Para-nitro Group Research Articles

Bis(2,4-dinitrophenolato)(triethanolamine)calcium(II)

The title complex, bis(2,4-dinitrophenolato-O,O 2 )-(2,2',2''-nitrilotriethanol-N,O,O',O'')calcium(II), [Ca(C 6 H 3 N 2 O 5 ) 2 (C 6 H 15 NO 3 )], is monomeric and the Ca 2+ ion is eight-coordinate. Both dinitrophenolate ligands coordinate to the metal ion by their phenolic O atoms and one O atom of the ortho-nitro group. Ca is further coordinated by all the O atoms and the N atom of triethanolamine, the O atoms of which are also hydrogen-bond donors. The phenolic O atoms and one O atom of a para-nitro group take part in intermolecular hydrogen bonding.

Synthesis and characterization of polyacrylates containing charge transfer groups

Polyacrylates containing para-nitro azobenzene have been synthesized by free radical polymerization. The influence of the length of the spacer of the homopolyacrylates (HPn, n=3,4,6), content of methyl acrylate in the copolyacrylates (CP6) with para-nitro azobenzene groups on the thermal properties, such as liquid crystallinity, Tg and Tm, was studied by DSC, WAXD and polarized optical microscopy. Among the polymers studied, only the homopolyacrylate (HP6) with six carbon atoms in the spacer exhibited a nematic phase. The second-harmonic generation (SHG) signal of the poled HP6 film was detected qualitatively by Maker-fringer method.

The 18-crown-6 potassium salt of a Meissenheimer anion, [K(C7H3Cl3N3O6)(C12H24O6)

The title compound crystallizes as a centrosymmetric dimer, bis(μ-4-trichloromethyl-1,3,5-trinitro-2,5-cyclohexadien-1-ido)-1κ 2 O 1 ,O 1' :2κO 3 ;1κO 3 :2κ 2 O 1 ,O 1' -bis[(1,4,7,10,13,16-hexaoxacyclooctadecane-κ 6 O)potassium], [{K(C 12 H 24 O 6 )} 2 (μ-C 7 H 3 Cl 3 N 3 O 6 ) 2 ], in which the coordination of the (18-crown-6)potassium ions is completed by a bidentate para nitro group from one anion and a monodentate ortho nitro group from the other. The CCl 3 group is axial and points away from the centre of inversion. The K + ion is 0.782 (2) A out of the mean plane of the six crown O atoms

The effect of EU4093 (azumolene sodium) on the contraction of intrafusal muscle in the soleus muscle of the anaesthetized rat.

1. EU4093 (azumolene sodium) is a direct acting, skeletal muscle relaxant with structural similarities to dantrolene sodium in that the para-nitro phenyl group of dantrolene sodium is replaced by a para-bromo phenyl group. 2. The effect of EU4093 on the twitch of the intact rat soleus preparation is nearly maximal at a dose of 20 mg kg-1. This dose of EU4093 reduces the amplitude of the twitch to 31.9% of the control value. By comparison, dantrolene sodium reduced the twitch amplitude to 31.3% of the control value at a dose of 5 mg kg-1. 3. The contraction of intrafusal muscle as measured by the response of spindle afferent discharge was also reduced by EU4093. 4. The most significant difference between the effect of EU4093 and dantrolene sodium on the contraction of intrafusal muscle was that EU4093 had an appreciable depressant action at high stimulation frequencies at which dantrolene sodium had only a minimal relaxant effect on the intrafusal muscle contraction. 5. The significance of this difference in the actions of EU4093 and dantrolene sodium is discussed in terms of the possible effect of the drug in the intact animal and human patient. It is concluded that, because the discharge frequency is not likely to move into the high frequency range at which dantrolene sodium and EU4093 have significantly different effects, the overall effect of these two drugs is likely to be similar.

Adamantylmethyl analogues of chloramphenicol

The synthesis and biological activity of novel adamantylmethyl analogues of chloramphenicol are described. Substituting the polar para-nitro group on the phenyl ring with a non-polar lipophilic adamantylmethyl moiety resulted in a diminished antimicrobial activity. At a daily dose of 3 mg/kg the threo-4-[2′-tricyclo[3.3.1.1 3,7]decylidene)-methyl-1-[1″, 3″-dihydroxy-2″-(α,α-dichloroacetamido)propyl]benzene caused a significant loss of humoral immuno-competence in the T-dependent Kennedy plaque assay in mice.

