09/04/2003 MEDC 501 Fall 2003 1

MEDC 501 Introductory Medicinal Chemistry

√ Bond, chemical bonding, ionic bond, hybridization, hybrid

orbitals, hybdrization in methane, ethylene, acetylene,

benzene, and aromatics

√ Bond polarity, electronegativity, Kier-Hall eN scale,

dependence of physical and chemical properties, and

structure on bond polarity

√ Consequences of bond polarity, inductive effect, pkA

values, resonance effect, cumulative effects, molecular

action of drugs

Topics to be covered

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Periodic Table

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Bonds define

Chemical Bonds

These are responsible for

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Chemical Bond

Chemical Bonds

Types of Bonds

Orbitals

Types of Orbitals

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Shapes of Orbitals

Orbitals

s - orbital p - orbital

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Ionic Bond - NaCl

Electronic Structure

11Na :: 1s22s22p63s1

17Cl :: 1s22s22p63s23p5

11Na+ :: 1s22s22p63s0 = 10Ne17Cl- :: 1s22s22p63s23p6 = 18Ar

Properties of an ionic bond

Relationship to drugs

Na+…….Cl-

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Can 6C form ionic bonds?

Electronic Structure

6C :: 1s22s22px12py

1

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Hybridization

+

s -orbital

sp - orbital

n AO give n HOp -orbital

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Hybridization in Carbon

6C :: 1s22s22px12py

1

1H :: 1s1

6C :: 1s22spx22spy

22spz2

sp3 hybridization …… CH4

6C :: 1s22s12px12py

12pz1

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sp2 hybridization …… CH2=CH2

Hybridization in Carbon

6C :: 1s22s22px12py

1 6C :: 1s22s12px12py

12pz1

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sp2 hybridization …… CH2=CH2

Hybridization in Carbon

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Hybridization in Carbon

sp hybridization …… CH=CH

6C :: 1s22s22px12py

1 6C :: 1s22s12px12py

12pz1

sp hybridorbital

ππππ orbitalsσσσσ orbitals

p orbitals

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Hybridization in Carbonsp2 hybridization …… benzene C6H6