SCCH 223
Organic
Chemistry 1
รศ.ดร.ชุลีวลั ย์ ราษฎร์วริ ุ ฬห์กิจ
What is Organic Chemistry
• The study of organic compounds
– Organic compounds
• Compounds obtained from living organisms (1700)
–
–
–
–
Glycerol from animal fats
Tartaric acid from grapes
Lactic acid from sour milk
Citric acid from lemon etc.
• Urea was prepared from ammonium cyanate
(1828)
– NH4CNO --- NH2CONH2
– Organic compounds (up to date)
• are carbon-containing compounds which normally
accompanied by hydrogen atom. More often,
organic molecules contain atoms of oxygen,
nitrogen, phosphorus, sulphur or the halogens
– Fullerene C-60 / Diamond /graphite
– Gasoline / glutathione / capsaicin / pesticide
– Carbohydrate, amino acid, phospholipid,
Why C is so important?
• Carbon atom
– Row 2
• Size : capable to form bonds with variety of atoms
(C-C; C-O; C-N; C-X; C-H; C-Si; C-S; C-P)
– Column 4
• 4 valence electrons : four covalent bonds with
varieties (single, double and triple bonds)
picture from Organic Chemistry,
McMurry
5
1
Atomic Orbitals
s orbital
p orbital
picture from Organic Chemistry,
McMurry
d orbital
6
px orbital
py orbital
picture from Organic Chemistry,
McMurry
pz orbital
7
12
C
6
Electron configuration of carbon
-
2
1S
2
2S
2
2p
8
Energy
2p
2s
1s
Ground-state carbon
picture from Organic Chemistry,
McMurry
9
Energy
2p
2s
1s
96 kcalmol
Ground-state carbon
picture from Organic Chemistry,
McMurry
10
Energy
3
2p
2s
1s
96 kcalmol
Ground-state carbon
Excited-state carbon
picture from Organic Chemistry,
McMurry
11
Hybridization
sp3
12
Sp3 Hybridization
picture from Organic Chemistry,
McMurry
13
Ethane (CH3-CH3)
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
14
• Sp2-Hybridization
picture from Organic Chemistry,
Solomom, Fryhle & Johnson
15
H
• Ethene (C2H4)
H
C
H
picture from Organic Chemistry,
Solomom, Fryhle & Johnson
C
H
16
• Sp-Hybridization
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
17
• Ethyne (C2H2)
H
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
C
C
H
18
• Hybridization / bond angle / bond length in
ethane, ethene and ethyne
Ethyne
Ethene
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
Ethane
19
Example of Organic Compounds
H3C
CH3
H3C
OH
H3C
CH3
C
CH3
CH3
CHCH 2CH2C CHCH 2OH
H3C
CH3
CH3
H3C
O
HOOC
N
N
H
N
N
O
N
OH
CH2OH
N
Vitamin B6
Aspartame
Cocaine
H
N
OCOCH3
HO
CH3
O
H
N
PhH2C
O
S
O
N
CH3
CH3
O
Aspirin
H
CH2OH
H3C
C6H5
CH3
Caffeine
COOH
HO
COOCH3
H2N
O
O
OH
CH2OH
OCH3
O
CH3
H
Glucose
Cholesterol
N
OH
H
HO
Menthol
H3C
H
HO
Geraniol
O
CHO
CH3
Penicillin G
H3C
HN
OCH2CH3
O
COOH
Paracetamol
O
H2N
Tamiflu
20
Homework 1
• How Nitrogen atom or Oxygen atom get
hybridized? (sp3 sp2 sp)
• Show the electron configuration of those
hybridization
21
Molecular Structures
Geometry of Molecules
and Physical Properties
รศ.ดร.ชุลีวลั ย์ ราษฎร์วริ ุ ฬห์กิจ
– Electronegativity
• Electronegativity is the ability of an atom to attract
electrons
• It increases from left to right and from bottom to top in the
periodic table
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
23
• Molecular Dipole (m)
+

-
• In diatomic molecules a dipole exists if the two atoms are of different
electronegativity
• In more complicated molecules the molecular dipole is the sum of
the bond dipoles
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
24
m = 1.08
m=0
H Cl
O
C
H
O
Cl
H
m = 0.24
F
H
m = 1.85
O
H
N
H
H
Cl
Cl
m = 1.47
N
m = 1.02
C
F
F
Polar / non-polar?
