L18 QSAR Analysis DB

Question 1

What does QSAR involve

Answer 1

• QSAR uses the structures of active compounds to define the receptors pharmacophore
• Allows you to Quantify the relationship between chemical structures of compounds and their biological activities.
• Involves deriving mathmatical equations relating to structure and activity. The equation is used to calculate or predict the activity of the ‘new’ molecule

Question 2

Hansch analysis

Answer 2

Hansch analysis predicts the physico-chemical properties + biological activity of molecules. It quantifies chemical structures in terms of electronic, steric and solubility properties

Question 3

Free wilson analysis

Answer 3

Gives information on Biological activity of molecules it does’t give any information on the chemical properties.

Question 4

Hammett substituents, Draw its symbol and what does it apply to

Answer 4

It is an electronic property that applies to structures that are attached to aromatic rings. At the META and PARA positions.

Question 5

is pKa lower or higher for electron withdrawing groups on aromatics? and what does this mean for hammetts substituent constant?

Answer 5

pKa it is lower.. Hammetts constant is positive

Question 6

For electon donating groups is pKa lower or higher? and what does this mean for hammetts substituent constant?

Answer 6

pKa is higher (than benzoic acid) hence Hammetts constant is negative

Question 7

What electonegative symbol is used to describe the inductive effect of aliphatic substutuents

Answer 7

sigma with a 1 underscore.

Question 8

What is the symbol of taft’s substituent constant? what does it measure?

Answer 8

sigma *. It measures the polar effect of substituents in aliphatic compounds. It’s calculated from rate constants for acid and base hydrolyses of esters.

Question 9

whats the symbol for steric properties for the Taft’s constant? How are they calculated?

Answer 9

Es - steric properties are calculated directly from molecular models as it gives the exact volume.

Question 10

What is the symbol for the Solubility properties and is it Tafts, Hansch, or Hammetts?

Answer 10

Hansch substituent constant has the Pi symbol. Computed from 1-octanol-water partition coeffiecents.

Question 11

How do you calculate the fragmentation contants

Answer 11

computed from molecular structure. LogP = sum total NF

n = number of a given type of chemical group

f = group fragment increment.