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Unit 3Organic Chemistry
Chemistry 2202
Introduction
● Organic Chemistry is the study of the molecular compounds of carbon.eg. CH4 CH3OH CH3NH2
● Organic compounds exclude oxides of carbon and ions containing carbon.ie. CO CO2 KCN CaCO3
are NOT organic compounds!!
History of Organic Chemistry● Started when medicine men extracted
chemicals from plants and animals as treatments and cures
● First defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius
● Berzelius believed in Vitalism - organic compounds could only originate from living organisms through the action of some vital force
● organic compounds originate in living or once-living matter
● inorganic compounds come from "mineral" or non-living matter
● In 1828, Friedrich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound).
NH4OCN(aq) (NH2)2CO(s)
inorganic organic
http://en.wikipedia.org/wiki/Urea
What’s this?
(NH2) 2CO - (NH2)2CO
di-urea
● organic chemistry branched into disciplines such as polymer chemistry, pharmacology, bioengineering and petro-chemistry
● 98% of all known compounds are organic
● The huge number of organic compounds is due mainly to the ability of carbon atoms to form stable chains, branched chains, rings, branched rings, multiple rings, and multiple bonds (double and triple bonds) to itself and to many other non-metal atoms.
Sources of Organic Compounds
1. Carbonized Organic Matter- fossil fuels such as coal, oil, and natural
gas - basis for the petrochemical industry
2. Living Organisms eg: - penicillin from mold - acetylsalicylic acid (Aspirin) from the
bark of a willow tree
3. Invention
- antibiotics, aspirin, insulin, vanilla flavoring, and heart drugs are manufactured from organic starting materials
- plastics
Structural Isomers
● Structures that have the same molecular formula, but different structural formulas are called structural isomers
eg. C4H10
Practice: Draw all structural isomers of C5H12 and C6H14
CH3 CH2
CH2
CH3
butane
CH3
CH
CH3
CH3
2-methylpropane
They have the same molecular formula (C4H
10), but
different structural formulas. They are isomers and are different compounds and have different properties such as boiling point.
Structural Isomers
● structural isomers have the same chemical formula but have different chemical and physical properties.
Classifying Organic Compounds Organic
Compounds
Hydrocarbons HydrocarbonDerivatives
• Alcohols• Ethers• Aldehydes• Ketones• Carboxylic Acids• Alkyl Halides• Esters• Amines• Amides
Aliphatic
AlkAnes
AlkEnes
AlkYnes
Aromatic (benzene based)
● hydrocarbons consist of carbon
and hydrogen atoms only
eg. Methane - CH4 ● hydrocarbon derivatives have one or
more hydrogen atoms replaced by another nonmetallic atom
eg. bromomethane - CH3Br
methanol - CH3OH
● aliphatic hydrocarbons have carbon atoms bonded in chains or rings with only single, double, or triple bonds
● aromatic hydrocarbons contain at least one 6 carbon benzene ring
Organic Worksheet #1
Aliphatic Hydrocarbons
1. Alkanes● Alkanes are hydrocarbons that have only
single bonds between carbon atoms
● general formula CnH2n+2
eg. C3H8 C6H14
IUPAC prefixes
Prefix # of carbon atoms
meth 1
eth 2
prop 3
but 4
pent 5
hex 6
hept 7
oct 8
non 9
dec 10
Complete this table for the first
10 alkanes
methane CH4
ethane
propane
methane CH4
ethane C2H
6
propane C3H
8
butane C4H
10
pentane C5H
12
hexane C6H
14
heptane C7H
16
octane C8H
18
nonane C9H
20
decane C10
H22
● A series of compounds which differ by the same structural unit is called a homologous series
eg. each alkane increases by CH2
What is the next member of this homologous series?
SiO2Si2O3 Si3O4 _____
Representing Alkanes (4 ways)
1. Structural formulas
eg. propane
H – C – C – C – H
HHH
HHH
● Hydrogen atoms may be omitted from structural formulas
eg. propane
– C – C – C –
2. Condensed Structural Formula
eg. propaneCH3-CH2-CH3
3. Line Structural Diagrams
eg: propane
(the endpoint of each segment is a carbon atom)
4. Expanded Molecular Formulas
eg. propane
CH3CH2CH3
● An alkyl group has one less hydrogen than an alkane.
