- First kinetic discrimination between carbon and oxygen reactivity of enols
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(Chemical Equation Presented) Nitrosation of enols shows a well-differentiated behavior depending on whether the reaction proceeds through the carbon (nucleophilic catalysis is observed) or the oxygen atom (general acid-base catalysis is observed). This is due to the different operating mechanisms for C- and O-nitrosation. Nitrosation of acetylacetone (AcAc) shows a simultaneous nucleophilic and acid-base catalysis. This simultaneous catalysis constitutes the first kinetic evidence of two independent reactions on the carbon and oxygen atom of an enol. The following kinetic study allows us to determine the rate constants for both reaction pathways. A similar reactivity of the nucleophilic centers with the nitrosonium ion is observed.
- Garcia-Rio, Luis,Mejuto, Juan C.,Parajo, Mercedes,Perez-Lorenzo, Moises
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Read Online
- A further study of acetylacetone nitrosation
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The nitrosation of acetylacetone (AcAc) has been revised in an aqueous acid medium of perchloric acid and buffers of mono-, di-, or tri-chloroacetic acid. The results show that in the presence of buffers, under conditions of [nit] ? [AcAc] (nit = sodium nitrite) the reaction cannot be studied by UV-Vis spectroscopy, contrary to the recently published paper by Garcia-Rio et al. (J. Org. Chem., 2008, 73, 8198). The present study also corroborates the previously published mechanism of AcAc nitrosation, where no base-catalysis was observed. Contrarily, the low effect of buffers was attributed to the formation of nitrosyl chloro-, dichloro- or trichloro-acetate salts that are new nitrosating agents.
- Iglesias, Emilia,Brandariz, Isabel
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- Synthesis and spectroscopic studies of trans-bis-(3,5-dimethyl-4-nitrosopyrazole) dimer
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Bis-(3,5-dimethyl-4-nitrosopyrazole) dimer was prepared by reaction of acetyl acetone with nitrous acid and condensation with hydrazine. Spectroscopic techniques, including IR, UV, 1H NMR, and 13C NMR, and CHN analysis were used to identify the product.
- Al-Shamkhani, Zeki A. Nasir,Essa, Ali Hashem
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- Effects of β-Cyclodextrin on the Keto-Enol Equilibrium of Benzoylacetone and on Enol Reactivity
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Both β-cyclodextrin and sodium dodecyl sulfate micelles shift the benzoylacetone keto-enol equilibrium to the enol tautomer by preferentially binding the enol form. The UV-vis spectroscopic method was used to quantify the temperature and solvent effects on the keto-enol equilibrium of benzoylacetone in aqueous acid medium. The comparison between the thermodynamic parameters resulting from the binding of the benzoylacetone enol to sodium dodecyl sulfate micelles and from the inclusion of both keto and enol tautomers into the β-cyclodextrin cavity allows us to draw a picture of the possible complex formed in each case. 1H NMR results suggest that benzoylacetone-enol protrudes deeper inside the β-cyclodextrin cavity, whereas the keto tautomer could only have the phenyl ring enclosed in the β-cyclodextrin cavity interior. Nitrosation in acid medium of benzoylacetone in the presence of β-cyclodextrin is reduced below that of free benzoylacetone, indicating that the cyclodextrin complex protects the benzoylacetone enol tautomer, which is in perfect accordance with our picture of the enol·β-cyclodextrin complex.
- Iglesias, Emilia,Ojea-Cao, Vicente,Garcia-Rio, Luis,Leis, J. Ramon
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Read Online
- A 2D Zinc Coordination Polymer Built from the Mono-deprotonated 4,4′-Azobis(3,5-dimethyl-1H-pyrazole) Ligand
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4,4′-Azobis(3,5-dimethyl-1H-pyrazole) (H2azbpz) in its mono-deprotonated form as a pyrazole-pyrazolate ligand was assembled together with zinc(II) into the two-dimensional coordination polymer [Zn(Hazbpz)NO3]·1.25DMF with sql-a topology, constituted by the dinuclear {Zn2(μ-pz)2(Hpz)2}2+ secondary building unit. The μ3- bridging mode of the ligand is in analogy to bridging modes observed for 4-(4-pyridyl)pyrazolates ligands. After the removal of the DMF solvent molecules, ethanol can be adsorbed up to a maximum uptake of 276 mg·g–1 at p/p0 = 0.9 in an S-shaped adsorption isotherm, corresponding to two ethanol molecules per [Zn(Hazbpz)NO3] formula unit. The desorption isotherm reveals that only one EtOH is desorbed until p/p0 = 0.4 and the other one remains hydrogen-bonded in the framework until very low pressures.
