- Infrared Spectrum of Matrix-Isolated Hexamethylenetetramine in Ar and H2O at Cryogenic Temperatures
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The infrared spectra of hexamethylenetetramine (HMT) isolated in an argon matrix at 12 K, frozen in H2O at temperatures from 12 to 200 K, and as a pure solid, are reported.The results of ultraviolet photolysis of matrix-isolated HMT and HMT frozen in H2O ice are also presented, and implications for infrared astronomy and astrochemistry are discussed.Furthermore, a simple technique for incorporating large nonvolatile organic molecules into a matrix is described.
- Bernstein, Max P.,Sanford, Scott A.,Allamandola, Louis J.,Chang, Sherwood
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Read Online
- Cyanocarbon Acids: Direct Evidence That Their Ionization Is Not an Encounter-Controlled Process and Rationalization of the Unusual Solvent Isotope Effects
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The rate of exchange of the acidic hydrogen of tert-butylmalononitrile was examined by using as a tracer, and the process was found not to be inhibited by hydronium ions in dilute aqueous hydrochloric acid solutions.This rules out the Swain-Grunwald mechanism for this reaction under these conditions.The bromination of malonitrile was investigated under conditions where reprotonation of the dicyanomethyl carbanion and its reaction with bromine occur at comparable rates, and the bromination reaction was found to have a specific rate twice that for reprotonation.Reprotonation therefore cannot be a diffusion-controlled process, and malonitrile is not a "normal" acid.The unusually large solvent kinetic isotope effects found for these cyanocarbon acid ionization reactions are explained by postulating that the transferring hydrogen and its positive charge are becoming associated with a solvent cluster rather than with a single water molecule.The thermodynamic acidity constant of malonitrile was determined to be 11.41 in aqueous solution at 25 deg C.
- Hojatti, M.,Kresge, A. J.,Wang, W.-H.
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Read Online
- Hydrolysis study of fluoroorganic and cyano-based ionic liquid anions - Consequences for operational safety and environmental stability
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The hydrolytic stability of ionic liquid anions is a key property with regard to their technical applicability and environmental stability. From a technical point of view hydrolytic processes may lead to reduced durability, diminished technical performance and reduced operational safety in that corrosive and/or toxic hydrolysis products are formed. On the other hand, susceptibility to hydrolytic processes is advantageous where environmental stability and persistency are concerned, since hydrolysis is the most important abiotic degradation pathway in the environment. We investigated the hydrolytic stability of the most common ionic liquid anions, dicyanimide [N(CN) 2]-, tricyanmethanide [C(CN)3]-, tetracyanidoboranate [B(CN)4]-, bis(trifluoromethylsulphonyl)imide [(CF3SO2) 2N]-, trifluorotris(pentafluoroethyl)phosphate [(C 2F5)3PF3]- and 1,1,2,2-tetrafluoroethanesulphonic acid [H(C2F4)SO 3]-, as a function of pH (1, 7, 9 and 13) and temperature. The results show that there was no difference in hydrolytic stability as recorded for 1-ethyl-3-methylimidazolium (IM12) or for the alkali cations. All the anions were stable under neutral and slightly basic conditions (half-lives at 25 °C ?1 year). In strongly acidic and basic solutions, however, B(CN)4-, (CF3SO2)2N -, (C2F5)3PF3- and H(C2F4)SO3- were hydrolytically stable, whereas N(CN)2- and C(CN)3- were not. The kinetics of hydrolysis were recorded and Arrhenius plots were generated for the latter two anions. In addition, their hydrolysis pathways and the resulting products were identified via mass spectrometry. The cytotoxicity of hydrolysed IL solutions towards the mammalian cell line IPC-81 and the identified hydrolysis products (pure compounds) was investigated for a first estimate of their toxicological properties.
- Steudte, Stephanie,Neumann, Jennifer,Bottin-Weber, Ulrike,Diedenhofen, Michael,Arning, Juergen,Stepnowski, Piotr,Stolte, Stefan
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Read Online
- Preparation method of malononitrile and malononitrile prepared by preparation method
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The invention relates to the technical field of chemical synthesis methods, particularly to a malononitrile preparation method and malononitrile prepared thereof. The malononitrile preparation method comprises the following steps: mixing cyanoacetamide, a catalyst and a solvent, heating, refluxing, and introducing phosgene to synthesize malononitrile, wherein the mass ratio of the cyanoacetamide to the catalyst to the solvent is (2.5-3.5):(0.005-0.02):(7.5-10.5), the solvent is any one of dichloromethane, dichloroethane or methylbenzene, and the catalyst is any one or more of diethylamine, N,N-dimethylformamide or pyridine. According to the invention, cyanoacetamide is adopted to synthesize malononitrile in one step under the action of phosgene, wherein the required raw materials are cheap and easy to obtain, the synthetic reaction steps are few, harsh conditions are avoided, the operation is simple, stable and good in controllability, and the yield of the prepared malononitrile can reach 93% or above and is far higher than that of malononitrile obtained through other process schemes; and the preparation method is low in three-waste treatment cost, and has objective economic benefit.
