Interpretation:
A mechanism for the dehydration of 4-methylcyclohexanol catalyzed by phosphoric acid needs to be explained.
Concept Introduction:
A dehydration reaction takes place after the removal of water molecule/s from the reactant molecule. In the mechanism of any organic reaction, negative charge always attacks on the positive center, and removal of good leaving group takes place. The stability of a leaving group depends on the stability of the molecule which can be shown by inductive, hyperconjugation or resonance effect.
Explanation of Solution
Below is the mechanism for the dehydration of 4-methyl cyclohexanol catalyzed by phosphoric acid:
In the first step, lone pair of electrons attack on the H atom which results in the formation positive charge on the O of the -OH group of 4-methyl cyclohexanol.
Here, the good leaving group is H2O. The derivative of hydronium ion removes a water molecule to form a carbocation intermediate.
The nucleophile (H2PO4-) abstracts a proton from adjacent carbon of carbocation to form 4-methyl-1-cyclohexene.
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Chapter 22 Solutions
A Small Scale Approach to Organic Laboratory Techniques
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EBK A SMALL SCALE APPROACH TO ORGANIC LChemistryISBN:9781305446021Author:LampmanPublisher:CENGAGE LEARNING - CONSIGNMENT
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