Matching Drug Solubility and Melting Points

This question requires matching the aqueous solubility values of different drugs (List I) with their corresponding names and melting points (List II).

Analysis of Lists

List I: Aqueous solubility (moles/liter × $10^{-2}$) at 30°C

• A. 4.5
• B. 13.3
• C. 17.6
• D. 104

List II: Drugs with melting points (°C)

• I. 7-Propyl theophylline (99-100)
• II. Caffeine (238)
• III. Theophylline (270-274)
• IV. 7-Ethyl theophylline (156-157)

Matching Process

The general principle is that compounds with higher melting points often have lower aqueous solubility due to stronger intermolecular forces. Conversely, lower melting points suggest weaker forces and potentially higher solubility.

• Theophylline (III) has the highest melting point ($270-274^\circ C$), correlating with the lowest solubility ($4.5 \times 10^{-2}$ moles/L) - Match A-III.
• Caffeine (II) has the next highest melting point ($238^\circ C$) and corresponds to the next lowest solubility ($13.3 \times 10^{-2}$ moles/L) - Match B-II.
• 7-Ethyl theophylline (IV) has a significantly lower melting point ($156-157^\circ C$) and higher solubility ($17.6 \times 10^{-2}$ moles/L) - Match C-IV.
• 7-Propyl theophylline (I) has the lowest melting point ($99-100^\circ C$) and the highest solubility ($104 \times 10^{-2}$ moles/L) - Match D-I.

Correct Matching Summary

The correct pairings are:

• A matches with III
• B matches with II
• C matches with IV
• D matches with I

Therefore, the correct option is A-III, B-II, C-IV, D-I.