Lecture 7

Question 1

IntRAmolecular Forces

Answer 1

• Govern molecular properties, define structure & metabolism
• Influences absorption, distribution, metabolism, excretion, & toxicology
• Stronger than intermolecular forces

Question 2

IntERmolecular Forces

Answer 2

• Between molecules and determines macroscopic physical properties of liquids and solids
• Mediates drug receptor interactions and therefore pharmacology
• Strong enough to effect physical properties like melting point, boiling point, vapor, pressures, & viscosities
• Drives stability & dissolution properties of APIs

Question 3

Strengths of Bonds (Strongest to Weakest)

Answer 3

1. Covalent
2. Ionic
3. Hydrogen
4. Van der Waals
   * *Usually intermolecular forces = sum of interactions of different kinds**

Question 4

Determinants of Bond Strength (2)

Answer 4

1. Polarization

2. Lifetime

Question 5

Ionic Polarization & Lifetime

Answer 5

Polarization: full positive and negative charges
Lifetime: permanent

Question 6

Hydrogen Bond Polarization & Lifetime

Answer 6

Polarization: partial positive and negative charges
Lifetime: permanent

Question 7

Van der Waals Polarization & Lifetime

Answer 7

Polarization: partial positive and negative charges
Lifetime: transitory

Question 8

Salt Drugs

Answer 8

• often strong
• usually carboxylic acid salts with mono or polyvalent cations OR salts of amines (originally, mainly HCl)
• In solution = weaker since water gets in and pushes molecules farther away from each other and makes the bonds weaker

Question 9

Hydrogen Bonds Properties

Answer 9

• Differences in polarization makes defines the bond strength
• Larger differences = stronger bond via increased polarization
• Smaller differences = weaker bond via decreased polarization
• In organic molecules: can form dimers or intramolecular hydrogen bonds in some cases

Question 10

Van der Waals Properties

Answer 10

• weak forces that involve dispersion of charge across a molecule (dipole)
• includes London and Debye forces

Question 11

Debye Forces

Answer 11

• 1 permanent and 1 induced dipole
• permanent dipole polarizes neighboring molecule
• interaction between polar molecules occur
• lower energy & transient

Question 12

London Forces

Answer 12

• 2 induced dipoles
• no interaction between un-polar molecules
• induction process polarizes 2 molecules (random, excess of 1 charge induced
• interaction between molecules is VERY weak

Question 13

Intermolecular Hydrogen Bonding

Answer 13

• give proteins secondary structure that leads to them creating hydrophobic centers and hydrophillic surfaces
• drugs bind to targets using these forces as well

Question 14

Review of Bond Strength + Affects

Answer 14

• More & stronger bonds = increases MP, BP, and water solubility
• Less & weaker bonds = decreased MP, BP, and water solubility