Which of the following halides could be successfully used to form a Grignard reagent? A. CH3Br B. CCl4 C. C6H5I D. HCl

• A. C6H5I
• B. HCl
• C. CCl4
• D. CH3Br

Answer: (D)

Verified step by step guidance

1. Understand that a Grignard reagent is formed by the reaction of an organohalide (an alkyl or aryl halide) with magnesium metal in an anhydrous ether solvent.
2. Identify the key requirement: the halide must be attached to a carbon atom that can form a stable carbon-magnesium bond. This means the halide should be part of an alkyl or aryl group, not a molecule without carbon-halogen bonds suitable for this reaction.
3. Analyze each option: - CH3Br is methyl bromide, an alkyl halide, which can form a Grignard reagent. - CCl4 (carbon tetrachloride) has no suitable carbon-halogen bond for Grignard formation because all carbons are fully substituted with halogens and no reactive site is available. - C6H5I (iodobenzene) is an aryl halide, which can form a Grignard reagent under appropriate conditions. - HCl is not an organohalide; it is a hydrogen halide and cannot form a Grignard reagent.
4. Conclude that only halides attached to carbon atoms in alkyl or aryl groups (like CH3Br and C6H5I) can successfully form Grignard reagents.
5. Therefore, the correct choices for forming Grignard reagents are CH3Br and C6H5I.