- Photochemical Production of Ethane from an Iridium Methyl Complex
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An iridium methyl complex, [Cp?Ir(bpy)(CH3)]+, was prepared by electrophilic methylation of Cp?Ir(bpy) with CH3I and characterized electrochemically, photophysically, crystallographically, and computationally. Irradiation of the MLCT transition of [Cp?Ir(bpy)(CH3)]+ in the presence of CH3I in acetonitrile produces ethane, methane, propionitrile, and succinonitrile. A series of mechanistic studies indicates that C-C bond formation is mediated by free methyl radicals produced through monometallic photochemical homolysis of the Ir-CH3 bond.
- Pitman, Catherine L.,Miller, Alexander J. M.
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Read Online
- Reactions in water: Alkyl nitrile coupling reactions using Fenton's reagent
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(Chemical Equation Presented) The coupling reaction of water-soluble alkyl nitriles using Fenton's reagent (Fe(II) and H2O2) is described. The best metal for the reaction is iron(II), and the greatest yields are obtained when the concentration of the metal is kept low. Hydrogen-atom abstraction is selective, preferentially producing the radical α to the nitrile. In order to increase the production of dinitrile, in situ reduction of iron(III) to iron(II), using a variety of reducing agents, was investigated.
- Keller, Christopher L.,Dalessandro, James D.,Hotz, Richard P.,Pinhas, Allan R.
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Read Online
- Photocatalytic C-H activation and the subtle role of chlorine radical complexation in reactivity
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The functionalization of methane, ethane, and other alkanes derived from fossil fuels is a central goal in the chemical enterprise. Recently, a photocatalytic system comprising [CeIVCl5(OR)]2- [CeIV, cerium(IV); OR, -OCH3 or -OCCl2CH3] was disclosed. The system was reportedly capable of alkane activation by alkoxy radicals (RO·) formed by CeIV-OR bond photolysis. In this work, we present evidence that the reported carbon-hydrogen (C-H) activation of alkanes is instead mediated by the photocatalyst [NEt4]2[CeCl6] (NEt4+, tetraethylammonium), and RO· are not intermediates. Spectroscopic analyses and kinetics were investigated for C-H activation to identify chlorine radical (Cl·) generation as the ratelimiting step. Density functional theory calculations support the formation of [Cl·][alcohol] adducts when alcohols are present, which can manifest a masked RO· character. This result serves as an important cautionary note for interpretation of radical trapping experiments.
- Yang, Qiaomu,Wang, Yu-Heng,Qiao, Yusen,Gau, Michael,Carroll, Patrick J.,Walsh, Patrick J.,Schelter, Eric J.
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p. 847 - 852
(2021/05/28)
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- Combined preparation method of 2-cyano-3-chloro-5-trifluoromethylpyridine and succinonitrile
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The invention discloses a combined preparation method of 2-cyano-3-chloro-5-trifluoromethylpyridine and succinonitrile, and belongs to the field of organic chemistry. The method comprises the following steps: taking 2-fluoro-3-chloro-5-trifluoromethylpyridine and dichloroethane as raw materials, reacting in a potassium cyanide/sodium solution under the action of a phase transfer catalyst to obtaina mixed solution of 2-cyano-3-chloro-5-trifluoromethylpyridine and succinonitrile, layering, washing with water, and rectifying to obtain the 2-cyano-3-chloro-5-trifluoromethylpyridine with the content of more than 99% and the succinonitrile with the content of more than 99.9%. According to the method, the yield is high, the wastewater treatment is simple, byproducts are fully utilized, the yieldof the 2-cyano-3-chloro-5-trifluoromethylpyridine can reach 93%, and the yield of the succinonitrile can reach 95%.
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Paragraph 0024-0036
(2021/02/24)
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- Facile dehydration of primary amides to nitriles catalyzed by lead salts: The anionic ligand matters
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The synthesis of nitrile under mild conditions was achieved via dehydration of primary amide using lead salts as catalyst. The reaction processes were intensified by not only adding surfactant but also continuously removing the only by-product, water from the system. Both aliphatic and aromatic nitriles can be prepared in this manner with moderate to excellent yields. The reaction mechanisms were obtained with high-level quantum chemical calculations, and the crucial role the anionic ligand plays in the transformations were revealed.
