THE PRINCIPLES OF ORGANIC CHEMISTRY 53 



Alcohols are capable of combining with mineral acids to 

 .'torm salts, thus : — 



ECH2OH + HCl = RCl + H2O 



Aldehydes and Ketones.— The first product of the oxida- 

 tion of an alcohol is either an aldehyde or a ketone. Primary 

 alcohols jneld aldehydes, thus : — 



/H 

 R— CH2OH + = R— C + H3O 



Primary U 



alcohol Aldehyde 



Secondary alcohols yield ketones : — • 



R2=CH0H + = R2=C=0 + H2O 



Tertiary alcohols yield mixtures of aldehydes and ketones. 



It will be noted that both aldehydes and ketones contain 

 the group ^C=0 which is known as carbonyl ; in fact alde- 

 hydes differ only from ketones in that a complex residue R 

 replaces hydrogen in the latter. The group ^C^O is a 

 highly reactive group ; the German word readionsfahig, or 

 capable of reaction, is perhaps more expressive. 



As this group occurs in most of the carbohydrates, certainly 

 in most of the sugars, and possibly in cellulose, it is important 

 that its general reactions should be understood. The more 

 commonly used are the following. 



With ammonia an amino compound is produced thus : — 



'/OH 

 R=C=0 + NH3 = R=C 



With hydrocyanic acid we have the following : — 



/OH 

 R=C=0 + HCN = R=C 



XCN 



