Examples for solution
(C H 3 ) 3 C
O
+
C H 3 -I
50 o C
(C H 3 ) 3
O
C H3
(CH 3 )3 CO H
(C H 3 ) 3 C
Cl
+
C H 3 -O
the only
one product
S N 2 (jediný
produkt)
50 o C
CH 3 O H
C H 2 = C H(C H 3 ) 2
E2
the
only one
product
(jediný
produkt)
1
Examples for solution
C H3 C H2 C H2 C H2
Br
+
(C H 3 ) 3 C -O
50 o C
CH 3 O H
E2
C H 3 C H 2 C H= C H 2
hlav
níproduct
produkt
main
main
product
C H3 C H2 C H2 C H2
O
C (C H 3 ) 3 S N 2
v edlejší
produkt
side product
C H3C H2C H2C H2
Br
+
C H 3 -O
50 o C
CH 3 O H
C H3C H2 C H2 C H2
O
C H3
SN2
hlavmain
ní produkt
product
C H 3 C H 2 C H= C H 2
E2
v edlejší
sideprodukt
product
2
Examples for solution
C H 3 C H 2 C HC H 2 C H 3
50 o C
+
C H3 C H2
O
CH 3 CH 2 O H
Br
C H 3 C H 2 C H= C HC H 3
E2
hlav
ní produkt
main
product
C H 3 C H 2 C HC H 2 C H 3
SN2
OC H 2 C H 3
v edlejší
side produkt
product
CH3CH2CHCH2CH3
Br
+ (CH3)3C
O
50oC
CH3CH2OH
CH3CH2CH=CHCH3
hlavní
main produkt
product
E2
CH3CH2CHCH2CH3
SN2
OCH2CH3
side product
vedlejší
produkt
3
Examples for solution
I
H3 C
25 o C
H3 C
C H3
C H3
H3C
SN1
+
CH 3 O H
H
OC H 3
H3 C
H
OC H 3
C H3
H
H3C
I
E2
C H3O
H
H
C H 3 OH
50 o C
směs obou látek
mixture of two
components
hlavní
produkt
main
product
H
H3C
H
SN2
vedlejší
produkt
side product
H
OC H 3
4
Examples for solution
Br
CH3
Br
H
5
Pyrolytic elimination
Reactions are characteristic for acetates or xanthates –Chugaev
reaction and t-aminoxides – Cope elimination
Acetates pyrolysis
Reactions are cis- stereospecific and regiospecific
O
CH3
o
16 0 - 2 00 C
C
O
O
+
C H 2C H 2C H 2R
T
CH3
C
OH
H 2C
C H C H 2R
Reaction proceeds via cyclic intermediate
O
H 3C
C
H
O
CH3
C
O
CH
C
H2
R
OH
CHR
+
H 2C
6
Pyrolytic elimination
What is the product of (2R,3S)-2-(3-phenylbutyl)acetate?
O
CH3
CH3
3
CH3
3
(3 S )-
(3 S )-
C
O
2
1
*
CH
CH3
3
*
CH
4
2
4
Ph
CH3
Ph
2
4
Ph
H
1
1
2
2
H
O
O
4
H 3C C O
H
4
H
OCCH3
1
1
(2 R )-
(2 S )-
1.
2.
3.
4.
5.
6.
Composition of corresponding formula
Configuration determination
Transformation into perspective formula
Cis- (syn-) elimination
Determination of olefine configuration
Composition of proper name
3
CH3
H
C
C
(E)-2-phenylbut-2-ene
CH3
Ph
Ph
H
3
O
H
C
O
CH3
CH3
CH3
H 3C
CH3
7
Pyrolytic elimination
What is the product of pyrolysis of (1R,2R)-1,2-diphenyl-2deuterioethylacetate?
Ph
O
CH3
Ph
C
O
C
1
2
D
*
2
*
C
D
H
(2 R )-
3
4
1
H
Ph
O
3
4
H 3C C O
1.
2.
3.
4.
5.
6.
H
Composition of corresponding formula
Configuration determination
Transformation into perspective formula
Cis- (syn-) elimination
Determination of olefine configuration
Composition of proper name
H
1
(1 R )-
2
Ph
H 3C
O
D
H
C
Ph
C
(Z)-diphenylethene
Ph
-CH3COOD
H
O
H
C
Ph
H
Ph
8
Pyrolytic elimination – Chugayev reaction
Reactions are cis- stereospecific and regiospecific
Preparation of xanthate:
R
OR
N aO H
OH
+
CS2
+
CH3
I
S
C
S
RO
S
-
C
+
S
+
HO
-
RO
N aO H
C
R
HS
S
C
CH3
CH3
I
H 3C
S + N aI + H 2 O
S
Reactions proceed via cyclic state
H 3C
S
S
C
H 3C
H
O
S
C
O
CH
C
H2
R
SH
CH
+
R
H 2C
9
Pyrolytické eliminace
What is the product of (S)-methyl-(2R,3R)-O-(3-methylpent-2-yl) xanthate pyrolysis?
2
S
H 3 C -S
C
O
H
H
C
C
3
H 3C
4
(3 R )-
H
1
S
C H 2C H 3
2
H
CH3
C H 2C H 3
CH3
4
1
O -C -S C H 3
(2 R )-
3
CH3
(Z)-3-methylpent-2-ene
H 3C
H 3 C -S
CH3
C
H
C
CH3
C
C H 2C H 3
O
- CH3SH, COS
H
S
H
H 3C
CH3
H
H
S
C
C H 2C H 3
O
CH3
S -C H 3
CH2
CH3
10
Pyrolytic elimination – Cope reaction
Reactions are cis- stereospecific and regiospecific
Preparation of t-aminoxide
R
2
R
N
1
R
H 2O 2 / H
2
+
R
1
oxidation of t-amines
N
CH2
CH2
CH2
O
CH2
R
R
Reactions proceed via cyclic intermediate
R
R
1
R
N
H 2C
O
H 2C
2
CH2
1
N
O
H 2C
H
H
+
R
2
after reaction olefin and
substituted hydroxylamin are
obtained
11
Pyrolytic elimination
Cope elimination of N-oxides
H 3C
CH3
C H 2 -C H 2 N
o
HC
120 C
N
C
H
H 3C
CH3
o
160 C
CH3
N
CH2
OH
H
O
H 3C
N
C
O
H
O
+
CH3
CH3
O
H 3C
H 3C
CH2
H
N
H 3C
C
O
H
+
O
H
O
O
(C H 3 ) 2 N -O H
O
O
12
Hofmann elimination of quarternary ammonium hydroxides
Reaction starts with t-alkylamines, which in the following reaction are alkylated to
quaternary ammonium salts
In the further step they are transferred into quaternary ammonium hydroxides
13
Hofmann elimination of quarternary ammonium hydroxides
14
Hofmann elimination of quarternary ammonium hydroxides
Reactions are regiospecific, but not stereospecific
During the reaction the most acidic -hydrogen atom is split off.
( „antisaytzeff rule“ – that hydrogen atom splits off to produce the
least branched olefin
In the molecule there are 3
eliminated ----
-hydrogen atoms, which might be
in the reaction the most acidic proton splits off and the least
branched olefin is formed
15
Hofmann elimination of quarternary ammonium hydroxides
During reaction the most acidic -hydrogen atom splits off
Name this compound and carry out the
Hofmann elimination
in the molecule they are 2 different - hydrogen atoms, which might be
eliminated ---during the reaction the most acidic hydrogen is eliminated and
the least branched olefin is formed
16