- Ruan, Shixiang,Ruan, Jiancheng,Chen, Xinzhi,Zhou, Shaodong
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- Method for continuous preparation of nitriles by amides (by machine translation)
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The method comprises the following steps: preparing a lead salt supported by a molecular sieve by a lead salt and a molecular sieve through an impregnation method; and filling a molecular sieve-loaded lead catalyst into a fixed bed reactor. The amide or amide solution is sent into a fixed bed reactor from the top of the fixed bed to be subjected to catalytic dehydration, and the obtained reaction product is led out from the bottom of the fixed bed. The reaction product is separated to obtain the crude product of the nitrile corresponding to the amide. A fixed bed continuous production process is adopted, the reaction process is simple, the production efficiency is high, the product post-treatment is simple, and industrial production is easy to realize. (by machine translation)
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Paragraph 0033-0054; 0061-0066
(2020/12/15)
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- HCl·DMPU-assisted one-pot and metal-free conversion of aldehydes to nitriles
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We report an efficient HCl·DMPU assisted one-pot conversion of aldehydes into nitriles. The use of HCl·DMPU as both an acidic source as well as a non-nucleophilic base constitutes an environmentally mild alternative for the preparation of nitriles. Our protocol proceeds smoothly without the use of toxic reagents and metal catalysts. Diverse functionalized aromatic, aliphatic and allylic aldehydes incorporating various functional groups were successfully converted to nitriles in excellent to quantitative yields. This protocol is characterized by a broad substrate scope, mild reaction conditions, and high scalability. This journal is
- Hammond, Gerald B.,Mudshinge, Sagar R.,Potnis, Chinmay S.,Xu, Bo
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supporting information
p. 4161 - 4164
(2020/07/14)
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- Copper(II)-Photocatalyzed N-H Alkylation with Alkanes
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We report a practical method for the alkylation of N-H bonds with alkanes using a photoinduced copper(II) peroxide catalytic system. Upon light irradiation, the peroxide serves as a hydrogen atom transfer reagent to activate stable C(sp3)-H bonds for the reaction with a broad range of nitrogen nucleophiles. The method enables the chemoselective alkylation of amides and is utilized for the late-stage functionalization of N-H bond containing pharmaceuticals with good to excellent yields. The mechanism of the reaction was preliminarily investigated by radical trapping experiments and spectroscopic methods.
- Donabauer, Karsten,K?nig, Burkhard,Narobe, Rok,Yakubov, Shahboz,Zheng, Yi-Wen
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p. 8582 - 8589
(2020/09/23)
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- Method for continuous preparation of nitriles in a pipelined reactor (by machine translation)
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The method comprises the following steps that a tin catalyst is coated on the inner wall of the pipeline reactor; and the method comprises the following steps: coating a tin catalyst on the inner wall of the pipeline reactor. The amide solution and the catalytic auxiliary agent are mixed and then sent to a pipeline reactor, and the amide is dehydrated to generate nitrile at the reaction pressure of 0.1 - 2.0 mpa and 100 - 200 °C reaction temperature. The resulting reaction product was separated to give the crude product of the nitrile to which the amide corresponded. In the pipeline reactor, the corresponding nitrile is continuously prepared under the action of the tin catalyst, a dehydrating agent is not needed, byproducts only are water, and three wastes are reduced. (by machine translation)
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Paragraph 0036-0047; 0056; 0058
(2020/12/14)
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- Method for preparing nitrile by reacting acetone cyanohydrin with haloalkane
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The invention provides a method for preparing nitrile by reacting acetone cyanohydrin with haloalkane. According to the invention, by using acetone cyanohydrin as a cyaniding reagent, the problems, such as long reaction time, low yield, strict reaction conditions and the like enchanted in an existing preparation method in which highly toxic sodium cyanide or potassium cyanide or expensive trimethylsilyl cyanide is used as a cyanogen source, are solved. The method comprises the following steps: dissolving acetone cyanohydrin in a mixed solvent of a high boiling point dipolar aprotic solvent anda low boiling point aprotic solvent, adding a catalyst lithium hydroxide, stirring at 25-50 DEG C for one hour and then adding a haloalkane for continuous reaction for 2-3 hours; next, adding saturated saline water for washing twice, separating out an organic layer, and boiling off the solvent after drying, thereby obtaining a nitrile compound. The method for preparing a nitrile compound disclosed in the invention is characterized by low reaction toxicity, simple process, easy of operation, low production cost, and a yield of more than 95%.
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Paragraph 0043-0049; 0051-0058
(2019/08/20)
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- Double Dehydrogenation of Primary Amines to Nitriles by a Ruthenium Complex Featuring Pyrazole Functionality
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A ruthenium(II) complex bearing a naphthyridine-functionalized pyrazole ligand catalyzes oxidant-free and acceptorless selective double dehydrogenation of primary amines to nitriles at moderate temperature. The role of the proton-responsive entity on the ligand scaffold is demonstrated by control experiments, including the use of a N-methylated pyrazole analogue. DFT calculations reveal intricate hydride and proton transfers to achieve the overall elimination of 2 equiv of H2.
