The number of alkenes (including stereoisomers) which can produce 2 - butanol by the successive treatment of (i) `B_(2)H_(6)` in tetrahydrofuran solvent and (ii) alkaline `H_(2)O_(2)` solution is/are

Answer

To solve the problem of finding the number of alkenes (including stereoisomers) that can produce 2-butanol through the specified reactions, we will follow these steps:

### Step 1: Understand the Reaction Mechanism
The reaction involves hydroboration followed by oxidation. The hydroboration reaction uses B₂H₆ in tetrahydrofuran (THF) solvent, which adds across the double bond of alkenes according to the anti-Markovnikov rule. This means that the hydroxyl group (OH) will attach to the carbon with fewer hydrogen atoms.

**Hint:** Remember that hydroboration leads to the addition of boron and hydrogen across the double bond, favoring the less substituted carbon.

### Step 2: Identify the Structure of 2-Butanol
The structure of 2-butanol is CH₃-CH(OH)-CH₂-CH₃. This means that to produce 2-butanol, we need to form a carbon skeleton that can lead to this structure after hydroboration and oxidation.

**Hint:** Draw the structure of 2-butanol to visualize the required carbon framework.

### Step 3: Determine Possible Alkenes
To produce 2-butanol, we can start with alkenes that can lead to the required carbon skeleton upon hydroboration. The simplest alkene that can yield 2-butanol is 2-butene (CH₃-CH=CH-CH₃).

- **Cis-2-butene** (cis-CH₃-CH=CH-CH₃)
- **Trans-2-butene** (trans-CH₃-CH=CH-CH₃)

Both of these alkenes will undergo hydroboration to yield the same product, 2-butanol.

**Hint:** Consider the geometric isomers of alkenes that can lead to the same alcohol product.

### Step 4: Check for Other Possible Alkenes
Next, we need to consider if there are any other alkenes that, upon hydroboration and oxidation, could also yield 2-butanol:

1. **1-butene (CH₂=CH-CH₂-CH₃)**: Hydroboration of 1-butene will also lead to 2-butanol.
2. **Cyclobutene**: This cyclic alkene can also be considered, as it can rearrange and yield 2-butanol.

**Hint:** Think about the position of the double bond and how it can lead to the formation of the desired alcohol.

### Step 5: Count the Alkenes and Their Stereoisomers
Now we summarize the alkenes identified:
- **Cis-2-butene**
- **Trans-2-butene**
- **1-butene**
- **Cyclobutene**

For 2-butene, we have 2 stereoisomers (cis and trans). For 1-butene and cyclobutene, they do not have stereoisomers that lead to different structures.

**Final Count:**
- 2-butene (2 stereoisomers)
- 1-butene (1 structure)
- Cyclobutene (1 structure)

Total = 2 (from 2-butene) + 1 (from 1-butene) + 1 (from cyclobutene) = **4 alkenes**.

### Conclusion
The total number of alkenes (including stereoisomers) that can produce 2-butanol through the given reactions is **4**.

**Final Answer:** 4