Chlorinated compounds reactions

Chlorine compounds, reaction with molecular surface hydroxyl groups, 23 71... 

J.K. Hurst, P.A.G. Carr, F.E. Hovis, R.J. Richardson (1981). Hydrogen peroxide oxidation by chlorine compounds. Reaction dynamics and singlet oxygen formation. Inorg. Chem., 20, 2435-2438. 

Secondary reactions can occur to higher chlorinated compounds ... 

Reductive DechIorina.tion. Such reduction of chlorinated aUphatic hydrocarbons, eg, lindane, has been known since the 1960s. More recentiy, the dechlorination of aromatic pesticides, eg, 2,4,5-T, or pesticide products, eg, chlorophenols, has also been documented (eq. 10) (20). These reactions are of particular interest because chlorinated compounds are generally persistent under aerobic conditions. 

A U.S. patent describes the reaction of commercial oleic acid with hydrogen peroxide in acetic acid foUowed by air oxidation using a heavy metal compound and an inorganic bromine or chlorine compound to catalyze the oxidation. ExceUent yields of dibasic acids are obtained (up to 99%) containing up to 72% azelaic acid (55). 

The dissociation of hypochlorous acid depends on the pH. The unionized acid is present in greater quantities in acid solution, although in strongly acid solution the reaction with water is reversed and chlorine is Hberated. In alkaline solutions the hypochlorite ion OCL is increasingly Hberated as the pH is increased. The pH is important because unionized hypochlorous acid is largely responsible for the antimicrobial action of chlorine in water. Chlorine compounds are therefore more active in the acid or neutral range. The hypochlorites most commonly employed are sodium hypochlorite [7681-52-9] or calcium hypochlorite [7778-54-3]. 

Silicon Epitaxy. Silicon epitaxial films have superior properties. The applications are, however, limited by the high temperature of deposition, which is generally above 1000°C. These reactions use chlorinated compounds of silicon (tetrachloride, trichlorosilane, or dichlorosilane) as precursors as follows ... 

There are natural sources of brominated hydrocarbons as well as man-made sources, such as the "halons , which are used in fire extinguishers. Reaction 21 is very fast and generates Cl and Br atoms directly the cycle does not require a photolytic step. Although this cycle occurs with high efficiency, it is less important than the chlorine peroxide cycle because of the much smaller concentrations of bromine compounds in the stratosphere-parts per trillion vs. parts per billion for the chlorine compounds. 

Similar to the mixed-halide (Cl, I) 6-13 system, where more chlorine-rich reactions produced a new structure type, materials with an unprecedented zirconium cluster structure are obtained in the Na-Zr-(C1/I)-B system (also with. other cations, see below), when larger Cl/I ratios are used than above. Compounds characterized are Na[(Zr6B)(Cl,I)i4] and Ao.5[(Zr6B)(Cl,I)i4] (with A = Ca, Sr, Ba) [25, 26]. Single crystals of the cubic Na[(Zr6B)Clio.94(i)l3.o6] and... 

A number of preparations of mixed halogenophosphoranes from tervalent phosphorus-fluorine compounds have been reported. For example, acyclic and cyclic fluorine compounds have been converted to phosphoranes, such as (36) and (37), by treatment with chlorine. Similar reactions leading to AA-dialkylaminodichlorodifluorophosphoranes (38) have been described and the stability of (38) to exchange processes commented upon. iVA-Dialkylaminotetraiodophosphoranes (39) have been prepared from AA-dialkylaminodichlorophosphines and lithium iodide, although no detailed physical evidence for the structure of these unusual compounds has yet been reported. The preparation of bis-(A-alkylamino)difluorophosphoranes (4) has been described above (see Section lA). 

The same goes for temperature monitoring when preparing butyl-sodium from 1-dichlorobutane and sodium in a diethyl ether medium. Below -23°C the reaction only starts after a dangerous accumulation of chlorinated compound. Above this temperature the reaction is feasible, but difficult to control. 

A practical method of modification of polysaccharides by clean oxidation using H2O2 as oxidant and cheap iron phthalocyanine as catalyst has been developed. Since no acids, bases or buffers and no chlorinated compounds were used, a pure product can be recovered without additional treatment. Importantly, this flexible method provides materials with a wide range of DScho and DScooh just by an appropriate choice of the reaction conditions. Oxidized polysaccharides thus obtained possess various, tailormade hydrophihc/hydrophobic properties which have been tested successfully in cosmetic and other apphcations. 

Triphenylphosphine dichloride exhibits similar reactivity and can be used to prepare chlorides.18 The most convenient methods for converting alcohols to chlorides are based on in situ generation of chlorophosphonium ions19 by reaction of triphenylphosphine with various chlorine compounds such as carbon tetrachloride20 or hexachloroacetone.21 These reactions involve formation of chlorophosphonium ions. 

Halogenated (usually bromine or chlorine) compounds (inhibit free radical flame reactions). 

Bioremediation also has its limitations. Some chemicals are not amenable to biodegradation, for instance, heavy metals, radionuclides, and some chlorinated compounds. In some cases, the microbial metabolism of the contaminants may produce toxic metabolites. Bioremediation is a scientifically intensive procedure that must be tailored to site-specific conditions, and usually requires treatability studies to be conducted on a small scale before the actual cleanup of a site.13 The treatability procedure is important, as it establishes the extent of degradation and evaluates the potential use of a selected microorganism for bioremediation. A precise estimate on vessel size or area involved, speed of reaction, and economics can therefore be determined at the laboratory stage. 

The substitution reaction will continue in the presence of excess Cl2 to give the following chlorinated compounds ... 

This question is similar to question 10 in that two elements, phosphorus and chlorine in this case, have combined to give two different compounds. This time, however, different masses have been used for both of the elements in the second reaction. To see if the Law of Multiple Proportions is being followed, the mass of one of the two elements must be set to the same value in both reactions. This can be achieved by dividing the masses of both phosphorus and chlorine in reaction 2 by 2.500 ... 

Much of the known high-temperature chemistry of silicon-chlorine compounds is indirectly concerned with SiCl2. The reactions discussed below will serve as examples of those in which the intermediacy of SiCl2 is indicated. 

---