Free radical pathways in the nitrous acid deamination of α-aminonitriles

1992 ◽  
pp. 47-49
Author(s):  
Michael Bunse ◽  
Dirk Jödicke ◽  
Wolfgang Kirmse
Keyword(s):  
Free Radical ◽  
Nitrous Acid

Pyridazino[3,4,5-de]phthalazines. I. Synthesis of the heterocyclic system and key intermediates

1979 ◽  
Vol 57 (24) ◽  
pp. 3320-3331 ◽  
Author(s):  
John E. Francis ◽  
Karl J. Doebel ◽  
Paula M. Schutte ◽  
Edgar C. Savarese ◽  
Stephen E. Hopkins ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Clinical Trials ◽  
Free Radical ◽  
Carbon Tetrachloride ◽  
Hydrazine Hydrate ◽  
Nitrous Acid ◽  
Heterocyclic System ◽  
Acid Chlorides ◽  
Test Models ◽  
Methyl Cellosolve

1H-Pyridazino[3,4,5-de]phthalazine (4) and 3-hydrazino-1(or 9) H-pyridazino[3,4,5-de]-phthalazine (6) represent intramolecular hydrazones of the drugs hydralazine and dihydralazine, respectively. These novel heterocycles were synthesized by several different routes starting from 2,6-dimethylbenzoic acid, 3-methylphthalic anhydride, or hemimellitic acid. Tetrabromination of 2,6-dimethylbenzoic acid with bromine and carbon tetrachloride under free radical conditions followed by treatment with dilute aqueous hydrazine hydrate produced pure 4 in yields up to 58%. Treatment of 3-methylphthalic anhydride with 2 mol of N-bromosuccinimide under radical conditions followed by reaction of the dibromo compound with hydrazine hydrate in methyl Cellosolve produced 3-oxo-3H-2,9(or 1,2)-dihydropyridazino[3,4,5-de]phthalazine in 60% yield. This intermediate was converted to the 3-thiono compound or 3-chloro-1(or 9)H-pyridazino[3,4,5-de]phthalazine from which the hydrazine 6 was generated by hydrazine hydrate treatment. This hydrazine was further characterized by conversion with acid chlorides to novel tetracyclic condensed triazoles or by nitrous acid to a tetracyclic condensed tetrazole. The unsubstituted heterocycle 4 was uninteresting in pharmacological screens but the hydrazine 6 resembled hydralazine by lowering blood pressure in several animal test models and in limited clinical trials.

Anisole nitration during gamma-irradiation of aqueous nitrite and nitrate solutions: free radical versus ionic mechanisms

2010 ◽  
Vol 7 (2) ◽  
pp. 183 ◽  
Author(s):  
Gracy Elias ◽  
Bruce J. Mincher ◽  
Stephen P. Mezyk ◽  
Thomas D. Cullen ◽  
Leigh R. Martin
Keyword(s):  
Free Radical ◽  
Water Treatment ◽  
Condensed Phase ◽  
Aromatic Compounds ◽  
Nitrous Acid ◽  
Radical Reactions ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Beam Irradiation ◽  
Free Radical Reactions

Environmental context. The nitration of aromatic compounds is an important source of toxic, carcinogenic, and mutagenic species in the atmosphere. Gas phase nitration typically occurs by free radical reactions. Condensed-phase free radical reactions may also be relevant in fog and cloud water in polluted areas, in urban aerosols with low pH, in water treatment using advanced oxidation processes such as e-beam irradiation, and in nuclear waste treatment applications. This paper discusses research towards an improved understanding of nitration of aromatic compounds in the condensed phase under conditions conducive to free radical formation. Abstract. In the irradiated, acidic condensed phase, radiation-enhanced nitrous acid-catalysed, nitrosonium ion, electrophilic aromatic substitution followed by oxidation reactions dominated over radical addition reactions for anisole. This ionic mechanism would predominate in urban atmospheric aerosols and nuclear fuel dissolutions. Irradiated neutral nitrate anisole solutions were dominated by mixed nitrosonium/nitronium ion electrophilic aromatic substitution reactions, but with lower product yields. Solutions such as these might be encountered in water treatment by e-beam irradiation. Irradiation of neutral nitrite anisole solutions resulted in a statistical substitution pattern for nitroanisole products, suggesting non-electrophilic free radical reactions involving the •NO2 radical. Although often proposed as an atmospheric nitrating agent, NO2 radical is unlikely to have an important effect in the acidic condensed phase in the presence of more reactive, competing species such as nitrous acid.

