Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n
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Alkenes and Alkynes Contain C-C double and triple bonds General alkene formula C n H 2n PowerPoint PPT Presentation


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Alkenes and Alkynes Contain C-C double and triple bonds General alkene formula C n H 2n General alkyne formula C n H 2n-2 More reactive than alkanes Known as unsaturated hydrocarbons. H. H. H. C. C. H. Thermal cracking:

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Alkenes and Alkynes Contain C-C double and triple bonds General alkene formula C n H 2n

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Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

  • Alkenes andAlkynes

  • ContainC-C double and triple bonds

  • General alkene formula Cn H2n

  • General alkyne formula Cn H2n-2

  • More reactive than alkanes

  • Known as unsaturated hydrocarbons

H

H

H

C

C

H


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

  • Thermal cracking:

  • Process of breaking the long chain-alkanes found in petroleum into shorter chain alkanes and alkenes.

  • Multiple bonds are also formed by removing a

  • hydrogen chemically – dehydrogenation.

C C

C C

H

H

H

H

H

H

H

H

C C

C C

H

+ H2

H

H

+ H2

H

H

H

H

H


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

Alkenes / Alkynes are converted to alkanes by

hydrogenationoraddition reaction.


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

Naming Alkenes and Alkynes

  • Find parent chain with the double/triple bond.

  • Named as total carbons using ending ene / yne

  • Show the location of the bond by the carbon number separated with a hyphen. (2-pentene)

  • Number carbons from the end that gives the lowest

  • number to the double or triple bond.

  • Name alkyl branches as in alkanes.


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

ethene CH2= CH2

H

H

H

H

H

H

C ≡ C

C = C

H

H

H

H

ethyne CH ≡ CH

C

C

C

C

H

H


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

2-hexeneCH3CH=CHCH2CH2CH3

1

2

3

4

5

6

C - C - C - C

C - C =

3-hexyneCH3CH2C≡CCH2CH3

1

2

3

4

5

6

C ≡ C - C - C

C - C -


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

4-methyl-2-pentene

(4-methylpent-2-ene)

(Note, lowest number goes to the double bond)


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

CH3CH2CH(CH3)CH=C(C2H5)CH2CH3

7

6

5

4

3

2

1

3-ethyl-5-methyl-3-heptene

*Show double/triple bond in condensed formula.


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

Draw the structural formula for 1-butene.

CH2=CH–CH2–CH3

Draw a condensed for 2,5,5-trimethyl-2-hexene.

CH3C(CH3)=CHCH2C(CH3)2CH3

3

4

6

1

2

5


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

HC≡CCH2C(C2H5)2CH2CH(CH3)CH(CH3)CH3

1 2 3 4 5 6 7 8

4,4-diethyl-6,7-dimethyl-1-octyne


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

Draw a structural of 2,2,5,5-tetramethyl-3-hexyne.


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

  • Like Alkyl groups (trimethyl), prefixes and numbers must be used to indicate multiple double or triple bonds.

C = C – C = C

1,3-butadiene

4

1

2

3

C

3-methyl-1,4-pentadiyne

C ≡ C – C – C ≡ C

4

1

2

3

5


Alkenes and alkynes contain c c double and triple bonds general alkene formula c n h 2n

  • Alkenes: C=C, CnH2n , –ene.

  • Alkynes: C≡C, CnH2n-2 ,–yne.

  • Parent chain is numbered to give the double or triple bond the lowest number.

  • Draw the parent chain hydrocarbon with the double or triple bonds first.

  • Add in alkyl groups and then hydrogen so each

  • carbon has 4 bonds.


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