Step 1: Understanding the Concept:
The reaction between an alkyl halide and an alkoxide ion can proceed via nucleophilic substitution ($S_N2$) to form an ether (Williamson ether synthesis) or via elimination (E2) to form an alkene. The dominant reaction pathway depends heavily on the steric nature of the alkyl halide (primary, secondary, or tertiary) and the strength of the base.
Step 2: Key Formula or Approach:
Approach: Analyze the steric hindrance of the secondary alkyl halide reacting with a strong base, and specifically note the byproducts explicitly given in the reaction equation to deduce the mechanism.
Step 3: Detailed Explanation:
Let's examine the reactants:
- Sodium ethoxide ($\text{CH}_3\text{CH}_2\text{O}^-\text{Na}^+$): Acts as both a strong base and a strong nucleophile.
- Isopropyl chloride ($\text{CH}_3\text{CH(Cl)CH}_3$): A secondary ($2^\circ$) alkyl halide.
With secondary alkyl halides reacting with strong bases like alkoxides, the elimination (E2) pathway actively competes with, and often dominates, the substitution ($S_N2$) pathway.
The products explicitly stated in the question provide a definitive clue:
\[ \text{Sodium ethoxide} + \text{Isopropyl chloride} \longrightarrow \text{X} + \text{Ethanol} + \text{NaCl} \]
The formation of ethanol ($\text{CH}_3\text{CH}_2\text{OH}$) dictates that the ethoxide ion ($\text{CH}_3\text{CH}_2\text{O}^-$) acted purely as a base, not as a nucleophile. It abstracted a proton ($\text{H}^+$) from a $\beta$-carbon of the isopropyl chloride, leading to the concerted elimination of HCl (which neutralizes with the sodium ethoxide) and the formation of a carbon-carbon double bond.
Reaction details:
\[ \text{CH}_3\text{CH}_2\text{O}^- + \text{CH}_3-\text{CHCl}-\text{CH}_3 \xrightarrow{\text{E2}} \text{CH}_3\text{CH}_2\text{OH} + \text{CH}_2\text{=CH}-\text{CH}_3 + \text{Cl}^- \]
The organic product 'X' formed alongside ethanol and NaCl is an alkene, specifically propene.
If substitution had occurred instead, the product would have been an ether (2-ethoxypropane), and the byproduct would only be NaCl, with no ethanol produced.
Step 4: Final Answer:
The product 'X' is propene.