● General Formula: CnH2n + 1
● To name an alkyl group, use the prefix to indicate the # of carbon atoms followed by the suffix –yl
eg. -C7H15 heptyl
Alkyl Groups
Alkyl Groups
methyl -CH3
ethyl -C2H5 or -CH2CH3
propyl -C3H7 or -CH2CH2CH3
● Branched alkanes are alkanes that contain one or more alkyl groups
eg.
Alkyl Groups
2,4 - dimethylpentane
1. Find the longest continuous chain (LCC) of carbons(parent chain) and give it the alkane name.
2. Number the carbons in the parent chain starting from the end closest to branching. These numbers will indicate the location of alkyl groups.
Naming Branched Alkanes
Naming Branched Alkanes
3. List the alkyl groups in alphabetical order. Use Latin prefixes if an alkyl group occurs more than once. (di = 2, tri = 3, tetra = 4, etc. don't count for alphabetical order)
4. Use a number to show the location of each alkyl group on the parent.
5. Use commas to separate numbers, and hyphens to separate numbers and letters.
Naming Branched Alkanes
eg.
4-ethyl-3-methylheptane
Naming Branched Alkanes
eg.
7 6 5 4 3 2 1
ethyl
methyl
4-ethyl-3-methylheptane
Naming Branched Alkanes
CH3
CH2
C CH2 CH2 C
CH2
CH3
CH3
CH3
CH3
CH3
CH3
CH2
C CH2 CH2 C
CH2
CH3
CH3
CH3
CH3
CH3
3,3,6,6-tetramethyloctane
Practice:● p. 336 - 339 #’s 5 – 11
(Answers on p. 375)
Naming Branched Alkanes
CH3 CH2 CH
CH2 CH CH2
CH CH3
CH2CH3CH3
CH2 CH3
4,6-diethyl-2-methyloctaneParent chain: Octane2-methyl4,6-diethyl
12
34
5
6
78
CH3 CH2 CH CH3
CHCH3 CH
CH3
CH2
CH
CH2 CH3
CH2CH2
CH3
CH3 CH
CH3
C
CH3
CH2 CH3
CH
CH2 CH2 CH3
CH2
CH2 CH3
CH3 CH2 CH2 CH
CH2 CH2 CH3
CH
CH2 CH2 CH3
CH2 CH CH3
CH3
7-ethyl-3,4,5-trimethyldecane
3-ethyl-2,3-dimethyl-4-propylheptane
2-methyl-4,5-dipropyloctane
3-ethyl-2,2-dimethylhexane
3 – ethyl – 5 – methyl – 4,4 - dipropylnonane
CH3 C
CH3
CH3
CH
CH2 CH3
CH2 CH2 CH3
CH3 CH2 CH
CH2 CH3
C
CH2 CH2 CH3
CH2 CH2CH3
CH
CH3
CH2 CH2CH2
CH3
Organic Worksheet #2
Alkenes and Alkynes
● saturated hydrocarbons contain only single bonds between carbon atoms
eg. alkanes● saturated hydrocarbons have the
maximum number of hydrogen atoms bonded to carbon atoms
Alkenes and Alkynes
● unsaturated hydrocarbons contain double or triple bonds between carbon atoms
eg. alkenes and alkynes
Alkenes and Alkynes
● General Formulas:
– AlkenesCnH2n
– Alkynes CnH2n - 2
At least one double bond
At least one triple bond
Naming Alkenes and Alkynes
1. Name the longest continuous chain that contains the double/triple bond.
2. Use the smallest possible number to indicate the position of the double or triple bond.
Naming Alkenes and Alkynes
3. Branches are named using the same rules for alkanes.
4. Number the branches starting at the same end used to number the multiple bond.
For you to do!!
