Unsaturated Hydrocarbons Alkenes CHEMISTRY 11 MS. MCGRATH

Recall: Saturated hydrocarbons - Alkanes Have the maximum number of hydrogen atoms attached to each carbon atom Only contains single C–C bonds -ane suffix indicates an alkane compound with single bonds only Example: CH 3 –CH 2 –CH 3

Unsaturated Hydrocarbons Alkenes Hydrocarbons that contain one or more double bonds -ene suffix indicates these compounds have one or more double bonds Have the general formula C n H 2n to indicate the number of hydrogen atoms

Naming Alkenes Note: We are naming alkenes the new way – not like the textbook When the carbon chain of an alkene has four or more C atoms, number the chain to give the lowest number to the first carbon in the double bond. CH 2 =CH  CH 2  CH 3 but-1-ene CH 3  CH=CH  CH 3 but-2-ene CH 3  CH 2  C=C  CH 3 pent-2-ene

Naming Alkenes 1. Name the longest carbon chain that contains the double bond 2. Number the carbon chain starting from the end nearer the double bond 3. Give the location and name of each branch in alphabetical order 4. State the number of the first carbon with the double bond

Naming Alkenes Example: See page 346 in textbook. This name will be 3-ethyl, 2,2-dimethylhept-7-ene Complete # page 347

Cis-Trans Isomers See notes page 348 Complete #20 – 23 page 348 (Homework)