Aldehydes and Ketones

Aldehydes and KetonesAldehydes and Ketones

Chapter 5Chapter 5

Aldehydes and KetonesAldehydes and Ketones

Functional group is OFunctional group is O

The carbonyl l lThe carbonyl l l

group Cgroup C

Aldehyde = Carbonyl group is 1°Aldehyde = Carbonyl group is 1°

Ketone = Carbonyl group is 2°Ketone = Carbonyl group is 2°

AldehydeAldehyde

RCHO ArCHORCHO ArCHO

BenzaldehydeBenzaldehyde

KetonesKetones

RCORRCOR ArCOArArCOAr

ArCORArCOR

OO

C – C-C-CC – C-C-C

Naming AldehydesNaming Aldehydes

Drop –e from alkane and add –alDrop –e from alkane and add –al

MethanalMethanal Propanal Propanal

2-chlorohexanal2-chlorohexanal

PracticePractice

Naming Ketones (2 ways)Naming Ketones (2 ways)

1.1. IUPAC - # chain from the end IUPAC - # chain from the end closest to the carbonyl, give the closest to the carbonyl, give the carbon #, drop –e add –onecarbon #, drop –e add –one

2.2. Name the groups on either side Name the groups on either side of the carbonyl and follow with of the carbonyl and follow with ketone ketone list groups by order of list groups by order of sixe of molar mass (smaller 1sixe of molar mass (smaller 1stst))

PracticePractice

2-butanone2-butanone

methyl ethyl Ketonemethyl ethyl Ketone

3-hexanone3-hexanone

ethyl propyl ketoneethyl propyl ketone

Draw 2 – pentanone and name it the 2Draw 2 – pentanone and name it the 2ndnd way way

PracticePractice

For the “old” way to name a ketone to use a For the “old” way to name a ketone to use a phenyl, the ring must be bonded directly to phenyl, the ring must be bonded directly to the carbonylthe carbonyl

3-phenyl-3-propanone3-phenyl-3-propanone

ethyl phenyl ketoneethyl phenyl ketone

4-phenyl – 3 – butanone/no secondary name4-phenyl – 3 – butanone/no secondary name

PracticePractice

Preparation of AldehydesPreparation of Aldehydes

1.1. Oxidation of 1° Alcohols (lose HOxidation of 1° Alcohols (lose H22))

RCHRCH22OH OH PCC PCC CH2Cl2CH2Cl2 RCHO + H RCHO + H22

Catalysts are Catalysts are

PCC = Pyridinium chororchrmate,PCC = Pyridinium chororchrmate, C C55HH66NCrONCrO33ClCl

Dichloromethane = CHDichloromethane = CH22ClCl22

PracticePractice

Form Propanal by oxidationForm Propanal by oxidation

CHCH33CHCH22CHCH22OH OH CH CH33CHCH22CHO + HCHO + H22

Practice Practice

2. Oxidize 1-hexanol O2. Oxidize 1-hexanol O

C-C-C-C-C-C-OH C-C-C-C-C-C-OH (Catalyst)(Catalyst) C-C-C-C-C-C-H C-C-C-C-C-C-H

+ H+ H22

CHCH33(CH(CH22))44CHCH22OHOH (Catalyst)(Catalyst) CH CH33(CH(CH22))44CHOCHO

+ H+ H22

Practice Practice

Synthesize propanal (str)Synthesize propanal (str)

C-C-C + ClC-C-C + Cl2 2 C-C-C-Cl + HCl C-C-C-Cl + HCl

C-C-C-Cl + HC-C-C-Cl + H22O O C-C-C-OH + HCl C-C-C-OH + HCl

C-C-C-OH C-C-C-OH (Catalyst)(Catalyst) C-C-C=O + H C-C-C=O + H22

The 2The 2ndnd Reaction Type Reaction Type

2. Reduction of acid chlorides (add H2. Reduction of acid chlorides (add H22))

+ H+ H22 (Pt/Pd)(Pt/Pd) + HCl + HCl

RCOCl + HRCOCl + H22 (Pt/Pd)(Pt/Pd) RCHO + HCl RCHO + HCl

**Acid chlorides look like aldehydes, but Acid chlorides look like aldehydes, but have a –Cl where the end –H is. (We have a –Cl where the end –H is. (We will look at them more closely later)will look at them more closely later)

