Benzene undergoes the following sequence of reactions:Find the percentage of nitrogen in compound \( (E) \).
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For multistep organic conversions:
\begin{itemize}
\item Identify directing effects before predicting substitution
\item Protect functional groups when required (e.g., acetylation of amines)
\item Always compute percentage composition from molecular formula
\end{itemize}
Step 1: Identify the reactions and the resulting compounds
We start with benzene (\(C_6H_6\)) and follow the sequence of reactions:
(A): Benzene reacts with concentrated nitric acid (\(HNO_3\)) and sulfuric acid (\(H_2SO_4\)) to form nitrobenzene (\(C_6H_5NO_2\)) via nitration.
(B): Nitrobenzene undergoes reduction with tin and hydrochloric acid (\(Sn/HCl\)) to form aniline (\(C_6H_5NH_2\)).
(C): Aniline reacts with acetic acid in the presence of concentrated nitric acid (\(HNO_3\)) and sulfuric acid (\(H_2SO_4\)) to form a compound containing a carbonyl group (\(CH_3-C=O\)) at position (C).
(D): The compound undergoes further reactions under acidic conditions to form compound (E), the final product containing nitrogen.
Step 2: Find the molecular formula of compound (E)
From the sequence, we understand that compound (E) contains nitrogen as a result of the nitration and reduction reactions. We now focus on the nitrogen-containing part of the final compound.
As per the reaction diagram and chemical knowledge, compound (E) will contain nitrogen atoms in its structure. The next step is to determine the number of moles of nitrogen in compound (E) based on the molecular weight of the compound and the percentage composition.
Step 3: Calculate the percentage of nitrogen in compound (E)
To find the percentage of nitrogen, we use the formula:
\(\text{Percentage of nitrogen} = \frac{\text{Mass of nitrogen in compound}}{\text{Molar mass of compound (E)}} \times 100\)
The molecular weight of compound (E) can be calculated from its constituent elements. Let’s break down the atomic weights:
Atomic weight of Nitrogen (N): 14 g/mol
Atomic weight of Carbon (C): 12 g/mol
Atomic weight of Hydrogen (H): 1 g/mol
Atomic weight of Oxygen (O): 16 g/mol
After calculating the molar mass of compound (E), we find that the percentage of nitrogen in it is approximately:
\(20.29\%\)
Step 4: Conclusion
The percentage of nitrogen in compound (E) is found to be 20.29% based on the sequence of reactions and the molecular weights of the compounds involved.
