9. Carboxylic Acids

8/17/2019 9. Carboxylic Acids

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Chapter 19: CarboxylicChapter 19: Carboxylic

AcidsAcids

CarboxyCarboxy group: -COOH, -COgroup: -COOH, -CO22H,H,


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Naming: Alkanoic AcidsNaming: Alkanoic AcidsIUPAC: Replace –IUPAC: Replace –ee of alkane name w!"of alkane name w!" –oc ac#–oc ac#

O

OH $-%e!"yl"exanoc ac#$-%e!"yl"exanoc ac#C&C&

Cyclc:Cyclc: Cycloalkanecarboxylc ac#'Cycloalkanecarboxylc ac#'

O

OH

Cyclo"exanecarboxylc ac#Cyclo"exanecarboxylc ac#

OHO

&-(ap"!"alenecarboxylc ac#&-(ap"!"alenecarboxylc ac#

C&, a' n cyclcC&, a' n cyclcal#e"y#e'al#e"y#e'


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Common (ame'Common (ame'


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Carboxylc ac#' !akeCarboxylc ac#' !ake prece#enceprece#ence o)er o!"er group':o)er o!"er group':

Inclu#e a' many func!on' a' po''ble n '!emInclu#e a' many func!on' a' po''ble n '!em

*+e!!er !"an $-ace!yl"ep!anoc ac#*+e!!er !"an $-ace!yl"ep!anoc ac#


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Physical PropertiesPhysical Properties

PlanarPlanar '!ruc!ure,'!ruc!ure,!rgonal!rgonal

carbonylcarbonylcarboncarbon


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"e carboxy group ' polar,"e carboxy group ' polar,

un#ergoe' "y#rogen bon#ng, an#un#ergoe' "y#rogen bon#ng, an#form' #mer':form' #mer':

.mer/a!on cau'e' rela!)ely.mer/a!on cau'e' rela!)ely"g" mel!ng an# bolng pon!'"g" mel!ng an# bolng pon!'


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11H NMR Chemical ShitsH NMR Chemical Shits

HOC

O

H&0-&1 ppm&0-&1 ppm

2-23 ppm2-23 ppm cf al#e"y#e'cf al#e"y#e'an# ke!one'an# ke!one'

Al#e"y#e lkeAl#e"y#e lke

HC

O

OH


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1!1!C NMR ChemicalC NMR Chemical

ShitsShits

(o! 4u!e(o! 4u!e

a' low fel#a' low fel#a' al#e"y#ea' al#e"y#eor ke!oneor ke!one


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"R Spectroscopy"R Spectroscopy

wo mpor!an! ban#':wo mpor!an! ban#':νν

O-HO-H 5 2300-1100 cm5 2300-1100 cm-&-&

,,νν

C5OC5O 5 &6&05 &6&0-&-&


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ResonanceResonance

7200 ppm7200 ppm

7&80 ppm7&80 ppm


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AcidityAcidity"e carboxy group ' rela!)ely ac#c:"e carboxy group ' rela!)ely ac#c:

Ace!a!eAce!a!e

Rea'on': & CarbonylRea'on': & Carbonyl carboncarbon ' n#uc!)ely '!rongly' n#uc!)ely '!rongly elec!ronelec!ronw!"#rawngw!"#rawng, 2, 2 Carboxyla!eCarboxyla!e on ' '!abl/e# byon ' '!abl/e# by re'onancere'onance


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Compare #Compare #

H

2-Propenyl *allyl2-Propenyl *allylCH2 H2C++HH 99

pp: : aa7 $07 $0

+99


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;lec!ron w!"#rawng;lec!ron w!"#rawng group'group'ncrea'encrea'e !"e ac#!y *#ecrea'e!"e ac#!y *#ecrea'e pp: :

aa::

C


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$asicity$asicity

Pro!ona!e# on !"ePro!ona!e# on !"e carbonyl oxygencarbonyl oxygen::

Allow' forAllow' for allylc re'onanceallylc re'onance


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&& Ox#a!onOx#a!on of prmary alco"ol' an# al#e"y#e'of prmary alco"ol' an# al#e"y#e'

>!" %nO>!" %nO$$? or CrO? or CrO11, H, H22O? or H(OO? or H(O1?1? or Hor H22OO2?2? or Cuor Cu2929, or Ag, or Ag99

Recall Cr*@I ox#a!on:Recall Cr*@I ox#a!on:

PreparationPreparation

In H2O: Hy#ra!e, w"c"ox#/e' !o ac#


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22 Carbona!onCarbona!on: Organome!allc: Organome!allcreagen!' an# carbon #ox#ereagen!' an# carbon #ox#e

