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©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
REACTIONS AND MECHANISMSFor Final Exam
Reactions for Final Exam
Although you don’t need to know all of the mechanisms for these reactions, knowing themmakes it easier to understand the reactions and to figure out a reaction if you forget it. Consult thelecture notes for more details on the mechanisms.
ELECTROPHILIC ADDITION REACTIONS
HX
X+
X
OCH3
HgO2CCF3
NaBH4OCH3Hg(O2CCF3)2
CH3OH
R R
OH
R
OHgSO4H3O+
enol ketone
AlCl3Cl
OO
(note this is really an electrophilic substitution reaction)
CH3 CH3 CH3OHOH
O
O O H
Cl
O
MCPBAH3O+
CH3OHBr
Br2, H2O
halohydrin
epoxide
NaH
CH3Hg(OAc)2 CH3
OH
H2ONaBH4
1)2)
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
CH3BH3H2O2, OH- CH3
HOH
CH3 OsO4 CH3OHNaHSO3OH
1)2)
ELECTROPHILIC SUBSTITUTION REACTIONS
Br2FeBr3 Br
Cl2FeCl3 Cl
I2CuI2 I
HNO3H2SO4 NO2
SO3H2SO4 SO3H
R-ClAlCl3 R
R Cl
O
AlCl3 R
O OBr2
CH3CO2H
OBr
Br2 PBr3O
OH
O
OH
1)
2) H2OBr
NUCLEOPHILIC ADDITION REACTIONS
R OHR H
O1) NaBH42) H3O+
R OHR H
O1) LiAlH42) H3O+
R OHR OCH3
O1) LiAlH42) H3O+
R HR OCH3
O1) DIBAH2) H3O+ O
R PhR OCH3
O1) PhMgBr2) H3O+ OH
PhPh H
O
Ph HHO CNHCN
cyanohydrinKOH
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
O HO OHH2O
hydrate
+
H+ or -OHcatalyst
OR-NH2
H+ N R+
imine
OR2NH
H+ N RR+
enamine
O
ROHH+
RO OR
+ 2
an acetal
1,4-addition
OCH3NH2
O
NHCH3
1,4-addition
O O
Ph
1) Ph2CuLi2) H3O+
1,2-addition
O 1) PhMgBr2) H3O+ HO Ph
1,2-addition
O 1) PhLi2) H3O+ HO Ph
R Cl
OR Ph
1) PhMgBr2) H3O+ HO Ph
R OCH3
OR Ph
1) PhMgBr2) H3O+ HO Ph
C NCH3
1) CH3MgBr2) H2O
O
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
O+ Ph3P CH2
phosphoniumylide
CH2 + Ph3P O
1,2-addition
O 1) NaBH42) H3O+ HO H
1,2-addition
O 1) LiAlH42) H3O+ HO H
The addition of hydrides to carbonyls is also considered reductions and more examples are listedunder reduction reactions.
O
OMgBr OH
OH3O+MgBr
O C O
ELIMINATION REACTIONS
OHH3C CH3H2SO4
E1
OHPOBr3pyridine
E2
NH2
OCl S Cl
O
C N
OBr pyridine
O
SUBSTITUTION REACTIONS (SN1)
CH3OH
HCl CH3OH
H-H2O Cl
CH3
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
CH3O HCl
CH3
O HCl
OH
CH3Cl
(regioselective like SN1 but stereoselective like SN2)
SUBSTITUTION REACTIONS (SN2)
SO
Cl ClOHH S
O
O Cl Cl
PBr
Br BrOHH P
Br
O Br Br
SO
ClOH O Tos
Tos-Cl
pyridine
OH1) NaH
2) CH3IO CH3
O HI OH I OHI+
O HCl OH
ClCl
OH
O 1) PhMgBr
2) H2OPh
OH
Ph SHCH3I
Ph S CH3
R OH
O NaOH
R O
O
Na
CH3I
R OCH3
O
O 1) LDA2) CH3I
OCH3
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
OEt
O
EtO
O NaOEt, EtOH
R BrOEt
O
EtO
O
R
OEt
O
H3C
O NaOEtEtOH
R BrOEt
O
H3C
O
R
SUBSTITUTION REACTIONS (Nucleophilic Aromatic and Nucleophilic Acyl)
Cl
NaOH
25 °C
O2N NO2
NO2
OHO2N NO2
NO2
NaOH
340 °C2500 psi
Cl OH
H H
benzyne intermediate
R OH
O+ SOCl2
R Cl
O+ SO2 + HCl
R OH
O+
R
O+ HOH
RHO
O Heat
RO
O
R OH
O HA
R'OH R OR'
O
R Cl
O+
R
O+ NaClRNaO
O
RO
O
R Cl
O+ H2O R OH
O+ HCl
R Cl
O+ R'OH
R OR'
O+ Pyridine-HCl
