THE ORGANIC NON-NITROGENOUS DERIVATIVES. 91 



The glycolic acids which are found in the animal body may be 

 represented by the general formula C n H 2u O 3 . They comprise the 

 following bodies : 



Glycolicacid ............ CH 2 .OH.COOH 



Ethyl idene-lactic acid (paralactic acid) . CH 3 .CH(OH).COOH 



Ethylidene lactic acid(optically inactive) CH 3 .CH(OH).COOH = C 3 H 6 O 3 



Ethylidene-lsevo-lactic acid ...... CH 3 CH(OH).COOH =C,H 6 O 3 



/?-oxybutyric acid .......... CH.OH.CH 2 .CH 3 .COOH ^C^ELO, 



Leucinic acid ............ (CH 3 ) 2 .CH.CH 2 .CH.OH.COOH = C 6 H I2 O 3 



Of these acids, glycolic acid does not occur in the animal body, so 

 far as is known, but it is of interest owing to the fact that it is 

 closely related to glycocoll, and is derived from this in the same 

 manner in which leucinic acid is obtained from leucin, viz., by the 

 substitution of a hydroxyl group for the amido-group, as shown by 

 the equations : 



CH 2 .(NH 2 ).COOH -f H 2 = CH 2 (OH).COOH +NH 3 

 Glycocoll. Glycolic acid. 



(CH 3 ) 2 .CH.CH 2 .CH.(NH 2 ).COOH + H 2 O = 



Leucin. (CH 3 ) 2 .CH.CH 2; CH(OH).COOH + NH 3 



Leucinic acid. 



/?-oxybutyric acid is found only under pathologic conditions. 



Lactic acid and its isomeric compounds, as well as leucinic acid 

 and /3-oxybutyric acid, are all albuminous decomposition-products, 

 and in part, at least, derived from the amido-acids. The origin of 

 lactic acid, however, is not so clear, but we shall consider this ques- 

 tion in greater detail in a subsequent chapter. 



On reduction these acids can be transformed into fatty acids. 

 Lactic acid, as has just been shown, thus gives rise to butyric acid, 

 leucinic acid is similarly changed to capronic acid, etc. 



On oxidation /9-oxybutyric acid is transformed into diacetic acid, 

 which in turn is decomposed, with the formation of acetone and 

 carbon dioxide : 



CH,.CH.OH.CH 2 .COOH + O = (CH 3 .CO)CH 2 .COOH + H 2 O 



/3-oxybutyric acid. Diacetic acid. 



(CH 3 .CO)CH 2 .COOH = CO(CH 3 ) 2 + CO 2 

 Acetone. 



The bodies which are thus formed are of special interest to the 

 pathologist, as their accumulation in the animal body is apparently 

 capable of causing very serious disturbances. Acetone, in traces at 

 least, is also met with under normal conditions. 



On boiling with dilute mineral acids /9-oxybutyric acid is trans- 

 formed into an acid of the acrylic series (see below), viz., a-crotonic 



acid : 



CH 3 .CH(OH).CH 2 .COOH = 2H 2 O + CH 3 CH = CH.COOH 



a-Crotonic acid. 



The acids of the acrylic series can be represented by the general 

 formula C n H 2n _.,O >. Representatives of these are the a-capronic 

 acid, just referred "to, and oleic acid, which as a triglyceride rep- 