- Millan, Simon,Gil-Hernández, Beatriz,Hastürk, Emrah,Schmitz, Alexa,Janiak, Christoph
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- Reaction of 1,3-Dicarbonyl Compounds with Nitryl Chloride
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Reaction of 1,3-dicarbonyl compounds with nitryl chloride through substitution on the activated methylene group, resulted in the formation of chloro, dichloro and oximino derivatives. - Keywords: 3-Oxobutanoic acid ethyl ester; 2,4-Petanedione; reaction with nitryl chloride
- Prostenik, Mladen V.,Dumic, Miljenko,Bosnjak, Nada
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Read Online
- NSC 18725, a Pyrazole Derivative Inhibits Growth of Intracellular Mycobacterium tuberculosis by Induction of Autophagy
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The increasing incident rates of drug-resistant tuberculosis (DR-TB) is a global health concern and has been further complicated by the emergence of extensive and total drug-resistant strains. Identification of new chemical entities which are compatible with first-line TB drugs, possess activity against DR-, and metabolically less active bacteria is required to tackle this epidemic. Here, we have performed phenotypic screening of a small molecule library against Mycobacterium bovis BCG and identified 24 scaffolds that exhibited MIC99 values of at least 2.5 μM. The most potent small molecule identified in our study was a nitroso containing pyrazole derivative, NSC 18725. We observed a significant reduction in viable bacilli load of starved Mycobacterium tuberculosis upon exposure to NSC 18725. The action of NSC 18725 was “synergistic” with isoniazid (INH) and “additive” with other drugs in our checkerboard assays. Structure-activity relationship (SAR) studies of the parent compound revealed that pyrazole derivatives without a functional group at fourth position lacked anti-mycobacterial activity in vitro. The derivative with para-chlorophenyl substitution at the first position of the pyrazole ring was the most active scaffold. We also demonstrate that NSC 18725 is able to induce autophagy in differentiated THP-1 macrophages. The induction of autophagy by NSC 18725 is the major mechanism for the killing of intracellular slow and fast-growing mycobacteria. Taken together, these observations support the identification of NSC 18725 as an antimycobacterial compound, which synergizes with INH, is active against non-replicative mycobacteria and induces autophagy in macrophages.
- Arora, Garima,Behura, Assirbad,Dhiman, Rohan,Gagandeep, Garima,Gosain, Tannu Priya,Kandi, Shamseer Kulangara,Kidwai, Saqib,Rawat, Diwan S.,Shaliwal, Ravi P.,Singh, Padam,Singh, Ramandeep
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- Octanitropyrazolopyrazole: A gem-trinitromethyl based green high-density energetic oxidizer
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Environmental concerns demand the replacement of ammonium perchlorate (AP) by a green oxidizer in composite propellants. Herein, we report the synthesis and characterization of a novel green high-density energetic oxidizer octanitropyrazolopyrazole (ONPP). With its high specific impulse (256 s), high density (1.997 g cm-3) and good thermal stability (160 °C), ONPP can potentially replace AP. This journal is
- Mohammad, Khaja,Thaltiri, Vikranth,Kommu, Nagarjuna,Vargeese, Anuj A.
