ALDEHYDES AND KETONES

Ald h d STRUCTUREAldehyde

O

STRUCTURE

CR H

R = H, alkyl, aryl

Ketone

R H

O

R d R' lk l lC

R R'

R and R' = alkyl or arylR and R' cannot be hydrogen!

NOMENCLATURENOMENCLATURE

IUPAC Nomenclature of KetonesIUPAC Nomenclature of Ketones

Ch th l t ti b h i th t

IUPAC Nomenclature of KetonesIUPAC Nomenclature of Ketones

• Choose the longest continuous carbon chain that contains the carbonyl carbon

• Number from the end of the chain closest to the carbonyl carbon

• Ketone ending is -one

Do the ketones section of Organic Nomenclaturegprogram!

OEXAMPLES

C CH

O

CH 3

CCH 2

CH 2CH 3

2-Pentanone O

CCH2 CH

CH3 CH2CH3

CH2CH3CH3

4-Ethyl-3-hexanone

OO

CH CH3CH

CH3

3-Isopropylcyclopentanone

Common or Trivial NamesCommon or Trivial NamesKETONESKETONES

Common, or Trivial, NamesCommon, or Trivial, Names

• Name each group attached to the carbonyl group as an alkyl group

• Combine into a name, according to the pattern:

lk l lk l’ k talkyl alkyl’ ketone

NOTE This is not all one word!NOTE: This is not all one word!

Example of Common NamesExample of Common NamesO

CH 3

CCH 2

CH 2CH 3CH 3 CH 2 CH 3

Methyl propyl ketone OMethyl propyl ketone O

CCH3 CH3CCH2 CH2

CH3 CH3

Diethyl ketone

OSPECIAL CASESSPECIAL CASES

O

C CO

CCH3 CH3

di th l k t

C

diphenyl ketone

acetone

dimethyl ketonebenzophenone

diphenyl ketone

A common laboratorysolvent and cleaningagent C

OCH3g 3

methyl phenyl ketoneKNOW

acetophenoneKNOWTHESE

IUPAC Nomenclature of AldehydesIUPAC Nomenclature of Aldehydes

• Choose the longest continuous carbon chain that t i th b l bcontains the carbonyl carbon

• Number from the end of the chain closest to the • Number from the end of the chain closest to the carbonyl carbon (carbon #1!)

• Aldehyde ending is -al

Do the aldehydes section of Organic Nomenclatureprogram.

EXAMPLESEXAMPLES

CH CH Oaldehyde group is

CH3

CH2CH2

CH2C

O

H

always carbon 1

Hpentanal

CH CHCl

13CH3CH

CHC

O

HCH

1

2

3

4

HCH3

2-chloro-3-methylbutanal2 chloro 3 methylbutanal

Common Names of the AldehydesCommon Names of the AldehydesO

CH H

O

CCH H

O

CCH HCHH H CH3 H CH2 HCH3

O

Formaldehyde Acetaldehyde Propionaldehyde1 2 3

O

CC HCH2CH3

O

CC HCHCHCHC HCH2CH3 C HCH2CH2CH3

O

Butyraldehyde Valeraldehyde4 5

O

CCH2 HCH2CH2CH2CH3 RECOGNIZE22223

Caproaldehyde6

RECOGNIZETHESE

OSPECIAL CASESSPECIAL CASES

O

CCH H

CO

Hformaldehyde

O

C Hformaldehyde

CH CH

benzaldehyde

H CH3

acetaldehydeKNOWTHESEacetaldehyde

Forming Common Names of AldehydesForming Common Names of Aldehydes

OUSE OF GREEK LETTERS

C ω ε δ γ β α −−

C C C C C C H……. γ β

ω is always the end of the chain, no matter how long

CHO CHO

Cl

α-chlorocaproaldehyde

Cl

ω-chlorocaproaldehydeα chlorocaproaldehyde

( α-chlorohexanal )

ω chlorocaproaldehyde

( ω-chlorohexanal )

REACTIVITY OF THE C=O GROUPREACTIVITY OF THE C=O GROUP

NUCLEOPHILIC ADDITION

THE CARBONYL GROUPTHE CARBONYL GROUPGENERALIZED CHEMISTRY

THE CARBONYL GROUPTHE CARBONYL GROUP

nucleophilict at oxygen

H+ or E+electrophiles add here

O..