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Paragraph 0056-0103
(2021/05/01)
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- Malononitrile preparation method and malononitrile prepared thereof
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The invention relates to the technical field of chemical synthesis methods, in particular to a malononitrile preparation method and malononitrile prepared thereof. The malononitrile preparation methodcomprises the following steps that cyanoacetamide, a catalyst and a solvent are mixed, heated, refluxed and introduced with phosgene, and malononitrile is synthesized, wherein the mass ratio of the cyanoacetamide to the catalyst to the solvent is (2.5-3.5):(0.005-0.02):(7.5 to 10.5); the solvent is any one of dichloromethane, dichloroethane or methylbenzene; and the catalyst is any one or more ofdiethylamine, N, N-dimethylformamide or pyridine. According to the invention, cyanoacetamide is adopted to synthesize malononitrile in one step under the action of phosgene; the method has the advantages of cheap and easily available required raw materials, few synthesis reaction steps, no harsh conditions, simple operation, stability and good controllability, the yield of the prepared malononitrile can reach 93% or above and is far higher than that of other process schemes, and the preparation method has the advantages of low three-waste treatment cost and objective economic benefits.
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Paragraph 0056-0095; 0103
(2020/08/02)
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- Preparation method of malononitrile
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The invention discloses a preparation method of an important organic synthesis raw material malononitrile, which comprises the following steps: performing a reaction on chloroacetonitrile and hydrogencyanide as raw materials in a tubular reactor, and separating the reaction product by condensation and negative pressure distillation to obtain the malononitrile. The method has the advantages of mild reaction conditions, simple separation and purification process, high product yield and purity, energy saving, environmental protection and low cost.
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Paragraph 0044-0051
(2020/07/24)
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- Synthetic method of malononitrile
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The invention belongs to the technical field of organic synthesis, and provides a malononitrile synthesis method. The synthetic method comprises the following steps: adding dichloromethane and sodiumcyanide into a reaction kettle at a molar ratio of (1: 1)-(3: 1), slowly adding a catalyst into the reaction kettle under stirring and heating conditions, controlling the temperature in the reaction kettle to be 90 DEG C, and carrying out thermal preservation reaction for 5-9 hours after feeding is finished; after the reaction is finished, adding deionized water into an obtained reaction product to wash an organic phase for a plurality of times, separating out the organic phase, drying the organic phase, and rectifying to obtain malononitrile; wherein the catalyst is a composition of aluminumtrichloride and tetrabutylammonium bromide. According to the method, the malononitrile product is directly synthesized by taking cheap dichloromethane as a raw material through a one-step method, theprocess route is simple, and the cost is low.
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Paragraph 0011-0030
(2020/01/08)
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- Synthesis method of malononitrile
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The invention discloses a synthesis method of malononitrile. Metal hydride and dihalomethane are used as an initial reactant system; under the existence of metal iodate catalysts, a dipolar aprotic solvent is used as a reaction auxiliary agent to prepare a target product of malononitrile. The method has the advantages that through the addition of the reaction auxiliary agent for reaction promotion, the malononitrile hydrolysis or alcoholysis due to polar solvents of water, alcohol and the like can be avoided; high yield and high quality of malononitrile are ensured; the malononitrile with theyield higher than 91.0 percent and the purity higher than 99.3 percent can be obtained.
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Paragraph 0038-0041
(2019/02/06)
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- Synthesis method of malononitrile
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The invention relates to the technical field of malononitrile synthesis, and particularly discloses a synthesis method of malononitrile. The synthesis method of the malononitrile comprises the following steps: performing mixing treatment on a solvent, cyanoacetamide, phosphoryl chloride and solid phosgene to obtain suspension, heating to 50 to 90 DEG C, and performing heat-preservation reaction toobtain a malononitrile solution; performing heating distillation treatment on the malononitrile solution, recycling the solvent and the phosphoryl chloride to obtain a distillation residue; performing vacuum reduced pressure distillation treatment on the distillation residue to obtain the malononitrile. The synthesis method of the malononitrile has the advantages of simple process, convenient operation and low cost; the phosphoryl chloride and the solid phosgene are adopted as a mixed dehydrating agent, so that the yield and the quality of a product are greatly improved, and production of solid wastes is avoided.
