UNSATURATED ALCOHOLS, ALDEHYDES AND 

 FATTY ACIDS. 



Allyl alcohol, acrolein and acrylic acid are unsaturated compounds 

 and the first members of the series : 



Amongst the unsaturated acids there are several which occur in 

 nature. 



Allyl Alcohol. 



Preparation. 



Allyl alcohol is prepared by distilling glycerol at a temperature of 

 about 260 with oxalic acid. As stated on p. 94 the acid oxalic ester 

 of glycerol is formed ; on heating it to a high temperature the neutral 

 ester is produced and decomposed, yielding allyl alcohol and carbon 

 dioxide : 



CH 2 OH CH 2 O CO 



HOOC I 

 CHOH + I = CHOH COOH + H a O 



HOOC I 

 CH 2 OH COOH. 



CH 2 O CO CH 2 O CO 



CHOH COOH = CHO CO + H 2 O 

 CH 2 OH CH 2 OH. 



CH 2 O CO CH 2 



I I II 



CHO CO = CH + 2CO 2 



CH 3 OH CH,OH. 



The liquid which distils over between 220 and 260 is collected and 

 redistilled, the thermometer being placed in the liquid. Allyl alcohol 

 is present in the fraction boiling below 105. It is dehydrated with 

 potassium carbonate and again distilled. 



103 



