SUBSTITUTION PRODUCTS OF THE HYDROCARBONS 2i 



later and show how its relation to symmetrical di-brom-ethane 

 leads to ideas in regard to the structure of ethylene. Writing 

 the condensed structural formulas for these compounds we 

 have : 



CH3 - CH3 CH3 - CHBr2 CHsBr - CHaBr 



Ethane Unsymmetrical Symmetrical 



di-brom-ethane di-brom-ethane 



Ethylidene bromide Ethylene bromide 



This isomerism, as illustrated by the two di-brom-ethanes, 

 applies to all di-substituted ethanes so that for each class we 

 have unsymmetrical or ethylidene and symmetrical or ethylene 

 di-substituted ethanes. 



CYANIDES AND AMINES 



Cyanides. — When a halogen substitution product reacts 

 with potassium cyanide, KCN, a compound is formed in which 

 the halogen is replaced by the group or radical, CN. 



CHsCI + K)CN -> CH3 - CN + KI 



Methyl iodide Methyl cyanide 



This new compound is CH3 — CN and is known as methyl 

 cyanide just as CH3 — I is methyl iodide. This cyanogen 

 group may be substituted in practically any position where a 

 halogen atom is present and we therefore have a large number 

 of cyanide compounds. As we shall find, the simple cyanides 

 are directly related to the acids, and on that account are known 

 as acid nitrites. 



Among the compounds studied in inorganic chemistry the 

 cyanides occupied an important place. The cyanides of iron, 

 in particular the double cyanides, are noticeable for their color 

 and are important as dyes. The name cyanide comes from a 

 Greek word (cyanos) meaning blue. 



Amines. — By an analogous reaction to the one just described, 

 ammonia reacts with a halogen substitution product and a 

 compound is formed in which the halogen is replaced by the 

 group or radical, NH2, which is the radical of ammonia. 



