0000000000054994
AUTHOR
Andrzej A. Domański
showing 9 related works from this author
Azoxybenzene rearrangement catalyzed by solid acids
2008
Abstract For the first time, the potential of acidic cation-exchange resin (sulfonated polystyrene) to catalyze the Wallach rearrangement of azoxybenzene into 4-hydroxyazobenzene has been proved. This finding reveals an alternative reaction path possible in a heterogeneous process using solid acids and may help to clear some doubts concerning the rearrangement mechanism postulated so far. The resin-induced reaction was found to proceed exclusively in a non-polar medium. Reasonable yield was obtained particularly in isooctane due to favorable distribution of azoxybenzene throughout the resin's matrix. On the contrary, the HY type zeolite did not activate the rearrangement, most probably beca…
[5,10,15,20-Tetrakis(4-tert-butylphenyl)-porphyrinato-κ4N] zinc(II) toluene solvate
2007
The structure of the title compound, [Zn(C60H60N4)]·C7H8, represents a typical clathrate containing a host molecule of [5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrinato]zinc(II) and a toluene guest molecule. The Zn atom occupies an inversion center and exhibits ideal square-planar coordination, while the porphyrin group remains perfectly flat. The toluene molecule lies on an inversion center and is disordered.
Disorder in the crystals of trans-4-fluoroazoxybenzene. Synthesis, spectral properties, crystal structures and DFT calculations
2005
Abstract Two crystals of trans-4-fluoroazoxybenzene were obtained using two different methods. Oxidation of 4-fluoroazobenzene provided crystals of trans-4-fluoroazoxybenzene (I) consisting of two isomers; 51% α (ONN) and 49% β (NNO) isomer. From trans-amino-azoxybenzenes in Schiemann reaction it were obtained crystals of trans-4-fluoro-NNO-azoxybenzenes (II, β isomer) containing 4.7% of the α-isomer according to the HPLC analysis. The crystal structures of I and II were determined by the X-ray diffraction method. In the crystal I two nitrogen atoms of azoxy bridge and fluorine atom are disordered. In the crystal II, there are two independent molecules of trans-4-fluoroazoxybenzene; the mol…
Substituent effects in trans-p,p'-disubstituted azobenzenes: X-ray structures at 100 K and DFT-calculated structures.
2014
The crystal and molecular structures of twopara-substituted azobenzenes with π-electron-donating –NEt2and π-electron-withdrawing –COOEt groups are reported, along with the effects of the substituents on the aromaticity of the benzene ring. The deformation of the aromatic ring around the –NEt2group inN,N,N′,N′-tetraethyl-4,4′-(diazenediyl)dianiline, C20H28N4, (I), may be caused by steric hindrance and the π-electron-donating effects of the amine group. In this structure, one of the amine N atoms demonstrates clearsp2-hybridization and the other is slightly shifted from the plane of the surrounding atoms. The molecule of the second azobenzene, diethyl 4,4′-(diazenediyl)dibenzoate, C18H18N2O4,…
Twotrans-4-aminoazoxybenzenes
2001
Two isomeric trans-4-aminoazoxybenzenes, trans-1-(4-aminophenyl)-2-phenyldiazene 2-oxide (alpha, C(12)H(11)N(3)O) and trans-2-(4-aminophenyl)-1-phenyldiazene 2-oxide (beta, C(12)H(11)N(3)O), have been characterized by X-ray diffraction. The alpha isomer is almost planar, having torsion angles along the C(aryl)-N bonds of only 4.9 (2) and 8.0 (2) degrees. The relatively short C(aryl)-N bond to the non-oxidized site of the azoxy group [1.401 (2) A], together with the significant quinoid deformation of the respective phenyl ring, is evidence of conjugation between the aromatic sextet and the pi-electron system of the azoxy group. The geometry of the beta isomer is different. The non-substitute…
4-hydroxy-ONN-azoxybenzene
2000
The oxidation of 4-hydroxyazobenzene provided a mixture of two azoxy compounds, which were separated by column chromatography. The isomer with the higher melting point appeared to belong to the α (ONN) series, as determined by X-ray diffraction. The molecule, C12H10N2O2, is almost planar. The benzene rings are twisted by 11.7 (2) (substituted) and 4.1 (1)° (unsubstituted) with respect to the ONN plane. The molecules are connected to one another by strong O—H⋯O hydrogen bonds forming chains extended along [001], which are bound by much weaker C—H⋯O hydrogen bonds forming layers in the bc plane.
Dimethyl 4,4'-(diazenedi-yl)dibenzoate at 100 K.
2013
In the asymmetric part of the unit cell of the title compound, C16H14N2O4, there are two chemically equivalent but crystallographic independent half molecules. The geometric centre of each complete molecule lies on a crystallographic inversion centre. Both molecules are almost planar [mean deviations of atoms in the two molecules are 0.032 (2) and 0.044 (2) Å] and their geometries are similar. In the crystal, molecules are arranged in columns along theaaxis. There are no intermolecular donor–acceptor distances shorter than 3.4 Å.
trans-4-Bromo-ONN-azoxybenzene at 100 K.
2004
The crystal structure of the alpha isomer of trans-4-bromoazoxybenzene [systematic name: trans-1-(bromophenyl)-2-phenyldiazene 2-oxide], C(12)H(9)BrN(2)O, has been determined by X-ray diffraction. The geometries of the two molecules in the asymmetric unit are slightly different and are within approximately 0.02 A for bond lengths, approximately 2 degrees for angles and approximately 3 degrees for torsion angles. The azoxy bridges in both molecules have the typical geometry observed for trans-azoxybenzenes. The crystal network contains two types of planar molecules arranged in columns. The torsion angles along the Ar-N bonds are only 7 (2) degrees, on either side of the azoxy group.
Orthorhombic polymorphs of twotrans-4-aminoazoxybenzenes
2002
The two isomeric compounds 4-amino-ONN-azoxybenzene [or 1-(4-aminophenyl)-2-phenyldiazene 2-oxide], i.e. the alpha isomer, and 4-amino-NNO-azoxybenzene [or 2-(4-aminophenyl)-1-phenyldiazene 2-oxide], i.e. the beta isomer, both C(12)H(11)N(3)O, crystallized from a polar solvent in orthorhombic space groups, and their crystal and molecular structures have been determined using X-ray diffraction. There are no significant differences in the bond lengths and valence angles in the two isomers, in comparison with their monoclinic polymorphs. However, the conformations of the molecules are different due to rotation along the Ar-N bonds. In the alpha isomer, the benzene rings are twisted by 31.5 (2)…