alkenes and alkynes
TRANSCRIPT
Identify!
3-sec-butyl-1,1-dimethylcyclopentane
Identify!
4-ethyl-2-isopropylbicyclo[4.1.0]heptane
Identify!
2,6,6-trimethylbicyclo[3.1.1]heptane
Alkenes and Alkynes
Aliphatic
Saturated
Alkanes
Unsaturated
Alkenes Alkynes
Classification of Organic Compounds
Alkenes• compounds that contain carbon and
hydrogen and have at least one C C ‑double bond.• low melting and boiling point,
insoluble in water, relatively reactive• Molecular formula is CnH2n
Important Alkenes
Ethylene (ethene)
α-Pinene
cis-tricos-9-ene, ‘‘muscalure’’
Alkene NomenclatureSimple alkenes are named much like
alkanes, using the root name of the longest chain containing the
double bond.
Ethylene (ethene)
Alkene Nomenclature• When the chain contains more
than three carbon atoms, a number is used to give the location of the double bond.
• The chain is numbered starting from the C closest to the double bond, and the double bond is given the lower number of its two double-bonded carbon atoms.
1-butenebut-1-ene
Alkene Nomenclature
Cycloalkenes are assumed to have the double bond in the number 1 position.cyclohexene
Alkene Nomenclature• A compound with two
double bonds is a diene. A triene has three double bonds, and a tetraene has four.
• Numbers are used to specify the locations of the double bonds.
1,3-butadienebuta-1,3-diene
Alkene Nomenclature Step 1
• Find the longest chain that contains both carbon atoms of the double bond.
Pentene
Alkene Nomenclature Step 2
• Number the carbon chain from the end(carbon) that gives the multiple bond the lower number.
1-pentene1
2
3
4
5
Alkene Nomenclature Step 3
• Number and name the substituents, and write the name.
2,3-dimethyl-1-pentene2,3-dimethylpent-1-ene2-methyl
3-methyl
Alkene Nomenclature•Draw 2-methyl-3-heptene. What is its other IUPAC name?
2-methyl-hept-3-ene
Alkene Nomenclature•Identify the structure. Give its two IUPAC names.
1,3,5-heptatrienehepta-1,3,5-triene
Alkene Nomenclature•Draw 1,3,5,7-cyclooctatetraene.•What is its other IUPAC name?
cycloocta-1,3,5,7-tetraene
Alkene Nomenclature•Identify the structure. Give its two IUPAC names.
3-ethyl-1-heptene3-ethylhept-1-ene
Alkene Nomenclature•Draw 7-bromo-1,3,5-cycloheptatriene.•What is its other IUPAC name?
7-bromocyclohepta-1,3,5-triene
Alkene Nomenclature• Alkenes named as
substituents are called alkenyl groups.• They can be named
systematically (ethenyl, propenyl, etc.), or by common names.
CH2=methylene / methylidene
Alkene Nomenclature
• Vinyl (ethenyl)
• Allyl (1-propenyl)
• Crotyl (2-butenyl)
CH2=CH--
CH3CH=CH--
CH3CH=CHCH2--
Alkene Nomenclature•Identify the structure.
3-methylenecyclohexene
1
Alkene Nomenclature•Identify the structure.
3-vinyl-1,5-hexadiene3-vinylhexa-1,5-diene
1
Alkene Nomenclature•Identify the structure.
allyl chloride3-chloropropene
1
CH2=CH--CH2--Cl
Alkene Nomenclature•Identify the structure.
2,6-dimethyl-3-heptene2,6-dimethylhept-3-ene
1
Alkene Nomenclature•Identify the structure.
3,6-dimethyl-5-propyl-3-octene3,6-dimethyl-5-propyloct-3-ene
1
Alkene Nomenclature•Identify the structure.
4-isopropyl-1-cyclohexene4-isopropylcyclohex-1-ene
Alkene Nomenclature•Identify the structure.
6-chloro-4-ethyl-6-methyl-1,4-heptadiene6-chloro-4-ethyl-6-methylhepta-1,4-diene
1
Alkene Nomenclature•Draw 5-sec-butyl-nona-3,6-diene.•What is its other IUPAC name?
5-sec-butyl-3,6-nonadiene
Alkene Nomenclature•Draw 5-allylnona-2,6-diene.•What is its other IUPAC name?
5-allyl-2,6-nonadiene
Alkene Nomenclature•Draw 1,3,5-cyclohexatriene.•What is its most popular name?
Benzene, cyclohexa-1,3,5-triene
Alkene Nomenclature•Draw 1,3,5-cyclohexatriene.•What is its most popular name?
