Organic Chemistry The study of carbon compounds. Over 10 million compounds naturally exist More than...
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Transcript of Organic Chemistry The study of carbon compounds. Over 10 million compounds naturally exist More than...
Organic ChemistryThe study of carbon compounds.
Over 10 million compounds naturally existMore than 300 000 are synthesized
Inorganic vs Organic
– oxides of carbon (CO2, CO)
– carbonates,bicarbonates (NaHCO3,CaCO3)
– cyanides (NaCN, etc)
– any carbon attached to a metal and no H
• Hydrocarbons containing CxHy
Origin of organic compoundsOrigin of organic compounds• Originally from “organic” meaning life• Not just chemistry of life, chemistry of carbon
• Naturally occurring organic compounds are found in plants, animals, and fossil fuels
• All of these rely on the “fixing” of C from CO2
• Synthetic organic compounds are derived from fossil fuels or plant material
The diversity of carbon compounds is based on the fact carbon atoms Form 4 Bonds
• Forms strong covalent and nonpolar bonds with itself and other elements
Review:• Lewis Structure, Structural formula, Line diagrams
Carbon molecules form complex 3-D shapes
Common Molecular Shapes
• Tetrahedral
• Trigonal planar
• Linear
• Angular
• Trigonal pyramidal
Simplest HydrocarbonsSimplest HydrocarbonsC C C C
C C
C
C
C
C
C
C
H
H
H
H
H
H
C C C C C
H
H
H
H
H H
H
H
H
H
H
H
Alkanes Alkenes
Alkynes Aromatics
C C C C C
H
H
H
H
H
H
H
H
H
H
C C C C CH
H
H
H
H
H
H
H
Naming Hydrocarbons (nomenclature)
Naming: common vs. IUPAC• Common names used in the 1800’s are still used for some
compounds today: eg.
H C C HCommonly known
as Acetylene
• The International Union of Pure and Applied Chemistry (IUPAC) was established in 1900s
• Systematic method allows an infinite number of compounds to be named given a few rules
IUPAC: Ethyne
Mnemonic for first four prefixes
First four prefixes• Meth-
• Eth-
• Prop-
• But-
Monkeys
Eat
Peeled
Bananas
?Decade
Decimal
Decathalon
Other prefixes
• Pent-
• Oct-
• Dec-
• Hex-, Hept-, Non-
Alkanes
• Are straight or branched-chain containing only single bonds
• Are a homologous series –a group of compounds whose members differ by the addition of the same structural group
• Named by using prefix and ending -ane
TASK
• Write chemical and structural formula for all alkanes that contain up to 10 carbons
• Methane CH4 • Ethane CH3CH3
• Propane CH3CH2CH3
• Butane CH3CH2CH2CH3
• Pentane• Hexane• Heptane• Octane• Nonane• Decane• This is just the beginning……………………………………………………………..
You may have noticed that branching creates enormous variation
Try Naming TheseTry Naming These
CH3
CH2CH2
CH2CH2
CH2CH2
CH2CH2
CH3
Structural Isomers
• Substances with the same chemical formula by different arrangements of atoms
• Eg. Butane & 2 methyl-propane
***Isomers have different physical and chemical properties
TASK: Draw all the isomers for pentane and hexane
Did you know?• 3 isomers of pentane• 5 isomers of hexane• Heptane-9 • Octane-18 • Nonane-35 • Decane-75 • making a total of 150 different possible alkane
compounds containing 10 carbons.
C
C
C
CC H
HHH
H
H
HH H
H
Greater complexity exists because organic compounds can form Cyclic (ring) structures?
• Cyclic structures are circular• Have “cyclo” in name
• Eg. Cyclopropane Cyclopentane
CH2
CH2
CH2
TASK
• Study the following graphic.
• What 2 trends can be identified?
• Hypothesize why these trends exist.
• TASK 2: Compare, contrast and explain the physical properties of the first 10 alkanes
Background: formulas for HxCy
• CH single bonds Alkanes= CnH2n+2,
• CH with one double bond Alkenes= CnH2n,
• CH with two double bonds Alkynes= CnH2n-2
• Q - How many hydrogens in each of these:Alkane C6H
Alkene C22HCH3 CH3
Basic names of hydrocarbons• Hydrocarbon names are based on:
– 1) class – 2) # of C, – 3) side chain type – 4) position
Q - What names would be given to these:7C, 9C alkane2C, 4C alkyne1C, 3C alkene
heptane, nonaneethyne, butynedoes not exist, propene
Numbering carbonsQ- draw penteneA- Where’s the bond?
