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1.
Summary A study is presented of the thermoanalytical and gas chromatographic (GC) properties of the copper(II) complexes of twenty four tetradenate Schiff's bases. Variations in thermal stability, volatility and GC retention of the complexes are discussed in terms of stereo-electronic effects of the substituents. Although some complexes decomposed extensively during vaporization above 250°C all, apparently, survive chromatography intact at 200°C. Certain complexes were separated as distinct regio-isomers by GC. Fluorinated ligands still appear to be the most suitable derivatizing reagents for Cu(II). 相似文献
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Three different derivatives of macrocyclic tetraimine Schiff's base have been synthesized and explored as a neutral ionophores for preparing poly(vinyl chloride) based membrane sensors selective to Dy3+. The addition of sodium tetraphenyl borate and various plasticizers, viz., o-NPOE, DBP, DBBP, DOP and CN has been found to substantially improve the performance of the sensors. The best performance was obtained with the sensor no. 1 having membrane of Schiff's base (SL-1) with composition (w/w) SL-1 (4.5%): PVC (30.5%): o-NPOE (59.5%): NaTPB (5.5%). This sensor exhibits Nernstian response with slope 19.4 mV/decade of activity in the concentration range of 10−8 to 1.0 × 10−2 M Dy3+, performs satisfactorily over wide pH range of (2.8-7.2) with a fast response time (10 s). The sensor was also found to work satisfactorily in partially non-aqueous media up to 20% (v/v) content of acetonitrile, methanol or ethanol. The proposed sensor can be used over a period of 1.5 months without significant drift in potentials. The sensor has been also utilized for the determination of Dy3+ level in different soil samples. 相似文献
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Xian Jia Lu Yin Xuan Zhao Xing Shu Li 《中国化学快报》2007,18(3):275-278
Sciff bases 1 and 2, which were derived from chiral aminoalcohols, were used as ligands in Ti-catalyzed asymmetric alkynylation of aldehydes. Good enantioselectivities (up to 88% ee) and high chemical yields (80-90%) were obtained. 相似文献
5.
I. Iovel L. Golomba J. Popelis A. Gaukhman E. Lukevics 《Chemistry of Heterocyclic Compounds》2000,36(3):264-274
We have studied the reactions of (hetero)aromatic aldehydes with 2-aminopyridines. The results obtained suggest that molecular sieves play a role in these processes not only as a dehydrating agent but also as an acid catalyst. We have synthesized a series of novel heterocyclic azomethines.Dedicated to Professor M. A. Yurovskaya on her Jubilee.Latvian Institute of Organic Synthesis, Riga LV-1006 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–335, March, 2000. 相似文献
6.
Synthesis of Schiff's bases in aqueous medium: a green alternative approach with effective mass yield and high reaction rates 总被引:1,自引:0,他引:1
《Green Chemistry Letters and Reviews》2013,6(3):217-223
Abstract Schiff's bases constitute a class of pharmaceutical and medicinally important molecules. The conventional methods for the synthesis of Schiff's bases require long reaction times and use of organic solvents. We report a novel and eco-friendly condensation reaction method permitting the “green synthesis” of various Schiff's bases by stirring 1,2-diaminobenzene with various aromatic aldehydes in water as solvent. This method is experimentally simple, clean, high yielding, green, and with reduced reaction times. The product is purified by simple filtration followed by washing with water and drying processes. 相似文献
7.
