Vol. Ill, No. 5,] Reactions at Low Temperatures. 231 



ponnds desmbed by them are of tlie type H — ^^cr I^i<^*^^^' 

 Wevuer definitely says tliat tlie iodine atom in these ooiiii^ounds 

 exists in a tervalent capacity. 



On consulting the original paper in the Berichte, it was foiuul, 



however, that the authors only claim to have established the 

 formula of CI1^1<qi for methyl iodochloride, and that tbey did 



not even attempt to analyse and fix approximately a formula 

 for the compounds obtained from the higher alkyl iodides. 

 Taking all these facts into consideration, it seems most probable 

 that the compouiids obtained by Tliiele and Peter fi-om 

 n-propyl, isopropyl and butyl iodides were of the higher type 



Cl 



R — • T Qj and this might explain their more unstable Jiature 



CI 



as well as their formation at a greater degree of cold than that 

 used in the experiments described in the present paper. Stability 

 of the iodochlorides would then increase with the inciease in 

 weight of the attached hydrocarbon radicals. The methyl com- 

 pound MelCl^, is on this view still not isolated, perhaps Ijccause it 

 requires a greater degree of cold for its isolation. 



Besides the gi^eater degi^ee of cold used, there is another 



point of diiiereiice between the two methods of preparation, which 

 might in part account for the production of compounds of different 

 type. Thiele and Peter used a solution of chlorine in carbon 

 tetrachloride and petroleum, wliilst in the Avorlc described above 

 dry chlorine gas was used. One might natui'ally expect the for- 

 mation of different compounds by wet and dry methods. 



These compounds decompose with the formation of the ali- 

 phatic chlorides and iodine chloride. This decomposition, as well 

 as the reaction of these compounds with potassium iodide solution, 

 shows that they are not at all substitution compounds. Analysis 

 would fail to distiuguish between compounds of the types 



(Cn H2a+i) I<oi and CnH-in-i Cn Hen-i Clg I ; for the loss of the 



two hydrogen atoms would produce no appreciable decrease in 



weigtt. Werner suggests that these compounds might after all be 

 molecular compounds of the aliphatic chlorides and iodine 

 chloride. The unstable nature of tliese compounds renders a 

 rigorous proof of their consfcitatiou difficult. Tlie preparation of 

 iodoBo compounds (R-I=0) from these bodies would have settled 

 the matter, but on treatment with caustic soda solution, the iodo- 

 chlorides Avould decompose into alkyl chlorides as in the case of addi- 

 tion of water. When chlorine was passed into a cool chloroform 

 solution of butyl chloride and iodine, no precipitate could be de- 

 tected. Werner obtained some molecular compounds with ICl or 

 IClg but he did not attempt to obtain similar compounds with 



