carboxylic acids (1)

8/20/2019 Carboxylic Acids (1)

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Carboxylic acids:

R-COOH, R-CO2H,

Common names:

HCO2H formic acid L. formica ant

CH3CO2H acetic acid L. acetum vinegar

CH3CH2CO2H propionic acid G. “first salt”

CH3CH2CH2CO2H butyric acid L. butyrum butter

CH3CH2CH2CH2CO2H valeric acid L. valerans

R COH

O


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Carboxylic acids, common names:

…CH3(CH2)4CO2H caproic acid L. caper goat

CH3(CH2)CO2H ---

CH3(CH2)!CO2H caprylic acid

CH3(CH2)"CO2H ---

CH3(CH2)#CO2H capric acid

CH3(CH2)$CO2H ---

CH3(CH2)%&CO2H lauric acid oil of lauryl


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4 3 2 %

C'C'C'C'COδ γ β α used in common names

CH3CH2CH2CHCOOH

Br

CH3CHCH2COOH

CH3

α− bromovaleric acid β -methylbutyric acid

isovaleric acid


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COOH

COOH COOH COOH

CH3

CH3CH3

benzoic acid

o-toluic acid m-toluic acid p-toluic acid

special names


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IUPAC nomenclature for carboxylic acids:

parent cain longe*t, continuou* carbon cain tat contain*

te carbo+yl group alane, drop e, add oic acid

HCOOH metanoic acid

CH3CO2H etanoic acid

CH3CH2CO2H propanoic acid

CH3CH3CHCOOH 2-metylpropanoic acid

.r

CH3CH2CHCO2H 2-bromobutanoic acid


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dicarboxylic acids:

HOOC-COOH o+alic acid

HO2C-CH2-CO2H malonic acid

HO2

C-CH2

CH2

-CO2

H *uccinic acid

HO2C-CH2CH2CH2-CO2H glutaric acid

HOOC-(CH2)4-COOH adipic acid

HOOC-(CH2)-COOH pimelic acid

O, my/ 0uc good apple pie/


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CO2H

CO2H

CO2H

CO2H

CO2H

CO2H

phthalic acid isophthalic acidterephthalic acid

CCOOHH

CCOOHH

CCOOHH

CHHOOC

maleic acid fumaric acid


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salts of carboxylic acids:

name of cation 1 name of acid drop ic acid, add ate

CH3CO2 a *odium acetate or *odium etanoate

CH3CH2CH2CO2 H4 ammonium butyrate

ammonium butanoate

(CH3CH2COO)2g magne*ium propionate

magne*ium propanoate


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HO C

OH

O

NaO C

ONa

O

HO C

ONa

O

carbonic acid sodium bicarbonatesodium hydrogen carbonate

sodium carbonate

NaHCO3

Na2CO3


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physical properties:

polar 1 ydrogen bond relatively ig mp5bp

6ater in*oluble

e+ception* four carbon* or le**

acidic turn blue litmu* red

*oluble in 7 aOH

RCO2H 1 aOH RCO2- a1 1 H2O

*tronger *tronger 6eaer 6eaer acid ba*e ba*e acid


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RCO2H RCO2-

covalent ionic6ater in*oluble 6ater *oluble

Carboxylic acids are insoluble in ater, but soluble in !"

#a$%&

%8 9dentification8

28 0eparation of carbo+ylic acid* from ba*ic5neutral organic

compound*8

:e carbo+ylic acid can be e+tracted 6it a;8 aOH and

ten regenerated by te addition of *trong acid8


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Carboxylic acids, syntheses:

'& oxidation of primary alcohols

(C%)$% * + )Cr)$ (C$$%

)& oxidation of arenes

Ar( * +-n$., heat ArC$$%

/& carbonation of 0ri1nard rea1ents

(-12 * C$) (C$)-12 * %*

(C$$%

.& hydrolysis of nitriles

(C# * %)$, %*, heat (C$$%


13/43

'& oxidation of 'o alcohols:

