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oc-ch1.ppt
1. Medical chemistry is a subject that is funda-
mental to medicine.
It mainly includes two parts, medical
fundamental chemistry and medical organic
chemistry.
In 1st part, some chemical principle such as
chemical equilibrium, rates of reaction, redox
reaction and so on, were introduced;
in the 2nd part, hydrocarbon and their
derivatives were mainly concerned.
2. Chain Hydrocarbons
Cyclic Hydrocarbons
Halogen Compounds
Alcohols, Phenols, and Ethers
Aldehydes and Ketones
Carboxylic Acids and Their Derivatives
Amines and Other Nitrogen Compounds
……
4. 1.1 Definition
• Organic chemistry is defined as the study
of C/H-containing compounds and their
derivatives.
• Petroleum and coal are two vast natural
reservoirs from which many organic
materials are extracted.
5. 1.1 Definition
• In 1828, Wöhler,F. German chemist,
prepared UREA from an inorganic
compound.
NH4OCN H2N C NH2
O
6. 1.2 The Uniqueness of Carbon
• The number of organic compounds
(several million) far exceeds that of all
known inorganic compounds (about
90,000).
• And thousands of new ones are synthesized
and described each year.
• What is unique about the element C? Why
does it form so many compounds?
7. • The answers to these questions lie in
the structure of the C atom
the position of C in the periodic table
• These factors enable it to form strong
bonds with other C atoms and other
elements, such as H, O, N, and halogen.
1.2 The Uniqueness of Carbon
8. • Each organic compound has its own
characteristic set of physical and
chemical properties, which depend on the
structure of the molecule.
1.2 The Uniqueness of Carbon
9. 1.3 Structural Formula
• A molecular formula tells us what kind of
atoms and how many of each kind of
atom are present in a particular molecule.
• I.e., ethanol: C2H6O
• A structural formula also called a
constitutional formula, shows how the
atoms in a particular molecule are
connected or bonded together.
10. • To write correct structural formulas for
organic molecules, we should remember
the covalence numbers of the component
atoms.
• C, with a covalence number of 4, must
always have four bonds in any organic
compound, and each of the other
elements present must share the number
of bonds indicated by its own covalence
number.( H, Cl: 1; O: 2; N: 3)
1.3 Structural Formula
11. • A C atom may share one or more pairs of
electrons with another C atom or with other
elements, to form single bond, double bond,
and triple bond.
H H H H H
H－C－C－H H－C－N－H H－C－Cl
H H H H
H H H H
H－C－C－O－H H－C－O－C－H
H H H H
1.3 Structural Formula
12. • Ring (cyclic) compounds
H H H H
H－C－C－H H－C－C－H
H－C－C－H N
H H H
H O H
C C
H C C H
H H H H
1.3 Structural Formula
13. • Organic molecules with one double bond
H H H H H H
H－C＝C－H H－C＝C－C－H H－C＝O
H
• Organic molecules with two double bonds
H H H H H
H－C＝C＝C－C－H H C H
H C C
C C
H H
1.3 Structural Formula
14. • Organic molecules with one triple bond
H
H－C≡C－H H－C≡N H－C－C≡N
H
1.3 Structural Formula
15. • To summarize：
• Structural formulas show how atoms are
connected to one another in a molecule.
• The structural formula of a compound is
correct only if each element satisfies its
covalence number.
• The covalence number may be satisfied by
forming single or multiple bonds.
1.3 Structural Formula
16. Exercise
• Check the following structures to see whether
or not they represent possible compounds
within the rules of covalence. State either
“possible” or “impossible” for each.
CH3CH2CH2CH3 CH3－CH
CH3 CH2
17. 1.4 Condensed Structural Formulas
• In previous sections, we used expanded
structural formulas to represent organic
molecules, in which all bonds are shown.
H H H
H－C＝C＝C－C－H
H
• Although very useful in visualizing structures,
this method of representation is timeconsuming
and requires much space.
18. • Two kinds of condensed formulas
Partially condensed formulas
Fully condensed formulas
• Partially condensed formulas are those only
include the bonds of multivalent atoms and
leave out the bonds of mono-valent elements
(hydrogen and halogens).
H O O
H－C－C－O－H CH3－C－OH
H
1.4 Condensed Structural Formulas
19. – If we omit all bonds except carbon-carbon
multiple bonds, we have fully condensed
formulas.
H H O O
H－C＝C－C－O－H CH2=CH－C－OH
expanded formula partially condensed
formulas
CH2＝CHCOOH
fully condensed formulas
1.4 Condensed Structural Formulas
20. • Cyclic compounds can also be represented by
partially condensed and fully condensed
structural formulas.