Pg. 347 #'s: 17, 18, 19
Worksheet #3: Alkenes and alkynes
Cyclic Hydrocarbons
Cycloalkanes and cycloalkenes
cyclopentane
methyl
ethyl
1-ethyl-3-methylcyclopentane
3-ethyl-1-methylcyclopentane
1
2
3
methyl
1,2,3,4-tetramethylcyclohexane
Practice
Pg. 356 – 358 Pg. 358 #'s: 30-31
Worksheet #4
Aromatic Compounds
● Aromatic hydrocarbons contain at least one benzene ring.
● The formula for benzene, C6H6 , was determined by Michael Faraday in 1825.
● The structural formula was determined by August Kekulé in 1865.
Aromatic Compounds
Proposed formula:
Conflicting Evidence
● C=C double bonds are shorter than C-C single bonds. X-ray crystallography shows that all C-C bonds in benzene are the same length.
● Benzene reacts like an alkane, not like an alkene.
Modified structure
● Kekulé proposed a resonance structure for benzene.
● The resonance structure is an average of the electron distributions.
Aromatic Compounds
or
6 electrons shared6 carbon
atoms
Aromatic Compounds
● bonding electrons, once believed to be in double bonds, are delocalized and shared equally over the 6 carbon atoms
● the bonds in benzene are like “1½” bonds – somewhere between single and double.
Naming Aromatic Compounds● an alkyl benzene has one or more H
atoms replaced by an alkyl group.● name the alkyl groups, using numbers
where necessary, followed by the word benzene.
Aromatic Compounds
methylbenzene
propylbenzene
ethylbenzene
Aromatic Compounds
1,3-dimethylbenzene
1,4-dimethylbenzene
1,2-dimethylbenzene
Aromatic Compounds
● ortho- means positions 1 and 2 and is represented by "o"
● meta- means positions 1 and 3 and is represented by "m"
● para- means positions 1 and 4 and is represented by "p"
Aromatic Compounds
m-dimethylbenzene
p-dimethylbenzene
o-dimethylbenzene
Aromatic Compounds
● Benzene is treated as a branch if it is not attached to the terminal carbon of an alkyl group
● Benzene as a branch is called phenyl
Aromatic Compounds
CH2
CH2
CH3
CH3CHCH3
propylbenzene2-phenylpropane
Aromatic Compounds
CH3CHCHCH2CH2CH3
CH2CH3
3 – ethyl – 2 – phenylhexane
Aromatic Compounds
● Pg. 361 #’s 32 – 35
Geometric Isomers● Compounds with the same molecular formula, but different geometry of bonds
● Two types of shapes● Cis and Trans isomers● Cis – groups on the same side of the double bond
● Trans – groups on different sides of the double bond
● Cis/Trans written as part of the name● Ex: cis-2-butene or trans-2-butene
cis and trans isomers (p. 348)
cis and trans isomers (p. 348)
Properties of aliphatic hydrocarbons
● Because they are nonpolar, all hydrocarbons are insoluble in polar water.
● The boiling/melting point of alkanes is somewhat higher than alkenes but lower than alkynes.
● As the number of atoms in the hydrocarbon molecule increases, the boiling/melting point increases.
Hydrocarbon Production● Crude oil is a mixture of hydrocarbons.● Hydrocarbons are extracted from the ground at
well sites, then processed at refineries.● Fractional Distillation is a process used to
separate petroleum into its hydrocarbon components.
● This process relies on the different boiling points of each hydrocarbon.
substances with the highestboiling points condense closer to the bottom
Hydrocarbon Derivatives● Hydrocarbon Derivatives contain other
nonmetal atoms such as O, N, or halogen atoms.
● 9 types of derivatives:
(See p. 378 + ethers and organic halides)● the reactive group of atoms that gives a
family of derivatives its distinct properties is a functional group
Hydrocarbon Derivatives
● The general formula for a derivative is
R - functional group
where R stands for any alkyl group.
Hydrocarbon Derivatives
eg. ALCOHOLS R-OH
ethanol C2H5OH
propanol C3H7OH
CARBOXYLIC ACIDS R-COOH
ethanoic acid CH3COOH
propanoic acid C2H5COOH
1. Alcohols
● Have the hydroxyl functional group
General Formula: R - OH
Naming Alcohols (p. 387)
● The parent alkane is the longest chain that has an -OH group
● Replace the last -e in the alkane name with
the suffix -ol.● Add a number (smallest one) to indicate the
location of the -OH group.
