Alkane Nomenclature

1
Alkane Nomenclature

• Find longest straight carbon chain
• The number of carbons gives the root name for the
  hydrocarbon
• (prefix)(ane)

• meth-
• eth-
• prop-
• but-
• pent-
• hex-
• hept-
• oct-
• non-
• dec-

• Number the carbons
• Name substituents

• Make name

(number)-(substituent)(prefix)(ane)
2
Examples

• Name all the structural isomers of C5H12
• Draw the structure for
• 2,3-dimethyl-4-isopropyloctane

3
Know

• meth-
• eth-
• prop-
• but-
• pent-
• hex-
• hept-
• oct-
• non-
• dec-

• Standard prefixes for 1-10
• The alkyl substituents
• Methyl, Ethyl, Propyl, Butyl
• Isopropyl and tert-Butyl

4
Cyclic Alkanes

• Carbon atoms can form rings
• However, remember bond angles are 109.5
• 3 and 4-membered rings are very strained,
  reactive
• 5 and 6-membered rings very common
• Named as before, but add prefix cyclo-

5
Example

• What is the systematic name of the following?

• If two alkyl groups could receive the same
  numbers, number them by alphabetical priority

6

• Cyclohexane needs to pucker to form a ring

Fig 21.6 pg 1022
7
Crude oil processing
8
Distillation tower at a refinery Chevron
Richmond Refinery
9
Alkenes

• Unsaturated hydrocarbons with a double bond

10

• C-C single bonds rotate around bond

• CC double bonds no rotation
• This leads to
• cis-trans isomers

11

• cis-2-butene
• trans-2-butene

12
Alkene Nomenclature

• Similar to alkanes, except
• Root hydrocarbon name ends in ene
• Location of the double bond is indicated
• add the lowest-numbered double-bound carbon
  before root name
• Give double bond the lowest possible numbers

1-butene
2-butene
13

• Draw the structure for 4-methyl-2-pentene.
• Correction This is the correct name for the
  structure. Ensure that the double bond has the
  lowest possible numbers.
• However, you can add cis- or trans-
• above trans-4-methyl-2-pentene
• cis-4-methyl-2-pentene ?

14
Cylic Alkene Nomenclature

• For cyclic alkenes, place double bond between C1
  and C2
• Dont need to indicate position of double bond in
  name
• Ex Draw 3-methylcyclohexene

4-ethylcyclopentene
No Hyphen
15
Alkynes

• Contain a triple bond
• Named like alkenes, except suffix yne
• Example Name the following

1 2 3 4
Give the triple bond the lowest possible number
4-ethyl-2-hexyne