CH3CH2CH2CH2-OH 1 CrO3 CH3CH2CH2CO2H

n-butyl alcool butyric acid

%-butanol butanoic acid

CH3 CH3CH

3CHCH

2-OH 1


14/43


CH3

CH3

H3C

CH2CH3

!nO"# heat

!nO"# heat

!nO"# heat

COOH

COOH

HOOC

COOH

toluene benzoic acid

p-$ylene terephthalic acid

ethylbenzene benzoic acid

% CO2

note: aromatic

acids only3


15/43

/& carbonation of 0ri1nard rea1ent:

R-> Rg> RCO2g> RCOOH

Increases the carbon chain by one carbon&

g CO2 H1

CH3CH2CH2-.r CH3CH2CH2g.r CH3CH2CH2COOH

n-propyl bromide butyric acid

g CO2 H1

C

O

O

R!g& % R C

O

O-% %!g&

H%

R C

O

OH


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CH3

Br

!g

CH3

!gBr

CO2 H%

CH3

COOH

p-toluic acid

CH3Br 2# hv

CH2Br !g

CH2!gBr

CO2

H%

CH2 COOH

phenylacetic acid


17/43

.& %ydrolysis of a nitrile:

H2O, H1

R-C≡ R-CO2H

eat

H2O, OH

-

R-C≡ R-CO2- 1 H1 R-CO2H

eat

R-> 1 aC R-C 1 H1, H2O, eat RCOOH

%o alyl alide

Adds one more carbon to the chain&

(42 must be 'o or C%/3


18/43

CH3

Br 2# hvCH2Br

NaCN

CH2 CN

H2O# H%# heat

CH2 COOH

CH3CH2CH2CH2CH2CH2-Br

CN

CH3CH2CH2CH2CH2CH2-CN

H2O# H%# heat

CH3CH2CH2CH2CH2CH2-COOH

'-bromohe$ane

heptanoic acid

toluene

phenylacetic acid


19/43

CO2H

CH2OH

CH3

Br

C N

!gBr

!nO"# heat

!nO"

!gCO2( then H

%

H2O# H%# heat


20/43

carboxylic acids, reactions:

'& as acids

)& con5ersion into functional deri5ati5es

a6 acid chlorides

b6 esters

c6 amides

/& reduction

.& alpha4halo1enation

!& 7A8


21/43

as acids:

a6 ith acti5e metalsRCO2H 1 a RCO2

- a1 1 H2(g)

b6 ith bases

RCO2H 1 aOH RCO2- a1 1 H2O

c6 relati5e acid stren1th9

CH4 ? H3 ? HC≡CH ? ROH ? HOH ? H2CO3 ? (C$)% ? H@

d6 uantitati5e

HA 1 H2O H3O1 1 A- ioniBation in 6ater


22/43


23/43

H) % H2O

H3O% % )-

p o t e

n t i a l e n e r g y

ionization

GH

:e *maller te GH, te more te e;uilibrium lie* to te

rigt, giving a larger


24/43

R CO-

O

R C

O-

O

R CO

O

Re*onance *tabiliBation of te carbo+ylate ion decrea*e*

te GH, *ift* te ioniBation in 6ater to te rigt, increa*e*

te


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Jffect of *ub*tituent group* on acid *trengtF

CH3COOH %8" + %&-

ClCH2COOH %3! + %&-

Cl2CHCOOH ,3& + %&-

Cl3CCOOH 23,2&& + %&-

-Cl i* electron 6itdra6ing and delocaliBe* te negative

carge on te carbo+ylate ion, lo6ering te KJ, decrea*ing

te GH, *ifting te ioniBation to te rigt and increa*ing

acid *trengt8


26/43

7ffect of substituent 1roups on acid stren1th of ben;oic acids9

7lectron ithdrain1 1roups 6ill *tabiliBe te anion, decrea*e te GH, *iftte ioniBation to te rigt, increa*ing te


