- Solvent-free synthesis, spectral correlations and antimicrobial activities of some aryl imines
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A series of aryl imines have been synthesized by Fly-ash: H 2SO4 catalyzed microwave assisted process under solvent-free conditions. The yields of the imines have been found to be more than 87%. The purity of all imines has been checked using their physical constants and spectral data as published earlier in literature. The UV λmaxCN(nm), infrared νCN(cm-1), NMR δ(ppm) of CH and CN spectral data have been correlated with Hammett substituent constants and F and R parameters using single and multi-linear regression analysis. From the results of statistical analysis, the effect of substituents on the above spectral data has been studied. The antimicrobial activities of All synthesised imines have been studied using Bauer-Kirby method.
- Suresh,Kamalakkannan,Ranganathan,Arulkumaran,Sundararajan,Sakthinathan,Vijayakumar,Sathiyamoorthi,Mala,Vanangamudi,Thirumurthy,Mayavel,Thirunarayanan
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- Understanding solid/solid organic reactions
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The concept of an organic reaction between two macroscopic solid particles is investigated. Thus, we study several reactions that have been recently reported to proceed "in the solid phase" and clearly show that, in most cases, grinding the two solid reactants together results in the formation of a liquid phase. This is true both for catalytic transformations (e.g., aldol condensations and oligomerization of benzylic compounds) and for noncatalytic reactions (Baeyer - Villiger oxidations, oxidative coupling of naphthols using iron chloride, condensation of amines and aldehydes to form azomethines, homo-etherification of benzylic alcohols using p-toluenesulfonic acid, and nuclear aromatic bromination with NBS). This liquefaction implies the existence of a eutectic mixture with Tfusion below ambient temperature (although both reagents have higher than ambient melting points). In cases where heating is required, it is again clear that a phase change (from solid to liquid) occurs, explaining the observed reaction kinetics. On the basis of 19 experimental examples, we discuss the possibility of solid-phase organic reactions and the implications of these findings to the reaction between two solid reagents. A general description of such reactive systems is proposed, based on a consideration of the potential for eutectic (or peritectic) formation between the constituents of the liquid phases that arise during the process of mechanical mixing of the solid reagents and products.
- Rothenberg,Downie,Raston,Scott
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- Reactions of HDDA Benzynes with C,N-Diarylimines (ArCH=NAr')
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o-Benzynes can be utilized to construct heterocyclic motifs using various nucleophilic and cycloaddition trapping reactions. Acridines have been synthesized by capture of C,N-diarylimines with benzynes generated by classical methods (i.e., from ortho-elimination of precursor arene compounds), although in poor yields. We report here that these imines can be trapped by benzynes generated by the hexadehydro-Diels–Alder (HDDA) reaction in an efficient manner to produce 1,4-dihydroacridine products. These dihydroacridines were subsequently aromatized using MnO2 to provide structurally complex acridines.
- Arora, Sahil,Sneddon, Dorian S.,Hoye, Thomas R.
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- Direct synthesis of unsaturated β-amino acids
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Zinc bromide promoted addition of trimethylsilyl butenoate lithium enolates to aromatic aldimines. The corresponding β-amino acids were obtained in moderate to good yields as anti isomers. The reaction was believed to proceed via the zinc enolates. A tentative explanation of the selectivity in favour of the anti isomers was proposed.
- Bellassoued, Moncef,Grugier, Jér?me,Lensen, Nathalie
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- Dual Heterogeneous Catalyst Pd-Au@Mn(II)-MOF for One-Pot Tandem Synthesis of Imines from Alcohols and Amines
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A new Mn(II) metal-organic framework (MOF) 1 was synthesized by the combination of 4,4,4-trifluoro-1-(4-(pyridin-4-yl)phenyl)butane-1,3-dione (L) and Mn(OAc)2 in solution. 1 features a threefold-interpenetrating NbO net containing honeycomb-like channels, in which the opposite Mn(II)···Mn(II) distance is 23.5075(10) ?. Furthermore, 1 can be an ideal platform to support Pd-Au bimetallic alloy nanoparticles to generate a composite catalytic system of Pd-Au@Mn(II)-MOF (2). 2 can be a highly active bifunctional heterogeneous catalyst for the one-pot tandem synthesis of imines from benzyl alcohols and anilines and from benzyl alcohols and benzylamines.
