HYDROCARBONS I3, 



the name of mono-halogen methanes or methyl halides. The 

 reactions of these methyl haHdes lead to conceptions in regard 

 to the structure and relationship of other hydrocarbons and 

 other substitution products. 



SYNTHESIS OF HIGHER HYDROCARBONS 



Methane, CH4, is the simplest of a long series of similar com- 

 pounds which increase gradually both in carbon and hydrogen 

 content. The first six members of this series together with a 

 few of the highest may be given as an illustration. 



Methane or Paraflan Series of Hydrocarbons, C„H2n+2. 



CH4, Methane CeHu, Hexane 



C2H6, Ethane C7H16, Heptane 



CsHg, Propane C10H22, Decane 



C4H10, Butane C20H42, Eicosane 



CeHis, Pentane C60H122, Hexacontane 



Above the fourth member the prefix of the name denotes the 

 number of carbon atoms in the compound. It will be seen that 

 the successive compounds differ in composition by one carbon 

 and two hydrogens, i.e. by CH2, and that for the whole series 

 the general formula, C„H2„+2, holds. 



What are these compounds as to structure and constitution? 

 When methyl iodide, CH3I, is treated with sodium, ethane is 

 formed and the iodine unites with the sodium, forming sodium 

 iodide. The reaction takes place in the proportion of two 

 molecules of methyl iodide to one molecule (two atoms) of 

 sodium and yields one molecule of ethane and two molecules of 

 sodium iodide as follows: 



CH3 - (1+ Na - Na+ 1) - CH3 -> CH3 - CH3 + 2 NaT 



Methyl iodide Ethane 



This reaction means that ethane, C2H6, must be considered 

 as composed of two methyl radicals joined together, viz. 

 CH3— CH3. Using the complete structural formulas, we write 

 the reaction : 