- Dutta, Indranil,Yadav, Sudhir,Sarbajna, Abir,De, Subhabrata,H?lscher, Markus,Leitner, Walter,Bera, Jitendra K.
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supporting information
p. 8662 - 8666
(2018/07/09)
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- Direct cyanomethylation of aliphatic and aromatic hydrocarbons with acetonitrile over a metal loaded titanium oxide photocatalyst
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A platinum-loaded TiO2 (Pt/TiO2) photocatalyst promoted cyanomethylation of aliphatic hydrocarbons, namely cyclohexane and cyclohexene, with acetonitrile, where the photogenerated hole oxidatively dissociates the C-H bond of both the acetonitrile and the aliphatic hydrocarbons to form each corresponding radical species before their radical cross-coupling. The Pt/TiO2 photocatalyst was more active than the Pd/TiO2 photocatalyst in these reactions. In contrast, the cyanomethylation of benzene was promoted by the Pd/TiO2 photocatalyst or a physical mixture of the Pt/TiO2 photocatalyst and a Pd catalyst supported by Al2O3, while it was hardly promoted by the Pt/TiO2 photocatalyst alone. The temperature dependence of the reaction rate proved that the Pd nanoparticles on the TiO2 photocatalyst thermally function as a metal catalyst. These results clearly suggest that the Pd metal catalyst is necessary for the cyanomethylation of benzene. However, in the cyanomethylation of aliphatic hydrocarbons, the catalytic effect of the metal particles was not observed, meaning that the radical coupling takes place without the metal catalysis. Thus, it is concluded that in the case of the benzene cyanomethylation the Pd nanoparticles play dual roles, as a catalyst to catalyse the substitution reaction of benzene with the cyanomethyl radical, and as an electron receiver to reduce the recombination of the photoexcited electrons and holes in the TiO2 photocatalyst, although they could not contribute as a catalyst to the cyanomethylation of aliphatic hydrocarbons.
- Wada, Emiko,Takeuchi, Tomoaki,Fujimura, Yuki,Tyagi, Akanksha,Kato, Tatsuhisa,Yoshida, Hisao
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p. 2457 - 2466
(2017/07/22)
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- Preparation method of butanedinitrile
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The invention discloses a preparation method of butanedinitrile by alkyl dihalide and cyanide. The preparation method comprises the following steps of using alkyl dihalide and cyanide as raw materials, heating in a water and alcohol system, refluxing, and synthesizing, so as to obtain the butanedinitrile; filtering, extracting, and rectifying, so as to obtain a pure product. The preparation method has the advantages that by adopting the preparation technology, the operation is simple and convenient, the condition is mild, and the yield rate is relatively high.
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Paragraph 0007
(2018/02/04)
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- Synthetic method for methotrexate drug intermediate malononitrile
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The invention relates to a synthetic method for methotrexate drug intermediate malononitrile. The synthetic method includes the following steps that 3.9 mol of cyanoacetyl bromine, 0.56 mol of cuprous chloride, 4.6-4.9 mol of a 1,4-nitro-cyanobenzene solution and 500 ml of cyclohexane are added into a reaction container provided with a reactor, a thermometer and a dropping funnel, the stirring speed is controlled to be 150-190 rpm, the solution temperature is raised to 50 DEG C-55 DEG C to carry out a reaction for 5-8 h, pressure is kept at 8-10 kPa, the solution temperature is raised to 80 DEG C-85 DEG C to carry out a reaction for 90-130 min, the solution temperature is raised to 130 DEG C-135 DEG C to carry out a reaction for 4-6 h, the solution temperature is lowered to 10 DEG C-15 DEG C, and a solid is separated, filtered, washed with acetonitrile and ethanediamine, dehydrated with a dehydrating agent, and recrystallized in nitromethane to obtain crystal malononitrile.
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Paragraph 0015; 0016
(2016/11/09)
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- "Nanorust"-catalyzed benign oxidation of amines for selective synthesis of nitriles
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Organic nitriles constitute key precursors and central intermediates in organic synthesis. In addition, nitriles represent a versatile motif found in numerous medicinally and biologically important compounds. Generally, these nitriles are synthesized by traditional cyanation procedures using toxic cyanides. Herein, we report the selective and environmentally benign oxidative conversion of primary amines for the synthesis of structurally diverse aromatic, aliphatic and heterocyclic nitriles using a reusable "nanorust" (nanoscale Fe2O3)-based catalysts applying molecular oxygen.
