How will you prepare benzene from

Options

A. Benzene sulphonic acid
B. Phenol
C. Nitrobenzene
D. Benzoic acid

Answer

To prepare benzene from the given compounds (benzene sulfonic acid, phenol, nitrobenzene, and benzoic acid), we can follow these steps for each compound:

### 1. Preparation of Benzene from Benzene Sulfonic Acid
**Step 1:** Start with benzene sulfonic acid (C6H5SO3H).
**Step 2:** Treat benzene sulfonic acid with water (H2O) at a temperature of 150-200 °C in the presence of hydrochloric acid (HCl) and apply pressure.
**Step 3:** The reaction will yield benzene (C6H6) and sulfuric acid (H2SO4) as a byproduct.

**Chemical Equation:**
C6H5SO3H + H2O → C6H6 + H2SO4

### 2. Preparation of Benzene from Phenol
**Step 1:** Start with phenol (C6H5OH).
**Step 2:** React phenol with zinc dust (Zn) and heat the mixture.
**Step 3:** This reaction will produce benzene (C6H6) and zinc oxide (ZnO) as a byproduct.

**Chemical Equation:**
C6H5OH + Zn → C6H6 + ZnO

### 3. Preparation of Benzene from Nitrobenzene
**Step 1:** Start with nitrobenzene (C6H5NO2).
**Step 2:** Reduce nitrobenzene using tin (Sn) and hydrochloric acid (HCl) to form aniline (C6H5NH2).
**Step 3:** Treat aniline with sodium nitrite (NaNO2) and hydrochloric acid (HCl) to form benzene diazonium chloride (C6H5N2Cl).
**Step 4:** Finally, hydrolyze benzene diazonium chloride using sodium hydroxide (NaOH) and cyanide chloride (ClCN) to yield benzene (C6H6).

**Chemical Equation:**
1. C6H5NO2 + Sn + HCl → C6H5NH2 + SnCl2
2. C6H5NH2 + NaNO2 + HCl → C6H5N2Cl
3. C6H5N2Cl + NaOH + ClCN → C6H6 + byproducts

### 4. Preparation of Benzene from Benzoic Acid
**Step 1:** Start with benzoic acid (C6H5COOH).
**Step 2:** React benzoic acid with sodium hydroxide (NaOH) and heat to form sodium benzoate (C6H5COONa).
**Step 3:** Perform a decarboxylation reaction by heating sodium benzoate with calcium oxide (CaO) to remove carbon dioxide (CO2) and yield benzene (C6H6).

**Chemical Equation:**
1. C6H5COOH + NaOH → C6H5COONa + H2O
2. C6H5COONa + CaO → C6H6 + Na2CO3 + CO2

### Summary
In summary, benzene can be prepared from:
- Benzene sulfonic acid via hydrolysis.
- Phenol via reduction with zinc.
- Nitrobenzene via reduction to aniline and subsequent diazotization.
- Benzoic acid via decarboxylation of sodium benzoate.

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