Chapter 10: Problem 91
Which of the following pair represent different functional group containing
compound?
(A) \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{NH}_{2},
\mathrm{Me}-\mathrm{NH}-\mathrm{Me}\)
(B) \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH},
\mathrm{Me}-\mathrm{O}-\mathrm{Me}\)
(C) \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH}, \mathrm{Me}_{2}
\mathrm{CH}-\mathrm{OH}\)
(D) \(\mathrm{Me}-\mathrm{C}-\mathrm{NH}_{2}\)
Short Answer
Expert verified
The correct answer is Pair B: \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH}\), \(\mathrm{Me}-\mathrm{O}-\mathrm{Me}\), which contain different functional groups (hydroxyl and ether).
Step by step solution
01
Pair A: Identifying Functional Groups
Compound 1: \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{NH}_{2}\)
In this compound, the functional group is an amine group (-NH\(_{2}\)).
Compound 2: \(\mathrm{Me}-\mathrm{NH}-\mathrm{Me}\)
In this compound, the functional group is also an amine group (-NH-).
Since both compounds have the same functional group (amine), this pair does not contain different functional groups.
02
Pair B: Identifying Functional Groups
Compound 1: \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH}\)
In this compound, the functional group is a hydroxyl group (-OH).
Compound 2: \(\mathrm{Me}-\mathrm{O}-\mathrm{Me}\)
In this compound, the functional group is an ether group (-O-).
Since the compounds have different functional groups (hydroxyl and ether), this pair does contain different functional groups.
03
Pair C: Identifying Functional Groups
Compound 1: \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH}\)
In this compound, the functional group is a hydroxyl group (-OH).
Compound 2: \(\mathrm{Me}_{2}\mathrm{CH}-\mathrm{OH}\)
In this compound, the functional group is also a hydroxyl group (-OH).
Since both compounds have the same functional group (hydroxyl), this pair does not contain different functional groups.
04
Pair D: Identifying Functional Groups
Compound: \(\mathrm{Me}-\mathrm{C}-\mathrm{NH}_{2}\)
In this compound, the functional group is a nitrile group (-C\(\equiv\)N). There is no pair to compare in this option.
05
Final Comparison
Based on the above analysis, Pair B contains different functional groups (hydroxyl and ether) while Pair A and C contain the same functional groups (amine and hydroxyl, respectively). Therefore, the correct answer is Pair B: \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH}\), \(\mathrm{Me}-\mathrm{O}-\mathrm{Me}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Amine Group
The amine group is a core functional group in organic chemistry, typically consisting of a nitrogen atom attached to hydrogen atoms, alkyl groups, or aryl groups. It's represented by the general formula -NR2 where R can be hydrogen or hydrocarbon chains.
Let's take the case of the compound \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{NH}_{2}\) from our exercise. Here, 'Me' stands for a methyl group, a type of alkyl group, and \(\mathrm{NH}_{2}\) signifies the primary amine functional group attached to the carbon chain. Amines, like the example given, are found in various natural and synthetic compounds and have significant biological activity.
Amines can be primary (one carbon-nitrogen bond), secondary (two carbon-nitrogen bonds), or tertiary (three carbon-nitrogen bonds) depending on the number of alkyl or aryl groups attached to the nitrogen. For instance, in \(\mathrm{Me}-\mathrm{NH}-\mathrm{Me}\), we're dealing with a secondary amine since the nitrogen is bonded to two methyl groups.
Amines have a lone pair of electrons on the nitrogen, making them basic in nature and capable of forming hydrogen bonds. This gives amines a high boiling point and solubility in water. Recognizing the type of amine group is vital in organic chemistry, especially on competitive exams like JEE, where understanding the properties associated with different functional groups can lead to choosing the correct answer in multi-option questions.
Let's take the case of the compound \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{NH}_{2}\) from our exercise. Here, 'Me' stands for a methyl group, a type of alkyl group, and \(\mathrm{NH}_{2}\) signifies the primary amine functional group attached to the carbon chain. Amines, like the example given, are found in various natural and synthetic compounds and have significant biological activity.
Amines can be primary (one carbon-nitrogen bond), secondary (two carbon-nitrogen bonds), or tertiary (three carbon-nitrogen bonds) depending on the number of alkyl or aryl groups attached to the nitrogen. For instance, in \(\mathrm{Me}-\mathrm{NH}-\mathrm{Me}\), we're dealing with a secondary amine since the nitrogen is bonded to two methyl groups.
Amines have a lone pair of electrons on the nitrogen, making them basic in nature and capable of forming hydrogen bonds. This gives amines a high boiling point and solubility in water. Recognizing the type of amine group is vital in organic chemistry, especially on competitive exams like JEE, where understanding the properties associated with different functional groups can lead to choosing the correct answer in multi-option questions.
Hydroxyl Group
A hydroxyl group is one of the simplest and most important functional groups in organic chemistry. It consists of an oxygen and a hydrogen atom, represented as -OH. The presence of this group in a molecule is characteristic of alcohols.