- Jagadeesh, Rajenahally V.,Junge, Henrik,Beller, Matthias
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- Straightforward synthesis of 1,2-dicyanoalkanes from nitroalkenes and silyl cyanide mediated by tetrabutylammonium fluoride
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A straightforward synthesis of 1,2-dicyanoalkanes by reacting nitroalkenes with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride is described. The reaction proceeds through a tandem double Michael addition under mild conditions. Employing the hypervalent silicate generated from trimethylsilyl cyanide and tetrabutylammonium fluoride is essential for achieving this transformation. Mechanistic studies suggest that a small amount of water included in the reaction media plays a key role. This protocol is applicable to various types of substrates including electron-rich and electron-deficient aromatic nitroalkenes, and aliphatic nitroalkenes. Moreover, vinyl sulfones were found to be good alternatives, particularly for electron-deficient nitroalkenes. The broad substrate scope and functional group tolerance of the reaction makes this approach a practical method for the synthesis of valuable 1,2-dicyanoalkanes.
- Kiyokawa, Kensuke,Nagata, Takaya,Hayakawa, Junpei,Minakata, Satoshi
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supporting information
p. 1280 - 1285
(2015/02/19)
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- Common origins of RNA, protein and lipid precursors in a cyanosulfidic protometabolism
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A minimal cell can be thought of as comprising informational, compartment-forming and metabolic subsystems. To imagine the abiotic assembly of such an overall system, however, places great demands on hypothetical prebiotic chemistry. The perceived differences and incompatibilities between these subsystems have led to the widely held assumption that one or other subsystem must have preceded the others. Here we experimentally investigate the validity of this assumption by examining the assembly of various biomolecular building blocks from prebiotically plausible intermediates and one-carbon feedstock molecules. We show that precursors of ribonucleotides, amino acids and lipids can all be derived by the reductive homologation of hydrogen cyanide and some of its derivatives, and thus that all the cellular subsystems could have arisen simultaneously through common chemistry. The key reaction steps are driven by ultraviolet light, use hydrogen sulfide as the reductant and can be accelerated by Cu(I)-Cu(II) photoredox cycling.
- Patel, Bhavesh H.,Percivalle, Claudia,Ritson, Dougal J.,Duffy, Colm D.,Sutherland, John D.
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p. 301 - 307
(2015/04/14)
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- METHOD FOR PRODUCING DINITRILE COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for producing a dinitrile compound from a nitrile compound which can use not only a highly toxic substance such as hydrogen cyanide or acrylonitrile but also a stable and safe substance such as acetonitrile as raw materials without requiring to use an expensive catalyst. SOLUTION: There is provided a method for producing a dinitrile compound by dimerization of a nitrile compound by a dielectric barrier discharge. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0047; 0050
(2017/07/11)
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- Thermal decomposition of diethylketone cyclic triperoxide in polar solvents
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The thermolysis of diethylketone cyclic triperoxide (3,3,6,6,9,9-hexaethyl- 1,2,4,5,7,8-hexaoxacyclononane, DEKTP) was studied in different polar solvents (ethanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, and acetonitrile). The rate constant values (kd) are higher for reactions performed in secondary alcohols probably because of the possibility to form a cyclic adduct with the participation of the hydrogen atom bonded to the secondary carbon. The kinetic parameters were correlated with the physicochemical properties of the selected solvents. The products of the DEKTP thermal decomposition in different polar solvents support a radical-based decomposition mechanism. CSIRO 2014.
- Barreto, Gaston P.,Alvarez, Elida E.,Eyler, Gladys N.,Canizo, Adriana I.,Allegretti, Patricia E.
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p. 881 - 886
(2014/07/07)
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- A heterogeneous palladium catalyst hybridised with a titanium dioxide photocatalyst for direct C-C bond formation between an aromatic ring and acetonitrile
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A palladium catalyst hybridised with a titanium dioxide photocatalyst can promote cyanomethylation of an aromatic ring by using acetonitrile, where the photocatalyst activates acetonitrile to form a cyanomethyl radical before the C-C bond formation using the palladium catalyst.
- Yoshida, Hisao,Fujimura, Yuki,Yuzawa, Hayato,Kumagai, Jun,Yoshida, Tomoko
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supporting information
p. 3793 - 3795
(2013/05/22)
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- Molecular iodine in aqueous ammonia: Oxidative fragmentation of oxiranes to nitriles
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Oxiranes undergo oxidative fragmentation, when treated with iodine in aqueous ammonia, to give nitriles. The reaction goes via formation of 1,2-amino alcohols as intermediates followed by CC bond cleavage. Advantages of the method are use of off-the-shelf nonexplosive, unlike previously used potentially explosive o-iodoxybenzoic acid, reagents, mild reaction conditions, and easy work-up procedure.