:δ+

δ-

O..

::-

C δ+

C+

electrophilic Nu:

nucleophiles attack here

electrophilic at carbon

NUCLEOPHILIC ADDITION TO C=ONUCLEOPHILIC ADDITION TO C=O

MECHANISMS

IN ACID AND IN BASEIN ACID AND IN BASE

Nucleophilic Addition to CarbonylNucleophilic Addition to CarbonylBasic or Neutral SolutionBasic or Neutral Solution

: :..

:_

OO..

Basic or Neutral SolutionBasic or Neutral Solution

an+ :Nu

slow:O

CC

Nu

analkoxideion

-

Nu

:..

:O :..O H

fast

_

C

Nu

+ H2O C

Nu

fast

or on adding acid

BASIC SOLUTIONGood nucleophiles

d t b BASIC SOLUTIONand strong bases(usually charged)

Nucleophilic Addition to Carbonyl Nucleophilic Addition to Carbonyl Acid CatalyzedAcid Catalyzed

O H:O fast

+:..

Acid CatalyzedAcid Catalyzedmore reactive toaddition than the un-

CC+ H+ fast

protonated precursor

slow:

..

O HO H+..

+ :NuCC

Nu (+)

Acid catalysis speeds the rate of addition of

k l hil d

ACIDIC SOLUTIONweak nucleophiles andweak bases (usually uncharged). pH 5-6

stronger acidprotonates thenucleophile

CYANOHYDRINSCYANOHYDRINS

Addition of CyanideAddition of Cyanide :C N:

O O: : : :.. _

yyBuffered to pH 6-8

+ CN_

R C R R C R

CN

O O H: : :.. _ ..

R C R

CN

+ R C R

CN

OH2

a cyanohydrin

A cyanohydrinIn acid solution there would be little CN-, and HCN (g) would be a problem (poison).

CYANIDE ION BONDS TO HEMOGLOBINCYANIDE ION BONDS TO HEMOGLOBIN

CN..

Cyanide bonds (irreversibly) to the

CYANIDE ISIS A POISON

CH3

C (irreversibly) to thesite (Fe II) whereoxygen usually bonds.

..

N NCH3

Y di fN

N

N

NCH3 CH3

FeYou die ofsuffocation -lack of oxygen.

CH3

CH CH COOH CH2CH2COOH

CH3

CH2CH2COOH 2 2

HCN is a gas that you can easily breathe into your lungs.

ORGANOMETALLICSORGANOMETALLICS

Addition of Organometallic ReagentsAddition of Organometallic ReagentsSynthesis of Alcohols

M_ +..

Addition of Organometallic ReagentsAddition of Organometallic Reagents

+

M

R M

O

C R C R

O: : : :ether

(R-MgBr)

H O

R RR

(R-Li)k

:R - H2OH +

O H:..These reagents cannot

exist in acid solution

workupstep

R C R

O H

+ M(OH)x

:exist in acid solution

l h lR

alcohol

Summary of Reactions of Summary of Reactions of Organometallics with Organometallics with Carbonyl CompoundsCarbonyl CompoundsCarbonyl CompoundsCarbonyl Compounds

All reviewt • Organometallics with ketones yield

tertiary alcohols• Organometallics with aldehydes yield

to you

• Organometallics with aldehydes yield secondary alcohols

• Organometallics with formaldehyde yieldOrganometallics with formaldehyde yieldprimary alcohols.

• Organometallics with carbon dioxide yieldcarboxylic acids.

etc.