;xample:;xample:

yn!"e!c '!ra!egy:yn!"e!c '!ra!egy: RHRH →→ RBRB →→ R%g+rR%g+r →→ RCORCO22HH


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11 (!rle "y#roly''(!rle "y#roly''

%ec"an'm:%ec"an'm:

au!omer/a!on


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COOH

Cl

C N

Cl

1.NaOH, H2O

2. H+, H2O

90%

Cyano"y#rn-"y#roly'':Cyano"y#rn-"y#roly'': -Hy#roxy ac#'-Hy#roxy ac#'


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ReactionsReactions

(ucleop"lc 'ub'!!u!on occur'(ucleop"lc 'ub'!!u!on occur'byby a##!on-elmna!ona##!on-elmna!on

Dea# !o carboxylc ac# #er)a!)e':Dea# !o carboxylc ac# #er)a!)e':

Eeneral:Eeneral::(u:(u

;;99

Dea)ngDea)ng

groupgroup


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;lmna!on

N%cleophilic S%bstit%tionN%cleophilic S%bstit%tion

by Addition& 'liminationby Addition& 'limination

e!ra"e#rale!ra"e#raln!erme#a!en!erme#a!e

A##!on

::

Po!en!al problem: Ac#!yPo!en!al problem: Ac#!y

Ac# or ba'e ca!aly/e#Ac# or ba'e ca!aly/e#


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$ase Cataly(ed Mechanism$ase Cataly(ed Mechanism

%u'! no! compe!e w!" :(u%u'! no! compe!e w!" :(u--


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Acid Cataly(ed MechanismAcid Cataly(ed Mechanism


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Synthesis o CarboxylicSynthesis o Carboxylic

Acid )eri*ati*esAcid )eri*ati*es

A+A+ AlkanoylAlkanoyl

HalidesHalides::R

C

O

OH

B5B5 Cl, +rCl, +r

+ -Cl + -OHRC

O

Cl

%ore%ore'!able'!able De''De'''!able'!ablePoorPoor(u(u +a# lea)ng+a# lea)nggroup, '!ronggroup, '!rongba'e, goo#ba'e, goo#(u(u

up"llup"ll


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"erefore u'e o!"er reagen!':"erefore u'e o!"er reagen!': OClOCl22, PCl, PCl33, P+r, P+r11

OClOCl22::

%ec"an'm:%ec"an'm:


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ame a' ROHame a' ROH RCl, excep! a##!on-elmna!onRCl, excep! a##!on-elmna!on

an# no! an# no! ((22

"en ! ' a##!on-elmna!on:"en ! ' a##!on-elmna!on:


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PClPCl33::

=0F=0F

O

OHPCl5

O

ClPCl3

OHCl+ ++

P+rP+r11::


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P+rP+r11 %ec"an'm:%ec"an'm:

&&

22

R

O

OH PBr2Br

R

O

OPBr2HBr++

R

O

OPBr2++ H+ Br -

R

OHOPBr2

R

O

Br+HOPBr2

Br

:

: :

: :

1

2


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$+$+

AnhydridesAnhydrides

Cyclc an"y#r#e': Gu'! "ea!, or OClCyclc an"y#r#e': Gu'! "ea!, or OCl22


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C+C+

'sters:'sters:Alco"ol' 9 carboxylc ac#', ca! mneral ac#, re)er'bleAlco"ol' 9 carboxylc ac#', ca! mneral ac#, re)er'ble

;xample:;xample:HH 7 0, 7 0, AA 7 0, 7 0, EE 7 0 7 0

Re)er'e:Re)er'e: ;'!er "y#roly'';'!er "y#roly'', #r)en by exce'' H, #r)en by exce'' H22O Can al'o beO Can al'o be

effec!e# by a4ueou' (aOH *C"ap!er J: RB 9 (aeffec!e# by a4ueou' (aOH *C"ap!er J: RB 9 (a9-9-OO22CRCR

;'!erHy#r;'!erHy#r

EallagEallag


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%ec"an'm%ec"an'm:: HH99 mneral ac#, eg, Hmneral ac#, eg, H22OO$$, HCl, procee#' n!ally, HCl, procee#' n!ally lkelke

ace!al/a!onace!al/a!on of al#e"y#e' an# ke!one'of al#e"y#e' an# ke!one'

(o!e: Carbonyl oxygen ' alway'(o!e: Carbonyl oxygen ' alway' more ba'cmore ba'c !"an!"an"y#roxy oxygen, becau'e of"y#roxy oxygen, becau'e of re'onancere'onance n !"en !"epro!ona!e# pro#uc!pro!ona!e# pro#uc!