- Jadhav, Ravindra R.,Akamanchi, Krishnacharya G.
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p. 162 - 164
(2013/03/28)
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- Synthesis of biobased succinonitrile from glutamic acid and glutamine
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Succinonitrile is the precursor of 1,4-diaminobutane, which is used for the industrial production of polyamides. This paper describes the synthesis of biobased succinonitrile from glutamic acid and glutamine, amino acids that are abundantly present in many plant proteins. Synthesis of the intermediate 3-cyanopropanoic amide was achieved from glutamic acid 5-methyl ester in an 86 mol % yield and from glutamine in a 56 mol % yield. 3-Cyanopropanoic acid can be converted into succinonitrile, with a selectivity close to 100 % and a 62 % conversion, by making use of a palladium(II)-catalyzed equilibrium reaction with acetonitrile. Thus, a new route to produce biobased 1,4-diaminobutane has been discovered. Copyright
- Lammens, Tijs M.,N?tre, Jér?me Le,Franssen, Maurice C. R.,Scott, Elinor L.,Sanders, Johan P. M.
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experimental part
p. 785 - 791
(2012/05/04)
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- METHOD FOR MANUFACTURING COMPOUNDS INCLUDING NITRILE FUNCTIONS
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A process for the preparation of compounds containing nitrile functions and, more specifically, compounds containing two nitrile functions, such as succinonitrile and adiponitrile, is described. A process for preparing dintrile compounds obtained by reacting ammonia with an aqueous solution of a dicarboxyl compound in the presence of a silicon orthophosphate catalyst is also described.
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Page/Page column 2
(2011/12/12)
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- Highly efficient solvent-free catalytic hydrogenation of solid alkenes and nitro-aromatics using Pd nanoparticles entrapped in aluminum oxy-hydroxide
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Solid alkenes and aromatic nitro compounds are readily hydrogenated to the corresponding alkanes without further reduction of other functional group and amino compounds in nearly quantitative yields in the presence of Pd nanoparticles entrapped in aluminum oxy-hydroxide under the solvent-free condition.
- Chang, Fei,Kim, Hakwon,Lee, Byeongno,Park, Sungho,Park, Jaiwook
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experimental part
p. 4250 - 4252
(2010/09/07)
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- Catalyst for the Preparation of Fumaronitrile and/or Maleonitrile
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The invention relates to a catalyst comprising a titanium dioxide carrier and a mixture of metal oxides comprising at least one oxide of a metal selected from the group consisting of vanadium and tungsten and silicon oxide, comprised in such an amount that silicon (Si) is present in the catalyst in an amount of at least 1.0 wt %, relative to the weight of the catalyst. The invention also relates to a process for the preparation of fumaronitrile and/or maleonitrile by ammoxidation of C4-straight chain hydrocarbons in the presence of a catalyst according to the invention.
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Page/Page column 3-4
(2008/06/13)
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- Rhodococcus nitrile hydratase
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The invention relates to a Rhodococcus polynucleotide cluster which contains nucleotide sequences which encode polypeptides having the activity of a nitrile hydratase, of an auxiliary protein P15K which activates this enzyme and of a cobalt transporter, to transformed microorganisms in which the nucleotide sequences encoding these proteins are present in increased quantity, and to the use of the transformed microorganisms for preparing amides from nitriles.
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- Chemistry of α-Amino Nitriles. Exploratory Experiments on Thermal Reactions of α-Amino Nitriles
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The paper extends a previously published report on chemical properties of α-amino nitriles and of members of the C3H4N2 ensemble (Scheme 1) as observed in experiments carried out under non-aqueous conditions.The reactions investigated and the observations made are summarized in some detail in the English footnotes (*) referring to Schemes 1-17 and Fig. 1.
- Xiang, Yi-Bin,Drenkard, Susanne,Baumann, Karl,Hickey, Deirdre,Eschenmoser, Albert
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p. 2209 - 2250
(2007/10/02)
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- ELECTROCHEMICAL TRIFLUOROMETHYLATION OF OLEFINS; PRODUCT-SELECTIVITY AND MECHANISTIC ASPECTS
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Trifluoroacetic acid (TFA) can be converted almost quantitatively to the trifluoromethyl radicals by electrochemical oxidation of TFA.The electrolysis is conducted in an MeCN-H2O-(Pt) system using an undivided cell.The electrochemically generated CF3. radicals can attack mostly electron-deficient olefins leading to the trifluoromethylated carbon radicals of which chemical and electrochemical fate can be controlled by current density, reaction temperature, and substituents of olefins.