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Paragraph 0029; 0030; 0031; 0032; 0033; 0034; 0035-0053
(2018/05/16)
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- Corresponding amine nitrile and method of manufacturing thereof (by machine translation)
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The present invention relates to a nitrile manufacturing method, which has characteristics of significantly-reduced ammonia source consumption, low environmental pressure, low energy consumption, low production cost, high nitrile purity, high nitrile yield and the like compared with the method in the prior art, wherein nitrile having a complicated structure can be obtained through the method. The present invention further relates to a method for producing a corresponding amine from the nitrile.
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Paragraph 0136; 0137; 0140
(2018/07/15)
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- Corresponding amine nitrile and method of manufacturing thereof
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The invention relates to a preparation method of nitrile. Compared with the prior art, the preparation method has the characteristics of obvious reduction of the usage amount of ammonia sources, low environmental pressure, low energy consumption, low production cost, high purity and yields of nitrile products, and the like, and can be used for obtaining nitrile with a more complex structure. The invention also relates to a method for preparing corresponding amine with nitrile.
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Paragraph 0136; 0137; 0140
(2018/05/24)
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- Corresponding amine nitrile and method of manufacturing thereof
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The invention relates to a preparation method of nitrile. Compared with the prior art, the preparation method has the characteristics of obvious reduction of the usage amount of ammonia sources, low environmental pressure, low energy consumption, low production cost, high purity and yields of nitrile products, and the like, and can be used for obtaining nitrile with a more complex structure. The invention also relates to a method for preparing corresponding amine with nitrile.
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Paragraph 0137; 0138; 0139; 0140; 0141
(2018/07/15)
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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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- Organocatalyzed and uncatalyzed C=C/C=C and C=C/C=N exchange processes between knoevenagel and imine compounds in dynamic covalent chemistry
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Molecular diversity generation through reversible component exchange has acquired great importance in the last decade with the development of dynamic covalent chemistry. We explore here the recombination of components linked by C=C and C=N bonds through reversible double-bond formation, and cleavage in C=C/C=C and C=C/C=N exchange processes. The reversibility of the Knoevenagel reaction has been explored, and C=C/C=C C/C exchanges have been achieved among different benzylidenes, under organocatalysis by secondary amines such as L-proline. The substituents of these benzylidenes were shown to play a very important role in the kinetics of the exchange reactions. L-Proline is also used to catalyze the reversible C=C/C=C exchange between Knoevenagel derivatives of barbituric acid and malononitrile. Finally, the interconversion between Knoevenagel derivatives of dimethylbarbituric acid and imines (C=C/C=N exchange) has been studied and was found to occur rapidly in the absence of catalyst. The results of this study pave the way for the extension of dynamic combinatorial chemistry based on C=C/C=C and C=C/C=N exchange systems.
- Kulchat, Sirinan,Meguellati, Kamel,Lehn, Jean-Marie
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p. 1219 - 1236
(2015/04/14)
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- A convenient method for synthesis of bis-2,2′-(1,3,4-thiadiazole) and bis-3,3′-(1,2,4-triazole) derivatives
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Reactions of the bis-hydrazonoyl chloride 1 with ketene N,S-acetal 2 and the active methine thioanilides 4 and 6 provide a new convenient site-selective synthetic strategy to functionalized bis-3,3′-(1,2,4-triazoles) 3 and bis-2,2′-(1,2,4-thiadiazoles) 5 and 7.
- Shawali, Ahmad S.,Sayed, Abdelwahed R.,Zayed, Mohie M.
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experimental part
p. 311 - 314
(2011/12/04)
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- Study on the Pd/C-catalyzed (retro-)Michael addition reaction of activated methylene compounds to electron-poor styrenes
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Palladium on carbon (10 % Pd/C) efficiently catalyzes the (retro-)Michael addition of activated methylene compounds 2a-d, such as malononitrile (2b), to mono- and doubly activated styrenes 1a-h to give the adducts 3a-l. The scope and limitations are described. The Knoevenagel condensation reaction of benzaldehyde and 2b or ethyl cyanoacetate (2c) is also catalyzed by 10 % Pd/C. In these cases the Michael adducts can even be prepared in a three-component reaction. A mechanism, with as first step the oxidative addition of 2a-d to Pd0, is proposed. Palladium on carbon (10 % Pd catalyzes the (retro-)Michael addition of activated methylene compounds 2a-d to mono- anddoubly activated styrenes. The scope and limitations of the reaction are described. A mechanism is proposed. Copyright
- Nikishkin, Nicolai I.,Huskens, Jurriaan,Verboom, Willem
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scheme or table
p. 6820 - 6823
(2011/02/26)
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- The Ever-surprising chemistry of boron: Enhanced acidity of phosphine·boranes
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The gas-phase acidity of a series of phosphines and their corresponding phosphine·borane derivatives was measured by FT-ICR techniques. BH 3 attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110 kJ mol-1). This acidity-enhancing effect of BH3 is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High- level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3 association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3 group is present. Our study also shows that deprotonation of ClCH2PH2 and ClCH 2PH2·BH3 is followed by chloride departure. For the latter compound deprotonation at the BH3 group is found to be more favorable than PH2 deprotonation, and the subsequent loss of Cl- is kinetically favored with respect to loss of Cl - in a typical SN2 process. Hence, ClCH2PH 2·BH3 is the only phosphine·borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid.