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supporting information
p. 12945 - 12948
(2020/11/07)
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- Pyrazolyl-Imidazolium Ligands, Metal Organic Frameworks Comprising the Same and Method of Preparing the Same
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According to the present invention, a metal organic framework comprising a pyrazolyl-imidazolium ligand can be produced by synthesizing a ligand including an imidazolium group as a center and a pyrazole group bonded to either or both of the centers, and using the ligand to produce the metal organic framework comprising a pyrazolyl-imidazolium ligand. The pyrazolyl-imidazolium ligand is chemically or thermally stable and is useful for fuel cell or gas separation.COPYRIGHT KIPO 2018
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Paragraph 0073-0077
(2018/05/03)
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- A phosphine-mediated synthesis of 2,3,4,5-tetra-substituted N-hydroxypyrroles from α-oximino ketones and dialkyl acetylenedicarboxylates under ionic liquid green-media
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Background: The development of multicomponent reactions (MCRs) in the presence of task-specific ionic liquids (ILs), used not only as environmentally benign reaction media, but also as catalysts, is a new approach that meet with the requirements of sustainable chemistry. In recent years, the use of ionic liquids as a green media for organic synthesis has become a chief study area. This is due to their unique properties such as non-volatility, non-flammability, chemical and thermal stability, immiscibility with both organic compounds and water and recyclability. Ionic liquids are used as environmentally friendly solvents instead of hazardous organic solvents. Objective: We report the condensation reaction between α-oximinoketone and dialkyl acetylene dicarboxylate in the presence of triphenylphosphine to afford substituted pyrroles under ionic liquid conditions in good yields. Result: Densely functionalized pyrroles was easily prepared from reaction of α-oximinoketones, dialkyl acetylene dicarboxylate in the presence of triphenylphosphine in a quantitative yield under ionic liquid conditions at room temperature. Conclusion: In conclusion, ionic liquids are indicated as a useful and novel reaction medium for the selective synthesis of functionalized pyrroles. This reaction medium can replace the use of hazardous organic solvents. Easy work-up, synthesis of polyfunctional compounds, decreased reaction time, having easily available-recyclable ionic liquids, and good to high yields are advantages of present method.
- Shahvelayati, Ashraf S.,Ghazvini, Maryam,Yadollahzadeh, Khadijeh,Delbari, Akram S.
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- HETEROCYCLE SUBSTITUTED AMINO-PYRIDINE COMPOUNDS AND METHODS OF USE THEREOF
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The present disclosure relates to heterocycle substituted amino-pyridine compounds. The present disclosure also relates to pharmaceutical compositions containing these compounds and methods of treating cancer by administering these compounds and pharmaceutical compositions to subjects in need thereof. The present disclosure also relates to the use of such compounds for research or other non-therapeutic purposes.
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Paragraph 0460; 0461
(2016/04/20)
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- Synthesis, structure and properties of neutral energetic materials based on N-functionalization of 3,6-dinitropyrazolo[4,3-c] pyrazole
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3,6-Dinitropyrazolo[4,3-c]pyrazole (DNPP, 4) was prepared using an efficient modification process. Various neutral energetic derivatives of DNPP were synthesized from N-functionalization of imide (NH) group. All compounds were fully characterized by 1H and 13C nuclear magnetic resonance spectroscopy, infrared spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). The crystal structures of compounds 4·2H2O, 12 and 15 were confirmed by single-crystal X-ray diffraction, showing extensive hydrogen-bonding. The densities of neutral derivatives ranged from 1.74 to 1.95 g cm-3, and all compounds have positive heats of formation in the range of 18.8 to 863 kJ mol-1. Based on the measured densities and calculated heats of formation, theoretical performance calculations, including detonation pressures (27.1-41.5 GPa) and velocities (7819-9364 m s-1), were carried out using the Gaussian 09 program and Kamlet-Jacobs equations, and they compare favorably with those of TNT and RDX. These properties make them potential and competitive for use as new high energy-density materials.
