4.1-4.2 alkenes
Alkenes
-hydrocarbons that contain a carbon-carbon double bond
?Why does an alkene have two less hydrogens than an alkane?
-two carbons have two bonds-they are an unsaturated hydrocarbon
-there is a double bond present
-used for many purposes in biology such as ethene which is used to control a plants growth
?Why are they considered unsaturated?
-they have fewer than the maximum number of hydrocarbons because the double bonded carbons are in the way(remember carbon can only be bonded to 4 things)
Nomenclature of alkenes
-reminder-the functional group is the center of reactivity in a molecule
?What is an example of a functional group in an alkene?
-the double bond
-replace the suffix –ane with –ene
Name the following alkenes:
Naming Rules
1.The longest continuous chain containing the functional group(double bond) is number in the direction that gives the functional group suffix the lowest possible bond
Name the following
2.Name of substituent is cited before the name of the longest continuous chain BUT if the there is a functional group suffix and a substituent, the functional group suffix gets the lowest possible number
Name the following
3.If a chain has more than one double bond, we first identify the chain that contains all the double bonds by its alkane name, replacing the “ane” ending with the appropriate suffix diene, triene ect…You want to number the chain in the direction that yields the lowest number in the name of the compound.
Name the following:
4.List substituents cited in alphabetical order AND try to name having the lowest substituent numbers
Name the following
5.A number is NOT needed IN THE FORMAL NAME to denote the position of the double bond in a cyclic alkene because the ring is always numbered so that the double bond is between carbons 1 and 2
Name the following
6.Numbers are needed if the ring has more than one double bond
Name the following
1,4-cyclohexadiene 2-methyl-1,3-cyclopentadiene