- Hurtado, Marcela,Yanez, Manuel,Herrero, Rebeca,Guerrero, Andres,Juan Z. Davalos,Jose-Luis, M. Abboud,Khater, Brahim,Guillemin, Jean-Claude
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supporting information; experimental part
p. 4622 - 4629
(2009/12/29)
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- Room temperature dynamic polymers based on Diels-Alder chemistry
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Dynamers based on reversible Diels-Alder chemistry have been obtained and shown to undergo dynamic exchange at room temperature. Their study in solution by small-angle neutron scattering indicated the formation of long and highly flexible chains. Polydispersed molecules gave Tg values below room temperature, permitting the generation of a dynamic elastomer upon introduction of a dynamic cross-linking agent. The use of a system with a low equilibrium constant gives access to materials with interesting self-healing properties.
- Reutenauer,Buhler,Boul,Candau,Lehn
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experimental part
p. 1893 - 1900
(2009/09/28)
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- Unprecedented reaction between ethyl α-cyanocinnamate and o-phenylenediamine: Development of an efficient method for the transfer hydrogenation of electronically depleted olefins
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A reaction between ethyl α-cyanocinnamate and o-phenylenediamine under thermal conditions yielded 2-cyano-3-phenyl-propionic acid ethyl ester, 2-phenyl benzimidazole, and ethyl cyanoacetate. The mechanistic revelations led to the development of a simple and efficient transfer-hydrogenation process from the in situ generated benzimidazolines to activated olefins under solventless and catalyst-free conditions. Georg Thieme Verlag Stuttgart.
- Kumar, Satish,Kapoor, Kamal K.
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p. 2809 - 2814
(2008/02/13)
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- 6-substituted pyrazolo[3,4-d]pyrimidin-4-ones useful as cyclin dependent kinase inhibitors
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The present invention relates to the synthesis of a novel class of pyrazolo[3,4-d]pyrimidin-4-ones of formula (I), alternatively represented by the tautomer (II): that are potent inhibitors of the class of enzymes known as cyclin dependent kinases, which relate to the catalytic subunits cyclin dependent kinase 1-8 and their regulatory subunits know as cyclins A-H, K, N, and T. This invention also provides a novel method of treating cancer or other proliferative diseases by administering a therapeutically effective amount of one of these compounds or a pharmaceutically acceptable salt form thereof. Alternatively, one can treat cancer or other proliferative diseases by administering a therapeutically effective combination of one of the compounds of the present invention and one or more other known anti-cancer or anti-proliferative agents.
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- Pyrazole compounds
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Pharmaceutical compositions and compounds are provided. The compounds of the invention demonstrate anti-proliferative activity, and may promote apoptosis in cells lacking normal regulation of cell cycle and death. In one embodiment of the invention, pharmaceutical compositions of the compounds in combination with a physiologically acceptable carrier are provided. The pharmaceutical compositions are useful in the treatment of hyperproliferative disorders, which disorders include tumor growth, lymphoproliferative diseases, angiogenesis. The compounds of the invention are substituted pyrazoles and pyrazolines.
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- Process for the preparation of malononitrile
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The invention describes an improved process for the preparation of malononitrile by using a porous particulate solid substance as efficient absorbent. Cyanoacetamide is reacted with POCl3 as a dehydrating agent in a suitable solvent in the presence of an organic N-donor base as catalyst and a porous particulate solid substance as efficient absorbent. The product is then distilled under vacuum from the crude in the presence of a stabilizer into a receiver containing the same stabilizer, to obtain malononitrile of high purity and shelf-life.
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- Process for the production of malononitrile
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An improved process for the commercial production of malononitrile by the dehydration of cyanoacetamide employs cyanuric chloride in the presence of a catalytic amount of N,N-dimethylformamide and in a polar solvent that is removed by vacuum distillation at a temperature below 100° C. The N,N-dimethylformamide is added in a molar ratio of 0.16 moles for each mole of cyanoacetamide present in the starting solution.