pyridine
R Cl
O+ NH3 R NH2
O+ NH4Cl2
R Cl
O
R Ph
O1) Ph2CuLi2) H3O+
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
+ H2OO
O O
OH
O2
+ ROHO
O O
OR
O+
OH
O
+ NH3O
O O
NH2
O+
OH
O
+R OCH3
O+ H2O
R ONa
ONaOH (cat)CH3OH
Ph HHO C N
H3O+
Ph HHO C
OOH
R NH2
O+ H2O
R OH
OHA (cat)+ NH4A
CH3
OI2, NaOH
O
O
+ CHI3iodoform
OXIDATION REACTIONS
R R
OH CrO3
H3O+R R
O
R
OH CrO3
H3O+R OH
O
PCCR
OH
R H
O
R
O CrO3
H3O+R OH
O
H
OKMnO4
O
OH
O
OH
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
KMnO4 CO
OH
KMnO4 CO
OH
O
OH
OKMnO4 2
O
H
O1) O32) Zn, AcOH +
REDUCTION REACTIONS (note - hydride addition to carbonyls is also listed under thenucleohpilic addition section)
R OHR H
O1) NaBH42) H3O+
R OHR H
O1) LiAlH42) H3O+
R OHR OCH3
O1) LiAlH42) H3O+
R HR OCH3
O1) DIBAH2) H3O+ O
R HRC
1) DIBAH2) H3O+ O
N
1) LiAlH42) H3O+
Ph HHO C N
Ph HHO NH2
R OHR OH
O1) LiAlH42) H3O+
©���� Gregory R� Cook page � Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
R OHR OH
O1) BH32) H3O+
R Cl
OR OH
1) LiAlH42) H3O+
R Cl
O
R H
O1) LiAlH(Ot-Bu)32) H3O+
R NH2R NH2
O1) LiAlH42) H2O
O H2N NH2
KOH
N NH2
a hydrazone
H H
Pt, 2000 psi CH3
orRh/C, 15 psi
CH3
H2Pd/C
O
H2Pd/C
H2NO2Pd/C
NH2
SnCl2NO2 NH2H3O+
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
OTHER REACTIONS
NBSperoxides Br also benzylic
bromination
EWG+
EWG
KNH2Cl+ benzyne
intermediate
O O
H
OHheat
O O
H
OHheat
R Cl
O (CH3)2CuLiR CH3
O
Ph HHO C N
H3O+
Ph HHO C
OOH
H3O+, Heat
HO
O
OEt
O
EtO
O
R
R + CO2
H3O+, Heat
OEt
O
H3C
O
R
H3C
O
R+ CO2
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
MECHANISMS
Electrophilic Aromatic Substitution
BrBr
H BrH BrH
Br
-HBr Br
NEED TO KNOW MECHANISM
Carbonyl Addition Reactions
O
HA
Mechanism for Imine Formation
OH H2N RO N
H HR
H A O NH
R
H
Hemiaminal
Up to here this is identical to a hydration with amine as nucleophile instead of water
O NH
R
H
H-H2O
NH
RNH R
resonance structures
AN R
imine
HA
NEED TO KNOW MECHANISM
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
Acyl Substitution Reactions
NEED TO KNOW MECHANISM
O
HA
Mechanism for Enamine Formation
OHHN R
O NR
HR
H AO N
R
R
H
Hemiaminal
O NR
R
H
H-H2O
NR
RNR R
resonance structures
ANR
enamine
HA R
H
R
The only difference is this last step. There is no proton on the nitrogen to come off, so a proton is taken off of the alpha carbon
O HA
Mechanism for Acetal Formation
OH
OHR
O O HR
H A O O R
H
Hemiacetal-H2O
O RO R
resonance structures
HA
O O R
H
RAO O RR
OH
resonance structures
HO R
NEED TO KNOW MECHANISM
O O R
H
H
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
H
Fischer Esterification
R OH
O HA
R OH
OH R'OH
R OH
HO OR'H
A
R OH
HO OR'
R OH
HO OR'
HA
R
HO OR'R OR'
OH
R OR'
O A
NEED TO KNOW MECHANISM
OCH3
O OH
OCH3
O OHOH
O
Base Catalyzed Hydrolysis (Saponification)
+ OCH3 O
O+ HOCH3
Rapid acid-base reaction takes place
Carboxylate is a thermodynamic sink and makes the reaction essentiall non-reversible. To get the carboxylic acid, add acid to protonate.