- Uneyama, Kenji
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p. 555 - 562
(2007/10/02)
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- Electrochemical Hydrotrifluoromethylation of Fumaronitrile
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Electrooxidation of trifluoroacetic acid in the presence of fumaronitrile (1) in an MeCN-H2O-(Pt) system provides 2-(trifluoromethyl)succinonitrile (2) in a 65percent yield.The electrochemical reaction is remarkably affected by the reaction temperature.That is, at the ice-cooling temperature, a simple hydrogenation of 1 predominates, while at 50-55 deg C, the desired hydrotrifluoromethylation proceeds exclusively.The anodically generated trifluoromethyl radicals recombine with the succinonitrile radicals produced at the cathode, leading to the formation of 2.
- Uneyama, Kenji,Watanabe, Shunsuke
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p. 3909 - 3912
(2007/10/02)
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- Direct Spectroscopic Detection of Sulfonyloxy Radicals and First Measurements of Their Absolute Reactivities
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Two sulfonyloxyl radicals, CH3S(=O)2O., 2a, and 3-CF3C6H4S(=O)2O., 2b, have been generated by 308-nm laser flash photolysis (LFP) of their parent symmetrical peroxides in CH3CN solution, in which they have lifetimes of 7-20 μs.Both radicals exhibit a broad, structureless absorption similar to that known for SO4.- with λmax ca. 450 nm.This absorption can be bleached for 2a but not for 2b by firing a second laser at 480 nm, presumably reflecting a photoinduced cleavage of the H3C-SO3. bond.Radicals 2a and 2b react with the acetonitrile solvent by abstraction of a hydrogen atom, kH ca. 1.6*105 M-1 s-1, kH/kD ca. 2.0.Bimolecular rate constants for attack of these radicals on cyclohexane (viz., 1.9*108 and 6.5*108 M-1 s-1 for 2a and 2b, respectively) and chloroform (viz. ca., 3*105 M-1 s-1 for both) demonstrate that they are more reactive than almost all other oxygen-centered radicals.Product studies demonstrate that both the photodecomposition and the thermal decomposition of the parent peroxides yield the corresponding sulfonyloxy radicals, a result that contrasts with that we have previously obtained for the decomposition of 2, which yields radicals on photolysis but few if any radicals on thermolysis.Semiempirical AM1/PM3-UHF calculations on 2a are also reported.
- Korth, Hans-Gert,Neville, Anthony G.,Lusztyk, Janusz
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p. 8835 - 8839
(2007/10/02)
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- Photoinduced hydrometalation and hydrogenation of activated olefins with molybdenum and tungsten dihydrides (Cp2MH2)
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The early-transition-metal hydrides Cp2MoH2, Cp2WH2, and Cp2ReH rapidly form a series of electron donor-acceptor (EDA) complexes with various activated olefins as shown by the spontaneous appearance of vivid colors, the absorption energies of which correlate with the electron affinity of the olefinic acceptor and the oxidation (ionization) potential of the hydridometal donor in accord with Mulliken theory. Deliberate excitation of the charge-transfer absorption band leads to the quantitative hydrometalation of fumaronitrile by Cp2MoH2 at 25°C, and the structure of the σ hydrido alkyl adduct Cp2Mo(CHCNCH2CN)H (I) has been established by X-ray crystallography, (space group P21, monoclinic, with a = 8.090 (3) A?, b = 10.282 (4) A?, c = 8.316 (3) A?, β = 116.92 (3)°, V = 617 A?3, Z = 2, R = 0.028, Rw = 0.028 for 1802 reflections with I > 3σ having 2θ ≤ 60°). Under the same photochemical conditions, the tungsten analogue Cp2WH2 effects quantitative hydrogenation and leads to succinonitrile together with the olefinic π-adducts to tungstenocene in high yields. (In both cases, the thermal (dark) processes are nonexistent) The charge-transfer mechanism for olefin hydrometalation and hydrogenation stemming from charge separation in the EDA complex (i.e. [Cp2MH2?+,>C--C ?ox of the hydridometal species and the subsequent facile proton transfer from the labile cation radical Cp2MH2?+ (M = Mo, W) to the acceptor moiety. The close similarity of the photoinduced process for olefin hydrometalation and hydrogenation of various activated olefins with those effected thermally at higher temperatures is discussed.