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Page column 4
(2008/06/13)
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- Process for the preparation of malononitrile
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The invention describes an improved process for the preparation of malononitrile by using a porous particulate solid substance as efficient absorbent. Cyanoacetamide is reacted with POCl3as a dehydrating agent in a suitable solvent in the presence of an organic N-donor base as catalyst and a porous particulate solid substance as efficient absorbent. The product is then distilled under vacuum from the crude in the presence of a stabilizer into a receiver containing the same stabilizer, to obtain malononitrile of high purity and shelf-life.
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- Geminal dinitriles and their reactions: I. Hydrolysis of alkylidene- and cycloalkylidenemalononitriles in aqueous medium
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The kinetics of pseudounimolecular hydrolysis of alkylidene- and cycloalkylidenemalononitriles in an aqueous buffer at pH 7 were studied. Correlations between the rate constants and substituent effects were found to fit the Taft-Hancock equation. Electrochemical reduction of alkylidenemalononitriles was studied using 0.2 M tetraethylammonium iodide as supporting electrolyte. The half-wave reduction potentials are related to the substituent constants σ* by the Taft-Zuman equation. Anomalous behavior of 1,1-dicyano-2,3,3-trimethyl-1-butene was observed during the hydrolysis and electrochemical reduction at a dropping mercury electrode.
- Smirnov,Sevast'yanova
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p. 1703 - 1708
(2007/10/03)
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- New upper rim pyridine-bridged calix[4]arenes: Synthesis and complexation properties toward neutral molecules and ammonium ions in organic media
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A new series of calix[4]arenes, diametrically bridged at the upper rim with pyridino systems, has been synthesized. The shape, rigidity, and chemical structure of the bridge influence the host-guest complexation properties of these systems in solution toward several neutral molecules having acidic C-H bonds. Additionally, selective complexation of methylammonium tosylate in comparison with other ammonium salts has been observed and the strength of this complexation enhanced by electron-donor ability of the p-substituent on the pyridine moiety of the calixarene host. X-ray crystal structures of endo complexes of host 5 with malononitrile and nitromethane have been resolved, verifying specific C-H bonding with the hard oxygen and nitrogen atoms of the bridge and the soft aromatic ring of the calixarene.
- Arduini, Arturo,McGregor, William M.,Pochini, Andrea,Secchi, Andrea,Ugozzoli, Franco,Ungaro, Rocco
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p. 6881 - 6887
(2007/10/03)
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- Hexacyanocyclopropane. II. Reaction of Hexacyanocyclopropane with Aliphatic and Aromatic Amine Hydroiodides
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Reaction of hexacyanocyclopropane with aliphatic amine hydroiodides gives corresponding pentacyano-2-propen-1-ides and cyanogen iodide, whereas with aromatic amine hydroiodides unsubstituted and ring-substituted N-(tricyanovinyl)anilines or N,N-dialkyl-4-(tricyanovinyl)anilines, malononitrile, and iodine are formed.
- Nasakin,Lukin,Vershinin,Lyshchikov,Urman,Yashkanova
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p. 361 - 363
(2007/10/03)
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- Synthesis and Electrochemical Properties of 4-Phenyl-1-buten-3-yne-1,1,2-tricarbonitriles and Tricyanoacrylates
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The reaction of phenylacetylenes 4a-h copper(I) acetate (5) and TCNE (tetracyanoethylene) in THF/acetonitrile gave 4-phenyl-1-buten-3-yne-1,1,2-tricarbonitriles 6a-h. 4i did not react to give 6i.The phenylacetylenes 4b-i were prepared by a two-step synthesis starting from the corresponding phenyl halides 1b-i.The tricyanoacrylates 8 were synthesised from the corresponding cyanoacetates 7, TCNE and catalytic amounts of pyridine in THF. - Cyclovoltammetric investigations showed that the butenynes 6 and the tricyanoacrylates 8 are strong electron acceptors which can be easily reduced.The radical anions 6.- are unstable in acetonitrile and react irreversibly with 6 to give oligomeric anions 6.-n.Only 4-(2,4,6-trimethoxyphenyl)-1-buten-3-yne-1,1,2-tricarbonitrile (6h) is reduced to a radical anion 6h.- which associates with 6h in a reversible follow-up process to form a dimeric anion 6h2.-.By contrast, the tricyanoacrylates 8 can be reversibly reduced to their respective radical anions and dianions. - Keywords: Cyano compounds, conjugated / Phenylacetylenes / Radical anions / Electrochemistry
- Dulog, Lothar,Koerner, Bernd,Heinze, Juergen,Yang, Jianjun
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p. 1663 - 1672
(2007/10/02)
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- Application of Marcus Theory to Gas-Phase SN2 Reactions: Experimental Support of the Marcus Theory Additivity Postulate
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Through the analysis of sufficiently fast identity exchange reactions, the Marcus theory additivity postulate has been tested and verified for two sets of gas-phase SN2 reactions: X- + RCH2Y -> XCH2R + Y- (where X and Y = Cl and/or Br and R = CN, C6H5).Statistical RRKM theory, within the microcanonical variational transition state (μVTS) approximation, is used to interpret the experimental kinetic data for each reaction to estimate the activation energies relative to separated reactants.Complexation energies, determined experimentally, are used in conjunction with the data from the RRKM analysis to obtain potential surface energetics.The Marcus expression is then used to determine whether the intrinsic component of the activation energy for the cross reaction is the mean of the activation energies for the two corresponding identity exchange reactions.Good agreement is found for R = C6H5 and CN.
