Nomenclature of Alkanes and the IUPAC System
IUPAC System
- Name of an alkane with an unbranched chain of carbon atoms
- Prefix that indicates the number of carbon atoms
- Suffix -ane to show that the compound is a saturated hydrocarbon (alkane)
- Name of an alkane with a branched chain
- Parent name that indicates the longest chain of carbon atoms in the compound
- Substituent names that indicate the groups bonded to the parent chain
- Give each substituent a number to indicate the carbon atom to which the substituent is bonded - use a hyphen to connect the number to the name
- If there's one substituent, number the parent chain from the end that gives the substituent the lower number
- If there are two or more identical substituents, number the parent chain from the end that gives the lower number to the substituent encountered first
- The number of times the substituent occurs is indicated by the prefix di, tri, etc; use a comma to separate position numbers
- If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first
- If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent that comes first in the alphabet the lower number
- Alphabetize the name of the constituents and then add the prefixes di, tri, etc
- When there are two or more parent chains of equal length, choose the parent chain with the greater number of constituents
- Alkyl group: a substituent group derived from an alkane by the removal of a hydrogen atom
- Commonly represented by the symbol R-
- Named by dropping the -ane and adding -yl
- Substituents with unbranched chains are named by replacing the -ane with -yl
General IUPAC System
- The name given to any compound with a chain of carbon atoms consists of 3 parts: prefix, infix, and suffix
- Prefix: indicates the number of carbon atoms in the parent chain
- Infix: indicates the nature of the carbon-carbon bonds in the parent chain
- -an-:all single bonds
- -en-: one or more double bonds
- -yn-: one or more triple bonds
- Suffix: indicates the class of the compound
- -e: hydrocarbon
- -ol: alcohol
- -al: aldehyde
- -one: ketone
- -oic acid: carboxylic acid
Classification of Carbon and Hydrogen Atoms
Primary carbon: carbon bonded to one carbon
Secondary carbon: carbon bonded to 2 carbons
Tertiary carbon: carbon bonded to 3 carbons
Quaternary carbon: carbon bonded to 4 carbons
Primary hydrogen: hydrogen bonded to a primary carbon
Secondary hydrogen: hydrogen bonded to a secondary carbon
Tertiary hydrogen: hydrogen bonded to a tertiary carbon
Quaternary hydrogen: hydrogen bonded to a quaternary carbon