HYDROSORBIC ACID. 125 



slightly soluble in cold water, more easily in hot 

 water and in alcohol ; boiling point, 191. Sodium 

 amalgam produces no change in the acid in aqueous 

 solution, but when it is heated for a long time with 

 hydriodic aeid and a little amorphous phosphorus at 

 180-200, it is completely converted into valeric acid. 

 Fusing caustic potassa resolves it into acetic and pro- 

 pionic acids. Combines directly with bromine, form 

 ing the dibromide C 5 H 8 J3r 2 2 . Crystals fusing at 76. 

 This dibromide is converted into angelic acid by the 

 action of sodium amalgam and water. 



Methylcrotonic acid, C 5 H 8 2 (isomeric with angelic 

 acid), is produced from isoxyvaleric acid in the same 

 manner as methacrylic acid. Colorless needles, fusing 

 at 62 ; conducts itself towards fusing potassa the same 

 as angelic acid. 



4. HydrosorUc Acid. 

 2 = C 5 H 9 .CO.OH. 



Is produced by the action of sodium amalgam and 

 water on sorbic acid. Colorless liquid, of a sweaty 

 odor, but slightly soluble in water ; specific gravity, 

 0.969 ; boiling point, 201. Does not congeal at 18 ; 

 melting potassa resolves it into butyric and carbonic 

 acids. 



The following acids are isomeric: 



Pyroterebic acid, C 6 H 10 2 . Is produced by the 

 destructive distillation of terebic acid (see Oil of Tur 

 pentine). Oily liquid, boiling at 210. Is broken up 

 by means of fusing potassa, yielding acetic and butyric 

 acids. 



Ethylcrotonic acid, C 6 II 10 2 , is produced from 

 ethyl diethoxalate the same as methacrylic acid ; also 

 by heating ethyl diethoxalate for several hours with 

 concentrated hydrochloric acid at 130-150. Quad 

 ratic prisms, fusing at 41.5. Conducts itself towards 

 potassa the same as pyroterebic acid. 



11* 



