ALDEHYDES AND KETONES

Aldehyde

Ketone

O

CR H

R = H, alkyl, aryl

O

CR R'

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

STRUCTURE

NOMENCLATURENOMENCLATURE

• 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

IUPAC Nomenclature of KetonesIUPAC Nomenclature of Ketones

Do the ketones section of Organic Nomenclature program!

CH3

CCH2

CH2CH3

O

2-Pentanone

EXAMPLES

O

CCH2 CH

CH3 CH2

CH2

CH3

CH3

4-Ethyl-3-hexanone

O

CH

CH3

CH3

3-Isopropylcyclopentanone

Common, or Trivial, Common, or Trivial, NamesNames

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

• Combine into a name, according to the pattern:

alkyl alkyl’ ketone

NOTE: This is not all one word!

KETONESKETONES

CH3

CCH2

CH2CH3

O

Methyl propyl ketone

Example of Common NamesExample of Common Names

O

CCH2 CH2

CH3 CH3

Diethyl ketone

O

CCH3 CH3

acetone

dimethyl ketone

A common laboratorysolvent and cleaningagent

SPECIAL CASESSPECIAL CASES

CO

benzophenonediphenyl ketone

CO

CH3

acetophenone

methyl phenyl ketoneKNOWTHESE

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

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

• Aldehyde ending is -al

IUPAC Nomenclature of AldehydesIUPAC Nomenclature of Aldehydes

Do the aldehydes section of Organic Nomenclatureprogram.

EXAMPLES

CH3

CH2CH2

CH2C

O

Hpentanal

CH3CH

CHC

O

HCH3

Cl

2-chloro-3-methylbutanal

12

34

always carbon 1aldehyde group is

O

CH H

O

CCH3 H

O

CCH2 HCH3

O

CC HCH2CH3

O

CC HCH2CH2CH3

O

CCH2 HCH2CH2CH2CH3

Formaldehyde Acetaldehyde Propionaldehyde

Butyraldehyde Valeraldehyde

Caproaldehyde

1 2 3

4 5

6

Common Names of the AldehydesCommon Names of the Aldehydes

RECOGNIZE THESE

O

CH H

O

CH CH3

CO

H

SPECIAL CASESSPECIAL CASES

formaldehyde

acetaldehyde

benzaldehyde

KNOWTHESE

C

C C C C C C H

O

Forming Common Names of AldehydesForming Common Names of Aldehydes

CHO

Cl

-chlorocaproaldehyde( -chlorohexanal )

CHO

Cl

-chlorocaproaldehyde( -chlorohexanal )

USE OF GREEK LETTERS

…….

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

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

NUCLEOPHILIC ADDITION

OC

..:+

- OC

..:: -

+

THE CARBONYL GROUPTHE CARBONYL GROUP

electrophilic at carbon

nucleophilicat oxygen

Nu:nucleophiles attack here

H+ or E+electrophiles add here

GENERALIZED CHEMISTRY

NUCLEOPHILIC ADDITION TO C=ONUCLEOPHILIC ADDITION TO C=OMECHANISMS

IN ACID AND IN BASE

+ :Nuslow

: :..

:_

O

CC

O

Nu

:..

:

C

O

Nu

+ H2O

:..

C

O

Nu

Hfast

_

..

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

analkoxideion

BASIC SOLUTIONGood nucleophilesand strong bases(usually charged)

-

or on adding acid

+ :Nuslow

:..

O

C

H

C

O

Nu

H+

O

C

H:O

C+ H+ fast

+:..

..

Nucleophilic Addition to Carbonyl Nucleophilic Addition to Carbonyl Acid CatalyzedAcid Catalyzed

Acid catalysis speeds the rate of addition of weak nucleophiles and weak bases (usually uncharged).

more reactive toaddition than the un-protonated precursor

ACIDIC SOLUTION

(+)

pH 5-6stronger acidprotonates thenucleophile

CYANOHYDRINSCYANOHYDRINS

+ CN_

R C R

O

R C R

O

CN

R C R

O

CN

+ R C R

O

CN

H

: : : :

: : :

..

..

_

_ ..

OH2

A cyanohydrin

Addition of CyanideAddition of CyanideBuffered to pH 6-8

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

a cyanohydrin

:C N:

N

N

N

N

CH3

CH3

CH2CH2COOH CH2CH2COOH

CH3

CH3

Fe

CN..

CYANIDE ION BONDS TO HEMOGLOBINCYANIDE ION BONDS TO HEMOGLOBIN

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

CYANIDE ISIS A POISON

You die ofsuffocation -lack of oxygen.

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

..

ORGANOMETALLICSORGANOMETALLICS

+

(R-MgBr)

M_ +

H2OH +

R M

O

CR R

R C R

O

R

R C R

O

R

H

+ M(OH)x

: : : :

:

..

..

(R-Li)

Addition of Organometallic ReagentsAddition of Organometallic Reagents

ether

These reagents cannot exist in acid solution

workupstep

alcohol

:R -

Synthesis of Alcohols

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

• Organometallics with ketones yield tertiary alcohols• Organometallics with aldehydes yield secondary alcohols• Organometallics with formaldehyde yield primary alcohols.• Organometallics with carbon dioxide yield carboxylic acids.

etc.