- Ko,Bookman,Kochi
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p. 1833 - 1842
(2008/10/08)
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- THIONO COMPOUNDS. 7. OXIDATION OF THIOAMIDES IN RELATION TO ADVERSE BIOLOGICAL EFFECTS
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Thioacetamide, thioacetamide S-oxide (1), and thiopivalamide S-oxide (8) were oxidized with H2O2 in H2(18)O to generate the corresponding amides with at least 50percent 18O incorporation; hydrolysis of the S-oxides to the amides or 18O exchange with the amides occurs much more slowly.When 1 and trifluorothioacetamide (6) were oxidized with three and four equivalents of H2O2, respectively, in the presence of benzylamine, N-acetylbenzylamine (5) and N-benzyltrifluoroacetamide (7) were isolated in respective yields of 17percent and 37percent.These results are interpreted as evidence for an oxidative desulfurization mechanism involving nucleophilic attack at the carbon atom of an S,S-dioxide or trioxide intermediate as the major pathway; a minor pathway may involve the intermediacy of an oxathiirane S-oxide (3) or dioxide (4) species.Understanding is added to the behavior of S-oxides in aqueous solution, as well as to thermal stability in deuterochloroform.Also reported are studies of the preparation and properties of some N,N-dialkyl derivatives of 8, of reduction of 1 with NADH or NADPH, and of generation and trapping of species related to sulfoxylate ion.
- Hillhouse, John H.,Blair, Ian A.,Field, Lamar
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p. 169 - 184
(2007/10/02)
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- Redox Kinetics of Metal Complexes in Non-aqueous Solutions. Part 13. The Ferriin Oxidation of Aprotic Donors in Acetonitrile: Relationships between Donor and Reducing Capabilities
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The reactions of a variety of neutral donors (D) with ferriin in acetonitrile have been examined.The course of reaction and the products formed vary depending on the base strength and the structure of the donor, the two competing mechanisms discerned being (a) oxidation of D and (b) deprotonation of the residual water or the MeCN solutions initiating the reaction of hydroxide ions with ferriin.For the stability of ferriin solutions, there is a decrease in the order MeNO2 > MeCN > dmf > py > hmpa > Et3N which is the order of increasing donor numbers (DN).The very strong donors hmpa and Et3N (and all other aliphatic amines as well) are readily oxidized via charge transfer in an initially formed 1:1 complex Fe(phen)3D(3+) whose nature is discussed.In the case of Et3N, this complex dissociates spontaneously into ferroin and Et3N(+), the latter giving diethylvinylamine which polymerizes with release of diethylamine.For hmpa, charge transfer in Fe(phen)3(hmpa)(3+) needs base catalysis of a second hmpa molecule.The radical thus formed deprives hydrogen from acetonitrile forming succinonitrile.In contrast, Et3PO though being similar in basicity, is not oxidized.This comparison emphasizes the peculiar role of alkyl groups linked to nitrogen for the oxidation chemistry of organic substrates.Donors of donor numbers below that of hmpa are not oxidized noticeably but give rise to mechanism (b).The hydroxide formed displaces partly phen, a greenish precipitate separating identified as a novel high-molecular weight congener of tetrakis(phen)diaquo-μ-oxo-di-iron(III).The following stability order of radicals , derived from the donors, is suggested, dmf > hmpa > MeCN > R3N > dmso.Further, the ferriin oxidation of triphenylamine has been examined.
- Schmid, Roland,Soukup, Rudolf W.,Sapunov, Valentin N.
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p. 1045 - 1075
(2007/10/02)
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- Reactions of the 2,6-Di-tert-butyl-4-(N-tert-butylnitrono)-phenoxyl Radical
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The title compound, a phenoxyl radical containing a nitrono group, reacts with alcohols and tert-butylhydroperoxide yielding phenol and products of secondary solvent reactions.The reactions with lead tetraacetate, tert.-butoxy and 2-cyanoisopropyl radicals give high yields of cyclohexadienone adducts (6, 7 and 10) containing unchanged nitrono function.The reaction with dibenzoylperoxide, however, leads to the modification of the nitrono group yielding the N-benzoyloxycarboxamide (8).In the acidic decomposition of the tert-butoxy radical adduct we suggest a nitrenium ion (16) as an intermediate.
