Carbon tetrachloride, 127 tetravalence

We took advantage of the property of different solvents to extract selectively the tetravalent actinide and lanthanide elements. Some of them are sufficiently stable in the presence of oxidizing agents. Among the organonitrogen and organophosphorus compounds we used were tri-laurylmethylammonium (TLMA) salts and tributyl phosphate (TBP) in carbon tetrachloride. 

The berkelium (IV) extraction coefficients have been determined by stripping solvents previously loaded with tetravalent cerium and berkelium in the presence of sodium bismuthate. Sodium bismuthate has been found to be an efficient oxidizing agent for trivalent cerium. Because of its small solubility it does not affect the distribution coefficients of tetravalent cerium. These two properties have been demonstrated by comparing the distribution coefficients of cerium (IV) measured by spectrophotometry with those of cerium oxidized by sodium bismuthate and measured by beta counting of the cerium isotope tracer. The data are summarized in Table I and indicate no real difference in the distribution coefficients of cerium obtained by these two methods when using trilaurylmethylammonium salts-carbon tetrachloride as solvent. 

Similar mechanisms can be operative for a wide range of oxidizable chlorinated hydrocarbons with abstractable hydrogen atoms. In the case of chlorinated hydrocarbons with no abstractable hydrogen atoms or with tetravalent carbon in C(IV) state, reactions can be initiated by direct hole or electron transfer as in the case of trichloroacetic acid or carbon tetrachloride, respectively ... 

With potassium ethylxanthate in strong acid solution, technetium in the tetravalent or heptavalent state forms a purple complex which is readily extractable with carbon tetrachloride. Molybdenum behaves similarly (see page 320). 

The carbon atom is normally (exclusively, for our purposes) tetravalent. In compounds such as methane (CH4) and carbon tetrachloride (CCU) the four identical substituents surround it in a symmetrical tetrahedral geometry. If the substituent atoms are not identical, the symmetry is destroyed, but the general tetrahedral pattern is maintained. This is stiU true for each carbon atom in the interior of a linear polymer chain, where two of the substituents are chains. If a polyethylene chain were to be stretched out, for example, the carbon atoms in the chain backbone would lie in a zigzag fashion in a plane, with the hydrogen substituents on either side of the plane (Fig. 4.1). In the case of polyethylene, in which aU the substituents are the same, this is the only arrangement possible. With vinyl polymers, however, there are several possibilities. 

Essentially all the reactions so far reported which result in the formation of a C—Tc bond at a stereogenic carbon center involve addition of tetravalent perhalotellurium compounds (see also Houben-Weyl Vol. E12b, p299ff) to alkenes. The earliest report which examined the stereochemical aspects of such additions found that addition of tellurium tetrachloride and aryltellurium trichloride to cyclohexene affords (1,S, 2,S )-2-chlorocyclohexyltellurium trichloride (1) and aryl(lS, 2S )-2-chlorocyclohexyl]tellurium dichloride 2, respectively85 86. 

Unlike its Se and S analogs, tellurium tetrachloride adds to carbon-carbon double bonds, giving tetravalent organotelluriums ... 

---