THE HYDROCARBONS AND THEIR DERIVATIVES. FLAME 349 



be oxidized directly to acetic acid CH 3 .COOH by passing a mixture 

 of the vapor, with air, over specially prepared platinum as a 

 catalyst : 



C 2 H 5 .OH + 2 -> CHs.COOH + H 2 0. 



The first acid of this series is formic acid H.COOH, a corrosive 

 liquid secreted by red ants and present in stinging nettles. Acetic 

 acid (see p. 419) has many industrial uses. 



The lower members of the fatty acid series are perfectly mis- 

 cible with water, and are slightly ionized in aqueous solution. 

 By neutralization with bases we obtain salts, such as the formates 

 and the acetates. Only the hydrogen of the characteristic .COOH 

 group, it must be noted, is replaceable by metals. 



6. Ketgnes. When calcium acetate Ca(CH 3 .COO) 2 is heated, 

 acetone (CH 3 ) 2 .CO distils off: 



Ca(CH 3 .COO) 2 -CaC0 3 + (CH 3 ) 2 .CO 



The ketones resemble the aldehydes in many respects, but their 

 characteristic group : CO is not directly combined with hydrogen. 

 Acetone is a liquid boiling at 56, used in large quantities in the 

 industries as a solvent. 



*v 



7. Esters. Alcohols and acids interact slowly and incom- 

 pletely to form esters. Thus when ethyl alcohol and acetic acid 

 are used, we obtain pt.hyl fl.opt,a t^_ CVPT. nOQ C!TT ? 



C2H 5 .OH + CH 3 .COOH+H 2 + C 2 H 5 .COO.CH 3 



The action may be catalyzed by the addition of a little sulphuric 

 acid. 



The equation, as given above, bears certain resemblances to a 

 neutralization. It differs sharply, however, from a true neutrali- 

 zation in several respects. An alcohol is not a base, neither is an 

 ester a salt. Both classes of substances are non-ionized in solu- 

 tion. True neutralization takes place instantaneously, while 

 the foregoing action, and all like it, proceed very slowly. 