- Wladkowski, Brian D.,Brauman, John I.
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p. 13158 - 13164
(2007/10/02)
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- RADICAL CARBAMOYLATION OF 1,2,3-TRIAZINIUM 2-DICYANOMETHYLIDES
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The nucleophilic radical carbamoylation of 4,6-disubstituted 1,2,3-triazinium 2-dicyanomethylides occurred at their 5-positions followed by the elimination of dicyanomethylene to form 5-substituted 1,2,3-triazines.The reaction did not proceed when parent triazines were adopted as the substrates.
- Nagata, Kazuhiro,Itoh, Takashi,Okada, Mamiko,Takahashi, Hiroyuki,Ohsawa, Akio
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p. 855 - 857
(2007/10/02)
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- Studies on Uracils. 10. A Facile One-Pot Synthesis of Pyrido- and Pyrazolopyrimidines
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The reaction of functionalised uracils bearing amino and hydroxyamino groups at C-6 position (4 and 5) with strongly electrophilic cyano olefins (1,2 and 3) gave rise to pyridopyrimidines 7-9 in excellent yields.Hydrazine-substituted uracil 6 gave access to an efficient one-step synthesis of pyrazolopyrimidines 10.The capture of an eliminated hydrogen molecule by cyano olefins in the case of their reaction with 4 and 6 was confirmed by the isolation of dihydrocyano olefins.This fact further supported the plausible mechanism for the formation of compounds 7-10 via dihydropyrido- and dihydropyrazolopyrimidine intermediates A and C.
- Bhuyan, Pulakjyoti,Boruah, Romesh Chandra,Sandhu, Jagir Singh
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p. 568 - 571
(2007/10/02)
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- CRYPTATE ACIDITY SCALES. V. EQUILIBRIUM ACIDITY OF INDICATOR CH-ACIDS IN TETRAHYDROFURAN
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A scale of equilibrium cryptate acidity in tetrahydrofuran is constructed.Its distinguishing feature is the constancy of the contribution from ionic association.A method is proposed for determination of the constants for the association of the ions into ion pairs in dimethyl sulfoxide.
- Antipin, I. S.,Gareev, R. F.,Vedernikov, A. N.,Konovalov, A. I.
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p. 1039 - 1044
(2007/10/02)
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- Process for preparing dialkyl propanediimidate dihydrohalides
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An improved process for preparing a dialkyl propanediimidate dihydrohalide by reacting malononitrile, an alcohol, and hydrogen halide, wherein the improvement comprises conducting the reaction under greater than atmospheric pressure in a halobenzene, haloalkylbenzene or alkylbenzene solvent.
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- 2-ARYLIMINO-3-THIAZOLINES - FORMATION OF UNUSUAL TAUTOMERS OF 2-ARYLAMINO-THIAZOLINES - A REVISION
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In contrast to previously reported results the products formed in the reaction of arylthioureas with 3-bromomethyl-2-cyanocinnamonitrile are not 2-arylimino-3-thiazolines but 2-arylamino-4-dicyanomethyl-2-thiazolines.
- Liebscher, Juergen,Mitzner, Elke
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p. 4179 - 4180
(2007/10/02)
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- Nucleophilic Attacks on LL (Low LUMO) Substrates. Part 3. Molecular Stacking of 9-Methylenefluorene Derivatives as a Source of Zero-order Reactions
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The reactions of the three activated dibenzfulvene derivatives 9-dicyanomethylene, 9-dinitromethylene-, and 9-nitromethylene-fluorene (FDCN, FDN, and FN respectively) with NaOH in water containing 1percent dioxane were followed at 25 deg C.The reactions were found to be zero-order in the substrate and zero-order within a run in the hydroxyde.Overall, the reaction was first-order in the hydroxide.Under these conditions zero-order kinetics are also obtained for the reaction of CN- with FDCN. 'Normal' first-order kinetics were obtained under these conditions for the reaction of OH- with 1,1,diphenyl-2,2-dinitroethylene as well as for FDN when the dioxane concentration was increased to 25percent (v/v).It is suggested that owing to their planar structure these substrates undergo efficient stacking in the solution with only a small fraction left as a free rective monomer and the aggregate maintains a constant monomer concentration in the solution.A Tyndall effect of the aggregated particles could not be observed with the nacked eye.The particles also pass through a Whatman No. 1 filter paper.However, other observation such as solvent and temperature effects on the absorbance in the u.v. range strongly support the suggested explanation.
