Which of the following can be used for the preparation of propane ?

Options

A. `CH_(3)CH=CH_(2)underset(2CH_(3)COOH)overset(1.B_(2)H_(6))rarr`
B. `CH_(3)CH_(2)CH_(2)Clunderset(2.H_(2)O)overset(1.Mg//"ether")rarr`
C. `CH_(3)CH_(2)CH_(2)Ioverset("Red:P//HI//150^(@)C)rarr`
D. `CH_(3)CH_(2)CH_(2)COONaunderset(Delta)overset(NaOH//CaO)rarr`

Answer

To determine which of the following can be used for the preparation of propane, we will analyze the different methods mentioned in the video transcript.

### Step-by-Step Solution:

1. **Preparation from Propene and Diborane:**
- Propene (C3H6) can react with diborane (B2H6). In this reaction, diborane adds across the double bond of propene, forming an organoborane intermediate.
- When this intermediate is treated with acetic acid (CH3COOH), it undergoes hydrolysis to yield propane (C3H8).
- **Conclusion:** This method is valid for the preparation of propane.

2. **Preparation using Grignard Reagent:**
- In this method, we first form a Grignard reagent by reacting an alkyl halide (for example, bromoethane) with magnesium in dry ether.
- The Grignard reagent can then react with water (or an acid) to produce propane.
- **Conclusion:** This method is also valid for the preparation of propane.

3. **Reduction of Alkyl Iodide:**
- An alkyl iodide can be reduced using red phosphorus and iodine (or other reducing agents) to yield propane.
- The reduction process involves the removal of the halogen (iodine) and the addition of hydrogen, resulting in propane.
- **Conclusion:** This method is valid for the preparation of propane.

4. **Decarboxylation:**
- Decarboxylation involves the removal of carbon dioxide from a carboxylic acid. For example, if we take sodium propanoate (a carboxylic acid), heating it with soda lime (NaOH + CaO) will remove CO2 and yield propane.
- **Conclusion:** This method is valid for the preparation of propane.

### Final Answer:
All four methods mentioned (A, B, C, and D) can be used for the preparation of propane.

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