27/43

-H2, -HR, -R 2-OH

-OR electron donating-HCOCH3-C!H-R

-H->

-CHO, -COR -0O3H

-COOH, -COOR electron 6itdra6ing-C

-R 31

-O2


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Relative acid *trengtF


29/43

)& Con5ersion into functional deri5ati5es:

acid chlorides

R C

OH

O +OCl2

or ,Cl3

or,Cl

R C

Cl

O

CO2H % +OCl2 COCl

CH3CH2CH2 CO

OH

,Cl3CH3CH2CH2 C

O

Cl


30/43

esters

LdirectM e*terification H1

RCOOH 1 RNOH RCO2RN 1 H2O

-rever*ible and often doe* not favor te e*ter

-u*e an e+ce** of te alcool or acid to *ift e;uilibrium

-or remove te product* to *ift e;uilibrium to completion

LindirectM e*terificationRCOOH 1 KCl3 RCOCl 1 RNOH RCO2RN

-convert te acid into te acid cloride fir*t not rever*ible


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C C

O

O

CH3

% H2O

+OCl2

CCH3OH

O

OH

% CH3OH

O

Cl

H%


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amides

LindirectM only/

RCOOH 1 0OCl2 RCOCl 1 H3 RCOH2 amide

Pirectly reacting ammonia 6it a carbo+ylic acid re*ult* in

an ammonium *altRCOOH 1 H3 RCOO

- H41

acid ba*e

OH

O

3-!ethylbutanoic acid

,Cl3

Cl

O NH3

NH2

O


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CO

OH

,Cl3 CO

ClCO

NH2

NH3

NH3

amide

C

O

O NH"ammonium salt


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/& (eduction:

RCO2H 1 QiAlH

4 ten H1 RCH

2OH

%o alcool

Carboxylic acids resist catalytic reduction under normal

conditions&

RCOOH 1 H2, i

R

CH3CH2CH2CH2CH2CH2CH2COOH

Octanoic acid.Caprylic acid/

0i)lH" H%

CH3CH2CH2CH2CH2CH2CH2CH2OH

'-Octanol


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CH2 C

O

OH

H2# ,t

NR

0i)lH"

H%

CH2CH2OH


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.& Alpha4halo1enation: (Hell-olard-Selin*y reaction)

RCH2COOH 1 >2, K RCHCOOH 1 H>

>

T-aloacid

>2 Cl2, .r 2

COOH

Br 2#,NR .no alpha H/

CH3CH2CH2CH2COOH % Br 2#, CH3CH2CH2CHCOOH

Br pentanoic acid

2-bromopentanoic acid


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RCH2COOH % Br 2#, RCHCOOH % HBr

Br

NH2OHRCHCOOH

RCHCOOH

RCH1CHCOOHRCH2CHCOOH

Br

aminoacid

NH3

OH.alc/

then H%


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!& 7A8: (-COOH i* deactivating and meta- directing)

CO2H

CO2H

NO2

CO2H

+O3H

CO2H

Br

NR

HNO3#H2+O"

H2+O"#+O3

Br 2#e

CH3Cl#)lCl3

benzoic acid


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spectroscopy:

9R -COOH O'H *tretc 2&& 3&&& cm-% (b)

CO *tretc %!#& %"2 (*)

nmr -COOH %&8 %2 ppm


40/43

p-toluic acid

-COO'H

*tretcCO


41/43

COOH

CH3 a

b

c

c b a


42/43

Carboxylic acids, syntheses:

'& oxidation of primary alcohols

(C%)$% * + )Cr)$ (C$$%


Ar( * +-n$., heat ArC$$%

/& carbonation of 0ri1nard rea1ents

(-12 * C$) (C$)-12 * %*

(C$$%

.& hydrolysis of nitriles

(C# * %)$, %*, heat (C$$%


43/43

carboxylic acids, reactions:

'& as acids

)& con5ersion into functional deri5ati5es

a6 acid chlorides

b6 esters

c6 amides

/& reduction

.& alpha4halo1enation

!& 7A8

carboxylic acids (1)

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