Chapter 22Chapter 22Organic and Biological Organic and Biological

ChemistryChemistry

Organic ChemistryOrganic Chemistry• The chemistry of carbon

compounds.• Carbon has the ability to form

long chains.• Without this property, large

biomolecules such as proteins, lipids, carbohydrates, and nucleic acids could not form.

HydrocarbonsHydrocarbons• Four basic types:

o Alkaneso Alkeneso Alkyneso Aromatic

hydrocarbons

AlkanesAlkanes

• Only single bonds.• Saturated hydrocarbons.

o “Saturated” with hydrogens.

FormulasFormulas• Lewis structures of alkanes look like

this.• Also called structural formulas.• Often not convenient, though…

FormulasFormulas…so more often condensed formulas are

used.

Properties of AlkanesProperties of Alkanes

• Only van der Waals force: London force.• Boiling point increases with length of chain.

IsomersIsomers

Have same molecular formulas, but atoms are bonded in different order.

Organic NomenclatureOrganic Nomenclature• Three parts to a compound name:

o Base: Tells how many carbons are in the longest continuous chain.

Organic NomenclatureOrganic Nomenclature• Three parts to a compound name:

o Base: Tells how many carbons are in the longest continuous chain.

o Suffix: Tells what type of compound it is.

Organic NomenclatureOrganic Nomenclature• Three parts to a compound name:

o Base: Tells how many carbons are in the longest continuous chain.

o Suffix: Tells what type of compound it is.o Prefix: Tells what groups are attached to

chain.

Bases(Parent)Bases(Parent)

BranchesBranches

To Name a Compound…To Name a Compound…1. Find the longest chain

in the molecule(base).

2. Number the chain from the end nearest the first substituent(branch) encountered.

3. List the branches as a prefix along with the number(s) of the carbon(s) to which they are attached.

To Name a Compound…To Name a Compound…4.If there is more

than one type of branch in the molecule, list them alphabetically. Use prefixes,di-, tri-, to indicate multiple branches.

Example 1: Example 1: 2,2-2,2-dimethylpentanedimethylpentane

• The parent chain is indicated by the ROOT of the name - “pentanepentane”. This means there are 5 carbons in the parent chain.

CH3

CH2CH2

CH2CH3

• “dimethyldimethyl” tells us that there are TWO methyl branches on the parent chain. A methyl branch is made of a single carbon atom.

• “2,22,2-” tell us that BOTH methyl branches are on the second carbon atom in the parent chain.

CH31

CCH23

CH24

CH35

CH3

CH3

1

2

3

4

5

Example 2: Example 2: 3-ethyl-2,4-3-ethyl-2,4-

dimethylheptanedimethylheptane• The parent chain is

indicated by the ROOT of the name - “heptaneheptane”. This means there are 7 carbons in the parent chain.

CH3

CH2CH2

CH2CH2

CH2CH3

• “2,4-dimethyl2,4-dimethyl” tells us there are TWO methyl branches on the parent chain, at carbons #2 and #4.

• “3-ethyl3-ethyl-” tell us there is an ethyl branch (2-carbon branch) on carbon #3 of the parent chain.

1

2

3

4

5

76

CH3

CHCH

CHCH2

CH2CH3

CH2CH3

CH3 CH3

Example 3: Example 3: 2,3,3-trimethyl-4-2,3,3-trimethyl-4-

propyloctanepropyloctane• The parent chain is

indicated by the ROOT of the name - “octaneoctane”. This means there are 8 carbons in the parent chain.

• “2,3,3-trimethyl2,3,3-trimethyl” tells us there are THREE methyl branches - one on carbon #2 and two on carbon #3.

• “4-propyl4-propyl-” tell us there is a propyl branch (3-carbon branch) on carbon #4 of the parent chain.

1

2

34

5

7

6

8

1

23

45

7

6

8

CHC

CHCH2

CH2

CH2CH3

CH3

CH3

CH3

CH3CH2

CH2

CH3

Example 4: Name the Example 4: Name the

molecules shown!molecules shown!• parent chain has 5 carbons

- “pentane”• two methyl branches -

start counting from the right - #2 and #3

• 2,3-dimethylpentane2,3-dimethylpentane

CH3

CH2CH

CHCH3

CH3

CH3

• parent chain has 8 carbons - “octane”

• two methyl branches - start counting from the left - #3 and #4

• one ethyl branch - #5• name branches alphabetically

3,4-dimethyl3,4-dimethyl

4433

octaneoctane

55

5-ethyl-5-ethyl-

CycloalkanesCycloalkanes• Carbon can also form ringed structures.• Five- and six-membered rings are most

stable.o Can take on conformation in which angles are

very close to tetrahedral angle.o Smaller rings are quite strained.

AlkenesAlkenes

• Contain at least one carbon–carbon double bond.

• Unsaturated.o Have fewer than maximum number of

hydrogens.

Structure of AlkenesStructure of AlkenesThis creates geometric isomers, which differ from each other in the spatial arrangement of groups about the double bond.

Nomenclature of AlkenesNomenclature of Alkenes• Chain numbered so double bond gets smallest

possible number.• cis- alkenes have carbons in chain on same

side of molecule.• trans- alkenes have carbons in chain on

opposite side of molecule.

AlkynesAlkynes

• Contain at least one carbon–carbon triple bond.

• Carbons in triple bond sp-hybridized and have linear geometry.

• Also unsaturated.

Nomenclature of AlkynesNomenclature of Alkynes

• Analogous to naming of alkenes.• Suffix is -yne rather than –ene.

4-methyl-2-pentyne

Aromatic HydrocarbonsAromatic Hydrocarbons

• Cyclic hydrocarbons.• Molecule is planar.• Many aromatic

hydrocarbons are known by their common names.

Structure of Aromatic Structure of Aromatic CompoundsCompounds

• Two substituents on a benzene ring could have three possible relationshipso ortho-: On adjacent carbons.o meta-: One carbon between them.o para-: On opposite sides of ring.

Functional Functional GroupsGroups

Term used to refer to parts of organic molecules where reactions tend to occur.

AlcoholsAlcohols• Contain one or more hydroxyl groups, —OH

• Named from parent hydrocarbon; suffix changed to -ol and number designates carbon to which hydroxyl is attached.

EthersEthers

• Tend to be quite unreactive.• Therefore, they are good polar

solvents.

Carbonyl CompoundsCarbonyl Compounds• Contain C—O

double bond.• Include many

classes of compounds.

AldehydesAldehydesAt least one hydrogen attached to carbonyl carbon.

KetonesKetonesTwo carbons bonded to carbonyl carbon.

Carboxylic AcidsCarboxylic Acids• Have hydroxyl

group bonded to carbonyl group.

• Tart tasting.• Carboxylic acids

are weak acids.• Naming:

_____oic acid

CH3COOH

Carboxylic AcidsCarboxylic Acids

EstersEsters• Products of

reaction between carboxylic acids and alcohols.

• Found in many fruits and perfumes.

butanoate

AminesAmines• Organic bases.• Generally have strong, unpleasant

odors.

AmidesAmidesFormed by reaction of carboxylic acids with amines.This is the reaction that occurs between amino acids