OCH3
O HA
OCH3
OH
OCH3
OH H2O
OCH3
OH OH
H AOCH3
OH O H
HA
OCH3
OH O H
HOH
OH
OH
OH
OH
O A
Acid Catalyzed Hydrolysis
- HOCH3
NEED TO KNOW MECHANISMS
BEST METHOD
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
NH2
O HA
NH2
OH
NH2
OH H2O
NH2
OH OHH A
NH2
OH O H
HA
NH2
OH O H
HOH
OH
OH
OH
OH
O A
Acid Catalyzed Hydrolysis of Amides
NEED TO KNOW MECHANISM
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
Other Mechanisms that may be useful but do not need to know.
ClO2N NO2
NO2
NaOHO2N NO2
NO2
Cl OHO2N NO2
NO2
Cl OHO2N NO2
NO2
Cl OH
CH3OH
H+ CH3O
H
H
oxonium is a better leaving group than alcohol
-H2O CH3
3° alcohol 3° carbocationH
Acid Catalyzed Dehydration - E1 elimination
base
CH3
POBr3 Promoted Dehydration - E2 elimination
2° alcohol
PO
Br Br BrOH OH
PO
BrBr
N pyridinemild base
O PO
BrBr
HGood Leaving Group
pyridine
CH3OH
HCl CH3O
H
H
oxonium is a better leaving group than alcohol
-H2O CH3
3° alcohol 3° carbocationH
Acid Promoted Substitution - SN1 - 3° Alcohols
ClCl
CH3
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
Electrophile Promoted Substitution - SN2 - 1° and 2° Alcohols
2° alcohol
SO
Cl ClOHH S
O
O Cl
Good Leaving Group
Cl Cl
Inversion of Configuration
2° alcohol
PBr
Br BrOHH P
Br
O Br
Good Leaving Group
Br Br
Inversion of Configuration
OOHH+
OH
H HOOH
-H+
SN2
HO Br NaHO
BrO
Base Catalyzed Hydrocyanation
Ph H
O CN
Ph H
O CN
Ph H
HO CN
HCNbase
Ph H
HO C NH3O+
Ph H
HO C
O
OHPh H
HO C N1) LiAlH4
Ph H
HO NH2
cyanohydrin
HCN
2) H3O+heat
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
Wittig Reaction
P
triphenylphosphine
+R X Ph3P R
triphenylphosphonium salt
Xbase
O+ Ph3P CH2
phosphoniumylide
CH2 + Ph3P O
SN2
Ph3P R
triphenylphosphonium ylide
H H
ylides are prepared by SN2 reactions of phosphines with alkyl halides then deprotonation
ylides are nucleophilic and will react with carbonyls
Ph3P R
O+
OPPh3
Ph3P
O
a betaine
PPh3O+
R OH
O
Acid Chlorides
+ SOCl2R Cl
O
ClS
Cl
O
R O
OS
Cl
O Cl
H
base (solvent or Cl-)
R O
OS
Cl
O
+ SO2 + HCl
Cl
R OS
Cl
OO Cl
(This step may happen later after kicking off HOSOCl)
©���� Gregory R� Cook page �� Chem ��� Exam � Reactions and MechanismsNorth Dakota State University
O OHH+ Br Br OBr + HBr
OBr2
CH3CO2H
OBr pyridine
O
Br2 PBr3O
OH
O
OH
1)
2) H2OBr
PBr3
O
Br
H+ OH
Br
O
Br
Br
H2O
Br2
CH3
OI2, NaOH
O
O
+ CHI3iodoform
NaOH
CH2
OI2
CH2
OI
repeatC
OI
I IC I
I I
O OHNaOH
![SALCS for Common Geometries bonding)employees.oneonta.edu/viningwj/Chem342/SigmaMOdiagramsforTMs.pdfExample: Constructing a MO for Platinum Tetrachloride , 2[PtCl 4] ‐ d h 16 Pt](https://img.pdfslide.us/doc/110x75/6114404b4a5378058503e722/salcs-for-common-geometries-bonding-example-constructing-a-mo-for-platinum-tetrachloride.jpg)