- Chen, Gong-Jun,Ma, Hui-Chao,Xin, Wen-Ling,Li, Xiao-Bo,Jin, Fa-Zheng,Wang, Jing-Si,Liu, Ming-Yang,Dong, Yu-Bin
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p. 654 - 660
(2017/01/13)
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- Aerobic oxidation of amines to imines catalyzed by a ruthenium complex under solvent-free conditions
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A ruthenium complex [Et3NH]2[Ru(dipic)Cl3] showed high efficiency in the homo-coupling of primary amines and cross-coupling of benzylamine with anilines and aliphatic amines to the corresponding imines under air and solvent-free conditions. This protocol is an atom-economical green process and tolerates various substrates bearing both electron-donating and electron-withdrawing substituents.
- Zhang, Yuecheng,Lu, Fei,Huang, Rong,Zhang, Hongyu,Zhao, Jiquan
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supporting information
p. 10 - 13
(2016/04/26)
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- Exceptional effect of nitro substituent on the phosphonation of imines: The first report on phosphonation of imines to α-iminophosphonates and α-(N-phosphorylamino)phosphonates
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A novel and chemoselective method is reported for the simple phosphonation of imines. By change of the electronic effects of the substituents, this method offers the selective synthesis of either α-iminophosphonates or α-(N-phosphorylamino)phosphonates. The mild reaction condition makes this protocol very attractive for synthesis of these two classes of phosphorous compounds.
- Motevalli, Somayeh,Iranpoor, Nasser,Etemadi-Davan, Elham,Moghadam, Khashayar Rajabi
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p. 100070 - 100076
(2015/12/04)
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- Oxidation of aromatic anils by sodium perborate in aqueous acetic Acid Medium
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The kinetics of oxidation of 9 meta- and 15 para- substituted aromatic anils by sodium perborate were investigated in aqueous acetic acid medium. The reaction was second order with respect to aromatic anil and first order with respect to the sodium perborate. The increase of [H+] in this oxidation retards the rate of the reaction. The observed rate constant for the substituents were plotted against the Hammett constant, δ and a non-linear concave downward curve was obtained for the anils with substituents in the aniline moiety. The observed break in the log kobs versus δwas attributed to the transition state whereas the non-linear concave upward curve was observed for the substituents in the benzaldehyde moiety and a non-linear concave upward curve was observed for the substituents in the combination of aniline and benzaldehyde moiety. The electron withdrawing substituents fall on one side of the curve, having a negative ρvalue and the electron releasing substituents fall on the other side, with a positive ρvalue and a suitable mechanism was proposed.
- Venkatesh,Karunakaran
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p. 739 - 744
(2014/06/09)
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- Synthesis of 4-imino-2H,3H,5H-[1,2,5]thiadiazolidin-1-oxide through cycloaddition reaction of N-sulphinylanilines and N-(α-cyano-α-aryl) -methylanilines
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Through the normal mode of cycloaddition reaction of N-(α-cyano- α-aryl)-methylanilines (II) onto N-sulphinylanilines (III) has provided 2,3,5-triaryl-4-imino-2H,3H,5H-[1,2,5]thiadiazolidin-1-oxides (IV). The present protocol has advantage of convenient operation to synthesize heterocyclics in good yield.
- Kaur, Manpreet,Singh, Baldev
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p. 1157 - 1161
(2014/08/05)
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- Kinetic investigation of oxidation of aromatic anils by potassium peroxymonosulfate in aqueous acidic medium
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The kinetics of oxidation of aromatic anils to benzaldehyde and azobenzene by potassium peroxymonosulfate has been studied in aqueous acetic acid medium. The low dielectric constant of the medium facilitates the reactivity. It has been found that the variation in the ionic strength of the reaction has a negligible effect on the rate. Similarly, polymerization was not observed when acrylonitrile was added to the reaction mixture. This observation rules out the formation of any free radical in the reaction. The added Mn(II) increases the rate of the reaction, which indicates the involvement of two-electron transfer. Highly negative ΔS# values indicate a structured transition state. The deviation of the Hammett plot was noted, and a concave downward curve was obtained for the anils with substituents in the aniline moiety. The observed break in the log kobs versus σ is attributed to the transition state whereas the concave upward curve was observed for the substituents in the benzaldehyde moiety and in the combination of aniline and benzaldehyde moieties, and a suitable mechanism was proposed.
