Halogenated aromatic compounds, production

Of course, with so many different final products mixed together, the problem is to identify them. What structure is linked to what bead Several approaches to this problem have been developed, all of which involve the attachment of encoding labels to each polymer bead to keep track of the chemistry each has undergone. Encoding labels used thus far have included proteins, nucleic acids, halogenated aromatic compounds, and even computer chips. 

Volatile decomposition products may include HCl, HBr, HCN, COCI2, nitrogen oxides (NO ), aromatic hydrocarbons such as benzene, and/or halogenated aromatic compounds. 

Direct photoreactions of halogenated aromatic compounds in water have received considerably more attention. The products of direct photoreactions include photonucleophilic replacement of halogen by OH, reductive dehalo-genation (i.e., replacement of halogen by hydrogen), photooxidation, and photoisomerization. Several such reactions are exemplified by the photoreactions of DDE in natural waters (eq 12) (38). 

Table 1. Production and uses of halogenated aromatic compounds (more than one ring) [22, 24, 63, 65, 81, 95, 133,141]...

Aromatic compound Halogen Temp. ( C) Substitution products Ref. 

Another entry point for accumulation of organic in animal tissue and animal food products is direct ingestion of contaminated soil by grazing animals [44]. The compounds of main concern are the halogenated aromatics, including PCBs, organochlorine pesticides, PCDDs and PCDFs, which are resistant to metabolization and tend to accumulate in animal fat. The bioaccumulation factor (the ratio of the concentration of animal tissue or produce to the concentration in the diet) can be as high as 5-6 [43]. Compounds such as PAHs and phthalate esters are readily metabolised and excreted by the animals and thus do not accumulate in animal tissue or products. 

When two nitro-groups are introduced into the benzene ring the chief product is m-dinitrobenzene, which conforms to the following general laws of substitution. For aromatic compounds there are three important typical reactions 1, halogenation 2, nitration, and 3, sulpho-... 

The majority of systems studied have been aqueous solutions of either aromatic compounds or halogenated hydrocarbons. Such materials represent models for the major classes of organic pollutants in waste and ground water. The primary products resulting from the sonochemical treatment of phenol at 541 kHz (27 °C with bubbled air) are hydroquinone and catechol [22]. These compounds are easy to monitor and are clearly seen to be intermediates which disappear as the reaction progresses (Fig. 4.1). Similarly the sonolysis of aqueous 4-chlorophenol leads to products mainly characteristic of oxidation by OH radical e. g. 4-chlorocatechol but in both cases the final organic products are CO, CO2 and HCOOH (Scheme 4.2) [22-25]. 

Side-Chain Chlorination of Arylalkanes. Alkyl-substituted aromatic compounds can easily be halogenated at the benzylic position with chlorine or bromine.107 108,142 143 a-Monohaloalkylaromatics are usually the main products with both reagents. 

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