Chemistry 125: Lecture 71 April 20, 2011 Acids and Acid Derivatives Decarboxylation (J&F Ch. 17) Acyl Compounds (J&F Ch. 18) This For copyright notice see final page of this file R-Li & LiAlH4 (e.g. J&F Sec. 17.7f) stop at C=O? LiAlH4 OH H+ OAlH3 R C H R C H H H Decarboxylation (e.g. J&F 17.7g) malonic acid acid HO O -CO2 C O H 2 enol C OH O OH (concerted) Decarboxylation (e.g. J&F 17.7g) or CO2 as leaving group from XCO2- or RCO2• (e.g. J&F pp. 859-861) NH3 + H2O + carbonic acid carbamic acid Kolbe Electrolysis -e- fast at 4K ! R R R = CH3 R= (Kolbe 1848) R-R (~50% 1973) Decarboxylation (e.g. J&F 17.7g) or CO2 as leaving group from XCO2- or RCO2• (e.g. J&F pp. 859-861) RCO2H Ag2O Br2 RCO2Ag R-Br Br2 RBr R + AgBr + CO2 “Hunsdiecker Reaction” Patents 1936-44 CO2 Decarboxylation (e.g. J&F 17.7g) or CO2 as leaving group from XCO2- or RCO2• (e.g. J&F pp. 859-861) O=C=O RCO2 MgBr R-MgBr Ag2O RCO2Ag + ? Mg + AgBr + CO2 “Hunsdiecker Reaction” Patents 1936-44 H+ Alexander Porfiryevich Br2 RBr “R-” KCN “R+” H2O RC Borodin N H or HO RCO2H - + D 1833-1887 Published in 1861 Tony award 1954 (Kismet) A. Sdobnikov RCO2H Acid Derivatives (e.g. J&F Ch. 18) +3 +3 O -2 R C R CN nitrile H2O +3 R-CO2H +2 H2C=C=O X: ketene H2O -3 +3 H3C-CO2H CH3-C=O(X) strong & independent Spectroscopy (pp. 888-889) C=O strengthened by resonance CH3C O+: Cl 1746 CH3C 1727 + O: -OCH O nO *C-Cl nO *C-OMe O H 1681 CH3C CH3C CH3C 3 1715 O+ : 1806 C=O weakened by resonance CH3 NH2 nN *C=O % Transmission %T acyclic anhydride out in of phase phase cyclic imide out in phase of phase Interconversion of Acid Derivatives (e.g. J&F pp. 886, 890, Figs. 18.17,18.22) Leaving Group Hierarchy pKa Cl-H -8 - O R C X Y SOCl2 - ~5 R’CO2H RCO2H2O R’O-H transesterification ~16 Tetrahedral Intermediate acid-catalyzed (A/Dorsubstitution, rather than (as in Fischer esterification) pentavalent transition state as in SN2) R’2N-H K ~1 (shift by law of ~35 mass action) differences reinforced by resonance stabilization: O- O R R C Y: C Y+ Saponification K>>1 “I ain’t afraid to wash my hair in it.” “That there lard eats the lye.” RCO2 triglyceride - (fat) RCO2 RCO2 O R C OR HO pK K~5~10 HOR pK ~16 Lye KOH HO- RO- a a 11 RCO2K HO RCO2K HO RCO2K HO soap glycerine Going All the Way to C-OH (e.g. J&F pp. 891, 898-9, 903 (C-NH2)) Stopping Part Way to Preserve C=O (e.g. J&F pp. 892-893 (Fig. 18.22); 900 (Fig 18.38)) Acidic / Basic Hydrolysis of RCN pp. 904-905 O C-OH Acidic Hydrolysis of RCN Basic Hydrolysis of RCN Acyl Compounds from Ketene (J&F Sec. 18.11, p. 907) pKa = ~35 O (Nu = N) HNu H2C=C=O Nu: Nu or H+ catalyzed R3N H2C=C=O HCH2 C pKa = 17 H-OC(CH3)3 H+ H-SEt 87% pKa = ~10 93% -80°, 3 days pKa = ~31 H Ph-N-CH3 EtOH / H2O 75% Insertion into Acyl-R Bond Munich 1896 Victor Villiger Adolf v. Baeyer Baeyer-Villiger Reaction - 1900 (insert O) (e.g. J&F pp. 907-909) End of Lecture 71 April 20, 2011 Copyright © J. M. McBride 2011. Some rights reserved. Except for cited third-party materials, and those used by visiting speakers, all content is licensed under a Creative Commons License (Attribution-NonCommercial-ShareAlike 3.0). Use of this content constitutes your acceptance of the noted license and the terms and conditions of use. Materials from Wikimedia Commons are denoted by the symbol . Third party materials may be subject to additional intellectual property notices, information, or restrictions. The following attribution may be used when reusing material that is not identified as third-party content: J. M. McBride, Chem 125. License: Creative Commons BY-NC-SA 3.0