Chlorinated aromatic compounds, benzene

Table 2. Production and uses of chlorinated aromatic compound (Benzene derivatives) [105]...

The pyrolysis of vinylidene chloride produced a range of chlorinated aromatic compounds including polychlorinated benzenes, styrenes, and naphthalenes (Yasahura and Morita 1988), and a series of chlorinated acids including chlorobenzoic acids has been identified in emissions from a municipal incinerator (Mowrer and Nordin 1987). 

Regioselective chlorination. This N-chloroammonium salt (1) as well as N-chlo-ropiperidine, chlorinates aromatic compounds substituted with an electron-donating group with high para-selectivity. Benzene and toluene are attacked only slowly. 

Alternate pathways for the degradation of a substituted benzene, toluene. (Adapted from Rochkind, M.L., J.W. Blackburn, and G.S. Sayler. 1986. Microbial Decomposition of Chlorinated Aromatic Compounds. EPA/600/2-86/090.)... 

It is a typically aromatic compound and gives addition and substitution reactions more readily than benzene. Can be reduced to a series of compounds containing 2-10 additional hydrogen atoms (e.g. tetralin, decalin), which are liquids of value as solvents. Exhaustive chlorination gives rise to wax-like compounds. It gives rise to two series of monosubstitution products depending upon... 

The reactivity of Ce, C7, Cg aromatics is mainly associated with the benzene ring. Aromatic compounds in general are liable for electrophilic substitution. Most of the chemicals produced directly from benzene are obtained from its reactions with electrophilic reagents. Benzene could be alkylated, nitrated, or chlorinated to important chemicals that are precursors for many commercial products. 

Among the Friedel-Crafts alkylations of aromatic compounds with (chlorinated alkyl)silanes, the alkylation of benzene with (tt>-chloroalkyl)silanes in the presence of aluminum chloride catalyst was generally affected by two factors the spacer length between the Cl and silicon and the electronic nature of substituents on the silicon atom of (w-chloroalkyl)silanes. As the spacer length between the C—Cl and silicon increases from (chloromethyl)silane to (/i-chloroethyl)silane to (/-chloropropyl)silane, the reactivity of the silanes increases. As the number of chloro-groups on the silicon decreases from (chloromethyl)trichlorosilanes to (chloromethyl)methyldichlorosilanes to (chloromethyl)trimethylsilanes, the... 

Chlorination of aromatic compounds under irradiation has been studied extensively (Wagner, 1969). With benzene, the product is a mixture of stereoisomeric hexachlorocyclohexanes with yields 104pmol.J 1. This certainly points to chain reaction with the initiation either from a dissociation, Cl2 2C1, or from the participation of the first excited singlet state of benzene 0B2u) giving... 

Allylchlorosilanes undergo Friedel-Crafts alkylation with aromatic compounds such as benzene derivatives and ferrocene to give [p-(chlorosilyl)alkyl]arene compounds in the presence of Lewis acid catalyst. Allylsilanes containing two or more chlorine atoms on silicon react smoothly with benzene under mild conditions to give alkylation products in good yields [Eq. (15)]. In alkylations of benzene, the reactivity of the allylsilanes increases as the number of chlorine atoms on the silicon increases, but decreases as the number of methyl groups increases. Because the reactivity of allylsilanes is sensitive to the electronic nature of the substituents on the silicon atom, allylsilane selection is an important factor for alkylation reactions. 

Such xenobiotics as aliphatic hydrocarbons and derivatives, chlorinated ahphatic compounds (methyl, ethyl, methylene, and ethylene chlorides), aromatic hydrocarbons and derivatives (benzene, toluene, phthalate, ethylbenzene, xylenes, and phenol), polycyclic aromatic hydrocarbons, halogenated aromatic compounds (chlorophenols, polychlorinated biphenyls, dioxins and relatives, DDT and relatives), AZO dyes, compounds with nitrogroups (explosive-contaminated waste and herbicides), and organophosphate wastes can be treated effectively by aerobic microorganisms. 

