CARBOHYDRATES 



133 



atom becomes satisfied with the added bromine. In exactly 

 a similar way we have compounds in which the carbon is con- 

 sidered as triply linked with another carbon atom while only 

 the remaining bond is held by another element or group. Such 

 a hydrocarbon is the common illuminating gas, acetylene, C2H2, 

 and is represented as HC=CH. 



Now similar to each of these hydrocarbons we have an ho- 

 mologous series of higher hydrocarbons related to the simplest or 

 mother substance just as ethane and the higher paraffin hydro- 

 carbons are related to methane. These two series are known 

 as the ethylene series and the acetylene series. Their relation 

 to each other and to the methane series is readily seen if they 

 are placed together as represented by their structural formulas. 



Each of these unsaturated series, viz. the ethylene hydro- 

 carbons and the acetylene hydrocarbons, form derivatives, 

 such as alcohols, aldehydes and acids. These are exactly 

 analogous to those of the methane series. A few common 

 and important ones wdll be mentioned. 



Allyl alcohol 



Allyl aldehyde or Acrylic 



aldehyde (acrolein) 

 Acrylic acid 

 Crotonic aldehyde 

 Crotonic acid 

 Oleic acid, C18H34O2 



CHo = CH-CH20H 



CH2=CH-CH0 

 CH2 = CH-C00H 

 CH3-CH=CH-CH0 

 CH3-CH = CH-C00H 

 CH3-(CH2)7-CH = CH-(CH2)7-COOH 