- Li, Yanan,Shu, Yuanjie,Wang, Bozhou,Zhang, Shengyong,Zhai, Lianjie
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p. 84760 - 84768
(2016/11/06)
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- Fosmidomycin analogues with N-hydroxyimidazole and N-hydroxyimidazolone as a chelating unit
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Fosmidomycin has been reported to have many biological activities as an antibacterial and antimalarial, along with being a herbicidal agent. Its unique mode of action involves the inhibition of a key step of the non mevalonate pathway by blockade of a crucial enzyme, the 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), whose expression is present in bacteria, plasmodium parasites and higher plants, but not in mammals. Herein we report the development of fosmidomycin and of FR-900098 constrained analogues belonging to an unusual heterocyclic based complexing subunit involving N-hydroxyimidazoles and cyclic N-hydroxyureas.
- Midrier, Camille,Montel, Sonia,Braun, Ralf,Haaf, Klaus,Willms, Lothar,Van Der Lee, Arie,Volle, Jean-Noel,Pirat, Jean-Luc,Virieux, David
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p. 23770 - 23778
(2014/07/07)
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- Thermally stable 3,6-dinitropyrazolo[4,3-c]pyrazole-based energetic materials
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3,6-Dinitropyrazolo[4,3-c]pyrazole was prepared using an efficient modified process. With selected cations, ten nitrogen-rich energetic salts and three metal salts were synthesized in high yield based on the 3,6-dinitropyrazolo[4,3-c]pyrazolate anion. These compounds were fully characterized by IR and multinuclear NMR spectroscopies, as well as elemental analyses. The structures of the neutral compounds 4 and its salt 16 were confirmed by single-crystal X-ray diffraction showing extensive hydrogen-bonding interactions. The neutral pyrazole precursor and its salts are remarkably thermally stable. Based on the calculated heats of formation and measured densities, detonation pressures (22.5-35.4 GPa) and velocities (7948-9005 ms-1) were determined, and they compare favorably with those of TNT and RDX. Their impact and friction sensitivities range from 12 to >40 J and 80 to 360 N, respectively. These properties make them competitive as insensitive and thermally stable highenergy density materials.
- Zhang, Jiaheng,Shreeve, Jean'ne M.,Parrish, Damon A.
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p. 2953 - 2960
(2015/02/18)
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- Synthesis and study of prototropic tautomerism of 2-(3-chromenyl)-1- hydroxyimidazoles
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A series of novel derivatives of imidazole containing a chromenyl moiety in position 2 of the ring has been synthesized. A characteristic response of the chromenyl ring H-2 proton to its environment allows the study of the prototropic tautomerism of novel 1-hydroxyimidazoles in solution using 1H NMR spectroscopy. It has been shown that the predominance of one or another tautomer depends on the nature of the substituents of the imidazole ring, and the proton-donating/proton-withdrawing properties of a solvent. X-ray diffraction data for two of the compounds has revealed that in the solid state these 1-hydroxyimidazole derivatives exist as N-oxide tautomers.
- Nikitina, Polina A.,Kuz'Mina, Ludmila G.,Perevalov, Valery P.,Tkach, Iosif I.
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p. 3249 - 3256
(2013/05/09)
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- Nitrite ionic liquids (IL-ONO and [bmim]NO2) as effective nitrosonium sources for the synthesis of α-oximinoketones under mild heterogeneous conditions
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Ketones and β-diketones were nitrosated and converted to their corresponding α-oximinoketones using task-specific ionic liquids, 1-(4-nitritobutyl)-3-methylimidazolium chloride, IL-ONO, and 1-butyl-3-methylimidazolium nitrite at room temperature. The results from two ionic liquids are comparable and showed that these IL's are effective nitrosonium sources for the preparation of oximinoketones. The protocol is rapid, the yields are excellent, and the method is simple. Copyright
- Valizadeh,Shomali,Gholipour
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experimental part
p. 163 - 166
(2012/03/10)
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- A rapid synthesis of quinoxalines starting from ketones
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A fast and general synthesis of quinoxalines, performed in two stages or as a one-pot reaction, starting from ketones via their α-hydroxylimino ketone derivatives, and condensation of the latter with 1,2-diaminobenzene under microwave irradiation, is described.