PracticePractice

Form propanal by reductionForm propanal by reduction

CHCH33CHCH22COCl + HCOCl + H22 (Pt/Pd)(Pt/Pd) CH CH33CHCH22CHO + HClCHO + HCl

Synthesis of BenzaldehydeSynthesis of Benzaldehyde

The =O is not directly on the The =O is not directly on the benzene, so you can’t follow he benzene, so you can’t follow he steps for an alcohol – you have to steps for an alcohol – you have to use the following…use the following…

Synthesis of BenzaldehydeSynthesis of Benzaldehyde

+ -AlCl+ -AlCl33 + HCl + HCl

+ 2Cl+ 2Cl22 + 2HCl + 2HCl

+ H+ H22O O + 2HCl + 2HCl

Preparation of KetonesPreparation of Ketones

1. Oxidation of 2° alcohols1. Oxidation of 2° alcohols

OH OOH O

R-C-R’ R-C-R’ (Catlaysts)(Catlaysts) R-C-R’ + H R-C-R’ + H22

RCHOHR’ RCHOHR’ (Catlaysts)(Catlaysts) RCOR’ + H RCOR’ + H22

Practice Practice

Oxidize 2-pentanol (str, cond, name product)Oxidize 2-pentanol (str, cond, name product)

OH OOH O

C-C-C-C-C C-C-C-C-C (Catalyst)(Catalyst) C-C-C-C-C + H C-C-C-C-C + H22

2-pentanone/methyl propyl ketone2-pentanone/methyl propyl ketone

CHCH33CHOH(CHCHOH(CH22))22CHCH33 (Ctlyst) (Ctlyst) CHCH33CO(CHCO(CH22)2CH)2CH33

+ H+ H22

PracticePractice

Form methyl ethyl ketone (str, cond, name Form methyl ethyl ketone (str, cond, name reactant)reactant)

PracticePracticeSynthesize 3-heptanone (cond.)Synthesize 3-heptanone (cond.)CHCH33(CH(CH22))55CHCH33+Cl+Cl22CHCH33CHCH22CHCl(CHCHCl(CH22))33CHCH33 + +

HClHCl

CHCH33CHCH22CHCl(CHCHCl(CH22))33CHCH33 + H + H22O O

CHCH33CHCH22CHOH(CHCHOH(CH22))33CHCH33 + HCl + HCl

CHCH33CHCH22CHOH(CHCHOH(CH22))33CHCH3 3 (Cats)(Cats)

CHCH33CHCH22CO(CHCO(CH22))33CHCH33 + H + H22

The 2The 2ndnd Reaction Type Reaction Type

2. Friedel – Crafts Acylation - acyl group2. Friedel – Crafts Acylation - acyl group

RCORCO

O OO O

ArH + R-C-Cl –AlClArH + R-C-Cl –AlCl33 R-C-Ar + HCl R-C-Ar + HCl

ArH + RCOCl –AlClArH + RCOCl –AlCl33 RCOAr + HCl RCOAr + HCl

Benzene must bond directly to the C=OBenzene must bond directly to the C=O

PracticePractice

Form ethyl phenyl ketone (str, cond)Form ethyl phenyl ketone (str, cond)

C-C-C-Cl + -AlClC-C-C-Cl + -AlCl33 C-C-C- + HCl C-C-C- + HCl

CHCH33CHCH22COCl + CCOCl + C66HH66 –AlCl –AlCl33 CH CH33CHCH22COCCOC66HH55 + +

HClHCl

Form pentyl phenyl ketone (str, cond)Form pentyl phenyl ketone (str, cond)

Rxns of Aldehydes and KetonesRxns of Aldehydes and Ketones

1.1. Reduction of aldes and kets to alcoholsReduction of aldes and kets to alcohols

OO

R-C-H + HR-C-H + H2 2 –Pt/Pd–Pt/Pd R-C-OH R-C-OH

RCHO + HRCHO + H22 –Pt/Pd –Pt/Pd RCH RCH22OHOH

O OO O

R-C-R + HR-C-R + H2 2 –Pt/Pd–Pt/Pd R-C-R R-C-R

RCOR + HRCOR + H22 –Pt/Pd –Pt/Pd RCHOHR RCHOHR

PracticePractice

Reduce 2-hexanone (str,cond, name prod)Reduce 2-hexanone (str,cond, name prod)

