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
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