- Padmavathy,Nagendrappa, Gopalpur,Geetha
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experimental part
p. 544 - 547
(2011/03/18)
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- Microwave-assisted synthesis of photochromic fulgides
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The oxazole and indole based heterocyclic photochromic fulgides were synthesized from their corresponding fulgenic acid derivatives by clay catalysed microwave irradiation methodology. Improved yields of fulgides were observed by the microwave irradiation method as compared other chemical methods employed so far. The proportions of clay (montmorillonite KSF) and isopropenyl acetate play a key role in increasing the yields of fulgides. Indian Academy of Sciences.
- Nithyanandan, Sivasankaran,Saravanan, Chinnusamy,Senthil, Sengodan,Kannan, Palaninathan
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experimental part
p. 183 - 188
(2010/11/04)
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- Unusual domino Michael/aldol condensation reactions employing oximes as N-selective nucleophiles: Synthesis of N-hydroxypyrroles
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(Figure Presented) A facile synthesis of N-hydroxypyrroles has been developed using readily available α-carbonyl oximes and α,β-unsaturated aldehydes. The domino reaction proceeds through iminium activation of α,β-unsaturated aldehydes, Michael addition u
- Tan, Bin,Shi, Zugui,Chua, Pei Juan,Li, Yongxin,Zhong, Guofu
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supporting information; experimental part
p. 758 - 761
(2009/05/06)
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- Synthesis of 2,4,5-Trisubstituted Oxazoles
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2,4,5-Trisubstituted oxazoles were synthesized in good yields starting from α-methylene ketones by nitrosation, condensation with aldehydes and reduction with zinc in acetic acid at 40 deg C. (5-Methyl-2-phenyloxazol-4-yl)ethanol was prepared by reduction of ethyl (5-methyl-2-phenyloxazol-4-yl)acetate with LiAlH4.
- Cai, Xiao-hua,Yang, Hai-jun,Zhang, Guo-lin
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p. 1569 - 1571
(2007/10/03)
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- Silica sulfuric acid/NaNO2 as a novel heterogeneous system for the chemoselective α-nitrosation of β-diketones under mild conditions
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A combination of silica sulfuric acid and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of β-diketones to their corresponding α-nitroso or α-oximinoketones under mild and heterogenous conditions in moderate to excellent yields.
- Zolfigol, Mohammad Ali,Ghorbani Choghamarani, Arash
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p. 1623 - 1629
(2007/10/03)
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- Method for the production of trioxime derivatives
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The present invention relates to a process for preparing for preparing [sic] trioxime derivatives of the formula I in which the substituents R1 and R2 can be identical or different and can in each case be cyano, alkyl, haloalkyl and cycloalkyl and R3 and R4 can be identical or different and can in each case be alkyl, haloalkyl, cycloalkyl, alkylcarbonyl and arylalkyl, by the following reaction steps in water without isolation of the intermediates: A) nitrosation of 1,3-diketones of the formula II to give monooximes of the formula III, B) oximation of III with hydroxylamine derivatives of the formula IV H2N—OR3′??IV in which R3′ is hydrogen or a group R3 to give bisoximes of the formula V, C) alkylation of V with alkylating agents or acylation of V with acylating agents to give compounds of the formula VI and D) subsequent oximation of VI with hydroxylamine to give compounds of the formula I.
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- Materials and methods for the treatment of diabetes, hyperlipidemia, hypercholesterolemia, and atherosclerosis
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The subject invention provides pharmaceutical compounds useful in the treatment of Type II diabetes. These compounds are advantageous because they are readily metabolized by the metabolic drug detoxification systems. Particularly, thiazolidinedione analogs that have been designed to include esters within the structure of the compounds are provided. This invention is also drawn to methods of treating disorders, such as diabetes, comprising the administration of therapeutically effective compositions comprising compounds that have been designed to be metabolized by serum or intracellular hydrolases and esterases. Pharmaceutical compositions of the ester-containing thiazolidinedione analogs are also taught.