scholarly journals THE PREPARATION AND SOME REACTION OF 2,2-DIPHENYL-1-(3,6-DINITR0-4-COUMARINYL) HYDRAZYL FREE RADICAL

1998 ◽  
Vol 6 (7) ◽  
pp. 59-66
Author(s):  
Petre Ionita ◽  
Marcela Rovinaru ◽  
Ovidiu Maior
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Crown Ether ◽  
Potassium Permanganate ◽  
1H Nmr ◽  
Sodium Nitrite ◽  
Nitrous Acid ◽  
Lead Dioxide ◽  
Epr Spectra ◽  
New Compounds

The new persistent 2,2-diphenyl-1-(3,6-dinitro-4-coumarinyl)hydrazyl free radical 4 was obtained by potassium permanganate or lead dioxide oxidation of the corresponding 2,2-diphenyl-1-(3,6-dinitro-4-coumarinyl)hydrazine 3; hydrazine 3 reacts with nitrous acid to give successively the 2-(p-nitrophenyl)-2-phenyl-1-(3,6-dinitro-4-coumarinyl) hydrazine 6 and 2,2-(p-nitrophenyl)-1-(3,6-dinitro-4-coumarinyl) hydrazine 7. Compound 6 results also from free radical 4 and sodium nitrite in the presence of 15-C-5 crown ether. The structure of new compounds was confirmed by means of TLC, UV-Vis, 1H-NMR, IR, and for the free radicals by the EPR spectra.

scholarly journals СИНТЕЗ ТА ДОСЛІДЖЕННЯ АНТИОКСИДАНТНОЇ АКТИВНОСТІ ДЕЯКИХ ПОХІДНИХ НА ОСНОВІ 4-ІМІНОТІАЗОЛІДИН-2-ОНУ

2015 ◽  
Author(s):  
Т. І. Чабан
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Nitrous Acid ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Free Radical Scavenging Activity ◽  
Basic Medium ◽  
Scavenging Activity ◽  
Dpph Radical

<p class="BodyText2" align="center"><strong>Synthesis and antioxidant activity evaluation of </strong><strong>some novel derivatives based on 4-iminothiazolydine-2-one</strong></p><p align="center">T.I. Сhaban</p><p> </p><p align="center">Lviv, Danylo Halytsky Lviv National Medical University</p><p align="center"><strong> </strong></p><p class="a"><strong>Summary</strong>: Thiazolydine derivatives belong to the group of biologically active compounds which are widely used in modern medical chemistry. They were shown to posses the wide range of biological actions.</p><p>4-Imino-2-thiazolydones are relatively unexplored with regard to their preparation synthetic protocols and biological action spectrum in the modern organic and pharmaceutical chemistry as compared to their 2-imino derivatives. Thus the objective of the present work was to synthesize a series of novel 4-imino-2-thiazolydone derivatives as the potential drug-like molecules.  </p><p>3-Aryl-thiazolydine-2,4-dions were firstly prepared using the common synthetic protocol and they were then subjected to thionation reaction with phosphorus pentasulfide leading to the appropriate 3-aryl-4-thioxo-thiazolydin-2-ones obtaining.</p><p>The above-mentioned derivatives were obtained under the conditions similar to that under which well-known 4-thioxo-thiazolydine-2-one (isorhodanine) synthesis was preceded. The synthetic potential of the synthesized compounds allowed 3-aryl-4-thioxo-thiazolydones treatment with 25 % ammonia aqueous solution leading to novel 3-aryl-4-imino-thiazolydine-2-one obtaining not mentioned in the scientific literature. The reaction proceeding was possible taking into account the advantage of thione group significant activity possessing  in 3-aryl-4-thioxo-thiazolydine-2-ones as cyclic thioamides owing to stronger electrophilic properties of thiocarbonyl group carbon atom as compared with carbonyl group in C<sup>4</sup> position of 3-aryl-thiazolydine-2,4-diones, consequently. One of the proofs of synthesized compounds structure was their acidic hydrolysis with 3-aryl-thiazolydine-2,4-ones generation.</p><p>The presence of active methylene group in C<sup>5</sup> position of 3-phenyl-4-imino-thiazolydine-2-one thiazolydine ring provided an entry for aldol condencation carrying out with the respective 3-phenyl-4-imino-thiazolydine-2-one 5-aryliden derivatives generation. We discovered that the high yield of the product could be achieved by introducing the equimolar amounts of  3-phenyl-4-imino-thiazolydine-2-one and appropriate aromatic aldehydes using monoaminoethanol as a catalyst.</p><p>The next stage of our strategy included the core heterocycle further structural modification in its C<sup>5</sup> position. In particular the nitrosylation reaction with nitrous acid was proceeded.  It was found that 3-phenyl-4-imino-thiazolydine-2-one could interact with nitrous acid obtained in its turn under sodium nitrite treatment with hydrochloric acid. Nitrosylation reaction allowed to achiev novel 5-isonitrozo-4-imino-3-phenyl-thiazolydine-2-one which was not mentioned in chemical literature. </p><p> The structures of the obtained compounds were confirmed by <sup>1</sup>H NMR spectroscopy and elemental analysis.</p><p>The antioxidant activity of the novel compounds was determined <em>in vitro</em> on basis of free radical scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. DPPH radical has found many applications due to its high stability in a methanolic solution and intense purple color. In its oxidized form, the DPPH radical has an absorbance maximum centered at a wavelength about 540 nm. The absorbance decreases when the radical is reduced by antioxidants. Its reduction affords 2,2-diphenyl-1-picrylhydrazine (DPPH-H), or the corresponding anion (DPPH<sup>–</sup>) in basic medium. The DPPH radical acts as a scavenger for other odd-electron species which afford para-substitution products at phenyl rings.</p><p>The pharmacology screening allowed to state that the synthesized compounds had been shown to possess the moderate antioxidant activity. So it may be concluded that    the functionalization of 4-iminotiazolidyn-2-one by its N<sup>3</sup> and C<sup>5</sup> positions did not lead to the free-radical-scavenging activity enhancement. </p>

