[2-(1-Adamantyl)-2-(R-thio)ethyl]imidazoles and 1-[2-(1-adamantyl)-2-(R-oxy)ethyl]imidazoles
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Compounds of the formula STR1 wherein R is alkyl, cycloalkyl, cycloalkyl lower alkyl, phenyl or phenyl lower alkyl, said phenyl and phenyl lower alkyl optionally substituted on the phenyl ring with one or more substituents independently selected from the group consisting of halo, lower alkyl and trifluoromethyl; and X is oxygen or sulfur with the proviso that X is not oxygen when R is phenyl or substituted phenyl; and the antimicrobial acid addition salts thereof are useful as antifungal, antibacterial and antiprotozoal agents.
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