CHAPTER II 



SUBSTITUTION PRODUCTS OF THE 



HYDROCARBONS 



HALOGEN COMPOUNDS 



Halogen Methanes 



As already explained, the halogen substitution products or 

 alkyl halides result from the substitution of one of the halogens 

 for an equivalent amount of hydrogen of the hydrocarbon. 

 This substitution does not take place directly except in a few 

 cases, and methods of preparation usually start with other 

 compounds than the hydrocarbons themselves. It is not 

 necessary for us to consider these reactions of preparation, as 

 they involve the alcohols, which we shall study later, and they 

 are not essential to an understanding of the group as a whole 

 and the special properties of a few common representatives. 

 The chief importance of these compounds is in synthetic re- 

 actions. Of the halogen substitution products of methane, 

 three are common substances. These are : 



Tri-chlor-methane, chloroform, CHCI3 

 Tri-iodo-methane, iodoform, CHI3 

 Tetra-chlor-methane, carbon tetrachloride, CCI4 



Chloroform is a heavy, colorless liquid possessing a sweet, 

 suffocating odor. It is non-inflammable and only slightly 

 soluble in water. It is one of the two most common anaesthetics, 

 its use as such being discovered in 1848 by Simpson, an English- 

 man. It is made from alcohol or from acetone by the action of 

 chlorine. 



Iodoform is a yellow, crystalline solid almost insoluble in 



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