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Chapter 21 : Organic Chemistry
Organic chemistry:Organic chemistry:The study of the compounds of carbon.
• 85% of all known compounds are organic.
• Carbohydrates, lipids, proteins, enzymes, nucleic acids, hormones, vitamins, and almost all other chemicals in living systems are organic compounds.
< Abundance of the elements in the Earth’s crust.
Chapter 21 : Organic Chemistry
Why is organic chemistry a separate discipline within chemistry?
OrganicOrganic InorganicInorganic
Vitalism:Vitalism: a “vital force” present in living organisms was believed to be necessary to produce an organic compound.
The experiment of Wöhler in 1828 was the first in a series of experiments that led to the demise of the vital force theory. See reaction below:
NH4Cl AgNCO H2N-C-NH2
OAgCl+ heat +
Ammoniumchloride
Silvercyanate
Urea Silverchloride
Chapter 21 : Organic Chemistry
Structural formula:Structural formula: Shows the atoms present in a molecule as well as the bonds that connect them.VSEPR model:VSEPR model: The most common bond angles are 109.5°, 120°, and 180°.
180°
120°
109.5°
H
Chapter 21 : Organic Chemistry
Hydrocarbon:Hydrocarbon: A compound composed only of carbon and hydrogen.
H-C C-HH-C-C-HH
H
H
H HC C
H
H H
Hydrocarbons
Alkanes(Chapter 11)
Alkenes(Chapter 12)
Alkynes(Chapter 12)
Arenes(Chapter 13)
Only carbon-carbon single
bonds
One or more carbon-carbondouble bonds
One or morecarbon-carbontriple bonds
One or morebenzene-like
rings
Ethane Ethene(Ethylene)
Ethyne(Acetylene)
Benzene
Alkanes Alkenes AlkynesArenes
(Aromatics)
Chapter 21 : Organic Chemistry
Alkanes:Alkanes: Hydrocarbons that contain only carbon-carbon single bonds.
CH4 CH4C2H6 CH3CH3C3H8 CH3CH2CH3C4H10 CH3(CH2)2CH3C5H12 CH3(CH2)3CH3
C6H14 CH3(CH2)4CH3C7H16 CH3(CH2)5CH3C8H18 CH3(CH2)6CH3C9H20 CH3(CH2)7CH3C10H22 CH3(CH2)8CH3
CH4 CH4C2H6 CH3CH3C3H8 CH3CH2CH3C4H10 CH3(CH2)2CH3C5H12 CH3(CH2)3CH3
C6H14 CH3(CH2)4CH3C7H16 CH3(CH2)5CH3C8H18C9H20C10H22
CondensedStructural Formula
MolecularFormulaName
decane
nonane
octane
heptane
hexane
pentane
butane
propane
ethanemethane
CondensedStructural Formula
MolecularFormulaName
CondensedStructural Formula
MolecularFormulaName
decane
nonane
octane
heptane
hexane
pentane
butane
propane
ethanemethane
CondensedStructural FormulaName
The first 10 alkanes with unbranched chains:
Chapter 21 : Organic Chemistry
Line-angle formulaLine-angle formula:1. A line represents a single bond.2. A vertex and a line terminus represent a carbon atom.3. Hydrogen atoms are not shown in line-angle formulas.
CH3CH2CH2CH3CH3CH2CH3 CH3CH2CH2CH2CH3CH3CH2CH2CH3CH3CH2CH3 CH3CH2CH2CH2CH3PentaneButanePropane PentaneButanePropane
Condensedstructural
formula
Line-angleformula
Ball-and-stick model
Chapter 21 : Organic Chemistry
Alkyl group: Alkyl group: A substituent group derived from an alkane by removal A substituent group derived from an alkane by removal of a hydrogen atom.of a hydrogen atom.•Commonly represented by the symbol R-.Commonly represented by the symbol R-.•Named by dropping the -ane from the name of the parent alkane Named by dropping the -ane from the name of the parent alkane and adding the suffix -yl.and adding the suffix -yl.