HYDRATESHYDRATESHYDRATESHYDRATES

Addition of WaterAddition of Water

O O HH+

+ H2OCR R'

R C R'H

O H

a hydratealdehyde or ketonefavored

hydrates are unstableand cannot be isolatedin most cases

most hydrates revert to an aldehyde or ketone as soon as they formor ketone as soon as they form

+ H2O

O

CR C R'

O H

CR R'O H

ACID CATALYSISACID CATALYSIS

H+

ACID CATALYSISACID CATALYSIS

RECALL

O HO

OH

H..

: :+

+..

O H..OO: : O H

+

:

NAcid catalysis enhances the reactivity

:NuAcid catalysis enhances the reactivityof the carbonyl group - nucleophilicaddition proceeds more easily. weak nucleophiles

can react

Water is a weak nucleophile.

WATER ADDS TO THE CARBONYL GROUP OF WATER ADDS TO THE CARBONYL GROUP OF ALDEHYDES AND KETONES TO FORM HYDRATESALDEHYDES AND KETONES TO FORM HYDRATES

OH

HH

+

ALDEHYDES AND KETONES TO FORM HYDRATESALDEHYDES AND KETONES TO FORM HYDRATES

catalyzed by atrace of acid

O H

CO HO

CO HH.. .. .. ..

: : : :+

O HH

OHH

OH

H

....

....

.. :+ a hydrate

H O HH O

HH

H....

..

..+

for most compounds the equilibriumfavors the starting materials In a reaction where all steps are

MICROREVERSIBILITY:g

and you cannot isolate the hydratep

reversible, the steps in the reversereaction are the same as those inthe forward reaction, reversed!

ISOTOPE EXCHANGE REVEALS THE PRESENCE ISOTOPE EXCHANGE REVEALS THE PRESENCE OF THE HYDRATEOF THE HYDRATE

f H O18O O

OF THE HYDRATEOF THE HYDRATE

18 an excess of H2O18

shifts the equilibriumto the right

O

R ROH2

O

R R18

18

+ H+

excess

O H

R CO

RO

H

18

+H2O18 -H2O

OH

18exchange shows the presence of a symmetricintermediateintermediate

SOME STABLE HYDRATESSOME STABLE HYDRATESthese also indicate that hydrates are possible

Cl OHOClδ−

y p

CCl

Cl HOHC

HCl

Clδ+δ−

chloral chloral hydrateδ−

OHO

120o expected60o required

109o expected

OHO

l l

109 expected60o required

sp2 sp3

cyclopropanone cyclopropanonehydrate

SOME ADDITIONAL STABLE HYDRATESSOME ADDITIONAL STABLE HYDRATESSOME ADDITIONAL STABLE HYDRATESSOME ADDITIONAL STABLE HYDRATES

C CH

O

OH

OHC C

O

HH

O

HH

O O

glyoxal

C CO

HPh

O

C CPh

O

HOH

OH

H Hphenylglyoxal

ACETALS ANDACETALS ANDHEMIACETALSHEMIACETALSHEMIACETALSHEMIACETALS

ACID CATALYSISACID CATALYSIS

H+

ACID CATALYSISACID CATALYSIS

RECALL

O HO

OH

H..

: :+

+..

O H..OO: : O H

+

:

NAcid catalysis enhances the reactivity

:NuAcid catalysis enhances the reactivityof the carbonyl group - nucleophilicaddition proceeds more easily. weak nucleophiles

can react

Alcohols are weak nucleophiles.

Addition of AlcoholsAddition of AlcoholsTWO MOLES OF ALCOHOL WILL ADD

O O Haddition of one mole

TWO MOLES OF ALCOHOL WILL ADD

R C R'

OROH R C

OR'

O

H

R+ hemiketal

H+

O R

O H O Raddition of second mole

R CO

R'H

ROH R CO

R'R

+ H O+H+

O R O R H

an aketal

The equilibria normally favor the aldehyde or ketone startingmaterial, but we will show how they can be made.

