Organic Chemistry

Reagents and their standard chemical compositions:

• Tollens' reagent: Ammoniacal silver nitrate $[\text{Ag}(\text{NH}_3)_2]\text{OH}$ $\rightarrow$ (III)
• Jones reagent: Chromium trioxide in aqueous sulphuric acid / acetone ($\text{CrO}_3 / \text{H}_2\text{SO}_4$) $\rightarrow$ (IV)
• Lucas reagent: Equimolar mixture of concentrated $\text{HCl}$ and anhydrous $\text{ZnCl}_2$ $\rightarrow$ (II)
• Fehling's solution B: Alkaline solution of sodium potassium tartrate (Rochelle salt) $\rightarrow$ (I)

Correct match: (A)-(III), (B)-(IV), (C)-(II), (D)-(I).

Reaction analysis:

• Hydration of unsymmetrical or non-ethyne alkynes in presence of $\text{H}_2\text{SO}_4/\text{HgSO}_4$ forms ketones (e.g., propyne gives acetone).
• Ozonolysis of tetra-substituted or tri-substituted alkenes produces ketones.
• Treatment of alkyl nitriles ($\text{R-CN}$) with Grignard reagents followed by acid hydrolysis yields ketones ($\text{R-CO-R'}$).
• Stephen's reaction involves the reduction of nitriles with stannous chloride ($\text{SnCl}_2$) in the presence of $\text{HCl}$ followed by hydrolysis to specifically yield aldehydes (not ketones):
  $$\text{R-CN} + \text{SnCl}_2 + \text{HCl} \rightarrow \text{R-CH=NH}\cdot\text{HCl} \xrightarrow{\text{H}_3\text{O}^+} \text{R-CHO}$$

Reaction analysis:

• Acid-catalyzed hydration of propene follows Markovnikov's rule, adding $-\text{OH}$ to the secondary carbon to form propan-2-ol (compound A):
  $$\text{CH}_3-\text{CH}=\text{CH}_2 + \text{H}_2\text{O} \xrightarrow{\text{H}^+} \text{CH}_3-\text{CH(OH)}-\text{CH}_3$$
• Hydroboration-oxidation of propene with diborane followed by alkaline $\text{H}_2\text{O}_2$ yields anti-Markovnikov addition of water, producing propan-1-ol (compound C):
  $$\text{CH}_3-\text{CH}=\text{CH}_2 \xrightarrow{\text{B}_2\text{H}_6 / \text{H}_2\text{O}_2, \text{OH}^-} \text{CH}_3-\text{CH}_2-\text{CH}_2\text{OH}$$
• Both compounds have the identical molecular formula ($\text{C}_3\text{H}_8\text{O}$) and the same functional group ($-\text{OH}$), differing only in the position of the hydroxyl group along the carbon chain (carbon-2 vs carbon-1). Therefore, compounds A and C are positional isomers.