ALKENES AND ALKYNES

Alkenes contain one or more double bonds Alkynes contain one or more triple bonds Since alkenes and alkynes are NOT bonded to the maximum possible number of atoms, these compounds are often referred to as unsaturated hydrocarbons Boiling points and melting points: alkynes < alkenes < alkanes Reactivity: alkynes > alkenes > alkanes

alkenes are used to synthesize polymers because they are reactive alkynes are very unstable. As a result, they rarely occur in nature When naming these molecules, there are a few extra rules to follow:  your main chain must include double or triple bonds at lowest position number (indicate position #)  when numbering the main chain, double and triple bonds have priority over alkyl groups

The chemical formula of alkenes follows a general formula For example: C 2 H 4 =ethene C 3 H 6 =propene C 4 H 8 =butene C n H 2n ALKENES (C=C):

Name the following: pentene2-methyl-4- * double bonds have priority Location of double bond 

Name the following: hexene2-ethyl-3- * main chain must include double bond

Name the following: heptadiene2,5-methyl- 2- * 2 double bonds

Name the following: hexene3- 2,3,4- trimethyl-

Name the following: hexadiene1,3-isopropyl-3-

The chemical formula of alkenes follows a general formula For example: C 2 H 2 =ethyne C 3 H 4 =propyne C 4 H 6 =butyne C n H 2n-2 ALKYNES (C  C):

Name the following: octyne4-ethyl- 3- * ethyl before methyl methyl- 6-

CH 3 – C – CH – C  CH CH 3 CH 2 – CH 3 CH 3 C(CH 3 ) 2 CH(CH 2 CH 3 )C  CH Name the following: pentyne3-ethyl-4,4-dimethyl-

Draw the following: (a) 3-methyl-2-pentene C C –C =C–C – C H 3 H 3 H H 2 H 3

Try drawing this one on your own: (b) 2,5,7-trimethyl-5-propyl-3-octyne CH 3 CH 3 CH 3 CH 3 CH C C C CH 2 CH CH 3 CH 2 CH 2 CH 3

Cyclic Hydrocarbons

Cyclic hydrocarbons are hydrocarbon ring structures When naming these molecules, the cyclic structure is always the main chain Number the carbons, in either direction, so that the branches have the lowest possible position number Double bonds have priority over alkyl groups have the prefix “cyclo”

Name the following: (a) CH 3 CH 2 CH 3 CH 3 cyclohexane2,4-dimethyl1-ethyl CH 3 (b) cyclopentene3,4-dimethyl cyclopentene3,4-dimethyl Do not need to # double bond (it has to be between 1 & 2)

Draw the following: (a)3,3-diethyl-2-methylcyclopentene (b)2-ethyl-1,4-dimethylcyclohexane CH 3 CH 2 CH 3 CH

HOMEWORK WS “Naming and Drawing Alkenes” WS “Naming and Drawing Alkynes WS “Naming and Drawing Cyclic molecules”