Solvent and Double Bond

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Lab #2 (Part A,B)

Due date: Oct 5, 2010

1 - Theory and mechanism

Epoxidation is a reaction of an alkene with a peroxycarboxylic acid (also called peracid) to produce an epoxide product, generally performed in inert solvents, such as dichloromethane. The epoxide product is a cyclic ether in which the ring contains three atoms. The alkene gains an oxygen from the peracid in a syn fashion. In this experiment, R-(-)-carvone is reacting with MCPBA, a peracid, to produce the epoxide product. Balanced equation:

C10H14O + C7H5ClO3 --> C10H14O2 + C7H5ClO2

Since the rate of reaction depends on the electronic density of the double bond, and R-(-)-carvone has two double bonds, the reaction is regioselective. The more electron-riched double bond will react faster. Mechanism:

Potassium permanganate is a strong oxidant and reacts readily with double bonds. In this experiment it is used to visually identify the production in the previous reaction, since it changes color from purple to yellow-brown if reacted with alkene under aqueous conditions. Balanced equation:

C10H14O2 + KMnO4 + 2H2O --> C10H16O4
Mechanism:

2 - Table of reagents
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|Compound |Mol Mass (g/mol) | |Dissolution of MCPBA in CH2Cl2 |solution was clear, MCPBA dissolved | |Dissolution of R-(-)-carvone in the solution |solution stayed clear | |1.5 h after reaction |solution was cloudy white |

Part B: Syn dihydroxylation and visualization using KMnO4 (on a TLC plate) |Important steps |Observations | |TLC after 15 min, dipped in KMnO4 solution...
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