310 



REPOBT — 1900. 



Structure of Isolauronolic Acid. — The structure of this acid is almost 

 certainly represented by the formula 



CH. 



.CMe,— CMe 



-CH, — C.COOH 



first suggested implicitly by Perkin ^ and independently by Bouveault ; ^ 

 and the grounds for this statement are briefly as follows : — 



It is inactive, and cannot be separated into active forms. It therefore 

 does not contain an asymmetric carbon atom. 



It is an o/3-unsaturated acid, as its dibromide loses carbon dioxide 

 and hydrogen bromide on treatment with soda or sodium carbonate, a 

 behaviour associated almost exclusively with a/3-dibromo acids. Moreover, 

 dihydroisolauronolic acid is readily brominated, as usual in the n-position, 

 and the mono-bromo acid on treatment with alkali affords isolauronolic 

 acid and a-hydroxydihydroisolauronolic acid.^ 



CMeo.CHMe 

 / 



\ 

 CH,. CBr.COOH 



a-Bromdihy droisolauronolic Acid . 



CMe2.CMe 



/ Ii 



/ CH2 I 



/ \ 



CHo— C.COOH 



\ Isolauronolic Acid. 



--^ CMeo.CHMe 



CH, 



,0H 



CHo— CH< 



\C00H 



a-Hydrosydiliydroisolauronolic Acid. 



The latter compound when heated with lead peroxide and acetic acid 

 affords a ketone which is identical with u/i/J-trimethylketopentamethylene, 

 obtained by distilling the barium salt of a/3/3-trimethyladipic acid.^ 



CMeo.CHMe 



CMe, . CHMe 



CMeo . CHMe 



/ 

 CH, 



/ 

 CH., 



CHo— C^ 



.OH 



^COOH 



CHo— CO 



CHo 



X 

 CHo 



COOH 



-COOH 



Striking confirmation of the above formula for isolauronolic acid is 

 afforded by the following series of reactions. 



Isolauronolic acid, when heated in closed tubes at 300°, loses carbon 

 dioxide, and is converted into a hydrocarbon, C>,H,4, which yields y-acetyl- 

 dimethylbutyric acid on oxidation. That the production of the hydro- 



' Ptoc. Chem. Soc, 1896, p. 191. - Bull. Sue. Chim. (iii.), 19, p. 462. 



» Noyes, Ber., 29, 2326 and 1000, and Perkin, Trans. Chcm. Soc, 73, 838. 

 ' Noyes, Ber. , 



