Which compounds will give positive iodoform tests?
(a) 1-phenylethanol
(b) pentan-2-one
(c) pentan-2-ol
(d) pentan-3-one
(e) acetone
(f) isopropyl alcohol

검증된 단계별 안내

Step 1: Understand the iodoform test. The iodoform test is used to identify compounds containing a methyl group directly attached to a carbonyl group (C=O) or a methyl group attached to a hydroxyl group (-OH) in secondary alcohols. These compounds produce a yellow precipitate of iodoform (CHI3) when treated with iodine and a base.

Step 2: Analyze compound (a) 1-phenylethanol. This compound contains a hydroxyl group (-OH) attached to a carbon that is directly bonded to a methyl group. Since it meets the criteria for the iodoform test, it will give a positive result.

Step 3: Analyze compound (b) pentan-2-one. This compound contains a methyl group directly attached to a carbonyl group (C=O). Therefore, it will give a positive iodoform test.

Step 4: Analyze compound (c) pentan-2-ol. This compound contains a hydroxyl group (-OH) attached to a carbon that is directly bonded to a methyl group. It meets the criteria for the iodoform test and will give a positive result.

Step 5: Analyze compound (d) pentan-3-one, (e) acetone, and (f) isopropyl alcohol. Pentan-3-one does not have a methyl group directly attached to the carbonyl group, so it will not give a positive test. Acetone has a methyl group attached to the carbonyl group and will give a positive test. Isopropyl alcohol has a methyl group attached to the hydroxyl group and will also give a positive test.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Iodoform Test

The iodoform test is a qualitative test used to identify the presence of methyl ketones or secondary alcohols that can be oxidized to methyl ketones. A positive result is indicated by the formation of a yellow precipitate of iodoform (CHI3) when the compound is treated with iodine and a base. This test is particularly useful in distinguishing compounds with specific structural features.

Methyl Ketones

Methyl ketones are a class of ketones that contain a methyl group (–CH3) adjacent to the carbonyl group (C=O). Compounds such as acetone and pentan-2-one are examples of methyl ketones, which will yield a positive iodoform test. The presence of this structural feature is crucial for the reactivity in the iodoform reaction.

Secondary Alcohols

Secondary alcohols are alcohols where the hydroxyl group (–OH) is attached to a carbon atom that is connected to two other carbon atoms. Compounds like 1-phenylethanol and isopropyl alcohol are secondary alcohols that can be oxidized to form methyl ketones, thus giving a positive iodoform test. Understanding the classification of alcohols is essential for predicting their behavior in chemical tests.

Which compounds will give positive iodoform tests? (a) 1-phenylethanol (b) pentan-2-one(c) pentan-2-ol(d) pentan-3-one(e) acetone (f) isopropyl alcohol