- Hoz, Shmaryahu,Gross, Zeev,Speizman, Dov
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p. 1143 - 1146
(2007/10/02)
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- 3-METHYL-2,3-DIHYDROBENZOTHIAZOLES AS REDUCING AGENTS. DYE ENHANCED PHOTOREACTIONS.
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Various types of electron deficient saturated carbon atoms are reduced in a visible light initiated process by N-alkyl-2,3-dihydrobenzothiazoles; these reactions are accelerated in the presence of Ru(bipy)3Cl2.The same ring system can act as an enolate carrier under electrophilic conditions.
- Mashraqui, Sabir H.,Kellogg, Richard M.
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p. 1453 - 1456
(2007/10/02)
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- Nucleophilic Addition of Olefins. 12. Solvent-Induced Change in the Rate-Limiting Step of the Hydrolysis of Benzylidenemalononitrile in Acidic Me2SO-Water Solution
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A kinetic study of the reversible, four-step hydrolysis of benzylidenemalononitrile (BMN) to form benzaldehyde and malononitrile in water and Me2SO-water mixtures (50percent, 60percent, and 70percent Me2SO (v/v)) is reported.At pHoOH, Scheme I, k34H2O), is rate limiting in all solvents.Above pH 2 the breakdown of the anionic intermediate, PhCH(O-)CH(CN)2 (T-O, Scheme I, k4), is rate limiting in water, while in the presence of Me2SO oxygen deprotonation of ToOH (k3B) becomes partially rate limiting at low buffer concentrations.A detailed kinetic analysis, coupled with a few assumptions about rates of diffusion-controlled proton transfers, allows one to estimate the rate and equilibrium constants of all kinetically important steps.This analysis shows that the solvent-induced change in the rate-limiting step is caused by an enhanced rate of breakdown of T-O(k4) in the Me2SO-containing solvents.This rate enhancement can be understood in terms of an increased "push" by the less solvated anionic oxygen of T-O.This increased "push" is somewhat attenuated by a reduced "pull" which arises from the slight destabilization of CH(CN)2(1-) in the Me2SO-containing solvents.On a more quantitative level the equilibrium constant, K4, for the breakdown of T-O into benzaldehyde and CH(CN)2(1-) correlates remarkably well with the estimated solvent activity coefficients of T-O and CH(CN)2(1-) .A correlation of the solvent effect on the rate constant, k4, of the breakdown of T-O with the same solvent activity coefficients suggests that the sensitivity of k4 to is greater than its sensitivity to .This "imbalace" is attributed to a rate-retarding effect which arises from early desolvation of the oxyanion in the transition state , an effect which is magnified in the less aqueous solvents.The direct breakdown of ToOH into benzaldehyde and malononitrile (k34H2O) probably occurs by a mechanism in which C-C bond cleavage is concerted with the removal of the OH proton by the solvent.Suggestive, though inconclusive, evidence is presented in favor of a transition state (2) in which oxygen deprotonation is coupled with protonation of the departing carbanion.
- Bernasconi, Claude F.,Kanavarioti, Anastassia,Killion, Robert B. Jr.
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p. 3612 - 3620
(2007/10/02)
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- Synthesis of 2-Thioxo-3-benzothiazolineacetonitrile and Related Products
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Attempts to thermally rearrange 2-benzothiazolylthioacetonitrile (1) to the titled compound 8 failed.The reaction of 3-chloromethyl-2-benzothiazolinethione with potassium cyanide in dimethylformamide (DMF) or dimethylsulfoxide (DMSO) at 25-30 deg C afforded 8 in 98percent yield.Whereas replacing the DMF or DMSO solvent with acetone furnished the unexpected sulfide 9 in 92percent yield.Substituting 3-chloromethyl-2-benzoxazolinethione as the electrophile in the same reaction gave the sulfide 10 in 95percent yield.Possible mechanisms and supporting nmr data are discussed.
- D'Amico, John J.,Suba, Lydia,Ruminski, Peter G.
