14 ORGANIC AGRICULTURAL CHEMISTRY 



N H H H 



I III 



H-C-(I+Na-Na+I)-C-H->H-C-C-H+2NaI 



H H H H 



Methyl iodide Ethane 



H H 



I I 

 Ethane, C2H6, is therefore CHs-CHs, or H-C-C-H 



I I 

 H H 



The monohalogen ethanes are exactly analogous to the mono- 

 halogen methanes and are, e.g., 



H H 



oxj r^TT T r^,. TJ o r^ T Monoiodo-ethane 



C±l3-C±l2i or M-U-C-i, (ethyl iodide) 



H H 



In an exactly analogous way propane, CsHg, may be made 

 from ethyl iodide (monoiodo-ethane) and methyl iodide in the 

 presence of sodium. 



CH3- CH2- (I+Na-Na+I) - CHs-^ CH3- CH2- CH3+ 2 Nal 



Ethyl iodide Methyl iodide Propane 



or 



H H H H H H 



H-C-C-(I+Na-Na+I)-C-H->H-C-C-C-H+2NaI 



II I III 



H H H H H H 



Ethyl iodide Methyl iodide Propane 



By this same general reaction each of the successive hydro- 

 carbons may be synthesized, and we find that the structure of 

 each is represented by a continually elongated chain of carbon 

 groups, the two end carbon groups being CH3 and all of the in- 

 termediate groups CH2. Also each hydrocarbon is the methyl 

 substitution product of the one preceding it. 



