161 research outputs found
Tautomerism and hydrogen bonding in reaction products from 4-aminopent-3-en-2-one and diazonium ions
No full textThe azo-coupling products have been prepared from 4-aminopent-3-en-2-one and 4-chloro- or 4-nitrobenzenediazonium ion.
Structure of the products obtained was studied by means of multinuclear NMR spectroscopy in CDCl3 solutions and X-ray
diffraction in solid state. Both products are predominantly present as azo forms in both the solution and the solid state, the azo
form content being higher in solid state. The substituent effect on azo-hydrazone tautomeric equilibrium of the substances is
more significant in solution than in solid state
Solution and solid state structure and tautomerism of azo coupled enaminone derivatives of benzoylacetone
No full textThe reaction of 4-substituted benzenediazonium tetrafluoroborates with 3-amino-1-phenylbut-2-en-1-one, 4-amino-4-phenylbut-3-en-2-one and their N-aryl derivatives 1a-1g has been used to prepare the respective azo coupling products i.e. compounds 2-5 from enaminone 1a, compounds 6-9 from enaminone 1c, compound 10 from enaminone 1d, compound 11 from enaminone 1e, compounds 12, 13 from enaminone 1f, compounds 14, 15 from enaminone 1b and compound 16 from enaminone 1g. Tautomerism of the azo coupling products prepared has been investigated in CDCl3 solutions by means of H-1, C-13 and N-15 NMR spectra. Crystal structures of selected products have also been investigated by means of X-ray diffraction
An NMR and X-ray study of the structure of the azo coupling product of 4-dimethylaminopent-3-en-2-one and benzenediazonium-tetrafluoroborate
No full text4-Dimethylaminopent-3-en-2-one reacts with two molecules of benzenediazonium-tetrafluoroborate to give compound 1. The structure of this compound was determined by means of X-ray analysis of its crystal and 1H, 13C and 15N NMR spectra of its solution in CDCl3. The molecule of this compound contains one azo group and one hydrazone group. The substance exists, both in crystal form and in solutions of concentrations above 0.1
mol-1, in the form of a dimer, in which the pair of molecules are bound by two hydrogen bonds N–H ... N. On diluting the
solution, the dimers decompose, the two forms being in an equilibrium that is rapid on the NMR time scale
Synthesis, NMR and X-ray characterisation of 6-substituted 4-amino-5-aryldiazenyl-1-arylpyridazinium salts
No full textA new simple method has been used to prepare 6-substituted 4-(subst. amino)-5-aryldiazenyl-l-arylpyridazinium salts from N-methyl- or N-aryl-3-amino-l-phenylbut-2-en-l-ones and 4-aminopent-3-en-2-ones and substituted benzenediazonium tetrafluoroborates or hexafluorophosphates. The structure of selected derivatives was studied by means of N-15 NMR spectra and X-ray
Novel 5-(4-substituted-phenyldiazenyl)-1,3,2 lambda(4)-oxazaborines and their rearrangement to 1,2,4,3 lambda(4)-triazaborines
No full textThe reaction of substituted benzenediazonium tetraphenylborates with the beta-enaminones derived from pentane-2,4-dione, 1-phenylbutane-1,3-dione, and 1,4-diphenylbutane-1,3-dione with a primary or secondary (N-methyl, N-phenyl) amino group in CH2Cl2 gives 5-(substituted-phenyldiazenyl)-2,2-diphenyl-4,6-disubstituted- 1,3,2 lambda(4)-oxazaborines or 5-(substituted-phenyldiazenyl)-2,2-diphenyl-3,4,6-trisubstituted-1,3,2 lambda(4)- oxazaborines, respectively. The reaction intermediate of these compounds has been identified, and a mechanism for the reaction has been suggested. Substituted 1,3,2 lambda(4)-oxazaborines gradually rearrange into 1,2,4,3 lambda(4)-triazaborines at temperatures above 100 degrees C
A simple new hydrazine-free synthesis of methyl 1,4,5-trisubstituted 1H-pyrazole-3-carboxylates
No full textConditions for successful syntheses of poly-
substituted pyrazole-3-carboxylates have been found. The
methodology consists in mixing equimolar amounts of
diazonium tetrafluoroborates and enaminoesters in pres-
ence of sodium acetate. 1-Methylpyrrolidone has appeared
to be the solvent of choice. The compounds prepared have
been characterized by means of nuclear magnetic reso-
nance (NMR) spectroscopy, elemental analysis, and in two
cases, also by X-ray diffraction. The advantage of the
methodology is a simple implementation without necessity
of working under inert atmosphere. The presence of other
functional groups enables further synthetic transformations
of the products
Structure and base catalysed cyclization of methyl (2,6-disubstituted-4-nitrophenylsulphanyl)ethanoates
No full textThe conformation of side chain –SCH2COOCH3 in title compounds in crystal agrees with the reactivity of these compounds
in base catalysed ring closure in solution. In the 2,4-dinitro derivative, the side chain is oriented towards the unsubstituted
ortho-position of benzene ring, in the case of the 2-methoxycarbonyl derivative towards this substituent
Formation of pyridazinium salts by azo coupling of N-substituted 3-amino-1-phenylbut-2-en-1-ones and diazonium salts
No full textTreatment of 3-(2,4-dimethoxyphenylamino)- and 3-methylamino-1-phenylbut-2-en-1-ones with some benzenediazonium tetrafluoroborates gives, besides the usual azo coupling products [i.e., 3-(substituted imino)-1-phenylbutane-1,2-di-ones 2- (4-substituted phenylhydrazones) and 2-(4-methoxy-phenyldiazenyl)-3-methylamino-1-phenylbut-2-en-1-one, respectively], the previously unreported 1,4,5,6-tetrasubstituted pyridazinium tetrafluoroborates. The pyridazinium salts have been identified by X-ray analysis and by their H-1, C-13, N-15, B-11 and F-19 NMR spectra. Their formation is most probably the result of nucleophilic attack on the carbonyl carbon by the nitrogen of the hydrazone group and subsequent dehydration
Lateral Water Diffusion in an Artificial Macroporous System: Modeling and Experimental Evidence
No full textA Three-Dimensional Channel Supramolecular Architecture Based on 3-Amino-2-(4-dimethylaminophenyldiazenyl)-1-phenylbut-2-en-1-one and Aromatic Guests
No full textIf crystallized from aromatic solvents (benzene, toluene, p-xylene, chlorobenzene), 3-amino-2-(4-dimethyl-
aminophenyldiazenyl)-1-phenylbut-2-en-1-one (1) forms a three-dimensional supramolecular H-bonding network with mole-
cular channels of approximately cylindrical shape in which the solvent molecules are placed in a defined manner. The aromatic
molecules are bound with the molecules of the network by means of weak intermolecular interactions of varying nature. The
X-ray structures provide detailed information on the bindingmotifs that consist ofC-H...O and C-H...pi bonds between the
aromatic solvent molecules and the benzoyl moiety of 1. The motifs are identical in all the four inclusion compounds analyzed
showing the robustness of this supramolecular synthon. Accordingly, the crystals adopt isostructural arrangements favored by the mutual orientation of the host molecules of 1 that make identical helical catemers by means of strong N-H...O
intermolecular hydrogen bonds. Thermal stability of the inclusion compounds of compound 1 with benzene, toluene, p-xylene,
and m-xylene has been studied by means of differential scanning calorimetry and thermogravimetric analysis methods
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