Introduction to Organic Chemistry: Nomenclature - Naming Organic Compounds Flashcards
Overview
- Count longest consecutive carbon chain and find prefix
- Look for functional groups and decide suffix
- Number functional groups if needed
- Look for side carbon branches and name them
- Number side carbon branches if needed
- Put name together
Count longest consecutive carbon chain find prefix
- Remember you can go in up, down, left or right (even diagonally in skeletal formula) when counting carbons
- Number carbon chain so lowest number possible is assigned to most important functional group
- Number of carbons should tell you prefix: meth, eth, prop, but
Look for functional groups and decide suffix
- Functional groups with higher priorities are put towards the end of the name of the compound
- Memorise priority list
Number functional groups if needed
- If there is more than one of the same functional group, state number of the carbon they are attached to
- Typically, number goes before functional group name
- 1, 3 - dichlorobutane
- Numbers separated by commas; numbers and words are separated by hyphens
- Use multipliers before functional group name and after position number to indicate how many times the functional group appears: di, tri, tetra, penta, hexa
Look for side carbon branches and name and number them
- If there are additional carbon branches that are not part of the longest consecutive chain, you must number and name them
- Branch or side chain is an alkyl group and have general formula of CnH2n+1
- Name them according to how many carbons are in a single side branch: methyl, ethyl, propyl
- Prefix same as alkanes but end in -yl instead of -ane
- Use multipliers if needed
- Provide which number carbon they are attached to
- 3 - methylpentane
Put name together
- Functional groups with higher priorities are put towards the end of the name of the compound
- Numbers typically come before functional group name
- Numbers are separated by commas
- Words and numbers are separated by hyphens
- Use suffix for most important functional group (and alkanes/alkenes)
- Use prefix for every other functional group
How do you add suffixes correctly?
• When using a suffix, add in the following way:
- If the suffix starts with a vowel- remove the –e from the stem alkane name
- e.g. Propan-1-ol, butan-1-amine, ethanoic acid, ethanoylchloride, butanamide
• If the suffix starts with a consonant or there are two or more of a functional group meaning di, or tri needs to be used then do not remove the the –e from the stem alkane name
- e.g. Propanenitrile, ethane-1,2-diol, propanedioic acid, propane-1,2,3-triol, Pentane-2,4-dione
Which functional groups have position numbers go in between the prefix and suffix?
• Alcohols
- These have the ending -ol and if necessary the position number for the OH group is added between the name stem and the –ol
- Butan-2-ol
• Ketones
- These have the ending -one and if necessary the position number for the ketone group is added between the name stem and the –one