Methyl bromide reacts with silver nitrate to form

Nitromethane

The correct answer is option 1. Nitromethane.

Let us break down the reaction between methyl bromide \((CH_3Br)\) and silver nitrate \((AgNO_)\):

Reaction Type: Nucleophilic Substitution

Methyl bromide, also known as bromomethane, contains a methyl group \((CH_3)\) bonded to a bromine atom \((Br)\). Bromine is more electronegative than carbon, making the \(C-Br\) bond polar, with a partial positive charge on the carbon and a partial negative charge on the bromine. This polarization allows methyl bromide to undergo nucleophilic substitution reactions where the bromine atom is replaced by another nucleophile (a molecule or ion that donates an electron pair).

Silver nitrate is commonly used in these reactions because silver ions (\(Ag^+\)) can precipitate out bromide ions \((Br^-)\) as **silver bromide \((AgBr)\), a solid. This precipitation drives the reaction forward.

Mechanism of Reaction

Step 1: Silver nitrate dissociation: In solution, silver nitrate dissociates into silver ions \((Ag^+)\) and nitrate ions \((NO_3^-\)).

\(AgNO_3 \rightarrow Ag^+ + NO_3^-\)

Step 2: Nucleophilic attack: The nitrate ion \((NO_3^-)\) acts as a nucleophile and attacks the carbon atom in the methyl bromide. The nucleophile replaces the bromine atom, which leaves as a bromide ion \((Br^-)\).

\(CH_3Br + NO_3^- \rightarrow CH_3NO_2 + Br^-\]

Step 3: Precipitation: The bromide ion formed during the reaction immediately reacts with the silver ion \((Ag^+)\) to form silver bromide \((AgBr)\), which precipitates out as a white solid:

\(Br^- + Ag^+ \rightarrow AgBr \, (precipitate)\)

This precipitation of \(AgBr\) is crucial because it drives the reaction forward by removing the bromide ion from the solution.

Product Formed: Nitromethane \((CH_3NO_2)\)

The organic product formed in this reaction is nitromethane , which has a nitro group \((NO_2)\) attached to the methyl group. Nitromethane is an important compound, used as a solvent, fuel, and intermediate in organic synthesis.

Full Reaction:

\(CH_3Br + AgNO_3 \rightarrow CH_3NO_2 + AgBr \, (precipitate)\)

Why Other Options Are Incorrect:

1. Methylamine: This is an amine, but the reaction with silver nitrate cannot convert methyl bromide into an amine, so this is incorrect.

2. Ethanamine: This compound would require a two-carbon chain, but methyl bromide contains only one carbon, so it cannot form ethanamine.

3. Grignard reagent: Grignard reagents are formed by the reaction of alkyl halides with magnesium in dry ether. Methyl bromide reacting with silver nitrate cannot produce a Grignard reagent

In summary, when methyl bromide reacts with silver nitrate , it undergoes nucleophilic substitution to form nitromethane, with silver bromide precipitating out as a by-product. This reaction is a typical example of how silver nitrate can facilitate the replacement of halide ions in alkyl halides.