Transcript Aldehydes and Ketones - Belle Vernon Area School District

Aldehydes and Ketones
Chapter 5
Aldehydes and Ketones
 Functional
group is O
The carbonyl
ll
group
C
Aldehyde = Carbonyl group is 1°
Ketone = Carbonyl group is 2°
Aldehyde
RCHO
ArCHO
Benzaldehyde
Ketones
RCOR
ArCOAr
ArCOR
O
C – C-C-C
Naming Aldehydes
–e from alkane and add –al
Methanal
Propanal
 Drop
2-chlorohexanal
Practice
Naming Ketones (2 ways)
1.
2.
IUPAC - # chain from the end
closest to the carbonyl, give the
carbon #, drop –e add –one
Name the groups on either side
of the carbonyl and follow with
ketone  list groups by order of
sixe of molar mass (smaller 1st)
Practice
2-butanone
methyl ethyl Ketone
3-hexanone
ethyl propyl ketone
Draw 2 – pentanone and name it the 2nd way
Practice

For the “old” way to name a ketone to use a
phenyl, the ring must be bonded directly to
the carbonyl
3-phenyl-3-propanone
ethyl phenyl ketone
4-phenyl – 3 – butanone/no secondary name
Practice
Preparation of Aldehydes
1.
Oxidation of 1° Alcohols (lose H2)
RCH2OH PCC CH2Cl2 RCHO + H2
Catalysts are
PCC = Pyridinium chororchrmate, C5H6NCrO3Cl
Dichloromethane = CH2Cl2
Practice
 Form
Propanal by oxidation
CH3CH2CH2OH  CH3CH2CHO + H2
Practice
2. Oxidize 1-hexanol
O
C-C-C-C-C-C-OH (Catalyst) C-C-C-C-C-C-H
+ H2
CH3(CH2)4CH2OH  (Catalyst) CH3(CH2)4CHO
+ H2
Practice
 Synthesize
propanal (str)
C-C-C + Cl2  C-C-C-Cl + HCl
C-C-C-Cl + H2O  C-C-C-OH + HCl
C-C-C-OH (Catalyst) C-C-C=O + H2
The 2nd Reaction Type
2. Reduction of acid chlorides (add H2)
+ H2  (Pt/Pd)
+ HCl
RCOCl + H2  (Pt/Pd) RCHO + HCl
*Acid chlorides look like aldehydes, but
have a –Cl where the end –H is. (We
will look at them more closely later)
Practice
 Form
propanal by reduction
CH3CH2COCl + H2  (Pt/Pd) CH3CH2CHO + HCl
Synthesis of Benzaldehyde
 The
=O is not directly on the
benzene, so you can’t follow he
steps for an alcohol – you have to
use the following…
Synthesis of Benzaldehyde
+
-AlCl3
+ HCl
+ 2Cl2 
+ 2HCl
+ H2O 
+ 2HCl
Preparation of Ketones
1. Oxidation of 2° alcohols
OH
O
R-C-R’ (Catlaysts) R-C-R’ + H2
RCHOHR’ (Catlaysts) RCOR’ + H2
Practice

Oxidize 2-pentanol (str, cond, name product)
OH
O
C-C-C-C-C  (Catalyst) C-C-C-C-C + H2
2-pentanone/methyl propyl ketone
CH3CHOH(CH2)2CH3 (Ctlyst) CH3CO(CH2)2CH3
+ H2
Practice

Form methyl ethyl ketone (str, cond, name
reactant)
Practice
 Synthesize
3-heptanone (cond.)
CH3(CH2)5CH3+Cl2CH3CH2CHCl(CH2)3CH3 +
HCl
CH3CH2CHCl(CH2)3CH3 + H2O 
CH3CH2CHOH(CH2)3CH3 + HCl
CH3CH2CHOH(CH2)3CH3  (Cats)
CH3CH2CO(CH2)3CH3 + H2
The 2nd Reaction Type
2. Friedel – Crafts Acylation - acyl group
RCO
O
O
ArH + R-C-Cl –AlCl3 R-C-Ar + HCl
ArH + RCOCl –AlCl3 RCOAr + HCl
Benzene must bond directly to the C=O
Practice

Form ethyl phenyl ketone (str, cond)
C-C-C-Cl +
-AlCl3 C-C-C-
+ HCl
CH3CH2COCl + C6H6 –AlCl3 CH3CH2COC6H5
+ HCl
Form pentyl phenyl ketone (str, cond)
Rxns of Aldehydes and Ketones
Reduction of aldes and kets to alcohols
O
R-C-H + H2 –Pt/Pd R-C-OH
RCHO + H2 –Pt/Pd RCH2OH
O
O
R-C-R + H2 –Pt/Pd R-C-R
RCOR + H2 –Pt/Pd RCHOHR
1.
Practice
Reduce 2-hexanone (str,cond, name prod)
O
OH
C-C-C-C-C-C + H2 –Pt/Pd C-C-C-C-C-C
2-hexanone

CH3CO(CH2)3CH3 + H2
–Pt/Pd
CH3CHOH(CH2)3CH3
Practice

Reduce Pentanal (str,cond, name prod)
The 2nd Reaction Type
2. Oxidation of aldehydes to carboxylic acids
O
*Carboxyl group: COOH
-C-OH
O
O
R-C-H –KMnO4 R-C-OH
RCHO –KMnO4 RCOOH
Examples
Oxidize ethanol
O
O
C-C-H –KMnO4 C-C-OH ethanoic acid
CH3CHO –KMnO4 CH3CO2H
*To name a carboxylic acid (must be on the
1st C), drop –e from alkane and add –oic
acid

Examples
Synthanize pentanoic acid (cond)
CH3(CH2)3CH3 + Cl2  CH3(CH2)3CH2Cl + HCl
CH3(CH2)3CH2Cl + H2O  CH3(CH2)3CH2OH +

HCl
CH3(CH2)3CH2OH–PCC/CH2Cl2CH3(CH2)3CHO + H2
CH3(CH2)3CHO –KMnO4 CH3(CH2)3CO2H
3RD Reaction Type
Rxn with alcohols to form hemiacetals and
acetals
*Works well with aldehydes but difficule with
ketones

Example with Ketone
O
OH
OR’
H+
H+
R-C-R + R’OH  R-C-R + R’OH  R-C-R +H2O
OR’
OR’
hemiacetal
acetal
RCOR + R’OH –H+ RCOR’(OH) + R’OH –H+
RC(OR’)2R + H2O
Example with Aldehyde
O
OH
OR’
H+
H+
R-C-H + R’OH  R-C-H + R’OH  R-C-H +H2O
OR’
OR’
RCHO + R’OH –H+ RCHOR’(OH) + R’OH –H+
RCH(OR’)2 + H2O
Practice Example
React butanal w/ propanol (str, cond)
O
OH
C-C-C-C-H + C-C-C
OH
–H+
OH
C-C-C-C-H + C-C-C
O-C-C-C
O-C-C-C
-H+
C-C-C-C-H + H2
O-C-C-C
Practice Example
Condensed version of the previous
example
CH3(CH2)2CHO + CH3CH2CH2OH –H+
CH3(CH2)2CH(O(CH2)2CH3)(OH) +
CH3CH2CH2OH –H+
CH3(CH2)2CH(O(CH2)2CH3)2 + H2

Practice

React 2-pentanone with ethanol (str, cond)