Chemistry Alkyl Halides BUMHS 2023
PMDC Verified Question 13 of 13
Which of the following statement is true about Grignard reagent (RMgX)?
A
RMgX is prepared in aqueous medium
B
RMgX is prepared in ether
C
RMgX does not react with water
D
RMgX inactive in ethanol
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: RMgX is prepared in ether
Concept:

Grignard reagents (\( RMgX \)) contain a highly nucleophilic and strongly basic carbanion-like carbon atom.

Solution:

  • Because they are incredibly strong bases, they will immediately react with any source of acidic protons (like water or ethanol) in a violent acid-base reaction, destroying the reagent to form an alkane.
  • To prevent this, they must be synthesized and stored in completely anhydrous (moisture-free) aprotic solvents.
  • Dry diethyl ether is the standard solvent because it lacks acidic protons and its oxygen lone pairs help stabilize the magnesium atom via coordination.


Why other options are incorrect:

  • Options A, C, & D: Aqueous mediums and ethanol provide acidic protons that will instantly quench (destroy) the Grignard reagent, forming an alkane. Therefore, it is highly reactive with water and ethanol, not inactive.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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