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
C
O
benzophenone
diphenyl ketone
C
O
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
1
2
3
4
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
C
O
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
O
C
..:+
- O
C
..::-
+
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=O
MECHANISMS
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
+:Nu
slow:
..
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
CH2CH2COOHCH2CH2COOH
CH3
CH3
Fe
C
N..
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
_+
H2O
H +
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
H
H
..: :
+
+
..
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
C
O
OHH
HO
C
O
OH
H
OH
H
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 C
O
R
OH
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
CCl
Cl
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 CH
O
HOH
OHC C
O
HH
O
C C
O
HPh
O
C CPh
O
HOH
OH
glyoxal
phenylglyoxal
ACETALS ANDACETALS ANDHEMIACETALSHEMIACETALS
O HO
OH
H
H
..: :
+
+
..
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'
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 AlcoholsAddition 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 startingmaterial, but we will show how they can be made.
C O
R
H
C
R
H
OH
ORC
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 HEMIACETALSACETALS AND HEMIACETALS
*older term *older term
hemiacetal
C
O
R R
H O
R
H
C
O
R R
H
OH R
C
O
R R
H
RHO
C
O
R R
H
RO
ORH
.. ..
..
..
..
..
..
..
..
: : :
:
:
:
++
+
..R O
H
H+
ACID CATALYZEDACID CATALYZEDFORMATION OF AFORMATION OF AHEMIACETALHEMIACETAL
ROH H2SO4 R O H
H
+ +
..
+
Normally the startingmaterial is favored -but a second moleculeof alcohol can reactif in excess (next slide)
Like a hydroniumion
firstaddition
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 ( 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
H2O
NaOH
+
H2O
hydrate
hemiacetal acetal
R-O-H
H2O
R-O-H
ADDITION OF WATER AND ALCOHOLSADDITION OF WATER AND ALCOHOLS
WATER
ALCOHOLS
C
OOH OR RO OR
C
OOH 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 air
2. 1,3,4,5,6-pentahidroksi-2-heksanon dengan air
3. propanal dengan metanol
4. Aseton dengan 1,2,3-propanatriol
Ramalkan apa produk reaksi sikloheksanon dengan :
1. CH3NH2
2. (CH3)2NH