Hydrogen-Chlorine Mixture

HC1 is formed by a chain mechanism with a very high yield (M /N value —103), presumably because of the high reactivity of the Cl atom. The chain is initiated by the production of H and Cl atoms. Dissociative electron capture by Cl2 requires about 1.6 eV energy. Therefore, presumably both kinds of ions are initially produced by excitation and ionization. The chain is propagated simply as follows  

Termination is by the recombination of H and Cl. There is complete corroboration of this mechanism from photochemical studies. This is undoubtedly a free-radical chain propagation mechanism. 

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The quantum efflciency of die inadiatioii of a hydrogen-chlorine mixture has the apparent value between 10" and 10 , but the coiTesponding value for the parallel bromine reaction is only about 10. Of course die real quantum efflciency can only reach the value of unity as an upper limit, and the large apparent value for the chlorine reaction indicates that once two chlorine atoms... 

Chains may be initiated in a variety of ways. We have spoken of the introduction of photons. Bombardment of hydrogen-chlorine mixtures by alpha particles gives results which are very similar to the bombardment with photons.18 The temperature coefficient is practically the same in the two cases and in each case several hundred thousand molecules react for each photon or ion produced. It seems likely, then, that the mechanism of the chain is the same in the two cases and the way in which the chain is started is relatively unimportant. 

The corresponding calculation applied to the photolysis of the hydrogen-chlorine mixture, leads to similarly remarkable results. Here the primary photo-chemical process is obviously to be regarded as that of the reaction,... 

T. I. Kunin and V. I. Serdyukov, Limits and Temperatures of Explosion of Hydrogen-Chlorine Mixtures in Hydrogen Chloride, J. Gen. Chem., USSR, Vol. 16, 1946, pp. 1421-1430. 

W. Umland, Explosive Limits of Hydrogen-Chlorine Mixtures, J. Electrochem. Soc., Vol. 101, 1954, pp. 626-631. 

Fluorinated and Ghlorfluorinated Sulfonic Acids. The synthesis of chlorinated and fluorinated sulfonic acids has been extensively reviewed (91,92). The Hterature discusses the reaction of dialkyl sulfides and disulfides, sulfoxides and sulfones, alkanesulfonyl haHdes, alkanesulfonic acids and alkanethiols with oxygen, hydrogen chloride, hydrogen fluoride, and oxygen—chloride—hydrogen fluoride mixtures over metal haHde catalysts, such as... 

Apart from chlorine (without or with carbon), carbon tetrachloride, phosgene, hydrogen chloride, and sulfur dioxide-chlorine mixtures, some of the metal chlorides can also function as chlorinating agents. The chlorinating action of metal chlorides is dramatically illustrated by the behavior of the silica lining in reactors used for the chlorination of titanium dioxide and beryllium dioxide. 

There is a risk of generating hydrogen/chlorine/oxygen mixtures during electrolytic preparation from brine. An explosive limits diagram for this ternary system is given. 

Both aliphatic and cycloaliphatic ethers 4, 11 and 13 react with a sulfur tetrafluoride/ hydrogen fluoride/chlorine mixture under mild conditions to give asymmetric chlorofluoro ethers in good yield, but under more rigorous conditions, cleavage of the C-O bond occurs and chlorofluoroalkanes arc the sole products.241... 

The influence of a number of chemical substances on these limits is known and has been studied in extraordinary detail the most active influence is exerted by the halides, whose admixture in small amounts makes mixtures of carbon monoxide, hydrogen and hydrocarbons with air incombustible. Yet the thermal properties of the mixtures change comparatively little. In our laboratory it was shown that the influence of admixtures on the limits is a result of their influence on the flame velocity the addition of tetrachloride stannic to hydrogen-air mixtures (Sadovnikov), or the addition of chlorine or tetrachloride carbon to mixtures of carbon monoxide with air and oxygen (Barskii, Drozdov) in amounts insufficient to fully flegmatize the mixture significantly decrease the flame velocity. 

The first reported preparations of sulfur chloride penta-fluoride involved the fluorination of sulfur(II) chloride, the chlorination of disulfur decafluoride, and the electrolysis of sulfur(II) chloride-hydrogen fluoride mixtures. Newer methods utilize the reaction between chlorine monofluoride and sulfur(IV) fluoride or the reaction between chlorine, cesium fluoride, and sulfur(IV) fluoride. The directions described here for the reaction between chlorine monofluoride and sulfur(IV) fluoride are for the preparation of substantial quantities if only a 1- or 2-g. sample is required, the modifications described in the last paragraph of the Procedure section may be employed or a batch pro-... 

Problem 5.2 Alkane chlorination is not a generally useful reaction because most alkanes have several different kinds of hydrogens, causing mixtures of chlorinated products to result. Draw and name all monochloro substitution products you might obtain by reaction of 2-methylpentane with Cl2-... 

These problems do not arise in the Resting (Munich) process in which the solution produced by the electrolytic manufacture of sodium chlorate is immediately reacted with hydrochloric acid and the chlorinedioxide-chlorine mixture formed blown off from the solution into a column. After separation the chlorine is reacted with hydrogen from the electrolysis to hydrogen chloride, which is fed back into the process. The only starting material in this process is thus chlorine, which is present in the chlorine dioxide obtained and in the hydrochloric acid which is fed back into the process. 

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