For example, when analyzing \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH}\), 'Me' is a methyl group, and the \(\mathrm{OH}\) signifies the hydroxyl group, making the compound an alcohol. Hydroxyl groups are polar due to the electronegativity difference between oxygen and hydrogen, which leads to the formation of hydrogen bonds with other molecules.
The hydroxyl group is responsible for the increased solubility of compounds in water and higher boiling points compared to hydrocarbons of similar molecular weight. This group is also highly reactive, making it an essential functional group for various chemical reactions in both laboratory synthesis and biological systems.
In the context of JEE organic chemistry, understanding the properties and reactions of hydroxyl-containing compounds is crucial. It involves recognizing the group's ability to partake in dehydration, oxidation, and substitution reactions, which can transform the compound into various other functional groups like ethers, aldehydes, ketones, or carboxylic acids.
For example, when analyzing \(\mathrm{Me}-\mathrm{CH}_{2}-\mathrm{OH}\), 'Me' is a methyl group, and the \(\mathrm{OH}\) signifies the hydroxyl group, making the compound an alcohol. Hydroxyl groups are polar due to the electronegativity difference between oxygen and hydrogen, which leads to the formation of hydrogen bonds with other molecules.
The hydroxyl group is responsible for the increased solubility of compounds in water and higher boiling points compared to hydrocarbons of similar molecular weight. This group is also highly reactive, making it an essential functional group for various chemical reactions in both laboratory synthesis and biological systems.
In the context of JEE organic chemistry, understanding the properties and reactions of hydroxyl-containing compounds is crucial. It involves recognizing the group's ability to partake in dehydration, oxidation, and substitution reactions, which can transform the compound into various other functional groups like ethers, aldehydes, ketones, or carboxylic acids.
Ether Group
The ether group, characterized by an oxygen atom connected to two alkyl or aryl groups, is another pivotal functional group in organic chemistry. It is represented as -R-O-R', where R and R' can be identical or different hydrocarbon groups.
An example from our exercise, \(\mathrm{Me}-\mathrm{O}-\mathrm{Me}\), illustrates an ether where both R and R' are methyl groups. This type of symmetrical ether is also known as dimethyl ether. Ethers are typically less reactive than alcohols due to the absence of the highly reactive hydrogen atom as seen in the hydroxyl group.
Ethers have relatively low boiling points and are not capable of forming hydrogen bonds among themselves, although they can with water, which contributes to their solubility. This functional group is often used as solvents for chemical reactions due to their stability and non-reactivity. Recognizing ethers is important for JEE preparation, as being able to distinguish them from similar looking alcohols or epoxides can be essential for answering questions accurately.
An example from our exercise, \(\mathrm{Me}-\mathrm{O}-\mathrm{Me}\), illustrates an ether where both R and R' are methyl groups. This type of symmetrical ether is also known as dimethyl ether. Ethers are typically less reactive than alcohols due to the absence of the highly reactive hydrogen atom as seen in the hydroxyl group.
Ethers have relatively low boiling points and are not capable of forming hydrogen bonds among themselves, although they can with water, which contributes to their solubility. This functional group is often used as solvents for chemical reactions due to their stability and non-reactivity. Recognizing ethers is important for JEE preparation, as being able to distinguish them from similar looking alcohols or epoxides can be essential for answering questions accurately.
Organic Chemistry for JEE
Organic Chemistry is a significant part of the JEE syllabus, which is one of the most competitive exams for students aspiring to enter engineering fields in India. Mastery of functional groups, like amine, hydroxyl, and ether, is essential for doing well on the JEE because they are the foundation upon which organic compounds' structure and reactivity are understood.
Preparing for JEE requires a deep understanding of concepts, such as the physical and chemical properties of compounds, reactivity patterns, mechanisms of various organic reactions, and stereochemistry. Knowing functional groups also plays a pivotal role in synthesis and identification of organic compounds, which forms a vital part of the JEE organic chemistry questions.
Candidates must practice identifying functional groups, predicting the outcome of reactions, and solving problems based on structure-activity relationships. They should be familiar with IUPAC nomenclature, isomerism, and the concept of stereoselectivity and stereospecificity. An understanding rooted in these fundamentals can significantly boost a student's performance in the organic chemistry section of the JEE.
Preparing for JEE requires a deep understanding of concepts, such as the physical and chemical properties of compounds, reactivity patterns, mechanisms of various organic reactions, and stereochemistry. Knowing functional groups also plays a pivotal role in synthesis and identification of organic compounds, which forms a vital part of the JEE organic chemistry questions.
Candidates must practice identifying functional groups, predicting the outcome of reactions, and solving problems based on structure-activity relationships. They should be familiar with IUPAC nomenclature, isomerism, and the concept of stereoselectivity and stereospecificity. An understanding rooted in these fundamentals can significantly boost a student's performance in the organic chemistry section of the JEE.
