Which of the following alkanols is dehydrated most readily?? 1)2-methy...
Answer:
Introduction:
Alkanols are alcohols that are composed of carbon, hydrogen, and oxygen atoms. They contain a hydroxyl (-OH) functional group attached to a carbon atom. Alkanols can undergo dehydration reactions to form alkenes in the presence of a strong acid.
Dehydration of alkanols:
Dehydration of alkanols is an elimination reaction that involves the removal of a molecule of water from the alcohol. The reaction requires the use of a strong acid catalyst, such as sulfuric acid or phosphoric acid. The acid protonates the hydroxyl group, making it a better leaving group, and facilitates the elimination of a molecule of water.
Effect of alkyl group on dehydration:
The ease of dehydration of an alkanol depends on the structure of the alcohol. The presence of alkyl groups attached to the carbon atom bearing the hydroxyl group can hinder the dehydration process. This is because the alkyl groups can stabilize the intermediate carbocation formed during the elimination reaction, making it more difficult to remove a molecule of water.
Comparison of alkanols:
1) 2-methyl-2-propanol: This alkanol has two alkyl groups attached to the carbon bearing the hydroxyl group. The steric hindrance caused by the alkyl groups makes it difficult for the hydroxyl group to be protonated by the acid catalyst. Therefore, this alkanol is the least likely to undergo dehydration.
2) 2-methyl-1-propanol: This alkanol has one alkyl group attached to the carbon bearing the hydroxyl group. The presence of the alkyl group can hinder the dehydration process, but to a lesser extent than in 2-methyl-2-propanol.
3) 1-pentanol: This alkanol has a linear structure with no alkyl groups attached to the carbon bearing the hydroxyl group. This makes it easier for the hydroxyl group to be protonated and for the molecule to undergo dehydration.
4) 1-butanol: This alkanol has a linear structure similar to 1-pentanol. However, it has a shorter carbon chain, which makes it more reactive and easier to undergo dehydration.
Therefore, the order of ease of dehydration is: 2-methyl-2-propanol < 2-methyl-1-propanol="" />< 1-pentanol="" />< 1-butanol.="" />
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