All reviewto you

HYDRATESHYDRATES

+ H2O

O

CR R'

R C R'

O

O

H

H

a hydrate

H+

hydrates are unstableand cannot be isolatedin most cases

Addition of WaterAddition of Water

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

aldehyde or ketonefavored

+ H2O

O

CR R'

R C R'

O

O

H

H

O HO

OH

HH

..: :

+

+..

ACID CATALYSISACID CATALYSIS

O H

+

..:

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

can react

RECALL

Water is a weak nucleophile.

O H

O HH

CO

OHH

HOCO

OH

HO

HH

H

O HH O

HH

H

.. ..

....

.. ..

..

....

..

: : : :

:

+

+

+ a hydrate

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

for most compounds the equilibrium favors the starting materials and you cannot isolate the hydrate

catalyzed by atrace of acid

In a reaction where all steps arereversible, the steps in the reversereaction are the same as those inthe forward reaction, reversed!

MICROREVERSIBILITY:

..+

an excess of H2O18

shifts the equilibriumto the right

R CO

RO

H

H

O

R ROH2

O

R R

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

18

18

18

+ H+

exchange shows the presence of a symmetricintermediate

+H2O18 -H2O

excess

OH

OHO

CClCl

Cl HOH

OHC

O

HCl

Cl

Cl

SOME STABLE HYDRATESSOME STABLE HYDRATES

chloral chloral hydrate

cyclopropanone cyclopropanone hydrate

120o expected60o required

109o expected60o required

sp2 sp3

+

these also indicate that hydrates are possible

SOME ADDITIONAL STABLE HYDRATESSOME ADDITIONAL STABLE HYDRATES

C CHO

HOH

OHC C

O

HH

O

C CO

HPh

OC CPhO

HOH

OH

glyoxal

phenylglyoxal

ACETALS ANDACETALS ANDHEMIACETALSHEMIACETALS

O HO

OH

HH

..: :

+

+..

ACID CATALYSISACID CATALYSIS

O H

+

..:

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

can react

RECALL

Alcohols are weak nucleophiles.

R C R'

OROH R C

OR'

O

H

R

R CO

R'O

H

RROH R C

OR'

O

R

R

+

+ H OH

+

Addition of AlcoholsAddition of Alcoholsaddition of one mole

addition of second mole

hemiketal

an aketal

H+

H+

TWO MOLES OF ALCOHOL WILL ADD

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

C OR

HC

R

H

OH

ORC

R

H

OR

OR

CR

R

OR

ORC

R

R

OH

ORC O

R

R

ROH

ROH

ROH

ROH

aldehyde

ketone

hemiacetal acetal

(ketal)*(hemiketal)*

ACETALS AND HEMIACETALSACETALS AND HEMIACETALS

*older term *older term

hemiacetal

CO

R R

H OR

H

CO

R R

H

OH R

CO

R R

H

RHO

CO

R R

H

RO

ORH

.. ..

..

..

..

..

..

..

..

: : :

:

:

:

++

+

..R OH

H+

ACID CATALYZEDACID CATALYZEDFORMATION OF AFORMATION OF AHEMIACETALHEMIACETAL

ROH H2SO4 R O HH

+ +..

+

Normally the startingmaterial is favored -but a second moleculeof alcohol can reactif in excess (next slide)

Like a hydroniumion

firstaddition

acetal

H OR

HO

R

H

CO

R R

H

RO

ORH

CO

R R

H

RO

H

CR R

RO

CO

R R

R

RO

H

CO

R R

R

RO

O HH

ORH

H

:....

....

.. :::

:..

..

..

..

..

....

..

:

::

::

CR R

RO: :+

+

+

+ +

+

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

Resonancestabilizedcarbocation

SN1

second addition

hemiacetal

remove

STABILITY OF ACETALS AND HEMIACETALSSTABILITY OF ACETALS AND HEMIACETALS

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

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

COR

ORC O

ROH

ROH

COR

OR

AQUEOUSACID

AQUEOUSBASE no reaction

H2SO4

H2O

H2ONaOH

+

H2Ohydrate

hemiacetal acetal

R-O-H

H2O

R-O-H

ADDITION OF WATER AND ALCOHOLSADDITION OF WATER AND ALCOHOLSWATER

ALCOHOLS

CO OH OR RO OR

CO OH OH

RO OR OROH+2

no reactionNaOHH2O

H2OH+ acetals are

stable to basebut not toaqueous acid

REAKSI OKSIDASI

OKSIDASI ALDEHID DAN KETON

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

asam karboksilat

Zat pengoksidasi : KMnO4, H, H2O

Reaksi Reduksi

Reaksi Reduksi

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

H2, katalis Zn/Hg, HCl

Reaksi Adisi-eliminasi

Reaksi Adisi-eliminasi

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

Ramalkan produk hemiasetal atau hemiasetal siklik dari:

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

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

Ramalkan apa produk reaksi sikloheksanon dengan :

1. CH3NH22. (CH3)2NH