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What is Organic Chemistry?
It is defined as the study of hydrocarbons (compounds of hydrogen and carbon) and their derivatives
Organic chemistry = Chemistry of carbon-based molecules
Organic molecules = Carbon-based molecules
30 million Organic Compounds
1.5 million Inorganic Compounds, 95% Containing Carbon atom
Why is it the element of life on earth?
• Has Four Bonding Electrons
• Unique Strong Covalent Bonds
• Strong Single, Double and Triple Bonds
Average Bond Energies (KJ mol-1)
C-C607 Si-Si 230 C-H416 Si-H 323 C-N754 Si-N 470 C-O 336 Si-O 368
O-Si-O = Sand and Rocks N-N 163 dan O-O 157
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• Carbon: unique in its ability to catenate [can form chains of atoms]
• Forms molecules composed of C-C bonds
C C C C C C C C C C C Some properties of organic molecules
Stability: composed of stable C-C covalent bonds
• Defined molecular structures
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Organic chemicals are universal
Organic
Chemicals
Biological matter
•
Plants
•
Animals
•
Microbes
Geological matter
•
Fossil Fuels
•
Other
Atmospheric
and
cosmic matter
Manufactured
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Biological organic chemicals
Sugars
Proteins
Fats & oils
Vitamins
DNA & RNA
Wood
Natural
rubber
Essential oils
Natural fibres
Antibiotics
Fermentation
products
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Organic chemicals in manufactured
products
Bio-active
products
Medicines
Veterinary medicines
Herbicides
Pesticides
Fungicides
Plant growth hormones
Medical imaging agents
Fertilizers Antiseptics
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Organic chemicals in manufactured
products
Materials
Fibres & clothings
Plastics
Coatings & lacquers
Packaging Paper Films
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Organic chemicals in manufactured
products
Foods
Sugars
Fats & Oils
Anti-oxidants Colourants
Flavourings Vitamins
Dietary supplements
Fibre
Fuels
“Petrol” “Diesel”
LPG
Natural gas
Coal
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Organic chemicals in manufactured
products
Miscellaneous
Lubricants
Cosmetics
Fragrances
Pigments
Dyes
Inks
Adhesives
Explosives
Detergents
Surfactants
Emulsifiers
Coolants
Photographic agents
Anti-scalants
Forensic chemicals
H
C
H
H
H
methane
Carbon has
4 valence
electrons
C
Stable Octet required
Simplest Organic molecule
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Covalent bonding
CCl
4- Covalent
NaCl - Ionic
[ Cl ]
–For more lessons, visit
C(6) - 1s
2
, 2s
2
, 2p
x
1
, 2p
y
1
, 2p
z
0
lowest energy state
Hybridization
C(6) - 1s
2
, 2s
1
, 2p
x
1
, 2p
y
1
,
2p
z
1
Excited state
4 sp
32s 2p
x
2py 2pz
+ + +
Methane is Tetrahedral
109.5
0Sp3 hybridized carbon
4 equivalent C-H bonds (s-bonds)
All purely single bonds are called s-bonds
H
C
H
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Electrophile dan Nucleophile?
Electrophile “electron lover” abbreviated
E
+species that is attracted toward a
negative center. Electrophile is Lewis
acid, H
+,ZnCl
2,
AlCl
3
Nucleophile “nucleus lover” abbreviated
Nu:
-species that is attracted to positive
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Nucleophilicity and Basicity
Nucleophilicity is a measure of reagent’s ability
to cause a substitution reaction
H
2O ROH Cl
-Br
- -OH
-OR I
--
CN
Increasing Nu: right
HO
-+ CH
3CH
2-Br CH
3CH
2OH + Br
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Basicity is a measure a reagent’s ability to accept
a proton in acid base reaction
I
-Br
-Cl
-ROH H
2O
-CN
-OH
-OR
Increasing basicity: right
HO
-+ H-Cl H
2O + Cl
-
CH
3CH-CH
2+
-OH CH
3CH=CH
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Background
Nucleophile - A Lewis Base with a pair of unshared electrons that seeks a positive part of
an atom.
Electrophile - A Lewis Acid seeking an electron pair Electrophilic Aromatic Substitution
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Leaving group?
Gugus pergi/gugus lepas in term substitution
reaction
Halida ions are good leaving group because
they are very weak bases
Increase reactivity RF RCl RBr RI
F
-is strong base than the other halida, poor
leaving group
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Hyperconjugation
Electrons in neighboring filled orbital stabilize vacant
antibonding orbital – net positive interaction
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Rotation of
Bond Is
Prohibitive
This prevents rotation about a carbon-carbon
double bond (unlike a carbon-carbon single bond).
Fractional distillation of crude oil
Petroleum Kerosene (C12-C16)
Bpt (200-250 ºC)
Heating oil (C15-C18) Bpt (250-300 ºC) Natural Gas (C1-C4)
Gasoline (C4-C12) Bpt (40-200 ºC)
Straight-chain alkanes are a pure fuel, because of engine knock.
n-Heptane has an octane rating = 0
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Late 18th century:
• Compounds from living organisms - Organic
• Compounds from lifeless matter – Inorganic
• Organic compounds thought to have ‘vital force’
Wöhler 1828
Ammonium cyanate
D
Urea(Heat)
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• Lactic acid composed of Carbon, Hydrogen and Oxygen
• Fixed proportion: 1C:2H:1O
• Empirical formula: CH2O
• Majority of ‘organic’ substances and many ‘inorganic’
composed of Carbon, Hydrogen and maybe other elements
• Mid 19th Century: re-define organic substances
• Those composed of Carbon, Hydrogen (usually) and other elements (maybe)
• 1850-1860: Concept of Molecules
• Atoms of Carbon and other elements connected by covalent bonds
