Search results for "amine"
showing 10 items of 7299 documents
Deprotonation of resorcinarenes by mono- and diamine bases: complexation and intermolecular interactions in the solid state
2014
The deprotonation of resorcinarenes by mono- and dibasic amines, viz. triethylamine (TEA) and its dibasic analogue, N,N′-dimethylpiperazine (DMPip), was studied and the resulting supramolecular complexes were analysed in the solid state, in solution and in the gas phase. In the solid state, 1:1 (2TEAH+·(ethyl-resorcinarene)2−·MeOH), 3:2 [DMPip·2DMPipH+·2(ethyl-resorcinarene−)] and 3:2 [2DMPip·DMPipH22+@(2methyl-ethyl-resorcinarene−)2·2MeOH] solid state complexes and interesting resorcinarene−⋯resorcinarene− supramolecular networks formed via enhanced hydrogen bonds involving the hydroxyl groups and the deprotonated hydroxyl groups of the resorcinarenes were observed. The host–guest complexe…
Stereoselective Synthesis of Chiral Piperidine Derivatives Employing Arabinopyranosylamine as the Carbohydrate Auxiliary.
2006
Stereoselective synthesis of 2-substituted dehydropiperidinones and their further transformation to variously disubstituted piperidine derivatives was achieved employing D-arabinopyranosylamine as the stereodifferentiating carbohydrate auxiliary. A domino MannichMichael reaction of 1-methoxy-3-(trimethylsiloxy)butadiene (Danishefsky's diene) with O-pivaloylated arbinosylaldimines furnished N-arabinosyl dehydropiperidinones in high diastereoselectivity. Subsequent conjugate cuprate addition gave 2,6-cis-substituted piperidinones, while enolate alkylation furnished 2,3-trans-substituted dehydropiperidinones. Electrophilic substitution at the enamine structure afforded 5-nitro- and 5-halogen…
A Diet for Dopaminergic Neurons?
2009
Parkinson's disease (PD) is the second most common neurodegenerative disease, which unfortunately is still fatal. Since the discovery of dopamine (DA) neuronal cell loss within the substantia nigra in PD, the past decades have seen the understanding of the pathophysiological mechanisms underlying the degenerative process advance at a very impressive rate. Nevertheless, there is at present no cure for PD. Although there are no proven therapies for prevention, a large body of evidence from animal studies has highlighted the paramount role of dietary factors in counteracting DA degeneration. Consistently, associations between the risk of developing PD and the intake of nutrients, individual fo…
A new mixed-valence hexanuclear cobalt complex, [Co4IICo2III(dea)2(Hdea)4)(piv)4](ClO4)2·H2O: Synthesis, crystal structure and magnetic properties
2010
A new Co II /Co III hexanuclear complex, [Co 4 II Co 2 III (dea) 2 (Hdea) 4 )(piv) 4 ](ClO 4 ) 2 ·H 2 O 1 , has been obtained by reacting cobalt(II) perchlorate, diethanolamine, and pivalic acid (H 2 dea = diethanolamine and piv = pivalato anion). The cobalt ions are held together by four μ 3 and four μ 2 alkoxo bridges as well as by four syn – syn carboxylato groups. The hexanuclear motif contains four Co(II) and two Co(III) ions. The {Co II 4 Co III 2 (μ 2 -O) 4 (μ 3 -O) 4 } core can be described as a four face-sharing monovacant and bivacant distorted heterocubane units. The cobalt(III) ions are hexacoordinated. Two of the cobalt(II) are hexacoordinated, while the two others are pentacoo…
Mechanismus der Umsetzung von 1,1-Diphenylhydrazin mit Azodicarbonsäure-diethylester
1979
Bei der Umsetzung von 1,1-Diphenylhydrazin (1a) mit Azodicarbonsaure-diethylester (2a) uber-lagern sich funf Reaktionsmechanismen: A und B) Oxidation des Diphenylhydrazins 1a durch den Azodicarbonsaureester 2a zum Aminonitren 8; Bildung des Tetrazens 10 entweder durch Dimerisierung von 8 oder uber das Tetrazan 11; Zerfall von 11 in N2 und Diphenylamin. — C) Addition des Aminonitrens 8 an den Azodicarbonsaureester 2a zum Aminoazimin 3a; Zerfall von 3a in das Urethan 4a und den Azidoameisensaureester 5a. — D) Isomerisierung des Aminoazimins 3a zu 13 und Reduktion von 13 durch 1a zum Tetrazen 14; Spaltung von 14 in Diphenylamin und das Azid 15; Zerfall von 15 in Ethylcyanat (17) und den Kohlen…
[2,5-Bis(dipropylamino)-4-(hydroxymethyl)phenyl]methanol
2021
The centrosymmetric title compound, C22H36N2O2, was prepared in five steps from diethyl succinate. The dipropylamino groups are almost orthogonal to the central phenylenedimethanol ring [dihedral angle = 87.62 (9)°]. In the crystal, the molecules are connected by O—H...N hydrogen bonds, forming (101) layers separated by the propyl chains.
