Question

What are $X$ and $Y$ respectively in the following reactions?

X → _CO B₂H₆ → _NaH → _(C2H5)2O Y

Options:

• (1) BH₃, 2CO; NaBO₂
• (2) BH₃, CO; NaBH₄
• (3) BH₃, CO; NaBO₂
• (4) BH₃, CO; Na₂B₄O₇

• A. $BH_3, 2CO; NaBO_2$
• B. $BH_3, CO; NaBH_4$
• C. $BH_3, CO; NaBO_2$
• D. $BH_3, CO; Na_2B_4O_7$

Hint:

Borane ($BH_3$) is a key reagent in boron chemistry and forms diborane ($B_2H_6$) upon dimerization. Sodium borohydride ($NaBH_4$) is commonly used as a reducing agent in organic synthesis.

Answer 1

The Correct Option is B

Step 1: Understanding the Reaction Sequence 
The given reaction sequence involves a series of transformations starting from $X$ and leading to $Y$. Let's analyze the stepwise reactions:
1. The first reaction suggests that $X$ reacts with carbon monoxide ($CO$) to form diborane ($B_2H_6$). This indicates that $X$ is borane ($BH_3$), which is a well-known precursor to diborane formation.
2. Diborane ($B_2H_6$) then reacts with sodium hydride ($NaH$), leading to the formation of sodium borohydride ($NaBH_4$).
3. The presence of diethyl ether ($(C_2H_5)_2O$) as a solvent helps stabilize the final product.
 

Step 2: Evaluating the Given Options 
- Option (1): Incorrect as it suggests $X = BH_3, 2CO$, which is not required for diborane formation.
- Option (2): Correct as it correctly identifies $X = BH_3$ and $Y = NaBH_4$.
- Option (3): Incorrect as it wrongly identifies $Y$ as sodium metaborate ($NaBO_2$).
- Option (4): Incorrect as it suggests $Y = Na_2B_4O_7$, which does not match the reaction sequence.
Thus, the correct answer is 

Option (2).