• In the fully condensed formulas, each corner
represents a CH2 for singly bonded carbon
atoms, or a CH when carbon is linked to another
carbon by a double bond.
H H
H－C－C－H H2C－CH2
H－C－C－H H2C－CH2
H H
1.4 Condensed Structural Formulas
21. H H
H C H CH2
C C HC CH
C C HC－CH
H H
• P211, exercise 2
1.4 Condensed Structural Formulas
22. 1.5 Bond Energy and Bond Length
• Atoms achieve a stable noble gas configuration
when they combine to form molecules, so we can
conclude that a molecule is more stable than the
isolated atoms.
• This stability is apparent in the release of energy
during the formation of the molecular bond.
• The amount of energy released when a bond is
formed is called the bond energy.
23. • Conversely, the same amount of energy would
have to be supplied to break the bond.
• The amount of energy that must be absorbed to
break a bond is called the bond dissociation
energy.
• For a given pair of atoms, the greater overlap of
the atomic orbitals, the stronger the bond and
the greater the amount of bond dissociation
energy.
1.5 Bond Energy and Bond Length
24. • Note that when two atoms are held together by
a single bond, the bond dissociation energy is
lower than when they are held together by
more than one bond.
Molecules Bond dissociation energy
(kcal/mole)
H3C－CH3 83
H2C＝CH2 146
HC≡CH 200
1.5 Bond Energy and Bond Length
25. • The distance between nuclei in the molecular
structure is called the bond length.
• For a given pair of atoms, the bond length
depends upon the extent of overlap of their
atomic orbitals, the greater overlap of the
atomic orbitals, the shorter the bond length.
• Note that when two atoms are held together by
more than one bond, the bond lengths become
shorter.
1.5 Bond Energy and Bond Length
26. Molecules Bond length (Å) Bond dissoci. energy
H3C－CH3 1.54 83
H2C＝CH2 1.34 146
HC≡CH 1.20 200
• We can conclude the bond length have the
inverse relation with bond energy .
• The shorter the bond length, the greater the bond
energy.
1.5 Bond Energy and Bond Length
27. Exercise
• For each structure, predict which of the two
bonds shown has (1) the greater bond
dissociation energy and (2) the longer bond
length.
• CH3－CH＝CH2
• CH3－C≡CH
• H2N－CH2－C≡N
O
• HC－OH
28. 1.7 Functional Groups
• Classify the organic compounds into some
families according to the functional groups
present.
• A functional group is a reactive portion of an
organic molecule, an atom, or a group of atoms
that confers on the whole molecule its
characteristic properties.
• All compounds with the same functional group
belong to one family.
29. • Members of a given organic family react in a
similar and predictable manner.
• For example, the hydroxyl group (OH), when it
is attached to a singly bonded carbon atom, an
alcohol is formed.
OH
CH3－OH CH3CH2－OH CH3CHCH3
Methyl alcohol Ethyl alcohol Isopropyl alcohol
R－OH General formula
1.7 Functional Groups
30. • The first three structures represent specific
alcohols of increasing carbon chain length.
• The fourth structure indicates the general
formula for all alcohols, R stands for a carbon
chain of any length attached to the functional
group.
1.7 Functional Groups
31. Table 1.6 Functional Groups and Classes of Organic Compounds
Class, General
formula
Functional
group
Specific examples
Alkane RH C－C H3C－CH3
Alkene R－CH＝CH2
C＝C H2C＝CH2
Alkyne R－C≡CH C≡C HC≡CH
Alkyl
halide
RX －X (F,Cl,Br,I) H3C－Cl
Alcohol R－OH, －OH, H3C－OH
Ether R－O－R’ －C－O－C－ H3C－O－CH3
Aldehyde
O
R－CH,
O
－C－H,
O
H－C－H
O
H3C－C－H
32. Table 1.6 Functional Groups and Classes of Organic Compounds
Class General
formula
Functional
group
Specific examples
Ketone
O
R－C－R’
O
－C－C－C－
O
H3C－C－CH3
Carboxyl
ic acid
O
R－C－OH
O
－C－OH
O
H－C－OH
O
H3C－C－OH
Ester
O
R－C－OR
O
－C－OR,
O
H3C－C－OCH3
Amine R－NH2, －C－NH2, H3C－NH2
‖
33. SUMMARY
• Definition of organic chemistry;
• Structure formula:
Expanded structural formulas
Partially condensed formulas
Fully condensed formulas
(covalence number)
• Bond length and bond dissociation energy;
• Functional groups
34. Exercise
• Group together those compounds that you
except to behave chemically in a similar
manner.
• CH3OH C2H4
CHBr3
• CH3CH2Cl HOCH2CH2OH
• CH3OCH2CH3 OH
• CH2F2
• CH3CH＝CH2 O
• CH3COOH
