Lecture 1 (Intro to MedChem) Flashcards
What is a lead compound?
A lead compound is like the first draft of a drug. It has the correct pharmacological effect but it is not perfect. It most likely needs to be tweaked to obtain the most optimal and effective drug function.
How are drugs improved?
By using a SAR (structure activity relationship) we can turn lead compounds into safe and effective drugs.
Two types of SARs?
Quantitative (QSAR)
Qualitative (SAR)
-this is the only one we are concerned with
How is a QSAR used?
Uses a mathematical relationship between PHYSICOCHEMICAL PROPERTIES to their pharmacological activity to predict the most potent structure.
Why won’t we be studying QSAR?
Because it cannot easily be extrapolated to new drugs. It requires extensive research for each drug.
How is a SAR used?
-uses the relationship of the STRUCTURE (arrangement of the functional groups) and the pharmacological activity of the drug
What are the chemical properties of drugs we need to consider?
- placement of covalent bonds
- EN
- electron effects of functional groups
- ED (electron donating)
- EW (electron withdrawing)
What drug properties are going to be affected by different things?
- potency absorption
- distribution
- metabolic profile
Describe sigma bonds
- single bonds
- formed by hybrid orbitals
- free rotation around this bond
Describe pi bonds
- double bonds
- formed by overlapping P orbitals
- no free rotation around this double bond
Define EN
ability to attract electron density
How does EN increase on the periodic table?
to the right and up it increases
What 2 ways can electron density move through a molecule?
- resonance
- induction
Define resonance
movement of electron density through pi bonds (conjugated system)
Every 1st bond is ____?
sigma
Every 2nd or 3rd bond is ___?
pi
What are sigma bonds made from?
hybridized orbitals (sp)
What are pi bonds made from?
leftover p orbitals
Define induction
movement of electron density through sigma bonds (saturated carbons)
How do you determine whether a functional group with be ED or EW?
Depends on:
- EN
- presence of lone pair electrons
- multiple bonds (geometry of the molecule)
Electronegative atoms with a lone pair (excluding halogens) are __ through _________.
ED
resonance
Alkyl groups - the more branched, the more _____.
donating
Attached group with a double bond O or N or triple bond N are __ through __________.
EW
resonance
pKa _____ for acids
low (inverse of Ka)
Ka ____ for acids
high (if they dissociate there is more of the ions than the acid - so a bigger number/ smaller number = high number)
pKa ____ for bases
high (inverse of Ka)
Ka ______ for bases
low (bases don’t like to dissociate so there would be less of the ions than the base - small number/big number = low number)
Ratio of ionization of a weak acid is what ratio?
[HA] / [A-]
unionized: ionized
Ratio of ionization of a weak base is what ratio?
[HB+] / [B]
ionized: unionized
To maximize ionization of HA to A-
pH > pKa
To minimize ionization of HA to A-
pKa > pH
To maximize ionization of B to HB+
pKa > pH
To minimize ionization of B to HB+
pH > pKa
We use pKa to measure ___ ________.
drug ionization
We always assume the solvent is _____?
WATER BITCHES
When we talk about the pKa of a base we will most likely be talking about ??
primary, secondary, or tertiary amines
What is the difference between primary, secondary, and tertiary amines?
Primary:
The N is attached to 1 R group and 2 H’s
Secondary:
The N is attached to 2 R groups and 1 H
Tertiary:
The N is attached to 3 R groups
How does the scale of basicity go for amines?
Secondary > Primary > Tertiary
What is a substituent?
-an atom or group of atoms substituted in place of a HYDROGEN on the parent organic compound
Describe alkanes
-tetrahedral
-sp3 hybrid
-bond angle 109.5
C-C bond length 1.5A
-non-polar (hydrophobic)
-ED ALWAYS