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Aug ‘171 Organic Chemistry
12.01 Organic Chemistry
Dr. Fred Omega GarcesChemistry 100Miramar College
Chemistry of Carbon
An Introduction to nomenclatures, structures and reactions
Aug ‘172 Organic Chemistry
What is Organic Chemistry ?
Organic Chemistry: Study of carbon containing compounds.Everything else is considered inorganic.
Over 5 million chemicals known of these200 - 300 thousands are inorganic.
Why are there so many organic compounds?
O CH
HH C C
H
HH
H CH
HC C
O C CB r
H
H
HNH
H
C lC C H
H
HH
O C CB r
C lH
CC
NH
C CH2
C
H2CH
CCC
CC
CC C C( )nF
F
F
F
F
F
F
F
CC C CH
H H
H
H H
CC C HB r
(CH2)8H3CB r
H
F
C l
H
H
CH3
H3C CH3
CH3C CH3
C
OH
HHH
CHOO
NO2CH3
CH3
H
B rCH3
H
H
CH3
B r
B rCO C CH3C C
NH2HO
H
OHC
H
OH
HO
OCH3
COH
O
CH3C CH2OH
H
CH3 CH2 CO
OH
OH
CH3 CH2 C OH
CH C CH3CH3
H2C CH
R CO
CH CH CH3H3CCH3
OH
H2C
H2CO
C
CO O
O
H3CCH3
+ H2
+ HBr
Aug ‘173 Organic Chemistry
The magic Carbon atom
Difference between organic and inorganic is C-atom ability to form very long chain
Inorganic compound will become unstable after with 12 or more atoms.C-atoms ability to form very strong covalent bond means molecules can possess 100 or more atoms
Aug ‘174 Organic Chemistry
Evolution of Organic Chemistry
“Can man artificially create a living animal from chemicals ?”
- magnitude of question concerning organic compoundPrior to 1828, organic compounds can only be obtained from living organismFredrick Wohler prepared urea - chemical in urine (an organic compound)
NH4Cl + AgNCO g NH2-CO-NH2 + Ag
Now a days the bulk of organic compoundsis manufactured in the lab.
Aug ‘175 Organic Chemistry
Source of Organic Compound
Organic chemicals isolate from nature. Nature has her huge laboratory and is constantly synthesizing chemicals through biosynthesis.
Today we can manufacture these same chemicals in the lab
Mescaline
CaffeineTetrahydrocannabinol THC
HO
H
H
HH
H
Ethanol
Aug ‘176 Organic Chemistry
Lewis Dot Structure :Number of bonds for nonmetal atom
Lewis Dot Structure and VSEPR: revisitedH C N O X
Val. e- 1 4 5 6 7
# Bonds 1 4 3 2 1H-H CH4 NH3 H2O H-Cl
Aug ‘177 Organic Chemistry
Forms of Carbons
Carbons with single bond :Methane, CH4 Tetrahedral 109.5° sp3
Carbons with double bondsethene, C2H6 Trig. planar 120° sp2
Carbons with triple bondsethyne C2H2 Linear 180° sp
HC CH
Aug ‘178 Organic Chemistry
Structure - Ways of presenting organic Compounds
Consider: Ethanol and dimethylether C2H6O Molecular formula - indicate type and number of atoms
C2H6O C2H6O Structure formula - shows connectivity of atoms in a compound
Ethanol Dimethylether
Condense formula - shows connecting group of atoms in a compoundEthanol, CH3CH2OH Dimethylether, CH3OCH3
Shorthand notation - shows hydrocarbon as "R" and functional group as is.Ethanol R-OH Dimethylether R-O-R’
Stick form - shows hydrocarbons as lines with functional groupEthanol Dimethylether
Isomers - Compounds that have the same formula but different structuresEthanol and dimethylether have the same formula but are different compounds
and therefore possesses different propertiesEthanol is the drinkable alcohol, while dimethyl ether was used as an anesthetic.
OHO
Aug ‘179 Organic Chemistry
Organic Compounds; the Family Tree.
