Functional Groups and IUPAC Flashcards
What are the 3 primary rules of naming an organic compound according to the IUPAC nomenclature scheme?
- Identify the molecule’s principal functional group and find the longest carbon chain containing that functional group.
- Number the carbon chain from one end such that the principal functional group receives the lowest possible number.
- Name all other functional groups according to this numbering scheme.
What is the prefix for carbon chains consisting of:
- 1 carbon?
- 2 carbons?
- 1 carbon = “meth-“
- 2 carbons = “eth-“
What is the prefix for carbon chains consisting of:
- 3 carbons?
- 4 carbons?
- 3 carbons = “prop-“
- 4 carbons = “but-“
What is the prefix for carbon chains consisting of:
- 5 carbons?
- 6 carbons?
- 5 carbons = “pent-“
- 6 carbons = “hex-“
What is the prefix for carbon chains consisting of:
- 7 carbon?
- 8 carbons?
- 7 carbon = “hept-“
- 8 carbons = “oct-“
What is an alkane?
An alkane is an organic molecule consisting of nothing but carbon and hydrogen atoms, connected with only single bonds.
All alkanes are named with an -ane suffix, with the prefix determined by the number of carbons in the chain. The three carbon chain below is called propane.
What is the name of this molecule?
This molecule is named pentane.
To name an alkane, identify the prefix based on the number of carbons in the chain containing the largest functional group, then attach the -ane suffix.
What is the name of this molecule?
This molecule is iso-butane, or 2-methyl-propane.
Historically, alkane chains which are branched at the very end have been named with the iso- prefix. While this may show up in passages, it is very rarely tested on the MCAT, since IUPAC has moved away from that old naming convention into the new system.
What is an alkene?
An alkene is an organic molecule consisting of nothing but carbon and hydrogen atoms, containing at least one carbon-carbon double bond.
All alkenes are named with an -ene suffix, with the prefix determined by the number of carbons in the chain. The molecule below is propene.
What is the name of this molecule?
This molecule is named 2-butene.
To name an alkene, identify the prefix based on the number of carbons in the chain containing the largest functional group, then attaching the -ene suffix, along with the number of the lowest-numbered carbon participating in the double bond.
What is an alkyne?
An alkyne is an organic molecule consisting of nothing but carbon and hydrogen atoms, containing at least one carbon-carbon triple bond.
All alkynes are named with an -yne suffix, with the prefix determined by the number of carbons in the chain. The molecule below is propyne.
What is the name of this molecule?
This molecule is named 1-butyne.
To name an alkyne, identify the prefix based on the number of carbons in the chain containing the largest functional group, then attaching the -yne suffix, along with the number of the lowest-numbered carbon participating in the triple bond.
What is the principal functional group in this molecule?
The amine -NH2 is the principal functional group.
In this molecule, 1-propanamine, -NH2 is the only functional group attached to the main carbon chain.
What is the principal functional group in this molecule?
The -OH group is the principal functional group.
In general, oxygen-containing groups take priority in nomenclature, and the more bonds to oxygen in the functional group, the higher its priority. This molecule, 1-amino-2-propanol, has the -ol ending to indicate highest priority even though the amino group is on the 1 carbon.
At what position does the highest-priority functional group reside in this molecule?
The -OH is on the 1 carbon position.
By definition, the chain is numbered to give the highest priority functional group the lowest possible number. Hence any time a group is at the end of the chain, it is in the 1 position by default. This would always be called 1-butanol, never 4-butanol.
At what position does the highest-priority functional group reside in this molecule?
The highest priority group is on the 2 carbon position.
Remember: oxygen-containing functional groups take priority over nitrogen-containing groups. The chain is numbered so that the -OH group resides at the lowest possible numerical position, making this a 4-amino-2-butanol molecule.
At what position does the Cl group reside in this molecule?
The Cl is on the 3 carbon position in this molecule.
By definition, the chain is numbered so that the highest-priority functional group gets the lowest possible number. In this molecule, 3-chloro-1-butanol, the -OH must be position 1 by default.
At what position does the Cl group reside in this molecule?
The Cl group is on the 3 carbon position.
When it comes to cyclic carbon chains, still number so that the highest priority group gets the lowest possible number, by default this is 1. Then, label in whichever direction results in the lowest possible number for the remaining functional groups. This molecule is 3-chlorocyclohexanol and would never be called 5-chlorocyclohexanol.
What is an alcohol?
An alcohol is an organic molecule which has an -OH as the highest-priority functional group.
All alcohols are named with an -ol suffix, with the prefix determined by the number of carbons in the chain. The molecule below is propanol.