Showing papers on "Nitroso published in 1977"

Nitrosoalkanes as Fe(II) Ligands in the 455‐nm‐Absorbing Cytochrome P‐450 Complexes Formed from Nitroalkanes in Reducing Conditions

Abstract: Primary and secondary aliphatic nitroalkanes RR'CHNO2, react with microsomal cytochrome p-450 in the presence of dithionite leading to new complexes with a Soret peak at 455 nm. The formation of these complexes is inhibited completely by CO and partially by metyrapone. However, once formed, their exogenous ligand is not displaced by excess CO. By deoxycholate treatment they are transformed into 423-nm-absorbing cytochrome P-420 complexes, which are spectrally similar to the corresponding RR'CHNO2-derived myoglobin complexes. The 455-nm-absorbing complexes are equally produced from RR'CHNO2 reduction, microsomal NADPH-dependent oxidation of the corresponding hydroxylamine RR'CHNHOH, or interaction of the nitrosodimer (RR'CHNO)2 with reduced cytochrome P-450. All the reported results are consistent with the involvement of a new class of ligands of cytochrome P-450-Fe(II), which are the unstable aliphatic nitrosomonomers RR'CHNO, whose nitroso group is isoelectronic with dioxygen and whose stabilisation results from their strong binding to heme-Fe(II), thus explaining the observed inhibition of the hydroxylating function of cytochrome P-450.

Mutagenicity screening of five methyl carbamate insecticides and their nitroso derivatives using mutants of Salmonella typhimurium LT2.

Abstract: The mutagenic activity of five methyl carbamate insecticides — carbaryl, baygon, BUX-Ten, landrin and methomyl — and their nitroso derivatives were investigated using histidine auxotrophs — his TA98, his TA100, his TA1535, his TA1537 and his TA1538 — of Salmonella typhimurium LT2 derived by Ames. The methyl carbamate insecticides did not cause a significant increase in the number of revertant colonies in any of the strains used. In contrast, the nitroso derivatives of the carbamate insecticides greatly increased the number of colonies on plates inoculated with strains his TA100 and his TA1535. We conclude that the nitroso derivatives of the tested methyl carbamate insecticides are potent mutagens; whereas, the parent insecticides are non-mutagenic.

Nitrosoalkanes as Fe(II) ligands in the hemoglobin and myoglobin complexes formed from nitroalkanes in reducing conditions.

Abstract: Primary and secondary aliphatic nitro compounds, R2CHNO2, react with myoglobin and hemoglobin, in the presence of sodium dithionite, leading to new complexes with Soret peaks respectively at 425 and 421 nm. These complexes are very stable even after disappearance of the starting nitro compounds and do not exchange their exogenous ligand after 10 h under 1 atm (101 325 Pa) CO. They are low-spin hexacoordinated myoglobin or hemoglobin complexes, as shown by the resonance Raman spectrum of the nitromethane-derived human hemoglobin complex which is similar to those of the known hemoglobin complexes with O2, CO, NO and nitrosobenzene. Evidence has been produced to show that the nitro compounds themselves do not bind to the hemoproteins; we propose that among the reduction derivatives produced in situ by dithionite, the corresponding unstable nitroso monomers, whose nitroso group is isoelectronic with dioxygen, are the actual ligands of the 425-nm or 421-nm-absorbing complexes.

Adhesive compositions comprising (a) halogenated polyolefin (b) aromatic nitroso compound and (c) lead salts

Abstract: Compositions comprising at least one halogen-containing polymer, at least one aromatic nitroso compound, at least one salt of certain inorganic and organic acids, and, optionally, at least one maleimide compound, have been found to be unexpectedly effective as storage-stable, single-package, one-coat adhesive systems for bonding a variety of elastomeric materials, including vulcanizable and vulcanized natural and synthetic elastomer compositions, to themselves and other structural substrates.