Organic Compounds
cyclo Aliphatics
Hydrocarbons Heteroatoms
AromaticAliphatics
Alkane
Alkene
Alkyne
O
CH3CH3
CNH
O
Aug ‘1710 Organic Chemistry
Alkanes CnH2n+2
Hydrocarbons with only single bonds
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
Pentane C5H12
The Alkanes
Aug ‘1711 Organic Chemistry
Degree of Carbon
a) primary carbons, 1° -a) carbons bonded to only one other carbon
b) secondary carbons, 2° -carbons bonded to two other carbons
c) tertiary carbons, 3° -carbons bonded to three other carbons
d) quaternary carbons, 4° -carbons bonded to four other carbons
C
CH2
CH3
CH
CH3
CH3
CH3CH3
Aug ‘1712 Organic Chemistry
Prefix and the Number of Carbons# of
CMolecularFormula
Prefix Alkanename
Structure and isomers
groupname
1 CH4 meth- methane CH4 methyl2 C2H6 eth- ethane ethyl3 C3H8 prop- propane propyl, i-propyl4 C4H10 but- butane
, butyl, iso-butyl
sec-butyl, tert-butyl5 C5H12 pent- pentane
, ,
pentyl
6 C6H14 hex- hexane etc... -
7 C7H16 hept- heptane -8 C8H18 oct- octane -9 C9H20 non- nonane -
10 C10H22 dec- decane -
Aug ‘1713 Organic Chemistry
Isomers are molecules with the same chemical formula but different structural formula.Pentane
n-pentane, iso-pentane, neo-pentane
Hexanen-hexane 2-methylpentane 3-methylpentane
2,4-dimethylbutane 2,2-dimethylbutane
Isomers
Aug ‘1714 Organic Chemistry
Alkyl group (in naming scheme)Alkyl group - An important idea in the naming scheme is the
group of atoms attached to a carbon chain.yl - suffix indicating group
First 5 alkyl groups and their isomers:
1. Methyl 2 . Ethyl
3 .Propyl: n-propyl, isopropyl
4 .Butyl: n-butyl, sec-butyl, iso-butyl, tert-butyl
5. Pentyl: n-pentyl, sec-pentyl, iso-pentyl, neo-butyl
H
HCH
H
H
HH
C
H
HC C
H
H H
HH
HC C
H
H
H H
H
methane g methyl ethane g ethyl
..
. . . .
..
Aug ‘1715 Organic Chemistry
IUPAC NomenclatureRules of the game:Alkane (CnH2n+2)
1. Find the longest continuous chain of carbon atoms. Assign this chain as the parent name .
2. Determine the substituents (groups) attached to the parent chain3. Assign attachment position of group to main chain by starting at end
which gives lowest position number.*4. Identical groups attached to the main chain are designated with
prefixes.2-di, 3-tri, 4-tetra, 5-penta
5. Different groups attached to main chain are written in alphabeticalorder.
6. Alkyl halides: Halogen atoms (group) are designated as halogen prefix.F - Fluoro, Cl-Chloro, Br- Bromo, I- Iodo
7. Alkyl groups (see previous page)
* The numbering scheme should be chosen such that the sum of the position in which group are attached add up to the lowest sum.
Aug ‘1716 Organic Chemistry
• Consider the following hexane compound:Heptane (C7H16)
1. Pentane
2. Methyl
3. Carbon # 2 & # 3
4. 2,3 = position methyl = group pentane = parent name
5. Two methyl g dimethyl
6. Name: 2,3-dimethylpentane
IUPAC nomenclature, an example
Aug ‘1717 Organic Chemistry
Functional GroupName -Suffix group Example
1 Aliphatics -ane, -ene,-yen
, , , , propane, propene, proyne
2 Alcohol -ol =
propanol3 Ether - ether ,
ethylpropylether4 Aldehydes -al
, propanal
5 Ketones -one
, propanone
6 Carboxylicacid
-oic acid,
propanoic acid7 Ester -ate
, methyl propanoate
8 amine -amine
, triethyl amine
9 amide -amide,
N-methylpropamide
C C C C C C
OHOH
R O R ' O
R C OH C O
H
R CO
R 'CO
R CO
OH CO
OH
R CO
O R 'CO
O
R NR '
R ' N
NR '
R 'RC
ONHC
O
Aug ‘1718 Organic Chemistry
Alkenes CnH2n • Alkynes CnH2n-2
Hydrocarbons with multiple bonds- Ethene, C2H4 - Ethyne,C2H2
- Propene, C3H6 - Propyne, C3H4
Note: If there is more than one multiple bond _ poly unsaturatedi.e.,
Alkenes and Alkynes
Aug ‘1719 Organic Chemistry
More on AlkenesGeometric Isomers
Cis 2-butene Trans 2-butene
Can’t rotate the double bond which makes these molecules unique compounds or Geometric isomers.Life example: 11-cis-retinal g all trans retinal
R
C
O
H
RH
Ohn
dark with enzyme Signals optic
nerve cellVisual pigment
(rhodopsin)
Aug ‘1720 Organic Chemistry
more rules of the game:
Alkene (CnH2n) -ene (suffix)1. - ene suffix for alkenes 2. Main chain must include the double bond.3. position of double bond indicated by prefix numbering location.4. For multiple double bonds :
di = 2 double bondstri = 3 double bonds
Alkyne (CnH2n-2) -yne (suffix)1. - yne suffix for alkynes2. Nomenclature rules are similar to that
of alkenes
Nomenclature: Alkenes and Alkyne
2-propyl-1-pentene
2-methyl-1,3,5-heptatriene
3-ethyl-4-methyl-1-hexyne
Aug ‘1721 Organic Chemistry
Aromatics: nomenclature1. Monosubstituted
a. group benzene
b. special name
2. Two substituted groups - use prefix for position
3. Three substituted groups- requires # scheme (lowest position scheme)
4. Benzene as a group- phenyl
NO2 Cl Br CH2CH3
OH CH3 NH2 CO
OH
Xo (ortho)
m(meta)p(para)
X1
2
34
5
Aug ‘1722 Organic Chemistry
Summary
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