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KETONES

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Aldehyde

Ketone

O

C

R HR = H, alkyl, aryl

O

C

R R'

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

STRUCTURE

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NOMENCLATURE

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Choose the longest continuous carbon chain that

contains the carbonyl carbon

Number from the end of the chain closest to thecarbonyl carbon

Ketone ending is -one

IUPAC Nomenclature of Ketones

Do the ketonessection of Organic Nomenclature

program!

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CH 3

C

CH 2

CH 2CH 3

O

2-Pentanone

EXAMPLES

O

C

CH2 CH

CH3 CH2

CH2

CH3

CH3

4-Ethyl-3-hexanone

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O

CH

CH3

CH3

3-Isopropylcyclopentanone

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Common, or Trivial, Names

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!

KETONES

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CH 3

C

CH 2

CH 2CH 3

O

Methyl propyl ketone

Example of Common Names

O

CCH2 CH2

CH3 CH3

Diethyl ketone

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O

C

CH3 CH3

acetone

dimethyl ketone

A common laboratory

solvent and cleaning

agent

SPECIAL CASES

C

O

benzophenone

diphenyl ketone

C

O

CH3

acetophenone

methyl phenyl ketoneKNOW

THESE

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Reaksi yang menghasilkan Keton

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Pembuatan keton dengan penambahan ikatan Karbon-

karbon Keton dapat dibuat dengan mengoksidasi alkohol sekunder

dari produk aldehid dengan Reagen Grignard

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NUCLEOPHILIC ADDITION TO C=O

MECHANISMS

IN ACID AND IN BASE

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+ :Nuslow

: :.. :_

O

CC

O

Nu

:..

:

C

O

Nu

+ H2O

:..

C

O

Nu

Hfast

_

..

Nucleophilic Addition to CarbonylBasic or Neutral Solution

an

alkoxide

ion

BASIC SOLUTIONGood nucleophiles

and strong bases

usually charged)

-

or on adding acid

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+:Nu

slow

:..

O

C

H

C

O

Nu

H+

O

C

H:O

C+ H

+ fast

+

:..

..

Nucleophilic Addition to Carbonyl

Acid 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 5-6

stronger acid

protonates the

nucleophile

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CYANOHYDRINS

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+ 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 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:

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ORGANOMETALLICS

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+

(R-MgBr)

M

_+

H2O

H+

R M

O

C

R R

R C R

O

R

R C R

O

R

H

+ M(OH)x

: : : :

:

..

..

(R-Li)

Addition of Organometallic Reagents

ether

These reagents cannot

exist in acid solution

workup

step

alcohol

:R -

Synthesis of Alcohols

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Summary of Reactions of

Organometallics with

Carbonyl Compounds

Organometallics with ketones yield

tertiaryalcohols

Organometallics with aldehydes yield

secondaryalcohols

Organometallics with formaldehyde yieldprimaryalcohols.

Organometallics with carbon dioxide yield

carboxylic acids.

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HYDRATES

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+ H2O

O

C

R R'

R C R'

O

O

H

H

a hydrate

H+

hydrates are unstable

and cannot be isolated

in most cases

Addition of Water

most hydrates revert to an aldehyde

or ketone as soon as they form

aldehyde or ketonefavored

+ H2O

O

C

R R'

R C R'

O

O

H

H

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O H

O

OH

HH

..

: :+

+

..

ACID 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.

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O H

O HH

C

O

OHH

HO

C

O

OH

H

OH

H

H

O H

H OH

H

H

....

..

..

.. ..

..

..

..

..

: : : :

:

+

+

+ a hydrate

WATER ADDS TO THE CARBONYL GROUP OF

ALDEHYDES AND KETONES TO FORM HYDRATES

for most compounds the equilibrium

favors the starting materials

and you cannot isolate the hydrate

catalyzed by a

trace of acid

In a reaction where all steps are

reversible, the steps in the reverse

reaction are the same as those in

the forward reaction, reversed!

MICROREVERSIBILITY:

..

+

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Mekanisme hidrasi dalam suasana basa

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Mekanisme

hidrasi dalamsuasana asam

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ACETALS ANDHEMIACETALS

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O H

O

OH

HH

..

: :+

+

..

ACID CATALYSIS

O H

+

..

:

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

can react

RECALL

Alcohols are weak nucleophiles.

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R C R'

O

ROH R C

O

R'

O

H

R

R C

O

R'

O

H

R

ROH R C

O

R'

O

R

R

+

+ H O

H

+

Addition of Alcohols

addition 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 starting

material, but we will show how they can be made.

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C OR

H

CR

H

OH

OR C

R

H

OR

OR

C

R

R

OR

ORC

R

R

OH

ORC O

R

R

ROH

ROH

ROH

ROH

aldehyde

ketone

hemiacetal acetal

(ketal)*(hemiketal)*

ACETALS AND HEMIACETALS

*older term *older term

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hemiacetal

C

O

R R

H O

R

H

C

O

R R

H

OH R

C

O

R R

H

RH O

C

O

R R

H

R

O

OR

H

.. ..

..

..

..

..

..

..

..

: : :

:

:

:

+ +

+

..R O

H

H

+

ACID CATALYZED

FORMATION OF A

HEMIACETAL

R OH H 2SO4 R O H

H

++

..

+

Normally the starting

material is favored -

but a second molecule

of alcohol can react

if in excess (next slide)

Like a

hydronium

ion

first

addition

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acetal

H O

R

H

OR

H

C

O

R R

H

RO

ORH

C

O

R R

H

RO

H

CR R

RO

C

O

R R

R

RO

H

C

O

R R

R

RO

O HH

ORH

H

:....

....

.. :::

:..

..

..

..

..

....

..

:

::

:

:

CR R

RO:+

+

+

+

+

FORMATION OF THE ACETAL ( from the hemiacetal )

Resonance

stabilized

carbocation

SN1

second

addition

hemiacetal

remove

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STABILITY 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

AQUEOUS

ACID

AQUEOUS

BASE no reaction

H2SO4

H2O

H2O

NaOH

+

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H2O

hydrate

hemiacetal acetal

R-O-H

H2O

R-O-H

ADDITION OF WATER AND ALCOHOLS

WATER

ALCOHOLS

C

OOH OR RO OR

C

OOH OH

RO OR OROH+2

no reactionNaOH

H2O

H2O

H+ acetals are

stable to base

but not to

aqueous acid

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REAKSI OKSIDASI

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OKSIDASI ALDEHID DAN KETON

Keton tidak mudah dioksidasi

Aldehid sangat mudah dioksidasi, menjadi

asam karboksilat

Zat pengoksidasi : KMnO4, H, H2O

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Reaksi Reduksi

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Reaksi Reduksi

Reduksi aldehid menghasilkan alkohol primer

Reduksi keton menghasilkan alkohol sekunder

Zat pereduksi:

H2, katalis

Zn/Hg, HCl

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Reaksi Adisi-eliminasi

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Reaksi Adisi-eliminasi

Aldehid + Amina Primer Imina

Aldehid + Amina sekunder Enamina

Aldehid + Amina tersier hidrazon

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Ramalkan produk hemiasetal atau

hemiasetal siklik dari:

1. 5-hidroksi-2-heksanon dengan air

2. 1,3,4,5,6-pentahidroksi-2-heksanon

dengan air

3. propanal dengan metanol

4. Aseton dengan 1,2,3-propanatriol

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Ramalkan apa produk reaksi sikloheksanon

dengan :

1. CH3NH2

2. (CH3)2NH

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