BIMOLECULAR NUCLEOPHILIC SUBSTITUTION REACTION SN 2... UNIMOLECULAR NUCLEOPHILIC SUBSTITUTION REACTION SN 1... Note: slow step is rate-determining step... BIMOLECULAR ELMINATION E2... EL
Trang 1ORGANIC CHEMISTRY
Dr Nam T S Phan
Faculty of Chemical Engineering
HCMC University of Technology Office: room 211, B2 Building
Phone: 38647256 ext 5681
Email: ptsnam@hcmut.edu.vn
Trang 2Chapter 3 : INTRODUCTION TO REACTION MECHANISMS
Trang 3• Substitution reaction: chemical reaction in which
1 atom / group replaces another atom / group in the structure of a molecule
• In a nucleophilic substitution reaction, a
nucleophile attacks / bonds with the positive center
Trang 5BIMOLECULAR NUCLEOPHILIC SUBSTITUTION REACTION (SN 2)
Trang 6UNIMOLECULAR NUCLEOPHILIC
SUBSTITUTION REACTION (SN 1)
Trang 7Note: slow step is rate-determining step
Trang 9BIMOLECULAR ELMINATION (E2)
Trang 11UNIMOLECULAR ELMINATION (E1)
Trang 12Weak base
Trang 13ELETROPHILIC ADDITION
REACTIONS (AE )
• Electrophilic: electron-seeking / loving
• Most electrophiles:
+ Are positively charged
+ Have an atom which carries a partial positive charge
+ Have an atom which does not have an octet
of electrons
An electrophilic addition reaction is an addition reaction where carbon-carbon double bonds or
Trang 15•Not a
carbocation, but a cyclic halonium
ion
• More
stable than carbocation
Trang 16NUCLEOPHILIC ADDITION
REACTIONS (AN )
more electronegative, has greater share of double-bond
Trang 17Reaction mechanism
A nucleophile Positive
center
slow
Rate-determining step
Trang 18Nucleophiles
Trang 19ELECTROPHILIC SUBSTITUTION
In an electrophilic substitution reaction, an
electrophile substitutes for a hydrogen of an
aromatic compound
Although benzene has 3 double bonds, the overall reaction is electrophilic substitution rather than
Trang 20Reaction mechanism
An electrophile
Rate-determining step
Trang 21An electrophile
Rate-determining step