NOMENCLATURE OF ALKENES • Ethylene is an acceptable synonym for ethene in the IUPAC system • Propylene, isobutylene and other common names ending in “ylene” are NOT acceptable IUPAC na
Trang 3NOMENCLATURE OF ALKENES
• Ethylene is an acceptable synonym for ethene in the IUPAC
system
• Propylene, isobutylene and other common names ending in
“ylene” are NOT acceptable IUPAC names
The IUPAC name of an alkene is obtained by replacing
the “ane” ending of the corresponding alkane with “ene”
Trang 5Note: Alkenes can have geometric isomers
Trang 7isomerization
Trang 8Eliminations of alkyl halides
Base
Trang 9Alkyne hydrogenations
Pd/CaCO 3 + Pb(OAc) 2 / quinoline
Trang 11Carbocation rearrangement
More stable
Trang 12More stable
Trang 13Stereochemistry
Racemic mixture
Trang 14Already has 1 asymmetric carbon
Trang 152 asymmetric carbons are created
Trang 16Additions of hydrogen bromide (A R )
Radical addition (A R ) – only for HBr
Electrophilic addition (A E)
Trang 17Reaction
mechanism:
Trang 18Additions of halogens
Trang 19Major
addition product – NOT a
dihalide
Trang 20Stereochemistry
Trang 2121
Trang 222 asymmetric carbons are created
Trans-2-butene Æ meso compound
Trang 23Additions of water – hydration reactions
Water is too weakly acidic to allow the hydrogen to act
as an electrophile
H 2 SO 4 , H 3 PO 4 …
Markovnikov’s rule
Trang 26Additions of borane: hydroboration-oxidation
Trang 27Regioselectivity:
Anti-Markovnikov
Trang 28Additions of hydrogen – hydrogenation
Trang 29Reaction mechanism:
Syn addition
Trang 30Stereochemistry
Trang 3131
Trang 32Alkene epoxidations – Anti hydroxylations
Trang 33Stereochemistry
Trang 34Reactions of epoxides
Trang 3535
Trang 36Stereochemistry Anti additions
Trang 37Syn hydroxylations of alkenes
Trang 38Reaction mechanism: Syn additions
Trang 39Permanganate cleavage of alkenes
Trang 40Ozonolysis of alkenes
Trang 41In the presence of an oxidizing agent, the products
will be ketones / carboxylic acids
Trang 42Polymerizations