Preparation of 2-Acetylcyclohexanone
Introduction 3
Results 4
Discussion 6
Conclusion 7
Experimental 7
References 8
Preparation of 2-Acetylcyclohexanone
Introduction
When hydrogens are present on the α-carbon of ketones (like the reaction used in this experiment), carbonyl compounds and aldehydes, they turn the compound slightly acidic1. These functional groups are removed by using a basic solution as shown in (i) below1. The product formed with water is stable only due to resonance, but does not form a very stable equilibrium.
Enamine reactions are used to avoid many problems usually associated with alkylating or acylating carbonyl compounds when they are reacted with aqueous sodium hydroxide1 as shown in reactions (ii) and (iv)1. The main problem being that the reaction results in a great number of crucial secondary side reactions, such as those in equations (iii), (iv) and (vi), and this in turn results in the main product formed in (i) being only available in small amounts because of the previously mentioned unstable equilibrium, while nucleophile OH- in equation (iii) is much higher1.
When the OH- reacts with alkyl halide (iii) or acyl halide (iv), the conjugate base will tend to react with the unreacted carbonyl compound by means of an aldol condensation reaction as shown in equation (vi)1.
Results
Preparation of the enamine Pyrrolidine Cyclohexanone
Molecular formula: C4H9N Molecular formula: C6H10O
Volume: 4.0 ml +. Volume: 5.0 ml
Density: 0.87 g cm-3 Density: 0.95 g cm-3
Boiling point: 87ºC Boiling point: 156ºC
Masses were worked out using densities:
Mass cyclohexanone = 0.947g/ml x 5ml = 4.739g Therefore moles = mass/molar mass = 4.739g/98.15g mol-1 = 0.0483 moles
Mass pyrrolidine = 0.866g/mol x 4.0 ml = 3.464g
Therefore moles = mass/molar mass = 3.464 / 71.11g mol-1
Addition of the acetic anhydride Enamine Acetic Anhydride
Molecular formula: C10H9N Molecular formula: C4H6O3¬
Results 4
Discussion 6
Conclusion 7
Experimental 7
References 8
Preparation of 2-Acetylcyclohexanone
Introduction
When hydrogens are present on the α-carbon of ketones (like the reaction used in this experiment), carbonyl compounds and aldehydes, they turn the compound slightly acidic1. These functional groups are removed by using a basic solution as shown in (i) below1. The product formed with water is stable only due to resonance, but does not form a very stable equilibrium.
Enamine reactions are used to avoid many problems usually associated with alkylating or acylating carbonyl compounds when they are reacted with aqueous sodium hydroxide1 as shown in reactions (ii) and (iv)1. The main problem being that the reaction results in a great number of crucial secondary side reactions, such as those in equations (iii), (iv) and (vi), and this in turn results in the main product formed in (i) being only available in small amounts because of the previously mentioned unstable equilibrium, while nucleophile OH- in equation (iii) is much higher1.
When the OH- reacts with alkyl halide (iii) or acyl halide (iv), the conjugate base will tend to react with the unreacted carbonyl compound by means of an aldol condensation reaction as shown in equation (vi)1.
Results
Preparation of the enamine Pyrrolidine Cyclohexanone
Molecular formula: C4H9N Molecular formula: C6H10O
Volume: 4.0 ml +. Volume: 5.0 ml
Density: 0.87 g cm-3 Density: 0.95 g cm-3
Boiling point: 87ºC Boiling point: 156ºC
Masses were worked out using densities:
Mass cyclohexanone = 0.947g/ml x 5ml = 4.739g Therefore moles = mass/molar mass = 4.739g/98.15g mol-1 = 0.0483 moles
Mass pyrrolidine = 0.866g/mol x 4.0 ml = 3.464g
Therefore moles = mass/molar mass = 3.464 / 71.11g mol-1
Addition of the acetic anhydride Enamine Acetic Anhydride
Molecular formula: C10H9N Molecular formula: C4H6O3¬
References: 1. http://www.courses.chem.psu.edu/chem36/Chem36H/IndivExpt1/435%20Acetylcyclohexanone.pdf – Accessed 11/08/08 2. http://en.wikipedia.org/wiki/Acetic_anhydride – Accessed 11/08/08 3. P. Y Bruice, Organic Chemistry, 4th Edition, Pearson Education Inc., 2004, USA pgs 747-753 4. http://www.freepatentsonline.com/4355097.html