The missing structures A and B in the reaction sequence :
`CH_(3) - CH = CH_(2) overset(B_(2)H_(6))to A overset (H_(2)O_(2)+NaOH) to B ` are given by the set :

Options

A. `CH_(3) - CH_(2) - CH_(2) - BH_(2), CH_(3) - CH_(2) - CH_(2) OH`
B. `(CH_(3) - CH_(2)-CH_(2))_(3) B, CH_(3) - CH_(2) - CH_(2)OH`
C. `(CH_(3))_(2) CH - CH_(2) - _(2), CH_(3) - CH(OH) - CH`
D. `(CH_(3) CHCH)_(2) BH, CH_(3)-CH_(2) - CH_(2) OH`

Answer

To solve the question regarding the missing structures A and B in the reaction sequence involving hydroboration oxidation, we will follow these steps:

### Step 1: Identify the starting material
The starting material given is **CH₃-CH=CH₂** (propene). This is an alkene that will undergo hydroboration.

**Hint:** Remember that alkenes are electron-rich and can react with electrophiles.

### Step 2: Understand the hydroboration reaction
The hydroboration reaction involves the addition of **B₂H₆** (diborane) to the alkene. In this reaction, diborane adds across the double bond of the alkene, resulting in the formation of a trialkylborane intermediate.

**Hint:** Hydroboration is a syn-addition process, meaning that both the boron and hydrogen add to the same side of the double bond.

### Step 3: Draw the intermediate structure A
When **B₂H₆** reacts with propene, it will form an organoborane compound. The boron atom will attach to the less substituted carbon (due to sterics), leading to the formation of **A**:

- Structure A: **CH₃-CH₂-CH₂-BH₂** (1-boropropane)

**Hint:** The boron atom will bond to the carbon that leads to a more stable carbocation upon further reactions.

### Step 4: Oxidation of the organoborane
The next step involves the oxidation of the organoborane with **H₂O₂** (hydrogen peroxide) in the presence of **NaOH**. This reaction converts the boron atom into a hydroxyl group (-OH), replacing the boron with an alcohol functional group.

**Hint:** The oxidation step transforms the boron compound into an alcohol, which is a common transformation in organic chemistry.

### Step 5: Draw the final product structure B
After the oxidation, the final product **B** will be:

- Structure B: **CH₃-CH₂-CH₂-OH** (propan-1-ol)

**Hint:** The final product will have the hydroxyl group (-OH) attached to the terminal carbon of the propyl chain.

### Summary of Structures
- Structure A: **CH₃-CH₂-CH₂-BH₂**
- Structure B: **CH₃-CH₂-CH₂-OH**

### Final Answer
The missing structures A and B are:
- A: **CH₃-CH₂-CH₂-BH₂**
- B: **CH₃-CH₂-CH₂-OH**