Herbicides, nitro compounds

SAFETY PROFILE Confirmed carcinogen with experimental carcinogenic data. Poison by ingestion. Moderately toxic by inhalation and possibly other routes. Experimental teratogenic and reproductive effects. A skin and severe eye irritant. Mutation data reported. A broad-spectrum herbicide. See also NITRO COMPOUNDS of AROMATIC HYDROCARBONS and ETHERS. When heated to decomposition it emits very toxic fumes of Cl" and NOx. 

Silica gel Alcohols, aldehydes, alkaloids, amines, amino acids, amphetamines, antibiotics, antioxidants, barbiturates, carbohydrates, flavonoids, herbicides, heterocyclic compounds, hydrocarbons, indoles, insecticides, ketones, lipids, nitro compounds, organic acids, peroxides, pesticides, phenols, plasticizers, polypeptides, steroids, terpenes, unsaturated compounds, vitamins. 

At the meta position, a multitude of functionalities have been reported to lead to herbicidally active compounds. One problem that, however, often leads to reduced potency is the presence of an electron-withdrawing substituent at the meta position combined with a potential leaving group at the 2-position (e.g., nitro or chloro) as this may give rise to dihydroxanthenones (19), which are known to be much less herbicidally active (Scheme 4.3.5) [4]. 

The polarographic and voltammetric determination of chlorinated compounds, S-triazines, 2,4-AD-herbicides, nitro-containing pesticides, paraquat, diquat, carbamate pesti-... 

Dermal (skin) absorption is a significant hazard for a number of volatile substances. These include aromatic compounds such as benzene and toluene nitro-compounds such as nitrobenzene, trinitrotoluene and nitro-propane several insecticides and herbicides hydrogen cyanide and organo phosphates. Protective clothing can minimize risks except where splashing and adsoprtion into cloth concentrates exposure to the skin. 

This far into a nitrosamine symposium it should hardly be necessary to point out that nitrosamines are technically just one of a group of Ji-nitroso compounds that also includes nitros-amides, nitrosocarbamates, nitrosoureas, etc. Or that nitrosa-table pesticides encompass all the categories just mentioned and more. Or that many diverse pesticides, including herbicides, insecticides, and fungicides have been converted to Ji-nitroso derivatives in the laboratory (a recent review contained a 3-page, probably incomplete, compilation), or that some of the Ji-nitroso compounds thus synthesized were determined to be carcinogenic in test animals or mutagenic in various assays. 

A foreign compound, which may act in this way is the herbicide nitrofen (2,4-dichloro-4 -nitro diphenyl ether), which causes a variety of malformations lethal to the neonate. There is no growth retardation or embryolethality at doses, which are teratogenic, however (Fig. 6.27), and therefore this exhibits the first type of dose-response relationship (see above). The... 

Nitroaromatic compounds (NACs) are one of the widespread contaminants in the environments. Sources of NACs are numerous they originate from insecticides, herbicides, explosives, pharmaceuticals, feedstock, and chemicals for dyes (Agrawal and Tratnyek, 1996). Under anaerobic conditions, the dominant action is nitro reduction by zero-valent iron to the amine. Other pathways do exist, such as the formation of azo and azoxy compounds, which is followed by the reduction of azo compounds to form amines. Also, in addition to the possibility of azo and azoxy compounds, phenylhydrox-ylamine may be an additional intermediate (Agrawal and Tratnyek, 1996). Nitrobenzene reduction forms the amine aniline. Known for its corrosion inhibition properties, aniline cannot be further reduced by iron. Additionally, it interferes with the mass transport of the contaminant to the surface of the iron. The overall reaction is as follows ... 

As can be seen from Table IV, the nitrophenyl analogs of the nicotinamides are inactive. Interestingly, the 2-(3-trifluoromethylphenyl ) benzamides (compound IV minus the nitro group) were moderate herbicides (less than 50% weed control at 1 lb). These compounds are also bleaching herbicides as are the well known 3-phenoxybenzamides. The 3-phenoxybenzamides are also known to be inhibitors of phytoene desaturase (11). 

---