Lecture 7 Flashcards

Intermolecular Forces Driving Dissolution

1
Q

IntRAmolecular Forces

A
  • Govern molecular properties, define structure & metabolism
  • Influences absorption, distribution, metabolism, excretion, & toxicology
  • Stronger than intermolecular forces
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2
Q

IntERmolecular Forces

A
  • 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
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3
Q

Strengths of Bonds (Strongest to Weakest)

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

Determinants of Bond Strength (2)

A
  1. Polarization

2. Lifetime

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5
Q

Ionic Polarization & Lifetime

A

Polarization: full positive and negative charges
Lifetime: permanent

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6
Q

Hydrogen Bond Polarization & Lifetime

A

Polarization: partial positive and negative charges
Lifetime: permanent

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7
Q

Van der Waals Polarization & Lifetime

A

Polarization: partial positive and negative charges
Lifetime: transitory

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8
Q

Salt Drugs

A
  • 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
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9
Q

Hydrogen Bonds Properties

A
  • 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
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10
Q

Van der Waals Properties

A
  • weak forces that involve dispersion of charge across a molecule (dipole)
  • includes London and Debye forces
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11
Q

Debye Forces

A
  • 1 permanent and 1 induced dipole
  • permanent dipole polarizes neighboring molecule
  • interaction between polar molecules occur
  • lower energy & transient
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12
Q

London Forces

A
  • 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
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13
Q

Intermolecular Hydrogen Bonding

A
  • give proteins secondary structure that leads to them creating hydrophobic centers and hydrophillic surfaces
  • drugs bind to targets using these forces as well
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14
Q

Review of Bond Strength + Affects

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