1 Alkenes

2 Alkanes:C n H 2n+2 saturated hydrocarbons Alkenes:C n H 2n unsaturated hydrocarbons ethene (ethylene) propene (propylene) 2-methylpropene (isobutylene) chloroethene (vinyl chloride)  -pinene (turpentine) oleic acid (a monounsaturated fatty acid)

3 Nomenclature alkenes:parent chain contains C=C C=C gets lowest numbers position of C=C indicated by lower of the two numbers 1-butene 4-methyl-1-butene 3-bromocyclohexene

4 Nomenclature polyenes:alkadiene, alkatriene, etc. 1,3-butadiene 5,5-dimethyl-1,3-cyclopentadiene bicyclo[2.2.1]-2,5-heptadiene

5 Nomenclature C=C and OH: alkenol higher priority group (OH) gets last suffix and lowest number 2-propen-1-ol 5-methyl-4-hexen-2-ol 2-cyclohexenol

6 Nomenclature as side groups: ethenyl (vinyl) 2-propenyl (allyl) 1-methylethenyl (isopropenyl) methylene vinyl chloride allyl alcohol isopropenyl bromide Examples 1-vinylcyclohexene methylenecyclopentane

7 Nomenclature Question. Give IUPAC names for the following compounds. To check your answers, click on the arrow.

8 Nomenclature Geometric isomers: cis and trans geometric isomers cis-2-butenetrans-2-butene

9 Nomenclature Geometric isomers: cis and trans cis trans cis cis, trans

10 Nomenclature E-Z notation The cis and trans designations apply only when there are two groups. cis, trans??

11 Nomenclature E-Z notation (E)-3-chloro-2-pentene(Z)-3-chloro-2-pentene 1.Determine the higher priority group on each end of the alkene. 2.If the higher priority groups are: on opposite sides: E (entgegen = opposite) on the same side: Z (zusammen = together) CH 3 > H Cl > CH 2 CH 3

12 Nomenclature E-Z notation Priority Rules: 1.look at the first atom attached to the alkene carbon 2.higher atomic number = higher priority 3.if same atomic number, higher atomic mass = higher priority (e.g., D > H, 13 C > 12 C, etc.) 4.if atoms are identical, examine next atoms along chain and apply rules 2 and 3. (H,H,H)(C,H,H)(C,C,H)(C,C,C) (Cl,H,H) Look for higher atomic number at first point of difference.

13 Nomenclature E-Z notation Priority Rules: 5.multiple bonds: treat each  bond as if it were another single bond to that type of atom

14 Nomenclature Question. Designate each double bond as E or Z, where applicable. Click on the arrow to check your answers. geraniol