Nomenclature

L.O.:

Name simple hydrocarbons.

Draw the structural formula from a given hydrocarbon name.

Starter questions

1. What is a hydrocarbon?2. Draw and name these molecules:a. CH4

b. C2H6

c. C2H4

d. C2H2

e. C2H5OHf. C2H5Brg. C2H3 OOH3. What families, or groups of hydrocarbons do

each of these belong to?

Hydrocarbons are organic compounds hat contain carbon and hydrogen only.

Saturated hydrocarbon: single bonds only

Unsaturated hydrocarbon: multiple carbon-to-carbon bonds

Aliphatic hydrocarbon: carbon atoms joined together in straight or branched chains.

Alicyclic hydrocarbon: carbon atoms joined in a ring structure.

This compounds belong to the same family. How can you describe them?

CH3

OH

CH3

CH2

OHCH3CH2

CH2

OH

CH2

CH2

CH2

OHCH3 CH3CH2

CH2

CH2

CH2

OH

Homologous series: family of organic compounds, with the functional group, but different carbon chain length.

Homologous series:

Same general formula, e.g. CnH2n+2

Each member differs from the next by CH2

Similar chemical reactivity

Length of chain affects bp and mp

Task

• List the first 10 members of the alkanes homologous series.

Number of carbons

Name of alkane

Stem

1 Methane meth-

2 Ethane eth-

3 Propane prop-

4 Butane but-

5 Pentane pent-

6 Hexane hex-

7 Heptane hept-

8 Octane oct-

9 Nonane non-

10 Decane dec-

Functional group: part of the organic molecule responsible for its chemical properties.

Each carbon has a tetrahedral shape with a bond angle of 109.5 o

Naming alkanes

• The longest alkane chain provides the base, or STEM, of the name

• Additional details, like where particular groups are, are added onto this stem

So 3-bromoheptane, is a heptane molecule with a bromine atom attached onto the third carbon

Different groups that can be added to alkanes

• The simplest is the alkyl group – these are simply smaller branches of alkanes off the longest chain

• We can also add halogens, so chlorine atoms are included as chloro-, bromine as bromo-

• Others include alcohols, carboxyl groups, arenes and aldehydes

Adding numbers

• The number of certain groups is given with the greek number prefix (bit before)

So dimethylbutane has 2 methyl groups

The position of each group along the main chain is given with numbers, so

Naming branched chain molecules

1. First we find the longest chain in the molecule. This makes the stem of the molecule

Butane

Naming branched chain molecules

1. First we find the longest chain in the molecule. This makes the stem of the molecule

2. Then we count how many branches there are of each kind of alkyl group. E.g. Two methyl groups becomes dimethyl, three becomes trimethyl etc

2-Methylpentane

Naming branched chain molecules

1. First we find the longest chain in the molecule. This makes the stem of the molecule

2. Then we count how many branches there are of each kind of alkyl group. E.g. Two methyl groups becomes dimethyl, three becomes trimethyl etc

3. Order the alkyl groups in alphabetical order, ignoring the di-, tri-, tetra- info

4. Use number in front of each group to indicate where on the chain it is.

4-Ethyl-3-methylheptane

Naming branched chain molecules

1. First we find the longest chain in the molecule. This makes the stem of the molecule

2. Then we count how many branches there are of each kind of alkyl group. E.g. Two methyl groups becomes dimethyl, three becomes trimethyl etc

3. Order the alkyl groups in alphabetical order, ignoring the di-, tri-, tetra- info

4. Use number in front of each group to indicate where on the chain it is.

2,2-dimethylbutane

Task:1)Draw the following moleculesa)Butaneb)2,4-dimethylpentanec)2-ethyl-4-methylhexaned) 2-ethyl-3-methylbutanee) 3-butyl-4-ethyl-5-propyldecane

Name each of the following hydrocarbons

C

CH 3

C H

H

H

C

H

H

C

H

H

C

H

H

CH

H

H CH 3

CH2

CH 3

CC

H

C H

H

H

C

H

HH

C

H

H

CH

H

H CH 3

Adding double bonds

• The number goes in front of the –ene suffix (bit at the end)

e.g. pent-2-ene has the double bond after the second carbon atom

But-1-ene

Task:1)Draw the following molecules:a)2-methylbut-2-eneb)Hex-2-ene2) Name the following alkenes

C

CH 3

C H

H

H

C

H

HH

C

H

CH

H

H

C

CH 3

C

CH 3

C H

H

H

C

H

H

CH

HH

CH

H

H

C

CH 3

C

H

C

H

H

H

C

H

H H

CH H

CH H

C

H

CH

H

H

Practice questions

• Name the five different isomers of hexane

• Draw all of the different isomers of the following molecules and give the systematic names to all:

HeptaneOctaneNonane

Naming hydrocarbonsL.O.:

Use the terms homologous series and functional group.

Understand the terms hydrocarbon, saturated, unsaturated.

State that alkanes and cycloalkanes are saturated hydrocarbons.

Explain the tetrahedral shape around each carbon atom present in an alkane.

State the names of the first ten members of the alkane homologous series.