A new approach to the construction of polycyclic skeletons of fused azines with nitrogen at the bridgehead based on a novel
reaction of cyclic Schiff's bases (1-alkyl-substituted 3,4-dihydroisoquinolines) with α-aminomethylenecarbonyl compounds (2-aminomethylene-cyclohexane-1,3-diones
or aminomethylenemalonic ester) was developed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1358–1360, July, 1997. 相似文献
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W. Schilf B. Kamie
ski A. Szady-Che
mieniecka E. Grech 《Journal of Molecular Structure》2004,700(1-3):105-108
In present work set of eight Schiff bases derived from substituted salicylaldehydes and aliphatic and aromatic amines has been studied in the solid state by 15N and 13C CPMAS NMR methods. 15N CPMAS NMR measurement is especially useful for investigation of the tautomerism in the compounds considered, owing to the large difference in the nitrogen chemical shifts of OH and NH tautomers. In the solid state, four of the compounds examined were shown by 15N CPMAS NMR to exist as OH tautomeric forms, and the remaining four as the corresponding NH forms with different stage of proton transfer process, from oxygen to nitrogen site.
This was confirmed by 13C CPMAS. The results reported were compared with those obtained for only two compounds in CDCl3 solutions (solubility problems). 相似文献
10.
Asymmetric transfer hydrogenation of ketones catalyzed by rhodium and iridium complexes with chiral bidentate Schiff's bases 总被引:1,自引:0,他引:1
Pavlov V. A. Vinogradov M. G. Starodubtseva E. V. Chel"tsova G. V. Ferapontov V. A. Malyshev O. R. Heise G. L. 《Russian Chemical Bulletin》2001,50(4):734-735
Rhodium and iridium complexes of Schiff's bases derived from (1R,2R)- and (1S,2S)-diaminocyclohexane catalyze asymmetric transfer hydrogenation of alkyl aryl ketones in PriOH at room temperature to give chiral secondary alcohols (up to 65% ee). 相似文献
11.
The synthesis of fused pyrimidines from the Schiff bases of aromatic ortho-nitrocarbaldehydes is reported. The Schiff bases after selective reduction of the nitro group on 10% Pd/C, followed by condensation of the amines formed with orthoesters, are transformed to the corresponding imidates. Heating of the latter in a sealed tube with an excess of ammonia (or with ammonia in ethanol) gives fused pyrimidines. The influence of various substituents in the aromatic ring of the imine moiety of the Schiff bases on the overall yield of fused pyrimidine derivatives has been investigated. Moderate electron-withdrawing groups gave the best results.Institute of Organic Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, PL-01-224 Warszawa, PolandTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 799–805, June, 2000. 相似文献
12.
The Lewis acid catalysed imide-amide rearrangement of oxazaphosphorimides to diazaphoshoramides is reported for the first time. In spite of the similarity to the previously reported Lewis acid catalysed imide-amide rearrangement of dioxaphosphorimides to oxazaphosphoramides we show that this rearrangement proceeds by a different mechanism, not involving the formation of an oligomeric intermediate. The oxazaphosphorimides are prepared in situ by the Staudinger reaction of the appropriate trivalent phosphorus compound with an azide and after the addition of BF3·OEt2, undergo rearrangement to the corresponding diazaphosphoramides. We have found that the rearrangement occurs with retention of configuration at the phosphorus atom and inversion of configuration at the rearranged carbon atom. When starting from chiral 1,2-aminoalcohol, substituted at the carbon atom that undergoes rearrangement, a mixture of diastereomers is obtained, but the diastereomeric ratio, initially obtained in the formation of the trivalent phosphorus compounds is maintained during the whole transformation. This implies that if the rearrangement is to be used for the preparation of chiral phosphoramides with defined stereochemistry at the phosphorus atom, a high diastereoselectivity during the preparation of the trivalent phosphorus precursors should be obtained. 相似文献
13.
The catalytic asymmetric rearrangement of functionalised cyclohexene and cyclopentene oxides has been studied using sub-stoichiometric amounts of a chiral lithium amide in combination with a stoichiometric amount of three different lithiated imidazoles. 1-Methylimidazole that had been lithiated at the C-2 aryl position gave the highest enantioselectivity (82% ee). With 1,2-dimethylimidazole that had been lithiated at the C-2 methyl group, epoxide ring opening occurred as an unexpected and competing process. Ultimately, ring opening was suppressed using a more sterically hindered imidazole. In all catalytic examples, a racemic background reaction (presumably due to rearrangement by the lithiated imidazoles) was observed. 相似文献
14.