Potentiation of bromotrichloromethane hepatotoxicity in male rats exposed to 10 ppm dietary chlordecone: Electron Microscopic and biochemical study

1990 ◽  
Vol 48 (3) ◽  
pp. 284-285
Author(s):  
O. M. Faroon ◽  
R. W. Henry ◽  
M. G. Soni ◽  
H. M. Mehendale
Keyword(s):  
Free Radical ◽  
Biochemical Study ◽  
Prior Exposure ◽  
Male Rats ◽  
Cellular Injury ◽  
Low Doses ◽  
Mixed Function Oxidase ◽  
Electron Microscopic ◽  
Potent Inducer ◽  
Cellular Energy

Previous work has shown that mirex undergoes photolytic dechlorination to chlordecone (CD) (KeponeR) in the environment. Much work has shown that prior exposure to nontoxic levels of CD causes potentiation of hepatotoxicity and lethality of CCl4, BrCCl3 and other halomethane compounds. Potentiation of bromotrichloromethane hepatotoxicity has been associated with compounds that stimulate the activity of hepatic mixed-function oxidase (MFO). An increase in the metabolism of halomethane by the MFO to a free radical initiates peroxidative decomposition of membranal lipids ending in massive cellular injury. However, not all MFO inducers potentiate BrCCl3 hepatotoxicity. Potentiation by much larger doses of phenobarbital is minimal and th at by a more potent inducer of MFO, mirex, is negligible at low doses. We suggest that the CD and bromotrichloromethane interaction results in a depletion of cellular energy and thereby reducing the cellular ability to undergo mitosis.

Deaminative carbonylative thioesterification of activated alkylamines with thiophenols under transition-metal-free conditions

2021 ◽  
Author(s):  
Fengqian Zhao ◽  
Xiao-Feng Wu
Keyword(s):  
Free Radical ◽  
Transition Metal ◽  
Metal Free

A transition-metal-free radical carbonylation of activated alkylamines with thiophenols has been successfully developed. Various thioesters were selectively produced with moderate to good yields.

1120: Citrate and Vitamin E Blunt the SWL-Induced Free Radical Surge in an In-Vitro MDCK Cell Culture Model

2004 ◽  
Vol 171 (4S) ◽  
pp. 295-295
Author(s):  
Fernando C. Delvecchio ◽  
Ricardo M. Brizuela ◽  
Karen J. Byer ◽  
W. Patrick Springhart ◽  
Saeed R. Khan ◽  
...  
Keyword(s):  
Cell Culture ◽  
Free Radical ◽  
Vitamin E ◽  
Mdck Cell ◽  
Cell Culture Model ◽  
Culture Model

Prognostic significance of serum free radical level in head injury

2005 ◽  
Vol 2 (2) ◽  
pp. 107-109
Author(s):  
A. Mishra ◽  
M.F. Huda ◽  
V.P. Singh ◽  
S. Mohanty ◽  
A. Sodhi
Keyword(s):  
Free Radical ◽  
Head Injury ◽  
Prognostic Significance ◽  
Serum Free
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