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Page 3; sheet 21
(2010/02/03)
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- Method for preparing trion-bis(oxime ether) derivatives andrion-mono and trion-bis(oxime ether) derivatives obtained therewith
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The present invention relates to a method for the production of trion-bis(oxime ether) derivatives of formula (I), wherein the substituents have the following meaning: R1, R3represent unsubstituted, partially or totally halogenated C1-C6-alkyl or C3-C6-cycloalkyl; R2, R4represent C1-C4-alkyl or a methyl substituted by C2-C4-alkenyl, C2-C4-alkinyl or phenyl and X represents oxygen or N—OH. The invention also relates to the intermediate products obtained with said method.
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- An efficient and chemoselective method for oximination of β-diketones under mild and heterogeneous conditions
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A combination of oxalic acid dihydrate and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of β-diketones to their corresponding α-oximinoketones in moderate to excellent yields under mild and heterogenous conditions.
- Zolfigol, Mohammad Ali
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p. 694 - 698
(2007/10/03)
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- Determination of keto-enol equilibrium constants and the kinetic study of the nitrosation reaction of β-dicarbonyl compounds
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The keno-enol equilibrium constants of acetylacetone, ethyl acetoacetate and ethyl benzoylacetate in water at 25°C are determined by studying the influence of surfactants on their UV-VIS spectra, following the method applied to benzoylacetone published recently. These measured equilibrium constants are used to obtain the reactivity of the ketones towards several nitrosating agents. For this end, the nitrosation reaction of benzoylacetone, acetylacetone, ethyl acetoacetate and ethyl benzoylacetate are studied in aqueous acidic solution in the presence and absence of Cl-, Br- or SCN-. Analysis of the kinetic data indicates that the rate-limiting step is, in every case, the reaction of the enol.
- Iglesias, Emilia
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p. 431 - 439
(2007/10/03)
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- Studies in nitrosopyrazoles. Part 1. Preparative and spectroscopic studies of some 3,5-dialkyl-4-nitrosopyrazoles
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The preparations of a number of 3,5-disubstituted- and 1,3,5-trisubstituted-4-nitrosopyrazoles are described and a range of physical properties of these compounds are measured. Comparison is made with some 2,6-disubstituted nitrosobenzenes and it is shown from 13C NMR spectroscopy that the effects of substitution by flanking tert-butyl groups are moderated in the case of the pyrazoles from those in the aromatic C6 ring due to a lessening of steric hindrance. It is also suggested that steric effects are evident in the preparation of 1,3,5-substituted-4-nitrosopyrazoles when one of the flanking groups to the NO is tert-butyl or phenyl, there being no such effect for the corresponding case of the isobutyl group.
- Cameron, Mailer,Gowenlock, Brian G.,Boyd, Alan S. F.
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p. 2271 - 2274
(2007/10/03)
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- Synthesis of some new 1-hydroxypyrazole-2-oxides and heterocyclic oximes
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α,β-Unsaturated oximes (Ia-c) are converted into 1-hydroxypyrazole-2-oxides (IIIa-c) and isoxazole (IV) by reaction with n-butyl nitrite and metal ions in pyridine.Reduction of IIIc with zinc in acetic acid furnishes the pyrazole V.However, reduction of IIIc with sodium dithionite yields the 1-hydroxypyrazole (VI).Acylation of IIIc affords the acyl derivative (VII).Reaction of hydroxylamine hydrochloride and benzaldehyde with oximes VIIIa,b and IXa,b affords O-methyloximinoisoxazoles (Xa,b).
- Fadda, A. A.
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p. 749 - 753
(2007/10/02)
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- Nitrosation of Acetylacetone (Pentane-2,4-dione) and some of its Fluorinated Derivatives
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Nitrosation Of acetylacetone (AA) (pentane-2,4-dione), 1,1,1-trifluoropentane-2,4-dione (TFA), and 1,1,1,5,5,5-hexafluoropentane-2,4-dione (HFA) occurs readily in acetonitrile using t-butyl nitrite under mildly acidic conditions.In this solvent the reactants exist primarily in their enol forms and the equilibrium constants KE have been estimated using 1H n.m.r.Kinetic studies at different acidities show that whilst AA reacts entirely via the enol form, TFA reacts via both the enol and enolate forms and HFA reacts only via the enolate anion.The results demonstrate both the deactivating effect of the CF3 group to electrophilic addition and also its acid strengthening effect.In all cases the rate-limiting step is the reaction of the nitrosating agent (probably NO+) with the enol or enolate.Similar results are reported for the reaction of TFA in dilute aqueous acid using nitrous acid, and also for the reactions catalysed by Cl-, Br-, and SCN-; again reactions occur simultaneously by way of the enol and enolate forms.