ACETALS AND HEMIACETALSACETALS AND HEMIACETALS

C OR

CR OH

CR ORROH ROH

C OH

CH OR

CH ORaldehyde

hemiacetal acetal

CR OR

CR OH

C OR

ROH ROHC

R ORC

R ORC O

R ketone

(k t l)*(h ik t l)* (ketal)*(hemiketal)**older term *older term

R OH H 2SO4 R O HH

+ +..

Like a hydronium

H OR

H.. ..+

+

H yion

CO

R R

H

CO

R R

H

CO

R R

H.. .. ..: : :

+

OH R

RHO..

.. ....

+

ACID CATALYZEDACID CATALYZED ORH:ACID CATALYZEDACID CATALYZED

FORMATION OF AFORMATION OF AHEMIACETALHEMIACETAL

firstaddition

CO

R R

H..:

R OH

++

Normally the startingmaterial is favored -but a second molecule

hemiacetal RO..:

..R OHof alcohol can react

if in excess (next slide)

FORMATION OF THE ACETAL ( FORMATION OF THE ACETAL ( from the hemiacetal ))

remove

H OR

H HO HH ....+

second

remove

HO

R

H

CO H

CO HH

CR R

O

:..

....:..

CR R+

second addition

CR R

RO

CR R

RO

CR R

RO.. ::: ..

CR R

RO:+

+SN1

O RHR ...... :

Resonancestabilizedcarbocation

hemiacetal

ORH C

O

R R

RH

CO

R R

R

OR

H.... ::

:+ +

acetal RO

ROH .... ::

STABILITY OF ACETALS AND HEMIACETALSSTABILITY OF ACETALS AND HEMIACETALS

Most hemiacetals are not stable, except for those of sugars(see later)(see later).

Acetals are not stable in aqueous acid, but they are stable to aqueous baseaqueous base.

COR ROH

AQUEOUS H2SO4COR

C OROH

AQUEOUSACID

2 4

H2O+

COR

OR

AQUEOUSBASE no reaction

H2O

NaOH

OR

ADDITION OF WATER AND ALCOHOLSADDITION OF WATER AND ALCOHOLS

H2O

hydrate

WATER

CO OH OH

y

R O H R O H

ALCOHOLS

R-O-H

H2O

R-O-H

CO OH OR RO OR

hemiacetal acetal

RO OR OROH+2

H2OH+ acetals are

stable to basebut not to

no reactionNaOH

H2Obut not toaqueous acid

REAKSI OKSIDASIREAKSI OKSIDASI

OKSIDASI ALDEHID DAN KETON

• Keton tidak mudah dioksidasi• Aldehid sangat mudah dioksidasi menjadiAldehid sangat mudah dioksidasi, menjadi

asam karboksilat

Zat pengoksidasi : KMnO4, H, H2O

Reaksi ReduksiReaksi Reduksi

Reaksi Reduksi

• Reduksi aldehid menghasilkan alkohol primer• Reduksi keton menghasilkan alkohol sekunderReduksi keton menghasilkan alkohol sekunder• Zat pereduksi:

H2 k liH2, katalis Zn/Hg, HCl

Reaksi Adisi-eliminasiReaksi Adisi-eliminasi

Reaksi Adisi-eliminasi

• Aldehid + Amina Primer Imina• Aldehid + Amina sekunder EnaminaAldehid + Amina sekunder Enamina• Aldehid + Amina tersier hidrazon

Ramalkan produk hemiasetal atauRamalkan produk hemiasetal atau hemiasetal siklik dari:

1 5-hidroksi-2-heksanon dengan air1. 5 hidroksi 2 heksanon dengan air2. 1,3,4,5,6-pentahidroksi-2-heksanon

dengan airdengan air3. propanal dengan metanol4. Aseton dengan 1,2,3-propanatriol

Ramalkan apa produk reaksi sikloheksanonRamalkan apa produk reaksi sikloheksanon dengan :

1. CH3NH22. (CH3)2NH