Organic Chemistry

“The most important hypothesis in all of

biology…is that everything that animals do,atoms do. In other words, there is nothingthat living things do that cannot be understood from the point of view that they are made of atoms acting according to the laws of physics.”

Richard Feynman (1918-1988)

Organic Chemistry and Hydrocarbons“Organic” originally referred to any

chemicals that came from organisms

1828 - German chemist Friedrich Wohler synthesized urea in a lab

Today, organic chemistry is the chemistry of virtually all compounds containing the element carbon

Allotropes of carbonCarbon exists naturally in three

forms: Graphite

Diamonds

Fullerenes

Organic Chemistry and Hydrocarbons

Over a million organic compounds, with a dazzling array of properties

Why so many? Carbon’s unique bonding ability!

Organic Compounds

Contain carbon

Have covalent bonds

Have low melting points

Have low boiling points

Burn in air (oxygen)

Are soluble in nonpolar solvents

Form large molecules

Alkanes

Contain C and H only

Contain single bonds C-C

Have 4 bonds to every carbon (C) atom

Are nonpolar

Straight chain alkanes:Contain any number of carbons atoms, one

after the other, in a chain. Each carbon atoms is bonded to 1 or 2 other carbon atoms.

Complete Structural FormulasShow the bonds between each of the atoms H H H C H H C H

H H

CH4 , methane

More Alkanes H H Condensed Structural

Formulas

H C C H CH3 CH3

H H Ethane

H H H

H C C C H CH3 CH2 CH3

H H H Propane

IUPAC NamesName # carbons Structural

Formula

Methane 1 CH4

Ethane 2 CH3CH3

Propane 3 CH3CH2CH3

Butane 4 CH3CH2CH2CH3

Pentane 5 CH3CH2CH2CH2CH3

IUPAC NAMESName # carbons Structural Formula

Hexane 6 CH3CH2CH2CH2CH2CH3

Heptane 7 CH3CH2CH2CH2CH2CH2CH3

Octane 8 CH3CH2CH2CH2CH2CH2CH2CH3

Nonane 9 CH3 CH2 CH2CH2CH2CH2CH2CH2CH3

Decane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

Learning Check Alk1A. What is the condensed formula

for H H H H

H C C C C H

H H H H

B. What is its molecular formula?C. What is its name?

Solution Alk1A. CH3CH2CH2CH3

B. C4H10

C. butane

Reactions of AlkanesCombustion

alkane + O2 CO2 + H2O + heat

Combustion In the CellMetabolic oxidation is combustion

C6H12 O6 + 6O2 6CO2 + 6H2O +

heat

glucose

Learning Check Alk2

Complete the combustion reaction for

C3H8 + O2 +

Balance your equation

Solution Alk2Step 1

C3H8 + O2 CO2 + H2O

Step 2

C3H8 + O2 3 CO2 + 4 H2O

Step 3

C3H8 + 5 O2 3 CO2 + 4 H2O

Learning Check Alk3Complete and balance the reaction for the complete combustion of C7H16

Solution Alk3Step 1

C7H16 + O2 CO2 + H2O

Step 2

C7H16 + O2 7 CO2 + 8 H2O

Step 3

C7H16 + 11 O2 7 CO2 + 8 H2O

Occur when a carbon atoms bonds with three or four carbon atoms.

Branched chain alkanes:

Substituents: take place of a hydrogen atom on a parent hydrocarbon.

Branched chain alkanes:

c c c c c c c c c c c c c

Parent alkane (propane)

Parent alkane (hexane)

substituent

Hydrocarbon substituentsAre called alkyl groupName ending with –ylMethyl group (CH3-)

Ethyl group (CH3CH2-)

Propyl group (CH3CH2CH2-)

Rules for naming branched alkanes1. Find the longest chain of carbons in the molecule

or parent chain. (not necessarily a straight line)

2. Number the carbons in parent chain. Start at the end that will give the groups attached to the chain the smallest numbers.

3. Identify with numbers the positions of the substituents on the chain.

4. Use prefixes to indicate the appearance of the same group more than once: di- (twice), tri- (three times)5. List the names of the substituents groups in alphabetical order.

6. Commas separate numbers, hyphens separate numbers and words. Name is written without spaces

Ex. 1 Name the following alkane:

CH3 CH2 CH CH3

CH3

1. Choose parent chain and name it

butane

1 2 3 4

4 3 2 12. Number parent chain in a way that substituents have smallest numbers.

3. Identify position of substituent group and name it.

2- methyl (located in carbon 2)

4. Not applicable

5. List substituent groups in alphabetical order. 2-methyl

6. Separate letters and numbers with hyphen

Ex.2 CH3 CH CH2 CH2 CH3

CH2

CH3

Ex.2 CH3 CH CH2 CH2 CH3

CH2

CH3

Parent alkane

Does not have to be a straight line, only longest chain.

Name of parent alkane: hexane

Ex.2 CH3 CH CH2 CH2 CH3

CH2

CH3

Number Parent alkane

Number in way that substituent group has smallest number.

Name and position of substituent group: 3-methyl

1

3 5 6

2

4

Ex.2 CH3 CH CH2 CH2 CH3

CH2

CH3

Name of organic compound

3-methylhexane

1

3 5 6

2

4

Cw p 226 #1

Writing structural formulas:1. Write the complete structural formula for 2,2-dimethylpropane

Writing structural formulas:1. Write the complete structural formula for 2,2-dimethylpropane

Write only the carbons first. Start with the parent alkane.

2,2-dimethylpropane

C C C

Writing structural formulas:1. Write the complete structural formula for 2,2-dimethylpropane

Number the parent alkane from left to right.

C C C 1 2 3

Writing structural formulas:

Identify the substituent groups and their position:

CH3

C C C

CH3

1 2 3

1. Write the complete structural formula for 2,2-dimethylpropane

2,2-dimethylpropane There are two (di) methyl groups (CH3-) in

carbon #2

Writing structural formulas:

Add the necessary hydrogen bonds so that each carbon has a maximum of 4 bonds.

H CH3 H

H C C C H H H CH3

1. Write the complete structural formula for 2,2-dimethylpropane

Classwork p226 #2,3

IsomersAre compounds that have the same molecular

formula but different structural formulas.Have different physical properties, like boiling point

and melting point and different chemical reactivities.

Ex. C4H10 CH3 CH2 CH2 CH3

butane

CH3 CH CH3

CH3

2-methylpropane

ClassworkDraw and name the isomers for the organic

compounds with the following molecular formulas:

a)C5H12 (3 different structures)

b) C6H14 (5 different structures)