1
Examples for solution
the only one product
the only one product

2
Examples for solution
main product
main product
main product
side product
side product

3
Examples for solution
main product
side product
main product
side product

4
Examples for solution
mixture of two components
main product
side product

5
Examples for solution


6
Pyrolytic elimination
Reactions are characteristic for acetates or xanthates –Chugaev reaction and t-aminoxides – Cope
elimination
Reactions are  cis- stereospecific and regiospecific
Reaction proceeds via cyclic intermediate
Acetates pyrolysis

7
Pyrolytic elimination
What is the product of (2R,3S)-2-(3-phenylbutyl)acetate?
(E)-2-phenylbut-2-ene
1.Composition of corresponding formula
2.Configuration determination
3.Transformation into perspective formula
4.Cis- (syn-) elimination
5.Determination of olefine configuration
6.Composition of proper name

8
Pyrolytic elimination
What is the product of pyrolysis of (1R,2R)-1,2-diphenyl-2-deuterioethylacetate?
1.Composition of corresponding formula
2.Configuration determination
3.Transformation into perspective formula
4.Cis- (syn-) elimination
5.Determination of olefine configuration
6.Composition of proper name
(Z)-diphenylethene
-CH3COOD

9
Pyrolytic elimination – Chugayev reaction
Reactions are cis- stereospecific and regiospecific
Reactions proceed via cyclic state
Preparation of xanthate:

10
Pyrolytické eliminace
What is the product of (S)-methyl-(2R,3R)-O-(3-methylpent-2-yl) xanthate pyrolysis?
(Z)-3-methylpent-2-ene
- CH3SH, COS

11
Pyrolytic elimination – Cope reaction
Reactions are cis- stereospecific and regiospecific
Reactions proceed via cyclic intermediate
Preparation of  t-aminoxide
oxidation of t-amines
after reaction olefin and substituted hydroxylamin are obtained

12
Pyrolytic elimination
Cope elimination of N-oxides

13
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

14
Hofmann elimination of quarternary ammonium hydroxides


15
Hofmann elimination of quarternary ammonium hydroxides
Reactions are regiospecific, but not stereospecific
During the reaction the most acidic b-hydrogen atom is split off.
( „antisaytzeff rule“ – that b-hydrogen atom splits off to produce the least branched olefin
In the molecule there are 3  b-hydrogen atoms, which might be eliminated  ----
in the reaction the most acidic proton splits off and the least branched olefin is formed

16
Hofmann elimination of quarternary ammonium hydroxides
During reaction the most acidic b-hydrogen atom splits off
in the molecule they are 2 different b- hydrogen atoms, which might be eliminated  ----
during the reaction the most acidic hydrogen is eliminated and the least branched olefin is formed
Name this compound and carry out the  Hofmann elimination