HO
OH
25
– Some cis-trans isomers show markedly difference in
the dipole moment
H
H
C
X
X
C
cis-
H
C
X
H
C
trans-
X
X = Cl, Br
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
26
• Intermolecular Forces
– The forces between molecules that determine
the physical properties (i.e. melting point, boiling
point and solubility) of compounds
• Stronger intermolecular forces resulted in higher
melting points and boiling points of compounds
• The important intermolecular forces are
– Van der Waals
– Dipole-dipole
– Hydrogen bond
Hydrogen bond > dipole-dipole > Van der Waal
27
– Van der Waals Forces (London dispersion forces)
• Van der Waals forces result when a temporary dipole in a
molecule caused by a momentary shifting of electrons
induces an opposite and also temporary dipole in an
adjacent molecule
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
28
– Dipole-Dipole Forces
• Dipole-dipole forces are between molecules with
permanent dipoles
– There is an interaction between + and - areas in
each molecule
– Molecules align to maximize attraction of + and parts of molecules
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
29
– Hydrogen Bonds
• Hydrogen bonds resulted from very strong dipole-dipole
forces
• There is an interaction between hydrogens bonded to
strongly electronegative atoms (O, N or F) and nonbonding
electron pairs on other strongly electronegative atoms (O, N
or F)
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
30
• Rank the melting point/ boiling point of different
compounds
OH
O
O
O
OH
OH
31
Which of the following compounds containing
H-bond as their intermolecular forces
32
– Solubilities
– Ability of compound (solute) to get dissolved or
become homogeneous with solvent. “Like disolves
Like”
• Water dissolves ionic solids by forming strong dipole-ion
interactions
picture from Organic Chemistry, Solomon, Fryhle & Johnson
33
• Water or polar solvents dissolve polar solids or polar
liquids
– Methanol (a water-like molecule) dissolves in water
in all proportions using hydrogen-bonding to the
water
picture from Organic
Chemistry,Solomon, Fryhle &
Johnson
34
• A large alkyl group can overwhelm the ability of the polar
group to solubilize a molecule in water
– Decyl alcohol is only slightly soluble in water
– The large alkyl portion is hydrophobic (“water
hating”) and overwhelms the capacity of the
hydrophilic (“water loving”) hydroxyl
picture from Organic Chemistry,
Solomon, Fryhle & Johnson
35
• Which of the following compounds dissolve well
in water (Hint: polar compounds with 4 carbons
or less will be able to dissolve well in water)
O
O
HO
OH
OH
O
O
OH
OH
O
O
O
COOH
36
Classification of Organic
Compounds
• By Functional Groups
– Functional group is a characteristic group of
atoms/bonds that possess a predictable
chemical behavior.
picture from Organic Chemistry,
McMurry
37
Variety of Functional Groups
H3C
CH3
H3C
OH
H3C
CH3
C
CH3
CH3
CHCH 2CH2C CHCH 2OH
H3C
CH3
CH3
H3C
O
HOOC
N
N
H
N
N
O
N
OH
CH2OH
N
Vitamin B6
Aspartame
Cocaine
H
N
OCOCH3
HO
CH3
O
H
N
PhH2C
O
S
O
N
CH3
CH3
O
Aspirin
H
CH2OH
H3C
C6H5
CH3
Caffeine
COOH
HO
COOCH3
H2N
O
O
OH
CH2OH
OCH3
O
CH3
H
Glucose
Cholesterol
N
OH
H
HO
Menthol
H3C
H
HO
Geraniol
O
CHO
CH3
Penicillin G
H3C
HN
OCH2CH3
O
COOH
Paracetamol
O
H2N
Tamiflu
38