Chemistry 125: Lecture 71April 20, 2011

Acids and Acid DerivativesDecarboxylation (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?

R C

OAlH3

H

HR C

OH

H

HH+

LiAlH4

Decarboxylation(e.g. J&F 17.7g)

malonic acid acid (concerted)

OH2

HO

OH

C O

C OH

O-CO2

enol

R

Kolbe Electrolysis

-e-

fast at

4K !

R R-R

R = CH3 (Kolbe 1848)

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)

H2O +

carbonicacid

NH3 +

carbamicacid

Decarboxylation(e.g. J&F 17.7g)

or CO2 as leaving group from XCO2- or RCO2•

(e.g. J&F pp. 859-861)

RCO2AgBr2

RBr+ AgBr + CO2

“Hunsdiecker Reaction”

RCO2HAg2O

R-Br

R

CO2

Br2

Patents 1936-44

Decarboxylation(e.g. J&F 17.7g)

or CO2 as leaving group from XCO2- or RCO2•

(e.g. J&F pp. 859-861)

Published in 1861

RCO2AgBr2

RBr+ AgBr + CO2

“Hunsdiecker Reaction”

RCO2HAg2O

?

1833-1887

Tony award 1954 (Kismet)

Alexander Porfiryevich

BorodinKCN RC N RCO2H H2O

H+ or HO-

R-MgBr

Mg

O=C=ORCO2 MgBr

+

H+

“R+”

“R-”

A. S

dobn

ikov

Patents 1936-44

Acid Derivatives (e.g. J&F Ch. 18)

X:

OR C NR C

nitrileH2C=C=O

ketene

+3 +3 +2 -2

H3C-CO2H+3 -3

H2O

R-CO2H+3

H2O

1681

CH3CO

NH2

CH3-C=O(X) strong & independent

1727

CH3CO

H

1715

CH3CO

CH3

CH3CO

OCH3

17461806

CH3CO

Cl+

-+

-

+

-

nN *C=OnO *C-Cl nO *C-OMe

: :

:

C=O weakened by resonance

C=O strengthened by resonance

Spectroscopy(pp. 888-889)

acyclic anhydride

in phaseout of phase

% T

ran

smis

sio

n

%T

out of phase

cyclic imide

in phase

X-

OR C

Interconversion of Acid Derivatives(e.g. J&F pp. 886, 890, Figs. 18.17,18.22)

-

Y-Tetrahedral Intermediate

(A/D substitution, rather thanpentavalent transition state as in SN2)

or acid-catalyzed(as in Fischer esterification)

Leaving Group Hierarchy

Cl-

R’CO2-

R’O-

R’2N-

differences reinforced by resonance stabilization:

+

-

R C

O

Y:

R C

O

Y

H2O transesterificationK ~1

(shift by law ofmass action)

-8

~5

~16

~35

RCO2H

SOCl2

H

H

H

H

pKa

Saponification K>>1

K ~1011OR-

OR C

-

HO-

OR-

RO-HO-

H

pKa ~5

pKa ~16RCO2K

RCO2K

RCO2K

HO

HO

HO

Lye KOH

soap glycerine

RCO2

RCO2

RCO2

triglyceride(fat)

“I ain’t afraid to wash my hair in it.”

“That there lard eats the lye.”

Going All the Way to C-OH (e.g. J&F pp. 891, 898-9, 903 (C-NH2))

Stopping Part Wayto Preserve C=O (e.g. J&F pp. 892-893 (Fig. 18.22); 900 (Fig 18.38))

Acidic / Basic Hydrolysis of RCNpp. 904-905

C-OH

O

Acidic Hydrolysis

of RCN

Basic Hydrolysis of RCN

Acyl Compounds from Ketene(J&F Sec. 18.11, p. 907)

H2C=C=O

Nu:

HCH2 C

O

Nu

HNu

or H+ catalyzed

93%

pKa = 17

pKa = ~31

pKa = ~10

H2C=C=OH-SEt

-80°, 3 days

75%Ph-N-CH3

H

EtOH / H2O

H-OC(CH3)387%

H+

pKa = ~35(Nu = N)

R3N

Insertion into Acyl-R Bond

Munich 1896

Adolf v. Baeyer

Victor Villiger

Baeyer-Villiger Reaction - 1900 (insert O) (e.g. J&F pp. 907-909)

End of Lecture 71April 20, 2011

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