A method for the determination of dimethylamine in air by collection on solid support sorbent with subsequent derivatization and spectrophotometric a…
2005
A new method for dimethylamine determination in air is reported. The proposed assay is based on the employment of C18-packed solid phase extraction cartridges for sampling. The retained amine is then derivatized inside the cartridges with the reagent 1,2-naphthoquinone-4-sulfonate. By observing the coloured area of the cartridge, a semiquantitative estimation of the amine can be made. It was also possible to distinguish between primary and secondary amines by visual inspection. Quantitative tests entailed desorption from the cartridges of the derivatives formed, and measurement of the absorbance of the collected extracts. The selected conditions were applied to quantify dimethylamine up to …
Sensitive determination of aliphatic amines in water by high-performance liquid chromatography with chemiluminescence detection.
2004
A sensitive method has been developed for liquid chromatographic determination of short aliphatic amines in water samples. Analytes are preconcentrated and dansylated on solid sorbents (C18 solid-phase extraction cartridges). The dansyl derivatives are chromatographed and post-column mixed with peroxyoxalate (TCPO) and H2O2 in order to perform chemiluminescence detection. Optimal results have been obtained using a sample volume of 5 ml. The method has been applied to the quantification or screening of several aliphatic amines: methylamine, ethylamine, butylamine, diethylamine, pentylamine and hexylamine. The screening procedure has been developed including also polyamines (putrescine, cadav…
Derivatization of amines in solid-phase extraction supports with 9-fluorenylmethyl chloroformate for liquid chromatography
1997
Abstract A new method based on reaction in solid-phase extraction cartridges with 9-fluorenylmethyl chloroformate is described for improved derivatization of amines prior to liquid chromatography. The effects of the reaction conditions, the kinetics of the reaction and the kind of packing material on the derivatization have been evaluated. The reliability of the described approach has been tested by derivatizing propylamine, diethylamine, diethanolamine, glycine, glutamic acid, p-aminobenzoic acid and β-phenylethylamine. Reaction yields compared with those of the analogous solution derivatizations were in the 44–169% range, and satisfactory linearity was achieved at concentrations of the am…
Rational synthetic design of well-defined Pt(bisethynyl)/Zn(porphyrin) oligomers for potential applications in photonics
2011
Well-defined oligomers of 1, 2, 3 and 4 units built upon the very soluble bis-1,15-(1,4-ethynylbenzene)-3,7,13,17-tetramethyl-2,8,12,18-tetrakis(n-hexyl) zinc(II) porphyrin ligand and the trans-bis(tri-n-butylphosphine)platinum(II) linker, with acetylene or trimethylsilane as end groups, has been prepared in the presence of a dichloromethane/diethylamine mixture (1 : 1 v/v) and CuX (X = Cl, I) at room temperature, analogue to a Sonogashira coupling. The new monodisperse organometallic oligomers were characterized by 1H, 31P NMR, UV-visible spectroscopies and MALDI-TOF mass spectrometry. The methyl groups placed at the 3,7,13,17-positions induces the locking of the C6H4 fragment in a perpend…