Rigid conformation in tert.‐butyloxycarbonyl‐l‐alanine ortho‐nitrophenyl ester

Ortho‐nitrophenyl esters of blocked amino acids have significantly higher aminolysis rates than the corresponding para‐nitrophenyl esters. This difference prompted a series of investigations that led to the present study. Single crystal X‐ray diffraction analysis of tert.‐butyloxycarbonyl‐l‐alanine o‐nitrophenyl ester has shown a rather rigid molecular conformation with very restricted rotation about the ester bond owing to the wedging of one of the nitro oxygen atoms between the two oxygens of the ester group. A para nitro group can not interact in a similar fashion and consequently can have many more rotamers. The C14H18N2O6 ester crystallizes in space group P21, with a = 5.180 Å, b = 9.726 Å, c = 15.616 Å and β= 92.36 Å. There is only one intermolecular hydrogen bond, N(1)H…O(0) at 3.125 Å, that links neighboring molecules into infinite chains. There are no intramolecular hydrogen bonds.

Substituted benzene cations formed by radiolysis: an electron spin resonance study

Exposure of dilute solutions of substituted benzenes in trichlorofluoromethane to 60Co γ-rays at 77 K gave the corresponding radical cations, which were detected and characterised by e.s.r. spectroscopy. In general, the e.s.r. results show that the SOMO is that predicted by theory and found from photoelectron spectroscopic studies, but several interesting facets have emerged. For the monosubstituted cations, (Ph–X)+, where X =CHO or CMeO, the SOMO is largely confined to the benzene ring, with no evidence for cations with a SOMO largely confined to the n oxygen orbital. For styrene and substituted styrene cations there is considerable delocalisation on to the olefin moiety (ca. 30%). Nitrobenzene cations have a nodal plane through the nitro group with zero spin density on nitrogen (a2), but they rearrange on annealing to give (RONO)+ cations with the unpaired electron strongly confined to the nitro group. For the disubstituted cations, the effect of a methyl group para to a nitro group is of interest since the alternative SOMO is selected (b1), giving a high spin density on the methyl group (AMe=20 G). However, delocalisation on to the nitro group remains small. The effect of para-cyano groups on the cations of halogenobenzenes is to increase the extent of delocalisation on to halogen, but no hyperfine splitting from 14N is detectable. The effect of a para-nitro group is to increase the spin density on the halogen still further.Benzyl derivatives, (PhCH2X)+, are of interest because of the range of conformations available. When X =Me, the methyl group lies close to the plane of the ring, giving maximum σ–π interaction with the methylene protons [A(1H)=29 G]. Curiously, for p-diethylbenzene cations, the major species seems to have the two methyl groups well removed from the nodal plane. Halogen substituents (X =Cl, Br) also give variable conformations, the in-plane site being favoured for chlorine, and the maximum out-of-plane site for bromine. However, the cation of p-nitrobenzyl chloride has a high spin density on chlorine. As with benzaldehyde, the SOMO for phenylacetaldehyde cations is clearly confined to the benzene ring rather than being the n oxygen orbital. In this case, the CHO group sits close to the plane of the ring, whereas the CMeO group is well removed from this plane.

Calorimetric study of the ionization process for 2,4-dinitrophenol in water—dimethylsulphoxide mixtures at 25°C

The ionization and solution enthalpies of 2,4-dinitrophenol were measured calorimetrically at 25°C in water—DMSO mixtures ranging from 0.1 to 0.8 mole fraction of DMSO. The greater acidity of 2,4-dinitrophenol with respect to 2,5-dinitrophenol is explained on the basis of the observation that in the anion the π-withdrawing resonance effect of the para nitro group stabilizes the benzene ring while in the undissociated molecule the contrary is true.

Microbial transformation of 2,4,6-trinitrotoluene and other nitroaromatic compounds.

