Structure of Simpler Organic Compounds. 59 



stance CH 3 CHBr 2 when both bromine atoms are united 

 to the same carbon atoms, and which is obtained by an 

 entirely different method (see p. 80).* 



Addition products can also be formed with halogen 

 acids, thus 



The following are the names of the lower members of 

 the olefine or ethylene series : 



Ethylene, C 2 H 4 

 Propylene, C 3 H 6 



Amylene, C 5 H 10 

 Hexylene, C 6 H 12 , etc. 



Butylene, C 4 H 9 



The names of the members of this series are char- 

 acterized by the termination ene in contrast with those 

 of the paraffin series, all of which end in the syllable ane. 

 The substances of the group do not possess the same 



O JfT Jt 



technological importance as those of the paraffin group, 

 but they have been employed extensively in the chemical 

 laboratory to effect various syntheses. As in the case 

 of the paraffin series, the boiling points increase with 

 increasing molecular complexity of the substances. Large 

 numbers of isomerides are possible, and isomerism is 

 influenced not only by the relative arrangements of the 

 carbon atoms, but by the position of the double bonds. 

 Thus CH 3 CH 2 CH : CH 2 is isomeric, but not identical 

 with CH 3 CH : CH CH 3 . The former is known as a- 

 and the latter as /3-butylene, the use of the Greek letters 

 being employed to indicate the degree of proximity of the 

 double bond to the terminal carbon atoms. 



THE ACETYLENE SERIES. 



A " homologous " series of hydrocarbons is also known, 

 which can be represented by the general formula C n H 2n _ 2 . 



* The bromine compounds are produced in the same manner as the chlorine 

 compound.; described on page 80, only PBr 5 is substituted for PC1 5 . 



