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Organic Chemistry
P 267
Hydrocarbon
• Hydro: hydrogen
• Carbon
• Additional element: Nitrogen, Oxygen, Sulphur
Atomic number of carbon = 6
Valence electrons of carbon = 4
Each carbon atom has 4 bond in compound
Ex: alkanes
Alkanes: hydrocarbon that consist of hydrogen and
carbon, (single bond)
CH4, methane
C2H6, ethane
C3H8, propane
C4H10, butane
C5H12, pentane
C6H14, hexane
C7H16, heptane
C8H18, octane
C9H20, nonane
C10H22, decane
Structure Types of Propane
Stick and ball model
Displayed Formula
3 dimensional Formula
H
Structural Formula
CH3CH2CH3
Molecular Formula
C3H8
H
H
H
H
H
H
H
Skeletal Formula
ALCOHOL (-OH)
PROPANE
PROPANOL
ALCANOIC ACID
BUTANE
BUTANOIC ACID
ALDEHID/ALCANAL
PENTANE
PENTANAL
KETONES
Butan-2-one
Alkylamine R-NH2
CH3CH2CH2NH2
Propylamine
ESTHER (Alkyl Alkanoate)
methyl propanoate
Hydrocarbon
with Branch
6
5 4 3
2 1
-Find the longest carbon chain, give the name
- Find branch and give the name to the Branch:
Same branch:
Carbon:Alkyl;
2 branchs: di
1 C atom: methyl
3 branchs: tri
4 branchs: tetra
2 C atom: ethyl
3 C atom: propyl
Halogen: F(Floro), Cl(Chloro), Br(Bromo), I(Iodo)
- Give the number, branch number is the smallest
number
2- Methyl Hexane
the branches names arranged alphabetically
3-bromo 9-chloro 4-methyldecan-3-ol
6-chloro 4-ethyl octan-3-one
Alcanal, and alcanoic numbering begin from C
attached to the function
5
4
3
2
1
4- methyl Pentanal
1
•
•
•
•
2
3
4
5
6 7
8
9
Same branch:
2 branchs: di
3 branchs: tri
4 branchs: tetra
4,6 -diethyl 2,4,7 -trimethyl nonane
Alcanal, and alcanoic numbering begin from C attached to the function
6-ethyl 3-floro 4,7-dimethyl octanoic acid
Remember that the branches names arranged alphabetically
Task
• Copy the table 15.2 page 270 in to your book
Determination of element mass in compound
Compound: AmBn
Mass of element A =
Mass of element B =
Find mass of carbon in 88 gr CO2
Mass of carbon =
=
= 24 gr
Determination of empirical formulae
of organic compound
100,00 g amino acid(CpHqOrNs) react with oxygen and
produced 117,10 g of carbon dioxide and 59,92 g of
water. In kjeldahl a second of amino acid produced
22,64 g ammonia, determine the empirical formula of
amino acid
Answer
- write the information
mass of amino acid = 100 gr
mass of carbon dioxide (CO2) = 117,10 gr
mass of water(H2O)= 59,92 g
mass of ammonia (NH3) = 22,64
• Find mass of carbon in carbon dioxide
= 31,94 g
• Find mass of hydrogen in water
= 6,66 g
• Find mass of nitrogen in ammonia
= 18,64 g
• Find mass of oxygen in amino acid
=mass of amino acid – carbon mass –
hydrogen mass - nitrogen mass
= 100 – 31,94 – 6,66 – 18,64
= 42,76 gr
• Compare mass of the elements
C
:
H
:
O
:
N
31,94 : 6,66
: 42,7
:
18,64
• Compare mol of the elements
31,94/12 : 6,66/1
: 42,76/16 : 18,64/14
2,67
: 6,66
: 2,67
:
1,33
• Divide by the smallest mole
2
:
5
:
2
:
1
• Determine the empirical formula
C2H5O2N
Reactions
Subtitution
H H
H H
H C C Br + OH- H C C OH + BrH H
H H
Addition
Double bondsingle bond
Triple bonddouble or single bond
H H
H C C H + H2O  H C C OH
H H
H H
Elimination
single bondDouble bond
double Triple bond
H H
H C C OH  H C C H + H2O
H H
H H
Hydrolysis
Reaction involve breaking covalent bonds by
reaction with water
H H
H H
H C C Br + H2O H C C OH + HBr
H H
H H
Breaking Bonds in Different Ways
Homolytic fission
Each atom break to free radical (atom with unpaired
electron

+
Heterolytic fission
Each atom break to ion (cation and anion)

++
-
Another example
Homolytic fission
CH3Br  CH3 + Br
Heterolytic fission
CH3Br  CH3+ + Br-
+
Carbocation
Cycloalkane
cyclopropane
cyclobutane
Methyl
cyclohexane
cyclopentan
e
cyclohexane
Alkylamine (R-NH2)
CH3NH2 methylamine
CH3CH2NH2 ethylamine
CH3CH2CH2NH2 propylamine
Alkenes C=C
ethene
CH2=CH2
propene
CH2=CH-CH3
butene
CH2=CH-CH2-CH3
pentene
CH2=CH-CH2-CH2-CH3
CH3-CH=CH-CH2-CH3
pent-2-ene
Double bond number is the smallest number in
the longest carbon chain
Isomerism
Structural isomer
Different structural formula same molecular
formula
CH3-CH2-CH2-CH3
Butane,
C4H10
Methyl propane,
C4H10
Functional isomerism
- Alcohol and eter
- Ethanol: CH3-CH2-OH, molecular formula: C2H6O
- Ether : CH3-O-CH3, molecular formula: C2H6O
- Aldehid and ketones
- pentanal:
- Penta-2-one
,molecular formula:C5H10O
C5H10O
- Alkanoic acid and esthers
- Propanoic acid
- Methyl ethanoate
Prove it !
Stereo isomer
Geometric isomer (cis-trans isomerism)
But-2ene: CH3-CH=CH-CH3
Cis-but-2-ene
trans-but-2-ene
Optical isomerism
use 3 dimensional formula
Occurs in the chiral molecules The star sign indicate
chiral center. Chiral
center is the carbon
atom which carries four
different groups
Butan-2-ol
Reactions Routes
Write the reactions routes to convert:
a. Propene to propanol
– pass propene and steam over heated phosphoric
acid catalyst under pressure
b. Propene to propanal
– pass propene and steam over heated phosphoric
acid catalyst under pressure untill propanol forms
– Distill on propanol to acidified potassium dichromate
Draw the structure of
5,7 dibromo, 2,6 dimethyl octan-3-one
Solution steps
Draw the longest chain
Give the number
Put the function
Put the branches
C
O
1 2 3 4
5 6 7
8
C-C-C-C-C-CC-C
C
B B