A variety of nitroaromatic compounds, including 2,4,6-trinitrotoluene (TNT), were reduced by hydrogen in the presence of enzyme preparations from Veillonella alkalescens. Consistent with the proposed reduction pathway, R-NO2 H2 leads to R-NO H2 leads to R-NHOH H2 leads to R-NH2, 3 mol of H2 was utilized per mol of nitro group. The rates of reduction of 40 mono-, di-, and trinitroaromatic compounds by V. alkalescens extract were determined. The reactivity of the nitro groups depended on other substituents and on the position of the nitro groups relative to these substituents. In the case of the nitrotoluenes, the para-nitro group was the most readily reduced, the 4-nitro position of 2,4-dinitrotulene being reduced first. The pattern of reduction of TNT (disappearance of TNT and reduction products formed) depended on the type of preparation (cell-free extract, resting cells, or growing culture), on the species, and on the atmosphere (air or H2). The "nitro-reductase" activity of V. alkalescens extracts was associated with protein fractions, one having some ferredoxin-like properties and the other possessing hydrogenase activity. Efforts to eliminate hydrogenase from the reaction have thus far been unsuccessful. The question of whether ferredoxin acts as a nonspecific reductase for nitroaromatic compounds remains unresolved.

Dipole moments, anisotropies of the polarizability, and conformations of aliphatic and aromatic sulfonyl chlorides

1. The ellipsoids of polarizability of dimethylsulfone, sulfuryl chloride, and methanesulfonyl chloride were determined, and the nonadditivity of the parameters of the bonds in the sulfonyl chloride group was demonstrated. 2. Substituted methane sulfonyl chloride exist in gauche conformations. 3. In benzenesulfonyl chloride and a series of its para-substituted derivatives, the aryls are situated in the C-S-Cl plane; the para-nitro group induces a 35° rotation.

The specificity of cellular immune responses in guinea pigs. I. T cells specific for 2,4-dinitrophenyl-o-tyrosyl residues.

Guinea pigs immunized with the hapten 2,4-dinitrophenyl (DNP) coupled directly to Mycobacterium tuberculosis of strain H37Ra (DNP-H37) show a variety of cell-mediated immune responses to DNP coupled to protein carriers. The cells responsible for this specific response are thought to be T lymphocytes for the following reasons: Guinea pigs immunized with DNP-H37 displayed delayed hypersensitivity reactions to several DNP-proteins and contact sensitivity to dinitrofluorobenzene. Peritoneal exudate lymphocytes (PELs) obtained from DNP-H37 immune animals respond to DNP-proteins with DNA systhesis and cause inhibition of macrophage migration. PELs are highly enriched in T lymphocytes and contain few immunoglobulin-bearing cells. Further depletion of immunoglobulin-bearing cells from this population does not diminish the in vitro proliferative response to antigen. Nitrophenyl conjugates of proteins lacking a paranitro group stimulated DNA synthesis poorly or not at all, indicating the importance of the paranitro group of DNP in antigen recognition by T cells in this system. In this respect, the specificity of T cells resembles that of DNP-specific antibody from the same animals. On the other hand, DNP conjugates of copolymers of glutamic acid and lysine and DNP conjugated to proteins via an interposed beta-alanyl-glycyl-glycyl spacer failed to stimulate DNA synthesis, although such compounds bind very efficiently to anti-DNP antibody. By contrast, DNP conjugates of synthetic polypeptide carriers containing as little as 7% tyrosine strongly stimulated DNA synthesis in DNP-H37 immune PELs. That the determinant responsible for this stimulation was DNP coupled to the hydroxyl group of tyrosine was shown by selective removal of DNP from tyrosine by thiolysis with 2-mercaptoethanol, which abolished their ability to stimulate T cells.

A comparison of the acidity and basicity of aromatic amines

The acidities of a series of anilines and diphenylamines are compared with their basicities. A plot of the acidity versus the basicity (pKHA on ordinate versus [Formula: see text]) of nine diphenylamines yields a straight line with a slope of 1.30. In a similar plot for 33 substituted anilines and diphenylamines, two types of behavior are observed. Those anilines and diphenylamines without an ortho- or para-nitro group fall about the line with a slope of 1.30, whereas those amines with at least one nitro group in the ortho or para position fall on a different, curved line with a slope of less than unity. The first conjugating nitro group thus has an anomalously large effect on the acidity, but not on the basicity, of aromatic amines. The reasons for this are discussed.An estimate of 33.5 is obtained for the pKHA of ammonia.