- Schulz, Manfred,Bach, Barbara,Reinhardt, Michael
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p. 579 - 587
(2007/10/02)
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- Photochemical Aromatic Cyanomethylation: Aromatic Substitution by Way of Radical Cations
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Photolysis at 254 nm of chloroacetonitrile in the presence of aromatic hydrocarbons led to ring cyanomethylation.In addition radical coupling products were found, especially with toluene where 3-phenylpropionitrile, succinonitrile, and bibenzyl accompanied the tolylacetonitriles.These same byproducts were obtained from toluene and chloroacetonitrile upon thermolysis with peroxide initiators, but no nuclear cyanomethylation was observed.The mechanism for aromatic cyanomethylation involves initial excitation of the aromatic hydrocarbons, followed by an electron transfer (probably by way of an exiplex) to chloroacetonitrile, which was found to quench aromatic fluorescence at high rates.Direct spectral evidence for the resulting radical cation with p-dimethoxybenzen was obtained by using flash laser spectroscopy.Loss of a chloride ion from the resulting radical anion produces a cyanomethyl radical in close proximity to an aromatic radical cation.Coupling leads to the aromatic substitution products whereas radicals escaping from the cage account for the observed byproducts.
- Kurz, M. E.,Lapin, S. C.,Miriam, K.,Hagen, T. J.,Qian, X. Q.
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p. 2728 - 2733
(2007/10/02)
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- Flash Pyrolysis of Selenides. Syntheses of Bibenzyls, Olefins, and Related Compounds
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Pyrolyses of a series of selenides and diselenides were studied. Selenides and diselenides bound with an active methylene group like benzyl gave a variety of substituted bibenzyls and related ethane derivatives in high yields. Other diselenides were easily caused to cleave to give various aromatic and aliphatic olefins in good yields together with elemental selenium. Lepidopterene, paracyclophane, and benzocyclobutene were prepared by thermal cleavage of their corresponding phenylselenomethyl-substituted compounds as an application of the pyrolysis concerned.
- Higuchi, Hiroyuki,Otsubo, Tetsuo,Ogura, Fumio,Yamaguchi, Hachiro,Sakata, Yoshiteru,Misumi, Soichi
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p. 182 - 187
(2007/10/02)
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- Photochemical Aromatic Cyanomethylation
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Cyanomethylation is accomplished by the photolysis of chloroacetonitrile in the presence of aromatics by way of electron transfer followed by radical coupling.
- Lapin, Stephen,Kurz, Michael E.
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p. 817 - 818
(2007/10/02)
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- AMMOXYDATION CATALYTIQUE DES HYDROCARBURES ET REACTIONS APPARENTEES. XXII. AMMOXYDATION DU BENZENE ET DU CYCLOHEXANE
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Benzene ammoxidation at 440-550 deg C/1 at. produces, on V-Mo, Ti-Mo, Bi-Mo (oxides) catalysts, unsaturated C4 (maleo and fumaronitriles) and C6 (mucononitrile and stereoisomers) dinitriles.These initial selectivities fall with increasing conversions, and C6 dinitriles disappear above 10percent conversion by thermal or catalytic degradation.The main initial stereoisomer cis-cis (mucononitrile) is consistent with a 1-2 attack of the aromatic ring, so far unknown in catalytic oxidations.Cyclohexane ammoxidation goes through the oxidative dehydrogenation to benzene and proceduces small amounts of C4 unsaturated dinitriles along with traces of C4, C5 and C6 saturated dinitriles coming from a different reaction path.In both cases, V-Mo and Ti-Mo are the best catalysts for dinitriles production; no C6 formed on Sn-Mo, Sb-Mo and Sn-Sb-Fe-catalysts.
- Simon, Gerard,Germain, Jean-Eugene
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p. 149 - 155
(2007/10/02)
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- Reaction of Guanidinium Salts with Alkyl Bromides and Acid Chlorides
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The guanidinium salt 1a reacts with alkyl bromides 2a-g and acid chlorides 2h-k to give the nitriles 3a-g and the acyl cyanides 3h-k, respectively.Acyl isocyanates 4a,b have been obtained from the guanidinium cyanate 1d and the acid chlorides 2h,l.Reaction of the alkyl bromides 2b,c,m,n and acid chlorides 2h,l with the guanidinium thiocyanate 1e affords alkyl thiocyanates 5a-d and acyl isothiocyanates 6a,b, respectively.
- Kantlehner, Willi,Kapassakalidis, Johannis J.,Speh, Peter,Braeuner, Hans-Juergen
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p. 389 - 393
(2007/10/02)
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- Process for preparing 2-pyrrolidones
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2-PYRROLIDONE OR A SUBSTITUTED 2-PYRROLIDONE IS PREPARED IN HIGH YIELDS BY HYDROGENATING SUCCINONITRILE, OR AN ALKYL-SUBSTITUTED SUCCINONITRILE, AT 50°-200° C. in the liquid phase, in the presence of ammonia and with a partial hydrogen pressure of about 1-50 atmospheres, then the reaction mixture is contacted with water at 100°-300° C. and the desired product recovered.
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