Photopolymerizable compositions containing nitroso dimers to selectively inhibit thermal polymerization

Abstract: Thermally stable photopolymerizable compositions comprise (i) at least one nongaseous ethylenically unsaturated compound, (ii) a nitroso dimer which is a noninhibitor of free-radical polymerization but thermally dissociates to nitroso monomer which is an inhibitor of free-radical polymerization, and (iii) an organic, radiation-sensitive free-radical generating system.

Pentamethylnitrosobenzene as a Spin-trapping Agent

Abstract: Pentamethylnitrosobenzene synthesized readily from pentamethylbenzene was studied for utilization in a spin-trapping technique. In a benzene solution it forms a dimer with a dissociation constant of 105.26exp(−50⁄RT) in units of kJ/mol. It traps the t-butyl radical with the trapping rate constant of 1.4×108 mol−1 dm3 s−1 at 299 K. It is thus an efficient spin-trapping agent, even though only a fraction of it is reactive with the short-lived free radicals because the equilibrium lies more on the side of the dimeric form. Electron spin resonance parameters were determined for the spin-adduct radicals derived from alkyl, alkoxyl, and phenyl radicals with this trapping agent. These free radicals were found to attach exclusively to the nitrogen atom of the nitroso compound.

Deamino derivatives of the kallikrein-trypsin inhibitor

Abstract: A demaino kallikrein-trypsin inhibitor obtained from cattle organs is characterized by (a) 0 to 3 lysine residues and/or 3 to 6 arginine residues and/or 1 to 4 tyrosine residues; (b) the 10- and/or 21-tyrosine residues being unsubstituted or substituted by at least one nitro, nitroso or amino in the ortho position relative to the phenolic hydroxy group; and (c) having protease inhibitory activity of BPTI and elastase inhibition activity.

In Vivo Formation of N-Nitroso Compounds and Detection of Their Mutagenic Activity in the Host-mediated Assay

Abstract: The formation of N -nitroso compounds in mouse stomach from equimolar doses of sodium nitrite and secondary amines or alkylurea derivatives given simultaneously by a stomach tube was estimated by measuring the mutagenic activity of the compounds in the i.p. host-mediated assay with the use of Salmonella typhimurium TA1950 as genetic indicator system. A mutagenic response in the bacteria was found after administration of the cyclic amines piperazine dihydrochloride, morpholine, and amitrole. The highest mutagenicity was exerted by piperazine dihydrochloride plus nitrite, while amitrole plus nitrite was only weakly mutagenic. No mutagenic activity was observed for equimolar doses of sodium nitrite plus dimethylamine hydrochloride, diphenylamine, methylbenzylamine hydrochloride, and phenmetrazine hydrochloride. All N -alkylurea derivatives tested were found to yield significant amounts of N -nitroso compounds, which allowed detection of their mutagenic activity in the host-mediated assay. The highest activity was shown by nitrite plus ethylenebis(thiourea), while methylurea and ethylurea were found to be less active in combination with nitrite. Dose-response curves for the mutagenic activity of N -nitrosamines were used to estimate the amounts of N -nitroso derivatives formed in vivo from the precursors after acute treatment of the mice. In the case of piperazine dihydrochloride, nitrosation of 50 to 70% was estimated, while for morpholine nitrosation ranged from 1 to 3%. The results are compared with those obtained in long-term carcinogenesis studies with sodium nitrite plus amines.

The reactions of transition metal chelates with organometallic compounds and their paramagnetic products. V—New possibilities in the generation of anion radicals by reactions of Grignard reagents and lithium alkyls in the presence of transition metal ions

Abstract: In the reactions of Grignard reagents and n-butyllithium the presence of transition metals and complexing solvents facilitates the formation of anion radicals. High radical concentrations, observable for some days at laboratory temperature, and very well resolved e.s.r. spectra of the following structural types have been obtained using a relatively simple procedure: aromatic hydrocarbons, heteroaromatics, aldehydes, ketones, α-diketones, enolates of β-diketones, quinones, sulphones, sulphoxides, nitro-, nitroso- and azo-benzenes, cyano compounds and phosphine oxides. It is suggested that the transition metals, according to the type of reactants and the experimental conditions, mediate the transfer of one electron to the substrate in many reactions and stabilize the intermediate products as anion radicals. The variation of solvents and organometallic compounds modifies the reduction power of such systems and leads to the radical products in a different reduction state. The procedure described is advantageously employable in the generation of anion radicals, and the effect of transition metals which has been found may widen the scope of this phenomenon to many different applications.

