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The study of carbon-based compounds and their properties.
Historically the distinction between inorganic and organic substances was based on whether or not they were produced by living systems. It was believed that some sort of “life force” was needed to synthesize them.
In 1828, the German chemist Freidrich Wohler (1800-1882) prepared urea from the inorganic salt ammonium cyanate by simple heating.
NH4OCN H2N—C—NH2
O
urea
Hydrocarbons: contain only hydrogen and carbon
Hydrocarbons
Aliphatic Aromatic
Alkanes Alkenes Alkynes Cyclic
Hydrocarbons can be divided into different types, depending on their bonding.
Naming Organic Molecules
Alkanes - - Carbon chain, no double or triple bonds. All single bonds (saturated)
Alkenes - - Carbon chain, contains double bond(s) (unsaturated)
Alkynes - - Carbon chain, contains triple bond(s) (unsaturated)
Naming Organic Molecules
There are two parts to the main name of each molecule…
prefix: tells the # of carbons in main chain or ring
suffix: tells the type of bonding in the chain or ring
Prefix: indicates number of carbon atoms in the main chain or ring
1 meth-
2 eth-
3 prop-
4 but-
5 pent-
6 hex-
7 hept-
8 oct-
9 non-
10dec-
Suffix: indicates types of bonds present
Alkanes: (all single bonds) ___ -ane
Alkenes: (double bond) ___ -ene
Alkyne: (triple bond) ___ -yne
Saturated Hydrocarbons: the ALKANES: chains of carbon
connected by single bonds: contain only single C-C bonds
Saturated v. Unsaturated fats
Saturated with H
Single bonds are free to rotate, so these fats can pack tightly (solid @ room temp)
Which one is saturated?
For a bit of a demonstration… Good Eats fat train analogy
Watch episode from 1:30 to 5:00
ALKANES
ALKANES
ALKANESpropane, C3H8
ALKANESbutane, C4H10
ALKANESpentane, C5H12
ALKANEShexane, C6H14
ALKANESoctane, C8H18
Don’t write this example down, but watch to see where we’re going with this…
(Although you will be required to include the H’s if you take IB Chemistry)
“Normal” v. Branched
“normal” hydrocarbons are straight chains; no branching
Branched-chain hydrocarbons – isomers of “normal” hydrocarbons; have same formula, but different structures
n-butane
2-methlypropane
n-pentane
2-methylbutane
Are there any other pentane isomers?
Another branched alkane:
2,2-dimethylpentane
cyclopentane
Cycloalkanes
Cycloalkanes cyclobutane
Cycloalkanes ________________________
methyl-
ethyl-
1
2
3
3
2
1
green or red?
-ethyl- -methylcyclopentane1 3
Unsaturated Hydrocarbons: ALKENES – contain C-C double bonds
2-pentene
Unsaturated Hydrocarbons: ALKENES – contain C-C double bonds
2,4-hexadiene
Unsaturated Hydrocarbons: ALKYNES – contain C-C triple bonds
1-butyne
Unsaturated Hydrocarbons: ALKYNES – contain C-C triple bonds
3-ethyl-1-pentyne
Aromatic Hydrocarbons:
benzene – the simplest aromatic hydrocarbon; has a symmetrical ring structure
Aromatic Hydrocarbons:
benzene – can be drawn like this…
Derivatives of benzene:
1-ethyl-2-methylbenzene
Derivatives of benzene:
1,2-dimethyl-4-propylbenzene
For your homework:
If a halogen is attached, use the following prefixes:
fluoro- chloro-bromo-iodo-
(instead of methyl-, ethyl-, propyl-, etc.)