494 CONSIDERATION OF CARBON COMPOUNDS. 



to a point of decomposition, and its presence is noticed by the pecu- 

 liar penetrating odor. 



Acrolein is a highly volatile liquid, boiling at 52.4 C. It has a 

 characteristic, penetrating odor and its vapors act on the eyes, causing 

 the secretion of tears. Acrolein shows in its chemical behavior its 

 aldehydic nature. It takes up oxygen forming acrylic acid; com- 

 bines with hydrogen forming allyl alcohol ; combines directly with 

 hydrochloric acid, ammonia, etc. 



Ketones or acetones. These are compounds containing the 

 bivalent radical carbonyl, CO <, to which two hydrocarbon radicals 

 are attached. The relation existing between carbonic acid, organic 

 acids, aldehydes, and ketones is best shown by the following formulas, 

 in which R stands for any hydrocarbon radical : 



Carbonic acid. Organic acid. Aldehyde. Ketone. 



While aldehydes are obtained by the oxidation of primary alcohols, ketones 

 are the first product of the oxidation of secondary alcohols. For instance : 



C 2 H 5 .CH 2 .OH + O = C 2 H 5 .COH + H 2 O. 



Primary propyl Propionic 



alcohol. aldehyde. 



. O = , CO + H 2 0. 



Secondary propyl Dimethyl 



alcohol. ketone. 



Ketones are neutral substances which resemble aldehyde in so far as they 

 have the power to unite directly with many substances with which aldehydes 

 combine ; as, for instance, with the acid sulphites. On the other hand, while 

 aldehydes readily take up oxygen directly and form acids, ketones are decom- 

 posed by oxidizing agents. 



Acetone, Acetonum, CH 3 .CO.CH 3 = 57.61 (Dimethyl-ketone). 

 This compound is obtained by the destructive distillation of acetates 

 (and of a number of other substances). The decomposition which 

 calcium acetate suffers may be shown by the equation : 



CH 3 COO\p __ CHgXpp, | p_p/-i 

 CH 3 COO/ Ca - CH 3 X C( CaC0 *- 

 Calcium acetate. Acetone. 



Acetone is a colorless liquid, boiling at 56.5 C. (133.7 1?.), rnis- 

 eible with water, alcohol, and ether in all proportions ; it has a pecu- 

 liar ethereal, somewhat mint-like odor, and burns with a luminous 

 non-sooty flame. 