-CH2CH3
-CH3
-CH2CH2CH3
-CHCH3CH3
-CH2CH2CH2CH3
-CH2CHCH3CH3
-CHCH2CH3CH3
-CCH3
CH3
CH3
tert-butyl
sec-butyl
isobutyl
butyl
isopropyl
propyl
ethyl
methylName
CondensedStructural Formula
CondensedStructural FormulaName
Chapter 21 : Organic Chemistry
IUPAC, How to name alkanes:IUPAC, How to name alkanes:1. The name for an alkane with an unbranched chain of carbon atoms consists of a prefix showing the number of carbon atoms and the ending -ane.ane.2. For branched-chain alkanes, the longest chain of carbon atoms is the parent chain and its name is the root name.3. Name and number each substituent on the parent chain and use a hyphen to connect the number to the name.4.Number the parent chain from the end that gives the lower number to the substituent encountered first.5.Indicate the number of times the substituent occurs by a prefix di-, tri-, tetra-, penta-, hexa-, and so forth.6.Use a comma to separate position numbers.7. Alphabetize the names of substituents first, and then insert these prefixes8.Do not include the prefixes di-, tri-, tetra- in alphabetizing.
CH3CHCH3
CH3
2-Methylpropane
12
3
CH2CH3
CH3CCH2CHCH2CH3
CH3
CH34-Ethyl-2,2-dimethylhexane
(not 2,2-dimethyl-4-ethylhexane)
23
45
61
IUPAC = International Union of Pure and Applied Chemistry
Chapter 21 : Organic Chemistry
Cyclic hydrocarbonCyclic hydrocarbon: A hydrocarbon that contains carbon atoms : A hydrocarbon that contains carbon atoms joined to form a ring.joined to form a ring.Cycloalkane: Cycloalkane: A cyclic hydrocarbon in which all carbons of the ring A cyclic hydrocarbon in which all carbons of the ring are saturated (has only carbon-carbon single bonds).are saturated (has only carbon-carbon single bonds).Cycloalkanes with ring sizes of from 3 to over 30 carbon atoms are Cycloalkanes with ring sizes of from 3 to over 30 carbon atoms are found in nature.found in nature.Five-membered (cyclopentane) and six-membered (cyclohexane) Five-membered (cyclopentane) and six-membered (cyclohexane) rings are especially abundant in nature.rings are especially abundant in nature.
Cyclopentane Cyclohexane
Isopropylcyclopentane1-tert-Butyl-4-methylcyclohexane
1 4
Physical properties:Physical properties:1. Non-polar (they dissolve in other non-polar solvents!)2. Melting/Boiling points and Density:
CH4CH3CH3CH3CH2CH3CH3(CH2)2CH3
CH3(CH2)3CH3CH3(CH2)4CH3CH3(CH2)5CH3CH3(CH2)6CH3CH3(CH2)7CH3CH3(CH2)8CH3
methane
ethanepropane
butane
pentane
hexane
heptane
octanenonane
decane
Name
CondensedStructrualFormula
mp(°C)
bp(°C)
-182
-183
-190-138
-130
-95
-90
-57-51
-30
-164
-88
-420
36
69
98
126151
174
(a gas)
(a gas)
(a gas)(a gas)
0.626
0.659
0.684
0.7030.718
0.730
*For comparison, the density of H2O is 1 g/mL at 4°C.
Mol wt(amu)
16.0
30.144.1
58.1
72.2
86.2
100.2
114.2128.3142.3
Density of Liquid
(g/mL at 0° C)*
Chapter 21 : Organic Chemistry
Natural gas• 90 to 95 percent methane. • 5 to 10 percent ethane, and • A mixture of other relatively
low-boiling alkanes.Petroleum• A thick, viscous liquid mixture of
thousands of compounds, most of them hydrocarbons formed from the decomposition of marine plants and animals.
Chapter 21 : Organic Chemistry
An alcohol may be primary (1°), secondary (2°), or tertiary (3°).
CH3-C-OH
H
HCH3-C-OH
CH3
HCH3-C-OH
CH3
CH3
A 1° alcohol A 3° alcoholA 2° alcohol
Example: C3H8O
Chapter 21 : Organic Chemistry
Example: C3H9N
Chapter 21 : Organic Chemistry
Example: C4H8O
Chapter 21 : Organic Chemistry
Example: C3H6O2
Chapter 21 : Organic Chemistry
Example: C3H6O2