Chapter 2: Problem 25
Draw the products formed when 2-propanol [(CH\(_3)_2\)CHOH], the main ingredient in rubbing alcohol, is treated with each acid or base: (a) NaH; (b) H\(_2\)SO\(_4\); (c) Li\(^{+-}\)N[CH(CH\(_3)_2]_2\); (d) CH\(_3\)CO\(_2\)H.
Short Answer
Expert verified
2-propanol forms an alkoxide with NaH and LDA, propene with H2SO4, and isopropyl acetate with CH3CO2H.
Step by step solution
01
Identifying Reaction with NaH
2-propanol reacts with sodium hydride (NaH). NaH is a strong base and will deprotonate the hydroxyl group (-OH) of 2-propanol to form an alkoxide ion. The alkoxide ion is (CH\(_3\))\(_2\)CHO\(^{-}\) and hydrogen gas (H\(_2\)) is released as a byproduct.
02
Identifying Reaction with H2SO4
2-propanol reacts with sulfuric acid (H\(_2\)SO\(_4\)). Concentrated H\(_2\)SO\(_4\) can dehydrate alcohols to form alkenes. When 2-propanol is treated with H\(_2\)SO\(_4\), it undergoes dehydration to form propene, CH\(_3\)CH=CH\(_2\), with the elimination of water (H\(_2\)O).
03
Identifying Reaction with LiN[CH(CH3)2]2
LiN[CH(CH\(_3\))\(_2\)]\(_2\) is known as lithium diisopropylamide (LDA), a strong, non-nucleophilic base. LDA will deprotonate 2-propanol's -OH, forming the same alkoxide ion, (CH\(_3\))\(_2\)CHO\(^{-}\), as in the reaction with NaH. No alkene is formed because LDA does not promote elimination.
04
Identifying Reaction with CH3CO2H
2-propanol reacts with acetic acid (CH\(_3\)CO\(_2\)H). In the presence of acetic acid, 2-propanol participates in an esterification reaction to form an ester, isopropyl acetate (CH\(_3\)COO(CH\(_3\))\(_2\)CH), and water. This reaction is typically slow and may require a catalyst such as sulfuric acid for completion.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Acid-Base Reactions
Acid-base reactions are fundamental in organic chemistry. They involve the transfer of protons (H\(^+\)) between molecules.
In the case of 2-propanol reacting with a strong base like sodium hydride (NaH), an acid-base reaction occurs as follows: the -OH group in 2-propanol donates a proton to the NaH.
The result is the formation of an alkoxide ion,
In the case of 2-propanol reacting with a strong base like sodium hydride (NaH), an acid-base reaction occurs as follows: the -OH group in 2-propanol donates a proton to the NaH.
The result is the formation of an alkoxide ion,
- Alkoxide Ion: The ion is (CH\(_3\))\(_2\)CHO\(^{-}\). It represents deprotonated 2-propanol, making it more reactive for other reactions.
- Hydrogen Gas: Produced as a byproduct, highlighting the efficiency of NaH as a strong base.
Dehydration Reactions
Dehydration reactions are a type of elimination reaction where water is removed from a molecule. These reactions can change alcohols into alkenes under the right conditions.
When 2-propanol is treated with sulfuric acid (H\(_2\)SO\(_4\)), a typical dehydration occurs. Here's how:
When 2-propanol is treated with sulfuric acid (H\(_2\)SO\(_4\)), a typical dehydration occurs. Here's how:
- Formation of Carbocation: 2-propanol converts into a carbocation (a positively charged ion) by losing water (H\(_2\)O), facilitated by the acidic environment.
- Creation of Propene: The carbocation loses a further proton to form propene (CH\(_3\)CH=CH\(_2\)).
Esterification
Esterification is an important chemical process where alcohol reacts with an acid to form an ester. This reaction is often facilitated by a catalyst to speed up the process.
For 2-propanol, reacting with acetic acid (CH\(_3\)CO\(_2\)H) results in an esterification reaction, leading to:
For 2-propanol, reacting with acetic acid (CH\(_3\)CO\(_2\)H) results in an esterification reaction, leading to:
- Formation of Isopropyl Acetate: 2-propanol and acetic acid combine to form isopropyl acetate (CH\(_3\)COO(CH\(_3\))\(_2\)CH), a sweet-smelling ester.
- Water as a Byproduct: Water is released during the process.
Organic Chemistry
Organic chemistry is the study of carbon-containing compounds and their properties. It explores how these compounds interact and transform under various conditions.
2-propanol provides a great example for exploring various reactions in organic chemistry:
2-propanol provides a great example for exploring various reactions in organic chemistry:
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Acid-Base Reactions: As seen with NaH and LDA, where proton exchange plays a central role in creating more reactive species.
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Dehydration: Transforming alcohols into alkenes, which are foundational compounds in organic synthesis.
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Esterification: Showcasing how alcohols can be transformed into valuable ester compounds.