Systemetic names

• Scheikunde
• Middelbare school
• havo, vwo
• Leerjaar 3

7.2 systematic naming

alkanes

Alkanes are saturated hydrocarbons

Their general formula is C_nH_2n+2

alkenes

Alkenes are unsaturated hydrocarbons. 

Their general formula is C_nH_2n

Naming

It is best to learn the first six unbranched alkanes by heart.

Branches end with -yl in stead of  -ane.

Steps nomeclature

1 Find the longest unbranched chain of carbonatoms.

2 Find the branches

3 Number the branches by location

Systematic naming

Step 1: Find thee longest chain of C-atoms.

Systematic naming

Step 1: Find thee longest chain of C-atoms.

Systematic naming

Step 1: Find thee longest chain of C-atoms.

Systematic naming

Step 2: Name the longest chain of C-atoms (main chain).

5 C = pentane 

                                   pent- = stem name

                                     -ane = suffix

Systematic naming

Step 3: Find the side chains and count their length in C's 

side chains: Alkyl-groups

Systematic naming

Step 3: Find the side chains and count their length in C's 

Systematic naming

Step 4: Side chains use the same stem name but another suffix -yl

(methyl) 

side chains are alkyl

methylpentane

Systematic naming

Step 5: Count the same side chain and add a prefix.

(mono is left out often)

Systematic naming

Step 5: Count how many of the same side chain.

(mono is left out often)

So we get: dimethyl

For the side chain we put a prefix:

dimethylpentaan 

Systematic naming

Step 6: number the C atoms in the main chain to give the side chains the lowest possible numbers.

Systematic naming

Step 7: put the number before the prefix

- Numbers are separated with a ,

- Numbers and letters are separated

with a -

Dus: 2,3-dimethylpentane

 

2,3-dimethylpentane

Done

Name this structural
formula

1. No clue
2. 3,3,4-trimethylpentane
3. dimethylhexane
4. 2,3,3-trimethylpentane

Which is the right systematic name?

1. 4-methylhexane
2. 1,3-dimethylpentane
3. 3-methylhexane
4. heptane

Isomers

Isomers are substances with the same molecular formula but a different structural formula.