Nitroso

About: Nitroso is a research topic. Over the lifetime, 3343 publications have been published within this topic receiving 44063 citations. The topic is also known as: oxoazanyl group & nitrosyl group.

Carcinogenic Nitroso Compounds

Abstract: Publisher Summary This chapter provides an overview of some of the relevant chemistry (general chemistry, preparation methods, and analytical methods) of the nitroso carcinogenic compounds and discusses the pathological lesions induced by these compounds and their mutagenic activity. Experimental studies on compounds like dimethylnitrosamine showed that they cause liver necrosis in rats, accompanied by hemorrhages into the liver and lungs and frequently an associated hemorrhagic ascites and blood in the lumen of the gut. Acute toxicity of other dialkyl and related nitrosamines cause liver damage, hemorrhagic lung lesions, convulsions, and coma. The neoplastic changes in the body organs (live, kidney, bladder, nose and nasal sinuses, lungs and bronchi, alimentary canal, nervous system, and skin) and the development of the malignant lesion caused by carcinogenic nitroso compounds are also illustrated in the chapter with the help of animal models. The variation in the response of different organs to the carcinogenic nitroso compounds is of interest in relation to the biochemical changes that may be essential for the initiation of a carcinogenic change. Many carcinogenic nitroso compounds are mutagenic. The nitroso mutagens act by the alkylation of the genetic material. The chapter also discusses the metabolism of nitroso carcinogens both in vivo and in vitro, along with their biochemical effects. The induction of cancers by single doses of rapidly eliminated nitroso carcinogens implies an interaction between the carcinogen and/or a product of its decomposition with some component or components of the cells, which must occur within a short time after administration. The nature of the proximate carcinogen and some of its possible interactions with cellular components and some serious carcinogenic hazards caused by the nitroso compounds are also discussed in the chapter.

Biodegradation of Nitroaromatic Compounds

Abstract: Nitroaromatic compounds are released into the biosphere almost exclusively from anthropogenic sources. Some compounds are produced by incomplete combustion of fossil fuels; others are used as synthetic intermediates, dyes, pesticides, and explosives. Recent research revealed a number of microbial systems capable of transforming or biodegrading nitroaromatic compounds. Anaerobic bacteria can reduce the nitro group via nitroso and hydroxylamino intermediates to the corresponding amines. Isolates of Desulfovibrio spp. can use nitroaromatic compounds as their source of nitrogen. They can also reduce 2,4,6-trinitrotoluene to 2,4,6-triaminotoluene. Several strains of Clostridium can catalyze a similar reduction and also seem to be able to degrade the molecule to small aliphatic acids. Anaerobic systems have been demonstrated to destroy munitions and pesticides in soil. Fungi can extensively degrade or mineralize a variety of nitroaromatic compounds. For example, Phanerochaete chrysosporium mineralizes 2,4-dinitrotoluene and 2,4,6-trinitrotoluene and shows promise as the basis for bioremediation strategies. The anaerobic bacteria and the fungi mentioned above mostly transform nitroaromatic compounds via fortuitous reactions. In contrast, a number of nitroaromatic compounds can serve as growth substrates for aerobic bacteria. Removal or productive metabolism of nitro groups can be accomplished by four different strategies. (a) Some bacteria can reduce the aromatic ring of dinitro and trinitro compounds by the addition of a hydride ion to form a hydride-Meisenheimer complex, which subsequently rearomatizes with the elimination of nitrite. (b) Monooxygenase enzymes can add a single oxygen atom and eliminate the nitro group from nitrophenols. (c) Dioxygenase enzymes can insert two hydroxyl groups into the aromatic ring and precipitate the spontaneous elimination of the nitro group from a variety of nitroaromatic compounds. (d) Reduction of the nitro group to the corresponding hydroxylamine is the initial reaction in the productive metabolism of nitrobenzene, 4-nitrotoluene, and 4-nitrobenzoate. The hydroxylamines undergo enzyme-catalyzed rearrangements to hydroxylated compounds that are substrates for ring-fission reactions. Potential applications of the above reactions include not only the biodegradation of environmental contaminants, but also biocatalysis and synthesis of valuable organic molecules.

Hetero Diels-Alder methodology in organic synthesis

Abstract: N-Sulfinyl Compounds and Sulfur Diimides. Imino Dienophiles. Nitroso and Thionitroso Dienophiles. Carbonyl Dienophiles. Thiocarbonyl and Selenocarbonyl Dienophiles. Miscellaneous Dienophiles. Oxabutadienes. Thiabutadienes. Azabutadienes. Heteroaromatic Azadienes. Each chapter includes references. Index.

Synthesis of azobenzenes: the coloured pieces of molecular materials

Abstract: Azobenzenes are ubiquitous motifs very important in many areas of science. Azo compounds display crucial properties for important applications, mainly for the chemical industry. Because of their discovery, the main application of aromatic azo compounds has been their use as dyes. These compounds are excellent candidates to function as molecular switches because of their efficient cis–transisomerization in the presence of appropriate radiation. The classical methods for the synthesis of azo compounds are the azo coupling reaction (coupling of diazonium salts with activated aromatic compounds), the Mills reaction (reaction between aromatic nitroso derivatives and anilines) and the Wallach reaction (transformation of azoxybenzenes into 4-hydroxy substituted azoderivatives in acid media). More recently, other preparative methods have been reported. This critical review covers the various synthetic methods reported on azo compounds with special emphasis on the more recent ones and their mechanistic aspects (170 references).