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Acetylacetone is a versatile bifunctional precursor to heterocycles because both keto groups may undergo condensation. For example, condensation with hydrazine produces pyrazoles while condensation with urea provides pyrimidines .
It is prepared by condensation of esters of trifluoroacetic acid with acetone. [2] According to an analysis by proton NMR spectroscopy, the compound exists predominantly (97% at 33 °C, neat) as the enol. For comparison under the same conditions, the percent enol for acetylacetone and hexafluoroacetylacetone are 85 and 100%, respectively. [3]
Condensation with diacetylpyridine and acetylacetone gives, respectively, diiminopyridine [2] and NacNac ligands. [ 3 ] Typical Schrock-style olefin metathesis catalysts feature bulky imides as spectator ligands .
The mechanism of the Knorr pyrrole synthesis begins with condensation of the amine and ketone to give an imine. The imine then tautomerizes to an enamine, followed by cyclization, elimination of water, and isomerization to the pyrrole. Mechanism of Knorr pyrrole synthesis
In 1,3-diketones, such as acetylacetone (2,4-pentanedione), the enol form is more favored. The acid-catalyzed conversion of an enol to the keto form proceeds by proton transfer from O to carbon. The process does not occur intramolecularly, but requires participation of solvent or other mediators.
In organic chemistry, the Claisen–Schmidt condensation is the reaction between an aldehyde or ketone having an α-hydrogen with an aromatic carbonyl compound lacking an α-hydrogen. It can be considered as a specific variation of the aldol condensation .
The classical acetoacetatic ester synthesis utilizes the 1:1 conjugate base. Ethyl acetoacetate is however diprotic: [3] CH 3 C(O)CH 2 CO 2 Et + NaH → CH 3 C(O)CH(Na)CO 2 Et + H 2
Substrates are broadly limited to methyl ketones and secondary alcohols oxidizable to methyl ketones, such as isopropanol.The only primary alcohol and aldehyde to undergo this reaction are ethanol and acetaldehyde, respectively. 1,3-Diketones such as acetylacetone also undergo this reaction. β-ketoacids such as acetoacetic acid will also give the test upon heating.