Lab 7 - Experiment #7: Synthesis of 4-methylcylohexene...

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CHEM 237 Lab Fall 2009 Objective The purpose of this experiment is to understand the mechanism of E1 elimination reaction through an acid- catalyzed dehydration of alcohols. 5 Reagents: 4-methylcyclohexanol (a mixture of cis and trans isomers): substrate 10 H 3 PO 4 (phosphoric acid): acid catalyst MgSO 4 Apparatus Round bottom flask 15 20 Filter funnel Reflux condenser Distillation head Theremometer TLC plate (SiO 2 ) Glass pipette and micropipette Graduate Cylinder (10 mL) Theory The elimination reaction can occur by E1 (stepwise) or E2 (single step) mechanism. In the elimination reaction by an E1 pathway, a good leaving group attached to the electron deficient carbon center departs, and a reactive carbocation (C+) is formed. An acidic proton (attached to β -carbon) will be removed by a neutral or mild base to generate alkene(s). E1 reaction typically produce more substituted (stable) alkenes as major products (Zaitzev’s rule). Synthesis of 4-methylcyclohexene from 4-metylcyclohexanol is shown in Scheme 1. 25
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This note was uploaded on 03/03/2010 for the course CHEM 237 taught by Professor Chong during the Fall '10 term at Illinois Tech.

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