We number C atoms
• Always start numbering for the carbon nearest the double bond the lowest number
• Q - Name these
C C C CCH3
H
H
H
H H H
HCH31
C2
C3
C4
C5
H
H
H
H H H
HCH35
C4
C3
C2
C1
H
H
H
H H H
H
Ethene
3-nonyne
2-buteneCH3
CH
CH
CH3
CH3 CH3
C2H4
1-pentene
Multiple multiple bonds
• Rules• Give 1st bond lowest #• include di, tri, tetra, penta, etc. before ene/yne• Comma between #s, hyphen between #-letter
2,3-heptadieneCH3CH3
CH3
CH2CCCCCCCH32,4,6-nonatriyne
C C C C
H
H
H
H
H
H
CH3CH2CH2CH=C=CH2
CH2CCH
CHCH2
2-butyne
1,2-hexadiene1,2,4-pentatriene
Cyclic structuresQ- Draw these:
cyclobutene 1,3-cyclopentadiene cyclopropane
CH2
CH
CH2
CHCC
C CCH
H H
H
H H
CH2
CH2
CH2
CH3 CH3
CH3
CH3Naming side chains
• Names are made up of: side chains, root
• Root is the longest possible HC chain• Must contain multiple bonds if present• Add -yl to get name of side chain
• Common side chains include:CH3- methyl CH3CH2- ethyl
CH3CH2CH2- propyl (CH3)2CH- isopropyl
• 2,3-dimethylpentane
CH3 CH3
CH3
CH3
CH3CH
CH3
*
ene
Naming side chainsExample: use the rules on the bottom of
handout to name the following structure
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
Rule 1: choose the correct ending
ene
Rule 2: longest carbon chain
Naming side chains
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
1-hexene ene
Rule 3: attach prefix (according to # of C)
Naming side chains
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
Rule 4: Assign numbers to each carbon
1-hexene
Naming side chains
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
Rule 4: Assign numbers to each carbon
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
1-hexene 1-hexene
Naming side chains
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
Rule 5: Determine name for side chains
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
1-hexene 1-hexene
Naming side chains
ethyl
methyl
methyl
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
1-hexene2-ethyl-4-methyl-4-methyl-1-hexene
Naming side chains
ethyl
methyl
methyl
Rule 6: attach name of branches
Rule 7: list alphabetically
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
1-hexene2-ethyl-4-methyl-4-methyl-1-hexene
Naming side chains
ethyl
methyl
methyl
Rule 8,9: group similar branches
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
1-hexene2-ethyl-4-methyl-4-methyl-1-hexene
Naming side chains
ethyl
methyl
methyl
Rule 8,9: group similar branches
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
2-ethyl-4,4-dimethyl-1-hexene
Naming side chains
ethyl
methyl
methyl
Try Naming Side Chains
CH3 CH2
CH CH3
CH2CH2
CH3
CH3 CH
CH
CH3
CH
CH3
CH2 CH2 CH3
CH2 CH3
CH3CH2CH CH CH CH2CH CH3
CH3
CH2CH3
CH3 CH3
3-methylhexane4-ethyl-2,3-dimethylheptane
5-ethyl-2,4,6-trimethyloctane
Naming side chains
3-ethyl-2-methylpentane
3-ethyl-1,5,5-trimethylcyclohexene
CH3CH
CHCH2
CH3
CH3
CH2CH3
CH3 CH3
CH3CH3
Name the structures below
Try Drawing These2,2-dimethyloctane
1,3-dimethylcyclopentane
1,1-diethylcyclohexane
6-ethyl-5-isopropyl-7-methyl-1-octene
Try Naming Try Naming
CH3 CH3
CH3
CH3
CH3
CH3
Aromatic Hydrocarbons
• Aromatic compounds contain benzene ring structures and their derivatives.
• Benzene (C6H6)• most commonly used organic (nonpolar)
solvent• very stable substance, unreactive • toxic if inhaled -carcinogenic• produced by processing coal, crude oil,
gasoline or the combustion of rubber tires
• if it occurs as a side chain it is called a phenyl group
Resonance• The properties of this compound can be explained by following theory:
-the chemical bonds between carbon atoms are not single or double-all bonds between carbons in the benzene ring are identical in length and strength -there is an even distribution of valence electrons around the entire molecule.
• The resonance of the single and double bonds accounts for the stability of aromatic compounds.
• This is illustrated by resonance structures:
There are 2 naming methods1) Numbering carbons2) ortho, meta, para (stomp)
Aromatic nomenclature
CH3
Ortho
Para
ST Meta
CH3
CH3
CH3
CH3
CH3CH3
1,2-dimethylbenzeneorthodimethylbenzene
1,3-dimethylbenzenemetadimethylbenzene
1,4-dimethylbenzeneparadimethylbenzene