- Crookes, Michael J.,Roy, Panchali,Williams, D. Lyn H.
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p. 1015 - 1020
(2007/10/02)
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- Nitrosation of Ketones: Clear Evidence for the Involvement of the Enol Tautomers
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Nitrosation of acetone and ethyl methyl ketone in the presence of a fairly high concentration of Cl(1-), Br(1-), or SCN(1-) is first order in and and zero-order in and , , and .This demonstrates that reaction occurs by nitrosation of the enol form of the ketone, and that under these conditions, enolisation is rate limiting.The measured rate constant for enolisation in the nitrosation experiments is in excellent agreement with that obtained earlier for halogenation and for hydrogen-exchange reactions.The same behaviour occurs with 1,3-dichloroacetone, except that here the enolisation is not acid-catalysed - again this agrees with the bromination work.With lower concentrations of added nucleophiles, for all four ketones, the rate equation includes terms first-order in and also in or , showing that the reaction of the enol with the nitrosating species in now rate-limiting.There is a very close analogy with the kinetic behaviour found in the halogenation of ketones.Analysis of the kinetic data reveals the reactivity sequence NOCl>NOBr>NOSCN (well known in N-nitrosation), and the reactivity of the enols is as expected for electrophilic addition.With acetylacetone, the rate-limiting step is always the reaction of the enol, due in part to the lower reactivity of the enol.In the absence of added nucleophiles, both acetone and ethyl methyl ketone react with N2O3, whereas the less-reactive 1,3-dichloroacetone and acetylacetone react preferentially with H2NO2(1+) or NO(1+) - a similar trend occurs in N-nitrosation of amines.
- Leis, J. Ramon,Pena, M. Elena,Williams, D. Lyn H.,Mawson, Simon D.
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p. 157 - 162
(2007/10/02)
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- The Synthesis and Application of Novel Nitrating And Nitrosating Agents
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Alcohols and phenols are efficiently nitrated with thionyl chloride nitrate or thionyl nitrate, even in the presence of an aromatic moiety.While thionyl chloride nitrate is suitable for nitration of primary OH-groups in carbohydrates, thionyl nitrate is reactive enough to react with secondary OH-groups as well.These reagents permit the highly selective nitration of the 5'-, 2',5'- and 3',5'-OH-groups of ribonucleosides to produce either mono- or diprotected nitro derivatives in high yields.Carbon acids and the enol form of some ketones are efficiently nitrated with trifluoromethanesulfonyl nitrate/potassium tert-butoxide.Lutidine N-oxide(2,6-(CH3)2C5H3N->O) was found to have marked effect on nitration reactions.Similarly, thionyl chloride nitrite and thionyl nitrite exhibit an excellent capacity for nitrosation of the aforementioned substrates
- Hakimelahi, Gholam H.,Sharghi, Hashem,Zarrinmayeh, Hamide,Khalafi-Nezhad, Ali
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p. 906 - 915
(2007/10/02)
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- Syntheses of 2-Arylimidazole Derivatives through Annelations Employing Benzylamines
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Annelations of benzylamines with hydroximino derivatives of pentane-2,4-dione or of alkyl acetoacetates, acetoacetamides, and acetoacetanilides, afford imidazole derivatives and provide easy incorporation of the benzylic carbon and nitrogen in the heterocycle.The limits of the reaction have been explored.
- Veronese, A.C.,Cavicchioni, G.,Servadio, G.,Vecchiati, G.
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p. 1723 - 1725
(2007/10/02)
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