Benzene, cyclohexa-1,3,5-triene
Alkynes• compounds that contain carbon and
hydrogen and have at least one C C ‑triple bond.• Relatively not common in nature
compared to alkenes• Molecular formula is CnH2n-2
Alkynes• Non-polar, nearly insoluble in water.• Many have mildly offensive odors.• Used by some plants for protection
against fungal diseases.
Important Alkynes
Ethyne (acetylene)
methylacetylene
Alkyne NomenclatureThe IUPAC
nomenclature for alkynes is similar to that for alkenes. We
change the -ane ending of the parent
alkane to –yne.
Propyne
Alkyne Nomenclature Step 1
• Find the longest chain that contains both carbon atoms of the triple bond.
Pentyne
2-pentyne
Alkyne Nomenclature Step 2
• Number the carbon chain from the end(carbon) that gives the multiple bond the lower number.
12
3 4
5
Alkyne Nomenclature Step 3
• Number and name the substituents, and write the name.
4-methyl-2-pentyne4-methylpent-2-yne
4-methyl
Alkyne NomenclatureIf a double bond and triple bond are on the same parent chain, naming priority will be given to the triple bond. The struture will be named as an alkyne.
1-penten-4-ynepent-1-en-4-yne
Alkyne NomenclatureIf the double bond and the triple bond are equidistant
from the ends of the chain, number the chain so that the double bond receives a lower number than the triple
bond (because “ene” comes before “yne” in the alphabet).
1-penten-4-ynepent-1-en-4-yne
1
4
Alkyne NomenclatureIf the double bond and the triple bond are equidistant
from the ends of the chain, number the chain so that the double bond receives a lower number than the triple
bond (because “ene” comes before “yne” in the alphabet).
2-methyl-1-penten-3-yne2-methylpent-1-en-3-yne
Alkyne Nomenclature•Identify the structure. Give its two IUPAC names.
4-ethyl-2-hexyne4-ethylhex-2-yne
Alkyne Nomenclature•Draw 6-bromo-2-methyl-3-heptyne.•What is its other IUPAC name?
6-bromo-2methylhept-3-yne
Alkyne Nomenclature•Draw 5,5-dimethyl-3-heptyne.•What is its other IUPAC name?
5,5-dimethylhept-3-yne
Alkyne Common Names• The common names of
alkynes describe them as derivatives of acetylene.•Most alkynes can be
named as a molecule of acetylene with one or two alkyl substituents.
Acetylene(Ethyne)
Alkyne Common Names
alkylacetylene dialkylacetylene
ethylmethylacetylene2-pentynepent-2-yne
Alkynyl Substituents• Alkynes named as
substituents are called alkynyl groups.• They can be named
systematically (ethynyl, propynyl, etc.), or by common names.
ethynylCH C
Alkynyl Substituents
1-propynyl
CH3C Cpropargyl
2-propynyl
CH C CH2
Alkyne Nomenclature•Identify the structure.
2,2,9,9-tetramethyl-3,5,7-dectriyne 2,2,9,9-tetramethyldec-3,5,7-triyne
Alkyne Nomenclature•Identify the structure.
3-propyl-1-heptyne3-propylhept-1-yne
Alkyne Nomenclature•Identify the structure.
2,2-dimethyl-3-hexyne2,2-dimethylhex-3-yne
Alkyne Nomenclature•Identify the structure.
7-chloro-4-isopropyl-2-hepten-5-yne7-chloro-4-isopropyl-hept-2-en-5-yne
Alkyne Nomenclature
6-methyl-7-methylene-2-nonyne
Numbering Priority•Multiple Bond• First Point of Branching•Greater No. of Branches•Alphabetical Ordering of
Branches
Naming Priority• Multiple Bond–(-enes, then –ynes.)
• Branches in Alphabetical Order–(includes iso- and cyclo-)
Organic Compounds
Hydrocarbons
Aliphatic Aromatic
Hydrocarbon Derivatives
Halogen Containing
Oxygen Containing
Alcohols and Phenols Ethers Aldehydes
and KetonesCarboxylic
AcidsAcid
Derivatives
Acid Chlorides Anhydrides Esters Amides
Nitrogen Containing
Amines
What is a functional group?
• a group of atoms that reacts as a single unit and determines the properties and structure of a class of compounds.
Priority of Functional Groups in Naming Organic Compounds
1. Acids2. Esters3. Aldehydes4. Ketones5. Alcohols6. Amines7. Alkynes, Alkenes8. Alkanes9. Ethers10. Halides