Über die Carbonylierung aromatischer Nitrosoverbindungen zu Arylisocyanaten in Gegenwart komplexer Rhodium‐ und Iridiumkatalysatoren

Abstract: In Gegenwart von Rhodium- und Iridiumcarbonylen werden aromatische Nitrosoverbindungen zu Arylisocyanaten carbonyliert. Die Reaktion ist jeweils von erster Ordnung bezuglich Nitrosoverbindung, Katalysator und Kohlenmonoxid. π-Acceptorliganden im Komplex und voluminose Substituenten in 2-Stellung der Nitrosoverbindung erhohen die Reaktionsgeschwindigkeit. Der geschwindigkeitsbestimmende Schritt der Reaktion ist die Desoxygenierung, die der Addition der Nitrosoverbindung an den Komplex folgt. On the Carbonylation of Aromatic Nitroso Compounds to Arylisocyanates in the Presence of Complex Rhodium and Iridium Catalysts Aromatic nitroso compounds are carbonylated to arylisocyanates in the presence of rhodium and iridium carbonyls. The reaction is first order in nitroso compound as well as catalyst and carbon monoxide. π-Acceptor ligands in the complex and voluminous substituents in position 2 of the nitroso compound increase the reaction rate. The rate determining step of the reaction is the desoxygenation following the addition of the nitroso compound to the complex.

Rearrangements involving a C-nitroso group: formation of dialkylhydroxylamines and nitroxides

Abstract: Photoaddition of a nitrosamine to α-pinene and 5-methylenebicyclo[2.2.1]heptene in acidified methanol solution gave the tertiary nitrosoalkanes derived from 1.2-addition across the double bonds in the latter case and from addition involving cyclobutane ring opening in the former case. Under the reaction conditions, these tertiary nitrosoalkanes underwent a rearrangement involving the C-nitroso-group and a labile pair of proximate π or σ electrons to form bridged bicyclic hydroxylamines. These hydroxylamines are easily oxidized by air to the corresponding nitroxide radicals; one of them is stable enough to be purified. Using bromotrichloromethane as solvent, the intermediate carbon radical in the photoaddition to 5-methylenebicyclo[2.2.1]heptene can be trapped to give a good yield of bromotricyclane derivatives.

1-Tetrahydroxycyclopentyl-3-nitroso-3-(2-chloroethyl)-urea antitumor agents

Abstract: Novel water-soluble nitrosourea derivatives of the formula ##STR1## WHEREIN R represents a 2', 3', 4', 5'-tetrahydroxycyclopentyl group exhibit high effectiveness in various animal tumor systems.

Nitrosourea derivative and its preparation

Abstract: NEW MATERIAL:Nitrosourea derivatives of formula I (R 1 is unsaturated nitrogen-containing heteromonocyclic group that may be substituted; R 2 is lower alkyl that may branch). EXAMPLE: 1-(4-Amino-2-methyl-5-pyrimidinyl)methyl-1-methyl-3-(2-chloroethyl)-3- nitrosourea. USE: Low-texicity medicines with antitumorigenic activity. PREPARATION: The nitrosation of a urea derivative of formula II is effected in an appropriate solvent as formic acid using a compound bearing nitroso groups as sodium nitrite at room or lower temperature, preferably 0W5°C, to prepare said nitrosorea derivative of formula I. COPYRIGHT: (C)1979,JPO&Japio

Photoreactivity of aqueous anionic NOx with hydrocarbons part I nitrite-heptane system under strong UV. radiation

Abstract: The reduction of nitrous ions, in solutions containing heptane suspended under vigorous stirring and irradiated with a strong UV source, is investigated. The formation of ammonium is used as a monitor of the process which also leads to the concurrent production of organic nitrates and nitrites, as well as of aldehydes and nitro, nitroso and ammino derivatives. An overall mechanism of ammonium formation and destruction is proposed and tested and the effects of NO inf2 sup− concentration, pH, radiation intensity and temperature are evaluated. Implications towards the importance of similar reactions which may occur under sunlight are discussed.