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p. 1479 - 1482
(2007/10/02)
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- Nucleophilic Addition to Olefins. 11. Kinetics of the Reversible Hydrolysis of Benzylidenemalononitrile in Water
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The hydrolysis of benzylidenemalononitrile (BMN) to form benzaldehyde and malononitrile (or its anion) is significantly reversible, with an equilibrium constant Kh=/=3.36x10-3 M in water at 25 deg C.It involves the following steps (see Scheme III): (1) nucleophilic attack by OH- or by water to form the adduct TOH(1-); (2) carbon protonation of TOH(1-) to form TOH0; (3) oxygen deprotonation of TOH0 to form TO(1-); and (4) collapse of the tetrahedral intermediate, TO(1-), to form benzaldehyde and malononitrile anion, which is in rapid equilibrium with malononitrile.There is also a direct, water-catalyzed breakdown of TOH0 to products.The pH-rate profile for the hydrolysis reaction has four phases, with the following rate-limiting steps: at pH>8, OH- attack on BMN; at pH 5-8, water attack on BMN which is subject to non-enforced general base catalysis; at pH 1-5, collapse of TO(1-); at pHOH0.Rate and equilibrium constants for all steps are calculated or estimated and compared with the same parameters in the hydrolysis of a β-nitrostyrene and benzylidene Meldrum acid.They provide new evidence that the nucleofugality of carbanions is relatively high in carbonyl-forming but low in olefin-forming eliminations.They also confirm previous observations according to which the intrinsic barriers in carbanion-forming reactions are much higher for nitro-stabilized than for cyano-stabilized carbanions.
- Bernasconi, Claude F.,Howard, Keith A.,Kanavarioti, Anastassia
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p. 6827 - 6835
(2007/10/02)
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- Process for preparing malononitrile
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Disclosed is a process for preparing malononitrile which comprises reacting diazoacetonitrile with hydrogen cyanide in the presence of a copper compound in a solvent. The diazoacetonitrile may be formed in a reaction mixture by reacting aminoacetonitrile with nitrous acid in a solvent, which is then subjected to the further reaction as such without isolating it from the reaction mixture.
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- Synthesis of the First Crystalline Thiaanthracenes, 9-Cyano- and 9-(Ethoxycarbonyl)-10-methyl-10-thiaanthracenes, and Their Reactions with Electrophiles
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The isolable and crystalline thiaanthracene derivatives 9-cyano- (9) and 9-(ethoxycarbonyl)-10-methyl-10-thiaanthracene (12) were synthesized in high yield for the first time by proton abstraction from the corresponding thioxanthenium salts (8a or 8b and 11) with sodium hydride in THF under a nitrogen atmosphere.Upon standing in THF at 50 deg C, thiaanthracenes 9 and 12 underwent thermal 1,4-rearrangement to give the corresponding thioxanthenes 13 and 14, respectively.The ylidic property of the thiaanthracenes was manifested by spectral and chemical evidences.Reactions of the thiaanthracenes with electrophiles such as dimethyl acetylenedicarboxylate and tetracyanoethylene are also described together with the course of the reactions.
- Hori, Mikio,Kataoka, Tadashi,Shimizu, Hiroshi,Ohno, Sachio
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p. 2468 - 2473
(2007/10/02)
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- Nucleophilic Addition to Activated Olefins. 3. Reactions of Piperidine and Morpholine with Benzylidenemalononitrile in 50percent Dimethyl silfoxide-50percent Water. Intrinsic Barriers in Nucleophilic Addition
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The reactions of piperidine and morpholine with benzylidenemalononitrile give rise to two observable kinetic processes.The first is measurable by the stopped-flow temperature-jump technique and is associated with the formation of a zwitterionic addition complex (T+/- in Scheme I) and subsequent deprotonation to form the anionic complex T-.The second process, which was monitored in the stopped-flow apparatus, refers to the cleavage of the addition complex T- into benzaldehyde and malononitrile (Scheme II).In the first process nucleophilic attack is rate limiting for the piperidine reaction but proton transfer is partially rate limiting in the morpholine reaction at low amine concentrations.This result implies that base catalysis in nucleophilic vinylic substitutions by amines might be a consequence of rate-limiting proton transfer in some cases.For a given equilibrium constant for the nucleophilic addition to an activated olefin the rate constants are higher for benzylidenemalononitrile (cyano activation) than for olefins activated by alkoxycarbonyl groups or the nitro group, implying a lower intrinsic barrier to nucleophilic attack in the former.The similarity of these results with finding on proton transfers involving carbon acids activated by the same substituents is discussed and related to a common origin.Analysis of the data referring to the cleavage of T- shows that protonation of T- on carbon, to form T0, is rapid, while cleavage of T0 into the iminium ion, PhCH=N+R2, and malononitrile anion is rate limiting.
- Bernasconi, Claude F.,Fox, John P.,Fornarini, Simonetta
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p. 2810 - 2816
(2007/10/02)
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