C OH
H
H
H
CC O
H
H
H
H
H
H
methanol
ethanol
eg. CCC O
H
H
H
H
H
H
H
H
CCC
O
H
H
HH
H
H
H
H
propanol
2-propanol
2-methyl-2-butanol
Properties of Alcohols (p. 389)
● Alcohols have H-bonding which makes their mp and bp higher than the corresponding alkane.
● Polarity decreases as the # of carbon atoms increases
● Long chain alcohols are less soluble in water than short chain alcohols.
Reactions of alcohols
Combustion
R-OH + O2 → CO2 + H2O
eg. Write the equation for the burning of butanol.
Reactions of alcohols
Substitution
R-OH + H-X → R-X + H2O
eg. Use structural formulas to show the reaction between 2-pentanol and HBr.
Reactions of alcohols
Elimination (Dehydration)
eg.
CCC OH
H
H
HHH
HH
H2SO4
CCC HHH
HH
H
+ H2O
2. Ethers
● Composed of two alkyl groups bonded to an oxygen atom.
● General Formula: R1-O-R2
● Naming ethers: p. 395– IUPAC name– Common name
O C C
H
H
H
H
H
CH
H
H
O C C C C
H
H
H
H
H
H
H
H
H
CCC
H
H
H
H
H
H
H
1-methoxyethane or ethyl methyl ether
1-propoxybutane or butyl propyl ether
O C C
H
H
H
H
H
CC
H
H
H
H
H
P. 395, 396 #’s 20 – 23
Worksheet: Ethers
1-ethoxyethane or diethy ether
3. Aldehydes (p. 402)
● Contain a carbonyl functional group at the end of a carbon chain.
General Formula:=
HR-C
O
Naming:● Use the alkane name for the longest
continuous chain.● Remove the –e and add the suffix –
aleg.
butane →butanal
CCCC O
HH
H
H
H
H
H
H
2,3 - dimethylpentanal
3 – ethyl – 3 - methylhexanal
4. Ketones (p. 402)
● Contain a carbonyl functional group in the ‘middle’ of a carbon chain.
ie. NOT on carbon #1
General Formula: =O
- R2R1-C
Naming:● Use the alkane name for the longest
continuous chain.● Replace the –e with the suffix –one● Use the smallest possible number for the
position of the C=O group.
CCCC
O
H
H
H
H
H
H
H
H
CCCCC
O
H
H
H
H
H
H
H
H
H
H
2 – butanone & 2 - pentanone
3 – fluoro – 4 – methyl – 2 - hexanone
5. Carboxylic Acids (p. 405)
Contain a carboxyl functional group
ie. -COOH
General Formula:
=O
- OHR1-C
● The “C” of COOH is always #1● Find longest chain with COOH● Drop the “e” of alkane name and replace with “oic” acid● Don't need to use 1 in naming for COOH place● Branching is same as always
3 – ethyl – 3 – methylpentanoic acid
CCC OH
OH
H
H
H
H
C C C CO
O H
H
H
H
H
H
H
H
Propanoic acid
Butanoic acid
6. Alkyl Halides (p. 390, 391)
Contain at least one halogen atom
General Formula: R – X
(X is F, Cl, Br, or I)
● Naming alkyl halides is the same as naming all other pure hydrocarbons except now there are halogen atoms involved.
● The “ine” of the halogens are dropped for “o”● Bromine --> Bromo; chlorine --> chloro
2,4 – dichloro – 1 - methylcyclohexane4 – fluoro – 2 - pentene
CCCC
Br
Br
Br
H
H
HH
H
H
H
CCCCC
Cl
Br
BrBr
Br
H
HHH
H
H
H
2,2,3 – tribromobutane & 1,2,3,4 – tetrabromo – 4 - chloropentane
CCCC
Br
Br
Br
H
H
HH
H
H
H
CCCCC
Cl
Br
BrBr
Br
H
HHH
H
H
H
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