Which of the following cannot act as a nucleophile?
H2O
CH3NH2
The Correct Option is D
Approach Solution - 1
A nucleophile is a species that is attracted to positive charge (nucleus) and donates an electron pair to form a chemical bond. Nucleophiles are typically electron-rich, meaning they have a lone pair of electrons or a negative charge.
Analyzing the Given Species:
(A) CH3O- (Methoxide ion): This has a negative charge and lone pairs of electrons on the oxygen, making it a good nucleophile.
(B) H2O (Water): Oxygen has two lone pairs of electrons, enabling it to act as a nucleophile, even though it's neutral.
(D) (CH3)3C+ (Tertiary Butyl Carbocation): This has a positive charge; therefore, it is an electrophile and cannot act as a nucleophile.
(E) CH3CH2O- (Ethoxide ion): This has a negative charge and lone pairs of electrons on the oxygen, making it a good nucleophile.
Therefore, the correct answer is (D) (CH3)3C+ (Tertiary Butyl Carbocation) because it is an electrophile.
Approach Solution -2
- (A) \( \text{CH}_3\text{O}^- \): This is the methoxide ion, which has a lone pair of electrons on oxygen. It can donate these electrons and act as a strong nucleophile.
- (B) \( \text{H}_2\text{O} \): Water has a lone pair of electrons on oxygen, making it a weak nucleophile.
- (C) \( \text{CH}_3\text{NH}_2 \): Methylamine has a lone pair of electrons on nitrogen, allowing it to act as a nucleophile.
- (D) \( \left(\text{CH}_3\right)_3\text{C}^+ \): This is a tertiary carbocation (\( \text{R}_3\text{C}^+ \)). Carbocations are electrophiles and do not have any lone pairs of electrons to donate. Therefore, they cannot act as nucleophiles.
- (E) \( \text{CH}_3\text{CH}_2\text{O}^- \): This is the ethoxide ion, which has a lone pair of electrons on oxygen. It can donate these electrons and act as a strong nucleophile.
Conclusion: The species that cannot act as a nucleophile is \( \left(\text{CH}_3\right)_3\text{C}^+ \).
Answer: (D)
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Concepts Used:
Organic Chemistry - Some Basic Principles and Techniques
Organic Chemistry is a subset of chemistry dealing with compounds of carbon. Therefore, we can say that Organic chemistry is the chemistry of carbon compounds and is 200-225 years old. Carbon forms bond with itself to form long chains of hydrocarbons, e.g.CH4, methane and CH3-CH3 ethane. Carbon has the ability to form carbon-carbon bonds quite elaborately. Polymers like polyethylene is a linear chain where hundreds of CH2 are linked together.
Read Also: Organic Compounds
Importance of Organic Chemistry:
Organic chemistry is applicable in a variety of areas including-
- Medicines: Example- Aspirin which is a headache medicine and Ibuprofen is a painkiller, both are organic compounds. Other examples include paracetamol.
- Food: Example- Starch which is a carbohydrate is an organic compound and a constituent of rice and other grains. It is the source of energy.
- Clothing: Example- Nylon, Polyester and Cotton are forms of organic compounds.
- Fuels: Examples- Gasoline, Petrol and Diesel are organic compounds used in the automobile industry at large.