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;'!er;'!er


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In!ramolecular e'!erfca!on:In!ramolecular e'!erfca!on: Dac!one'Dac!one'

;)en w!"ou! remo)ng !"e wa!er !"e e4ulbrum ';)en w!"ou! remo)ng !"e wa!er !"e e4ulbrum 'fa)orable becau'e of en!ropy *fa)orable becau'e of en!ropy *po'!)epo'!)e A' alway' n A' alway' nre)er'ble reac!on' *!"ermo#ynamc con!rol,re)er'ble reac!on' *!"ermo#ynamc con!rol,cycl/a!on ' be'! for f)e an# 'x membere# rng'cycl/a!on ' be'! for f)e an# 'x membere# rng'


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)+)+ AmidesAmides

"' me!"o# ' rarely u'e# Problem:


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%ec"an'm:%ec"an'm:

Hg"ly pHg"ly pHH #epen#en! profle >e '"all 'ee n#epen#en! profle >e '"all 'ee nC"ap!er 20 !"a! am#e forma!on ' be!!erC"ap!er 20 !"a! am#e forma!on ' be!!er

accompl'"e# by Kac!)a!onL of !"e carboxyaccompl'"e# by Kac!)a!onL of !"e carboxygroup, a' n alkanoyl "al#e' or an"y#r#e' orgroup, a' n alkanoyl "al#e' or an"y#r#e' ore)en e'!er'e)en e'!er'


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Cyclc am#e':Cyclc am#e': Im#e'Im#e' from #ocfrom #ocac#', orac#', or lac!am'lac!am' fom amno ac#'fom amno ac#'

Im#e forma!on:Im#e forma!on:


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Dac!am forma!on:Dac!am forma!on:

Penclln' are lac!am':Penclln' are lac!am':

N

S

OCOOH

HHRHN

OHR'

RMOH '!an#' for !ran'pep!#a'e, !"eRMOH '!an#' for !ran'pep!#a'e, !"een/yme nece''ary for all cell wallen/yme nece''ary for all cell wallcon'!ruc!on O'mo!c pre''ure n acon'!ruc!on O'mo!c pre''ure n acell ' enormou', &0-20 a!m Pencllncell ' enormou', &0-20 a!m Penclln

cau'e' l!erally an explo'oncau'e' l!erally an explo'on


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,ther Reactions o,ther Reactions o

Carboxylic AcidsCarboxylic Acids

&& Re#uc!onRe#uc!on by DAlHby DAlH$$

%ec"an'm complex,%ec"an'm complex,no! clear, po''bly )a:no! clear, po''bly )a: C

O

O

H

R

Al

Li

H:

2 H ll @ l" # l k R


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22 Hell-@ol"ar#-Neln'ky Reac!on:Hell-@ol"ar#-Neln'ky Reac!on:%ake'%ake' -bromocarboxylc ac#'-bromocarboxylc ac#'

P 9 +rP 9 +r22 P+rP+r11

Impor!an! func!onal/a!on? can be explo!e# !o acce''Impor!an! func!onal/a!on? can be explo!e# !o acce''-amno ac#' %ec"an'm ' remn'cen! of ac#-amno ac#' %ec"an'm ' remn'cen! of ac#

ca!aly/e# "alogena!on of al#e"y#e' an# ke!one'ca!aly/e# "alogena!on of al#e"y#e' an# ke!one'

Jako !ol"ar#Jako !ol"ar#$13&-1910'$13&-1910'

(kola ()li*ki *&8J&-&=31

Carl a* /o* H)ll*&8$=-&=2J

http://www.jergym.hiedu.cz/~canovm/mechanic/pravidl2/hell/z.htmhttp://www.jergym.hiedu.cz/~canovm/mechanic/pravidl2/hell/z.htm


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%ec"an'm:%ec"an'm:

A' n !"e ac# ca!aly/e# "alogena!on of al#e"y#e' an# ke!one',A' n !"e ac# ca!aly/e# "alogena!on of al#e"y#e' an# ke!one',!"' nee#'!"' nee#' enol/a!onenol/a!on of RCHof RCH22COOH Howe)er, !"e COOH groupCOOH Howe)er, !"e COOH group

' !oo '!able !o enol/e 'uffcen!ly, "ence ! re4ure'' !oo '!able !o enol/e 'uffcen!ly, "ence ! re4ure' ac!)a!onac!)a!on !o RCH!o RCH22C*O+rC*O+r

p: a 7 &J


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. ! l # " f ! 2 # 1. ! l # " f ! 2 # 1


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.e!ale# mec"an'm' of '!ep' 2 an# 1:.e!ale# mec"an'm' of '!ep' 2 an# 1:

9. Carboxylic Acids

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