Chlorine from chlorides

The iodine reacts with the chromic acid yielding iodic acid the latter, in the presence of concentrated sulphuric acid and especially on warming, liberates chlorine from chlorides, regenerating iodide. This explains the failure to form chromyl chloride. 

If iodide is present and the molecular ratio iodide chloride exceeds 1 15, the chromyl chloride formation is prevented completely in favor of the liberation of chlorine. This result is due to the production of iodic acid from iodide and chromic acid. In the presence of concentrated sulfuric acid, and especially on warming, the iodic acid liberates chlorine from chlorides with regeneration of iodide. 

Since chlorine is a structural element in relatively few minerals and rocks, the establishment of its presence or absence may be decisive in identification tests. The procedure given on page 546 for detecting traces of chlorine in fine chemicals can be employed here. The basis of the test is the production of free chlorine from chlorides on warming with chromic-sulfuric acid mixture, followed by exposure of the vapors to the yellow paper that has been impregnated with 4,4 -bis-dimethylaminothiobenzophenone. The paper turns blue if the test is positive. Since the color reaction responds to 0.2 y chlorine, fractions of 1 mg suffice for the detection of chlorine in minerals and rocks. This is shown in Table 5. 

Anhydrous hydrogen fluoride (as distinct from an aqueous solution of hydrofluoric acid) does not attack silica or glass. It reacts with metals to give fluorides, for example with heated iron the anhydrous iron(II) fluoride is formed the same product is obtained by displacement of chlorine from iron(II) chloride ... 

Electrolytic plant producing magnesium and chlorine from molten magnesium chloride. 

The practical problems He ia the separatioa of the chlorine from the hydrogea chloride and nitrous gases. The dilute nitric acid must be reconcentrated and corrosion problems are severe. Suggested improvements iaclude oxidation of concentrated solutions of chlorides, eg, LiCl, by nitrates, followed by separation of chlorine from nitrosyl chloride by distillation at 135°C, or oxidation by a mixture of nitric and sulfuric acids, separating the... 

Much later (Marcinkowsky and Berty 1973) it was proven that ethane did indeed have an effect. In the study of the inhibitor action of chlorinated hydrocarbons it was discovered that these compounds chlorinate the silver catalyst and ethane removes the chlorine from the catalyst by forming ethyl chloride. Since the inhibitor was in the 10 ppm range and similar quantities were used from the ethane present in about one volume percent, the small difference could not be calculated from material balance. The effect of ethane was only noticed as significant by the statistics, which justifies the statement made by Aris (1966) that, The need for sophistications should not be rejected unsophisticatedly. ... 

Chlorine is a member of the halogen (salt-forming) group of elements and is derived from chlorides by the action of oxidizing agents and, most frequently, by electrolysis. As a gas, it combines directly with nearly all elements. At 10 C, 1 volume of water dissolves about 3.10 volumes of chlorine at 30 C, only 1.77 volumes of CI2 are dissolved in 1 volume of water. 

Tubesheets form the end barriers to separate the shell-side and tube-side fluids. Most exchangers use single plates for tubesheets. However, for hazardous or corrosive materials such as chlorine, hydrogen chloride, sulfur dioxide, etc., where the intermixing due to leakage from shell- to tube-... 

Calcium chloride (CaCI2) is added to lower the melting point. The iron screen prevents sodium and chlorine from coming into contact with each other. 

Diphenyl diselenide has been prepared by disproportionation of phenyl selenocyanate in the presence of potassium hydroxide" or ammonia/ and by air oxidation of benzeneselenol. The preparation of benzeneselenol is described in an earlier volume in this series/ In the present procedure phenylselenomagnesium bromide formed from phenylmagnesium bromide and selenium is oxidized directly to diphenyl diselenide with bromine/ Thus the liberation of the malodorous and toxic hydrogen selenide and benzeneselenol is avoided. Benzeneselenenyl chloride has been prepared by thermal elimination of ethyl chloride from ethyl phenyl selenide di-chloride/ by thermal elimination of chlorine from phenylselenium trichloride," and by chlorinolysis of diphenyl diselenide with either sulfuryl chloride " or chlorine. " ... 

Phosphonate ester (10) is made from chloride (12) available by direct chlorination with photochemical generation of radicals. 

Thus, for the initial chlorination of the ore, ferric chloride can very well be used instead of elemental chlorine. From ferric chloride vapor chlorine can be regenerated by the reaction... 

In general, the electrolysis of a molten salt at inert electrodes produces the metal at the cathode, e.g., calcium from calcium chloride (melting point 774 °C). The anion is often a halide ion which, on discharge, yields the halogen, e.g., chlorine from calcium chloride. 

---