The experimental values of the gas-phase proton affinities for a variety of 4-substituted benzonitriles, 4-substitutedN, N-dimethylanilines, and 4-substituted benzaldehydes have been examined by means of correlation analysis techniques and by ab initio quantum mechanical methods (MP2/ 6-31G(d) level). From this study it is concluded that in the gas phase, 4-(dimethylamino)-benzonitrile essentially protonates on the dimethylamino group, while protonated 4-cyanobenzaldehyde is very nearly a 21 mixture of the carbonyl- and cyano-protonated forms.This work is dedicatedin memoriam to Professor Robert W. Taft. 相似文献
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A series of chiral Schiff bases ( L 1 – L 5 ) with different substituents in the salicylidenyl unit were prepared from condensation of 3‐aryl‐5‐ tert ‐butylsalicylaldehyde derivatives and optically active amino alcohols. Bromination of 3‐phenyl‐5‐ tert ‐butylsalicylaldehyde gave an unexpected product 3‐(4‐bromophenyl)‐5‐bromosalicylaldehyde, from which the corresponding Schiff base ligands L 6 and L 7 , derived from (S)‐valinol and (S)‐ tert ‐leucinol, respectively, were prepared. Ligands L 1 – L 7 were applied to the vanadium‐catalyzed asymmetric oxidation of aryl methyl sulfides. Under the optimal conditions, the oxidation of the thioanisole with H2O2 as oxidant in CH2Cl2 catalyzed by VO(acac)2‐ L 1 – L 7 gives good yields (74–83%) with moderate enantioselectivity (58–77% ee). Ligand L 7 , containing a 4‐bromophenyl group on the 3‐position and a Br atom on the 5‐position of the salicylidenyl moiety, displays an 80–90% ee for vanadium‐catalyzed oxidation of methyl 4‐bromophenyl sulfide and methyl 2‐naphthyl sulfide. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Arnold K Batsanov AS Davies B Grosjean C Schütz T Whiting A Zawatzky K 《Chemical communications (Cambridge, England)》2008,(33):3879-3881
(-)-Sparteine directed lithiation of N-Boc-pyrrolidine, alkylation with chloromethylboronate pinacol ester and acid-based deprotection provides homoboroproline HX salt in 94% ee, which is then an efficient enamine-type pyrrolidine catalyst in an asymmetric aldol reaction when neutralised and especially when esterified in situ with a tartrate ester, for example, providing 90% ee of the aldol adduct derived from acetone and p-nitrobenzaldehyde. 相似文献
18.
I. Iovel L. Golomba J. Popelis S. Grinberga S. Belyakov E. Lukevics 《Chemistry of Heterocyclic Compounds》2002,38(10):1210-1229
We have studied condensation of 2-, 3-, 4-pyridinealdehydes and 6-methylpyridine-2-aldehyde with 2-aminopyridine and its 3-, 4-, and 6-methyl derivatives in benzene in the presence of molecular sieves. The reactions occur even at room temperature to form the corresponding pyridyl-pyridyl azomethines, and also aminals. We have determined the optimal conditions for carrying out the processes with the aim of obtaining both types of products. We consider the characteristics of the mass spectra for the synthesized aldimines. We present the X-ray diffraction results for the two aminals. 相似文献
19.
Delong Liu 《Tetrahedron letters》2007,48(4):585-588
Novel air-stable C2-symmetric tetrasubstituted ruthenocene-based ligands were readily synthesized and used for palladium-catalyzed asymmetric allylic substitution showing excellent enantioselectivity and high catalytic activity. 相似文献
20.
The first example of the use of chiral ionic liquids as reaction media in the asymmetric Baylis-Hillman reaction was described using N-alkyl-N-methylephedrinium salts. Good yields and significant enantiomeric excesses were obtained. 相似文献