Benzene and its derivatives are used widely throughout the chemical industry as solvents and raw materials. Mono-, di-, and trichlorobenzenes are used directly as pesticides for their insecticidal and fungicidal properties. Benzene, toluene, and chlorobenzene are used as raw materials in the synthesis of at least 15 pesticides, although their main use is as a carrier solvent in 76 processes. Additional priority pollutant aromatics and chlorinated aromatics exist as impurities or as reaction byproducts because of the reactions of the basic raw materials and solvent compounds. 

The technology is best suited for the removal of water-soluble metals and organics. Organics that would most likely be mobilized by this process include aromatic compounds such as benzene, toluene, xylene, and phenolic compounds, as well as chlorinated solvents. Electroki-netic remediation is not a practical method of remediation for insoluble organics such as heavy hydrocarbons. 

Organic compounds, aromatic solvents (benzene, toluene, nitrobenzenes, and xylene), chlorinated aromatics (PCBs, chlorobenzenes, chloronaphthalene, endrin, and toxaphene), phenols and chlorophenols (cresol, resorcinol, and nitrophe-nols), polynuclear aromatics (acenaphthene, benzopyrenes, naphthalene, and biphenyl), pesticides and herbicides (DDT, aldrin, chlordane, BHCs, heptachlor, carbofuran, atrazine, simazine, alachlor, and aldicarb), chlorinated... 

Ozone reacts slowly with many types of water contaminants such as alicyclic taste or odor compounds, e. g. geosmin or THMs and unactivated aromatics such as chlorinated benzenes. Ozone will react faster with certain types of aromatic compounds, e. g. those carrying electron supplying substituents such as the hydroxyl group in phenol. If there is no... 

Many toxic substances, environmental pollutants, and hazardous waste compounds, such as benzene, toluene, naphthalene, and chlorinated phenols, are aromatic compounds (see Figure 1.14). 

As seen from the structural formulas in Figure 16.4, the organochlorine insecticides are of intermediate molecular mass and contain at least one aromatic or nonaromatic ring. They can be placed in four major chemical classes. The first of these consists of the chloroethylene derivatives, of which DDT and methoxychlor are the prime examples. The second major class is composed of chlorinated cyclodiene compounds, including aldrin, dieldrin, and heptachlor. The most highly chlorinated members of this class, such as chloredecone, are manufactured from hexachlorocyclo-pentadiene (see Section 16.3). The benzene hexachloride stereoisomers make up a third class of organochlorine insecticides, and the third group, known collectively as toxaphene, constitutes a fourth. 

One of the major uses of activated carbon is in the recovery of solvents from industrial process effluents. Dry cleaning, paints, adhesives, polymer manufacturing, and printing are some examples. Since, as a result of the highly volatile character of many solvents, they cannot be emitted directly into the atmosphere. Typical solvents recovered by active carbon are acetone, benzene, ethanol, ethyl ether, pentane, methylene chloride, tetrahydrofuran, toluene, xylene, chlorinated hydrocarbons, and other aromatic compounds [78], Besides, automotive emissions make a large contribution to urban and global air pollution. Some VOCs and other air contaminants are emitted by automobiles through the exhaust system and also by the fuel system, and activated carbons are used to control these emissions [77,78],... 

Activated aromatic compounds are chlorinated readily by (dichloroiodo)benzene. Generally, negligible amounts of ortAo-chloro isomers are produced from diverse aromatic compounds, e.g. salicylic acid gave its 5-chloroderivative (89%) [16]. Exceptions were noted in the chlorination of the triphenyl phosphinimine of aniline which afforded o- and p-products in the ratio 7 3 [17], and of 2-naphthol which gave its 1-chloroderivative (84%) [16]. (Dichloroiodo)benzene was superior for the chlorination of uracil bases and protected nucleosides, e.g. [18] ... 

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