PREPARATIONS 271 have the two substituents joined to the same carbon atom, symmetrically substituted ketones not being obtainable from the ester by the above methods. For other examples of the synthetic application of ethyl acetoacetate, see below and pp. 293 295. Methyl-phenyl-pyrazolone. The preparation of methyl-phenyl-pyrazolone illustrates one of the synthetic uses of ethyl acetoacetate, as distinct from those involving the hydrolysis of substitution derivatives. If ethyl acetoacetate is warmed with an equivalent quantity of phenyl-hydrazine, the corresponding phenylhydrazone (A) is readily formed. On CH 3 CO -r H 2 NNHC 6 U 5 CH 3 CiNNHC 6 H 6 I- H 2 O - I CH 2 COOC 2 H 6 CH 2 COOC 2 H 5 (A) further heating, ring formation occurs with the loss of ethanol and the pro-CH 3 CrNNHC 6 II 5 CH 3 C:N NC 6 H 6 I- C 2 H 5 OH -f I I CH 2 COOC 2 H 5 CH 2-CO (B) duction of methyl-phenyl-pyrazolone (B). To indicate the CH 3 CiN-NC 6 H 6 position of the substituents in the pyrazolone ring, the
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.