- Venkatesh,Karunakaran
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p. 542 - 550
(2013/07/26)
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- Substituent cross-interaction effects on the electronic character of the C=N bridging group in substituted benzylidene anilines - Models for molecular cores of mesogenic compounds. A 13C NMR study and comparison with theoretical results
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13C NMR chemical shifts δc(C=N) were measured in CDCl 3 for a wide set of mesogenic molecule model compounds, viz. the substituted benzylidene anilines P-X-C6H4CH=NC 6H4-p-Y (X = NO2, CN, CF3, F, Cl, H, Me, MeO, or NMe2; Y = NO2, CN, F, Cl, H, Me, MeO, or NMe2). The substituent dependence of δc(C=N) was used as a tool to study electronic substituent effects on the azomethine unit. The benzylidene substituents X have a reverse effect on δc(C=N): electron-withdrawing substituents cause shielding, while electron-donating ones behave oppositely, the inductive effects clearly predominating over the resonance effects. In contrast, the aniline substituents Y exert normal effects: electron-withdrawing substituents cause deshielding, while electron-donating ones cause shielding of the C=N carbon, the strengths of the inductive and resonance effects being closely similar. Additionally, the presence of a specific cross-interaction between X and Y could be verified. The electronic effects of the neighboring aromatic ring substituents systematically modify the sensitivity of the C=N group to the electronic effects of the benzylidene or aniline ring substituents. Electron-withdrawing substituents on the aniline ring decrease the sensitivity of δc(C=N) to the substitution on the benzylidine ring, while electron-donating substituents have the opposite effect. In contrast, electron-withdrawing substituents on the benzylidene ring increase the sensitivity of δc(C=N) to the substituent on the aniline ring, while electron-donating substituents act in the opposite way. These results can be rationalized in terms of the substituent-sensitive balance of the electron delocalization (mesomeric effects). The present NMR characteristics are discussed as regards the computational literature data. Valuable information has been obtained on the effects of the substituents on the molecular core of the mesogenic model compounds.
- Neuvonen, Helmi,Neuvonen, Kari,Fueloep, Ferenc
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p. 3141 - 3148
(2007/10/03)
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- Solid-state synthesis of Schiff bases
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A new preparative method for the synthesis of Schiff bases by the solid-state interaction of crystalline organic and organometallic aldehydes and amines is suggested. The possibility of direct synthesis of aldimines in the solid state from amine salts without isolation of the free amines is demonstrated.
- Khrushcheva,Loim,Sokolov
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p. 1952 - 1955
(2007/10/03)
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- SUBSTITUENT EFFECTS ON THE 31P, 13C, AND 1H NMR CHEMICAL SHIFTS OF SUBSTITUTED DIPHENYL 1-PHENYLAMINO-1-PHENYLMETHANEPHOSPHONATES AND THEIR ANIONS
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For a series of thirty-five novel diphenyl 1-phenylamino-1-phenylmethanephosphonates, substituted in the meta and para positions on the anilino and/or aryl ring, 31P chemical shifts show a good linear correlation with Hammett ?n and Taft ?0 parameters, the 31P nucleus being better shielded in the case of electron withdrawing substituents.The same pattern is observed for the phosphonate anions, except when para phenyl substituents can interact with the phosphorus atom by direct resonance.This inverse relationship is due to a field effect of the substituent dipole which polarizes ?-electron clouds in the molecule.A corresponding shift in ?-electron density is likewise observed for 13C resonances of the two diastereotopic phenoxy groups, the phenylamino and phenyl moieties.Vicinal CH-NH coupling is shown to be dependent on the rate of NH proton exchange as influenced by resonance, temperature and solvent effects.
- Smith, Scott J.,Zimmer, Hans,Fluck, Ekkehard,Fischer, Peter
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p. 105 - 120
(2007/10/02)
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- CONDENSATION REACTIONS BETWEEN AROMATIC ALDEHYDES AND SOME HETEROCYCLIC AROMATIC AMINES
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1,1-Diamino derivatives are obtained by means of reactions between 2-aminothiazole and aromatic aldehydes carried out in methanol (and in dimethyl sulphoxide).The reaction of amine with the C=N of imine occurs without catalyst and is an easier process than its addition to C=O.This behaviour is also displayed by a number of aromatic heterocycles and homocyclic amines and may be explained by considering the activating effect of the electron-withdrawing group present in the imine moiety.
- Forlani, Luciano,Sintoni, Marina,Todesco, Paolo E.
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p. 229 - 232
(2007/10/02)
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