APPENDICES 643 



removed, the vacant hand of the oxygen links to the vacant hand of the 

 terminal carbon to form an Aldehyde — 



H 



H— C— C = Ethyl Aldehyde. 



H H 



Ketones- — These are formed in the same way from the Secondary 

 Alcohols, a carbon atom, which is not the terminal one, being involved, 

 thus : — 



H H 



TT n P P R Acetone, the Ketone of Secondary 

 I I Propyl Alcohol. 



H H 



Acids. — If the hydrogen of the terminal carbon atom of the Aldehyde 

 is replaced by hydroxyl — OH an acid is produced — 







H 



I 

 H— C- 



I 

 H 



-C— 0— H Acetic Acid. 



The carboxyl group (to the right of the dotted line) is characteristic of the 

 acids. 



The oxidation may be carried on at each end of the line ; divalent acids 

 being thus produced — 





 II II 

 H— 0— C— C— 0— H Oxalic Acid. 



If, in the radicle of one of these acids, a hydrogen is replaced by hydroxyl 



— OH, an oxy-acid is formed, thus : — 



H H 



I I II 

 H— C— C— C— 0— H Propionic Acid. 



I I 

 H H 



This may be converted to the two Lactic acids called respectively a and 

 3 hydroxy-propionic acid, according to the carbon whif'h is oxidised. 



H OH 



I I II 

 a H— C— C— C— 0— H 



i I 

 H H 



OH H 



and 



/S H— C— C— C— 0— H 



i I 

 H H 



Similarly oxy-acids are formed from the divalent acids. 



