C) NH2 N2 NaOH, Br2 + NaBr +NaCO3 H20
Propose step by step mechanis of the figure below.
The Correct Answer and Explanation is :
Based on the reagents you mentioned — NH2, NaOH, Br2, NaBr, NaCO3, and H2O — this appears to be a sequence involving diazotization and subsequent reaction with bromine in the presence of sodium bicarbonate.
Here’s a possible step-by-step mechanism based on common organic reactions:
Step 1: Diazotization
- Reagents: NH2 (amine group), NaOH (base), and NaNO2 (which could be generated in situ).
- Reaction: The primary amine group (NH2) reacts with sodium nitrite (NaNO2) in the presence of a base (NaOH). This leads to the formation of a diazonium ion (Ar-N2+). The base helps deprotonate the amine group, making it more reactive towards the nitrite ion. The reaction mechanism is as follows:
- The amine group (NH2) is deprotonated by NaOH to form an anionic amine.
- The nitrite (NO2-) reacts with the anionic amine, leading to the formation of a diazonium ion.
Step 2: Substitution with Bromine
- Reagents: Br2, NaBr, NaCO3 (sodium carbonate), and water.
- Reaction: The diazonium ion (Ar-N2+) is highly reactive and undergoes nucleophilic substitution by bromine (Br-) in the presence of NaBr. The bromine displaces the diazonium ion, resulting in the formation of a bromo-aromatic compound (Ar-Br). NaCO3 may serve to maintain the basic conditions and stabilize the intermediate. Mechanism:
- The bromine reacts with the diazonium ion to form a bromo derivative, releasing nitrogen gas (N2) in the process.
- The sodium carbonate helps neutralize any excess acid formed during the reaction.
Step 3: Hydrolysis (if applicable)
- In some cases, NaOH and water can be used to further react with intermediates, but from the reagents you’ve listed, this step may not be necessary unless there’s an additional functional group to hydrolyze.
300-word Explanation:
This mechanism primarily describes the conversion of a primary amine into a diazonium salt, followed by a nucleophilic substitution with bromine. Diazotization is a key reaction in organic chemistry, particularly for aromatic compounds. The process is useful for introducing new substituents (in this case, a bromine atom) onto an aromatic ring.
The first step involves the deprotonation of the amine group by NaOH, facilitating its reaction with NaNO2. This results in the formation of the diazonium ion, which is highly reactive and prone to nucleophilic attack. In the second step, the diazonium ion undergoes electrophilic aromatic substitution with the bromine, displacing the diazonium ion to form a bromo-aromatic compound. The reaction is driven by the release of nitrogen gas, which is a stable and unreactive molecule. Sodium carbonate serves to neutralize the acidic by-products of the reaction, ensuring the reaction proceeds smoothly.
This series of reactions is essential in synthetic organic chemistry for functionalizing aromatic compounds and creating a wide range of derivatives for further use in pharmaceuticals, dyes, and other chemical applications.
If you would like me to generate an image of this process, let me know!