Cyclic Hydrocarbons Chemistry 11 Ms. Mcgrath

Cyclic Hydrocarbons Cyclic Hydrocarbons are hydrocarbon ring structures They occur when the ends of two hydrocarbon chains join together In order to do so, a hydrogen atom from each end carbon must be removed

Drawing - Cyclic Hydrocarbons Use a line diagram in a ring-like shape Each carbon-carbon bond is shown as a straight line Each corner ring represents a carbon atom Hydrogen atoms are not shown, but they are assumed to be present in the proper amounts

Naming - Cyclic Hydrocarbons Because of the ring structure, the naming rules for cyclic hydrocarbons are slightly different from those of straight chained hydrocarbons Here are four examples to name cyclic hydocarbons

Naming - Cyclic Hydrocarbons Example 1 Use the general formula: prefix + root + suffix Example: There are only single carbon-carbon bonds There are five corners (carbon atoms) in the ring There are no branches The name of this compound is: cyclopentane

Naming - Cyclic Hydrocarbons Example 2 When naming cycloalkanes, all carbon atoms are treated equally, meaning any carbon can be carbon number 1 In this example, only one branch is attached to the ring therefore the carbon that the branch is attached to is carbon number 1 Because the branch automatically get the gets the lowest position number no position number is required in the name The name of this compound is: methylcyclohexane

Naming - Cyclic Hydrocarbons Example 3 When there are two or more branches, each must have the lowest possible position number For this example, count the carbon with the ethyl group as carbon 1, then count in a counterclockwise direction This allows the branches to be in alphabetical order and to add position numbers in ascending order The name of this compound is: 1-ethyl-3-methylcyclohexane

Naming - Cyclic Hydrocarbons Example 4 There is a double bond here, therefore follow the same rules for alkenes (the double bond gets priority for the lowest number) One of the carbon atoms of the double bond must be carbon number 1 The branch must get the lowest number possible position number Here, the carbon on the bottom is carbon number 1, then we count counterclockwise so the carbon group containing the methyl group is carbon 3 The name of this compound is: 3-methylcyclohex-1-ene

Cyclic Hydrocarbons Complete #30, 31 Page 358