You will see later that these same rules are used in assigning priorities for determining absolute configuration in chiral molecules H "A-2-butene The rules for assigning e-z designations are as follows: 1. rank atoms directly attached to the double bond according to their atomic 2. if there is a tie at any substituent, look at the second, third, etc until a difference is found 3. multiple bonds count as multiples of that same atom 4. if the highest priority groups are on the same side of the double bond, the molecule is Z; if the highest priority groups are on opposite sides the molecule is E (atomic numbers shown in red) H Z-2-b1000-2-butene Z-3-bromomethyl-4-methyl-2-pentene E- 3-methyl-1, 3-pentadiene H H2BrC, cH 6C 6 CHa CCM HHH HHE ,,,M, (these indicate the atoms attached to each of the atoms directly attached to the alkene) Alkenes: Addition oxidation reactions HBrYou will see later that these same rules are used in assigning priorities for determining absolute configuration in chiral molecules. The rules for assigning E-Z designations are as follows: 1. rank atoms directly attached to the double bond according to their atomic number 2. if there is a "tie" at any substituent, look at the second, third, etc., until a difference is found 3. multiple bonds count as multiples of that same atom 4. if the highest priority groups are on the same side of the double bond, the molecule is Z; if the highest priority groups are on opposite sides, the molecule is E Alkenes: Addition & Oxidation Reactions