Reaction Between Semicarbazide And Cyclohexanone

Introduction Reactions don't always produce the same product, even if the reactants are kept constant. Some reactions have the capacity to produce two or more different products, depending on the reaction conditions and control such as thermodynamic and kinetic control. Thermodynamic control produces more stable products (University of Windsor, 2015). A kinetic control forms products at a faster rate faster rate because of its lower activation energy (UC Davis ChemWiki, 2015). By manipulating these controls, the desired products can be produced. For example, the kinetic product can be formed by maintaining a temperature low that prevents the reaction from ever reaching the activation energy barrier that’s required for the thermodynamic product to form. Similarly, the more stable thermodynamic product can be produced by raising the temperature and allowing the high activation energy barrier to be reached. The competing reactions are as follows:
The addition reaction takes place across the carbon-oxygen double bond and the elimination reaction took place when the water molecule left (Clark, 2015). To demonstrate these mechanisms, the reaction between a semicarbazide and a mixture of cyclohexanone and 2-furaldehyde was observed. Both 2-furaldehyde and cyclohexanone contain a carbonyl group. This allows semicarbazides to react with the carbonyl group to form a semicarbazone. That is, the double bonded oxygen on the carbonyl group and the two hydrogen of NH2 react to form a water molecule. Following the protonation of the carbonyl group, proton shift occurs and the water molecule leaves. This allows for the formation of a double bond between carbon and nitrogen. The reaction is as