In this laboratory exercise we will measure the Equilibrium Constant Kc for the keto-enol tautomerism of two -diketones and two -diketoesters. This will be accomplished by measuring the signal strength of key protons in the Nuclear Magnetic Resonance (NMR) spectrum of the equilibrium system. The influence of the solvent on the equilibrium position will be examined by considering the measured ...

The paper updates Isler's monograph of 1971 regarding the structures of naturally occurring carotenoids, their chemical reactions and their stereochemistry. Around ninety new structures are reported, including the new series of C30-carotenoids, enolized /3-diketones and several carotenoids with 2-hydroxy 3-rings. Progress in stereochemistry resulting in the configurational assignment of eleven ...

The reaction of α-azidochalcones with carboxylic acids has been investigated resulting in the formation of α-amido-1,3-diketones under microwave irradiation via in situ formation of 2H-azirine intermediates. An interesting reaction is described wherein, with trifluoroacetic acid at lower temperature, it affords highly substituted 2-(trifluoromethyl)oxazoles. These flexible transformations proce...

Unsaturated vegetable oils and their corresponding fatty acid derivatives constitute interesting renewable platforms for the preparation of heterocycles, notably through formation oxygenated intermediates. In this work, imidazoles were prepared from 1,2-diketones Debus-Radziszewski reaction. The reaction was optimized under microwave irradiation using a 1,2-diketone derived methyl oleate ammoni...

Silica supported phosphorus pentoxide (P2O5·SiO2) is an efficient catalyst for synthesis of 1,3,5-substituted pyrazoles via the condensation of 1,3-diketones and hydrazines. Simplicity of procedure, mild condition, being solvent-free, high yields, and easy workup are some advantages of this protocol.