Synthesis of nornicotine‐2,4,5,6‐d4 and its N′‐nitroso derivative

Abstract: Nornicotine-2,4,5,6-d4 and its N′-nitroso derivative were synthesized from pyridine-d5. Initially, pyridine-d5 was brominated in fuming D2SO4 to give 3-bromopyridine-d4. Treatment of this material with n-butyllithium and dry ice followed by acidification gave nicotinic acid-2,4,5,6-d4. Conversion of this substance to the acid chloride hydrochloride (via thionyl chloride) followed by treatment with absolute ethanol gave ethyl nicotinate-2,4,5,6-d4. The ester was condensed with N-trimethylsilyl-2-pyrrolidinone in the presence of n-butyllithium and diisopropylamine to give, after hydrolysis and decarboxylation, myosmine-2,4,5,6-d4. Reduction of this material with sodium borohydride gave nornicotine-2,4,5,6-d4. Conversion to the N′nitroso derivative was achieved by treatment with nitrous acid.

Process for the preparation of unsymmetrically 1,3-disubstituted nitroso ureas

Abstract: The invention relates to the preparation of unsymmetrically 1,3-disubstituted nitroso ureas from the corresponding N-substituted alkyl-N-nitrosocarbamoyl azide which is reacted with an amine, a diamine, an aminoalcohol, an aminoacid or an aminoacid derivative. The N-nitrosocarbamoyl azide is obtained by reacting the corresponding alkylcarbamoyl azide with nitrogen tetroxide in the cold. The alkylcarbamoyl azide is obtained by reacting the corresponding isocyanate with an alkali metal azide. The invention further relates to novel nitroso ureas obtained thereby, to novel N-substituted alkyl-N-nitrosocarbamoyl azides, and to novel therapeutic compositions containing, as the active ingredient, the novel nitroso ureas.

Photohardenable films having high resolution containing nitroso dimers

Abstract: Photohardenable films containing a photoactivated free-radical initiator and an inhibitor system composed of a noninhibiting nitroso dimer which dissociates to inhibiting nitroso monomer characterized by a dissociation constant of about 10-2 -10-10 in solution at 25° C. and a dissociation half-life of at least about 0.5 minute in solution at 25° C., and having an optical density to initiating radiation of about 0.02-1.25 have high resolution after exposure at the proper energy density and time.

Spectrophotometric determination of iron at the p. p. m. level in sugar samples with 2-nitroso-5-dimethylaminophenol

Abstract: Ppm amounts of iron in sugar samples were determined spectrophotometrically with 2-nitroso-5-dimethylaminophenol (nitroso-DMAP). The iron(II) complex formed with nitroso-DMAP, is stable in aqueous solution at about pH 9. The method is simple, rapid, selective and very sensitive (molar absorptivity: 4.0×l04l-mol−1-cm−1).

Iterative least‐squares analysis of dynamic n.m.r. spectra. Hindered rotation of the N‐nitroso group in N‐nitroso‐N‐cyanomethylmethylamine

Abstract: Iterative analysis of dynamic n.m.r. (d.n.m.r.) spectra by the least-squares method was applied to the entire proton spectrum of N-nitroso-N-cyanomethylmethylamine and, separately, to the CH3 and CH2CN sub-spectra. Resulting differences in the estimated rates of rotation of the NO group are discussed in terms of systematic errors which may be involved in determining spin exchange rates by d.n.m.r. methods. The most probable explanation is that quadrupolar broadening and then unresolved 14N1H spin–spin splitting may appear on increasing the temperature. Estimated entropies of activation indicate that the methyl sub-spectrum gives more reliable results.