Naming Organic Molecules

Organic molecules are named using the number of carbons they contain, and the functional groups that the molecule contains. As carbon can form 4 bonds there is a huge number of molecules that can be formed. Organic molecules derive their properties from the functional group of that molecule. The number of carbons is denoted by using prefixes, the functional groups are denoted by suffixes.

Prefixes for the carbons in a chain 1.Meth- 2.Eth- 3.Prop- 4.But- 5.Pent- 6.Hex- 7.Hept- 8.Oct- 9.Non- 10.Dec- Prefixes enumerating the number of side chains 1.N/A 2.di- 3.tri- 4.tetra- 5.penta-

Functional groups NameFunctional groupGroup general formula Naming suffix Branch chain-yl Alkane-C-C-C n H 2n+2 -ane Alkene-C=C-C n H 2n -ene Alkyne-C=C-C n H 2n-2 -yne Haloalkane-X eg. -Cl -Br -IR-XHalo- -ane. Alcohol-OHR-OH-anol Carboxylic Acid-COOHR-COOH-anoic acid Ester-COO-R-COO-R’-yl -anoate

1.Identify functional group 2.Count the number of Carbons in the longest chain 3.Name main chain 4.Count the carbon that the functional group is attached to and place this in between the prefix and the suffix Applying names

5.Identify branch chains 6.Count carbons in branch chain(s) 7.Put the branch chain name in front the main chain name 8.Count to which carbon the branch chain is attached to (make sure it’s the lowest number possible- count from both ends) 9.Put the number of the carbon in front of the branch chain name.

10.Where there are multiple branch chains use the branch chain prefixes to indicate how many there are of that type of chain 11.Number the carbons of the branch chains to achieve the lowest possible numbers. All carbons must be numbered from the same end 12. Assemble your molecule name!

Naming organic molecules - summary 1.Identify functional group 2.Name main chain – Number of carbons + functional group + poistion 3.Name branch chain(s) – Number of carbons in chains – Number of each type of chain – Which carbon the chain attaches to

Naming organic molecules - examples 1.Identify functional group 2.Name main chain – Number of carbons – functional group – Position of functional group 3.Name branch chain(s) – Number of carbons in chains – Number of each type of chain – Which carbon the chain attaches to 1.Double bond = alkene 2.Name main chain – 8carbons – -ene – 2 nd carbon – Oct-2-ene 3.Name branch chain(s) – No branch chain –.

Naming organic molecules - examples 1.Identify functional group 2.Name main chain – Number of carbons – functional group – Position of functional group 3.Name branch chain(s) – Number of carbons in chains – Number of each type of chain – Which carbon the chain attaches to 1.Carboxyl group on end = carboxylic acid 2.Name main chain – 8 carbons – -anoic acid – At end – Octanoic acid 3.Name branch chain(s) – No branch chain –.

Naming organic molecules - examples 1.Identify functional group 2.Name main chain – Number of carbons – functional group – Position of functional group 3.Name branch chain(s) – Number of carbons in chains – Number of each type of chain – Which carbon the chain attaches to 1.Hydroxyl group - alcohol 2.Name main chain – 5 carbons – -anol – 1 st or 5 th carbon – Pentan-1-ol 3.Name branch chain(s) – No branch chain –.

Naming organic molecules - examples 1.Identify functional group 2.Name main chain – Number of carbons – functional group – Position of functional group 3.Name branch chain(s) – Number of carbons in chains – Number of each type of chain – Which carbon the chain attaches to 1.Carboxyl group in the middle - ester 2.Name main chain =O side – 5 carbons – Double bonded O side – Pentanoate 3.Name branch chain(s) – 3 carbons – Singly bonded O side – Propyl – Propyl propanoate

Naming organic molecules - examples 1.Identify functional group 2.Name main chain – Number of carbons – functional group – Position of functional group 3.Name branch chain(s) – Number of carbons in chains – Number of each type of chain – Which carbon the chain attaches to 1.Hydroxyl group at the end - alcohol 2.Name main chain – 6 carbons – OH at the end – Hexan-1-ol 3.Name branch chain(s) – 1 carbon – Attached to 4 th carbon – 4-Methyl-hexan-1-ol

Haloalkanes Haloalkanes are alkanes with a halogen attached to the chain The alkane is named with the halogen and the alkane name eg. Bromo-pentane The number of the carbon to which the halogen is attached used to denote which isomer of bromo-pentane it is eg. 3-bromo- pentane, 1-bromo-pentane

Geometric isomers - cis and trans In alkenes the double bond fixes the position of side groups and branch chains relative to the functional group (the double bond) If the groups are on the same side, the molecule is prefixed with cis When the groups are on different sides the groups are prefixed with trans