136 ACETO ACETIC ESTER 



diethyl-hydroxybutyric ester. The substitution of the a-hydrogen 

 atom affects the compound according to the character of the 

 substituted group, making it more alcoholic or more acidic as that 

 group is more or less positive than hydrogen. By the action of phenyl- 

 hydrazin on acetoacetic ester phenyl-/3-hydrazo-crotonic ester, CH3 C 

 (N2 H2 C6 H5) : CHCOz R, melting at 50 is formed and by heating this 

 with mercuric oxid phenyl-/3-azocrotonic ester, CH3 C (N2C6H5): 

 CHCO2R, melting at 51° is obtained. The product obtained by the 

 action of bromin on acetoacetic is a mixture of the o. and the y brom- 

 derivatives. a-Brom-methyl-acetoacetic ester, CyHuBrOj, boiling at 

 107° at 30 m.m. pressure, is obtained b}^ treating sodmethyl-acetoacetic 

 ester or methyl-acetoacetic ester with bromin. When this is heated 

 in a sealed tube tetric acid is formed for which the author gives the 

 formula 



CH2 : C (OH) CCH3<^QQ> CCH3C (OH) : CH2 



«-Bromethylacetoacetic ester, Cg H13 Br O3 , is prepared similarly and is 

 described. Dibenzoyl-acetoacetic ester, C20H18O5. and triacetylacetic 

 ester, CH3 CO C (CH3 00)2 CO2 R, and acetylcarbintricarboxylic ester, 

 CH3COC (CO2 R)2C02R, are also described. A large number of 

 pyrazolone derivatives are prepared and studied, and the author decides 

 that their acid properties are due to the presence of an imido group. 

 The formula for phenylmethyl-pyrazolone he gives as 



C (CH3)— NH ) 



II [NC6H5 



CH— CO ) 



PECHMANN, H. v., 1891. 



Ber. 24, 3600; J. Chem. Soc. 62, 296. 

 Preparation of Dehydracetic Acid. 



By treating acetondicarboxylic acid with acetic anhydrid, a substance 

 either isomeric or identical with the carboxylic acid of dehydracetic 

 acid is produced. This may be easily changed into dehydracetic acid 

 by dissolving in soda, evaporating to dryness and precipitating the 

 aqueous solution with acetic acid. 



