Chlorine, reaction, with carbon

Carbon tetrachloride is a common commercial solvent It can be prepared by die reaction of chlorine gas with carbon disulfide. The equation for die reaction is... 

Dechlorination requires a much shorter contact time than organics removal (perhaps only 60 seconds at pH levels below 7.0 but 3 minutes at pH over 8.5). The process involves reaction with carbon as well as absorption, such that 1 lb of carbon typically reacts (and is used up) with between 3 and 6 lb of chlorine. 

Chloramine reactions do not release COj gas or destroy the integrity of the carbon. However, chloramine reactions are much slower than chlorine reactions with activated carbon. Finally, although carbon can effectively remove chlorine from potable water, it is more expensive than other dechlorination methods (9,10). 

The procedure starts with MnC>2 ore finely ground, which is subjected to alkaline oxidative fusion, giving K2MnC>4. From this species, the permanganate may be produced chemically by reaction with elemental chlorine or with carbon dioxide. 

All the foregoing precautions in connection with pre-chlorination relate to the practice of free-residual chlorination or superchlorination. When chlorine is applied in combination with ammonia to form chloramines, little or no reaction with carbon occurs. Furthermore, chloramines are less likely to form those chlorinous substances that are difficult to adsorb on carbon. 

The reaction of perchlorotoluene with triphenylphosphine has been studied (Diaz-Alzamora, 1968). It is noted that the reaction with carbon tetrachloride gives a mixture of (dichloromethylene)triphenylphosphorane and triphenylphosphine dichloride (Appel et al., 1976 Burn and Cadogan, 1963 Rabinowitz and Marcus, 1962). (The resulting reaction mixture was usually treated with water.) The sequence (49), involving a nucleophilic attack on chlorine, has been proposed. 

PTC has been used efficiently for chlorination of dialkylphosphite and subsequent phosphorylation of secondary amines, O-alkylhydroxylamines, alcohols, etc. (Atherton-Todd reaction) via halophilic reaction with carbon tetrachloride ... 

An enormous e-f-fort has been made on -finding new, phosgene—free routes to isocyanates. Phosgene, produced by reaction o-f carbon monoxide with chlorine, is an energy-intensive material, very poisonous and corrosive since it is a hydrolyzable chlorine derivative. One such process involves reductive carbonyl at i on o-f the nitro compounds by reaction with carbon monoxide 2,3,53 ... 

When lead is exposed to chlorine gas, the product of the reaction is PbClj. Only under more extreme conditions will PbCI form. However, when chlorine reacts with carbon, the product of the reaction is CCI4. Explain these differences. 

Reaction with Carbon Tetrachioride. Severe accidents have been caused by the rapid reaction of aluminum with anhydrous chlorinated solvents, such as in the degreasing of castings, in ball miUmg of aluminum flake with carbon tetrachloride (CCI4), or even in the case of aluminum used as a container at room temperature for mixed chlorinated solvents. The reaction with CCh, for example, has been shown to be... 

---