O OHO OH

C-C-C-C-C-C + HC-C-C-C-C-C + H22 –Pt/Pd –Pt/Pd C-C-C-C-C-C C-C-C-C-C-C

2-hexanone2-hexanone

CHCH33CO(CHCO(CH22))33CHCH33 + H + H22 –Pt/Pd–Pt/Pd CHCH33CHOH(CHCHOH(CH22))33CHCH33

PracticePractice

Reduce Pentanal (str,cond, name prod)Reduce Pentanal (str,cond, name prod)

The 2The 2ndnd Reaction Type Reaction Type

2. Oxidation of aldehydes to carboxylic acids2. Oxidation of aldehydes to carboxylic acids

OO

*Carboxyl group: COOH -C-OH*Carboxyl group: COOH -C-OH

O OO O

R-C-H –KMnOR-C-H –KMnO44 R-C-OH R-C-OH

RCHO –KMnORCHO –KMnO44 RCOOH RCOOH

ExamplesExamples

Oxidize ethanolOxidize ethanol

O OO O

C-C-H –KMnOC-C-H –KMnO44 C-C-OH ethanoic acid C-C-OH ethanoic acid

CHCH33CHO –KMnOCHO –KMnO44 CH CH33COCO22HH

*To name a carboxylic acid (must be on the *To name a carboxylic acid (must be on the 11stst C), drop –e from alkane and add –oic C), drop –e from alkane and add –oic acidacid

ExamplesExamples

Synthanize pentanoic acid (cond)Synthanize pentanoic acid (cond)

CHCH33(CH(CH22))33CHCH33 + Cl + Cl2 2 CH CH33(CH(CH22))33CHCH22Cl + HClCl + HCl

CHCH33(CH(CH22))33CHCH22Cl Cl + + HH22OO CH CH33(CH(CH22))33CHCH22OH + OH + HClHCl

CHCH33(CH(CH22))33CHCH22OHOH–PCC/CH–PCC/CH22ClCl22CHCH33(CH(CH22))33CHO CHO + H+ H22

CHCH33(CH(CH22))33CHO –KMnOCHO –KMnO44 CH CH33(CH(CH22))33COCO22HH

33RDRD Reaction Type Reaction Type

Rxn with alcohols to form hemiacetals and Rxn with alcohols to form hemiacetals and acetalsacetals

*Works well with aldehydes but difficule with *Works well with aldehydes but difficule with ketonesketones

Example with KetoneExample with Ketone O O H+H+ OH OH H+ H+ OR’OR’

R-C-R + R’OH R-C-R + R’OH R-C-R + R’OH R-C-R + R’OH R-C-R R-C-R +H+H22OO

OR’ OR’OR’ OR’

hemiacetal acetalhemiacetal acetalRCOR + R’OH RCOR + R’OH –H+–H+ RCOR’(OH) + R’OH RCOR’(OH) + R’OH –H+–H+

RC(OR’)RC(OR’)22R + R +

HH22OO

Example with AldehydeExample with Aldehyde

O O H+H+ OH OH H+ H+ OR’OR’

R-C-H + R’OH R-C-H + R’OH R-C-H + R’OH R-C-H + R’OH R-C-H R-C-H +H+H22OO

OR’ OR’OR’ OR’

RCHO + R’OH RCHO + R’OH –H+–H+ RCHOR’(OH) + R’OH RCHOR’(OH) + R’OH –H+–H+

RCH(OR’)RCH(OR’)22 + H + H22OO

Practice ExamplePractice Example

React butanal w/ propanol (str, cond)React butanal w/ propanol (str, cond)

O OH OH OHO OH OH OH

C-C-C-C-H + C-C-CC-C-C-C-H + C-C-C –H+–H+ C-C-C-C-H + C-C-CC-C-C-C-H + C-C-C

O-C-C-CO-C-C-C

O-C-C-CO-C-C-C

-H+-H+ C-C-C-C-H + HC-C-C-C-H + H22

O-C-C-CO-C-C-C

Practice ExamplePractice Example

Condensed version of the previous Condensed version of the previous exampleexample

CHCH33(CH(CH22))22CHO + CHCHO + CH33CHCH22CHCH22OH –H+OH –H+

CHCH33(CH(CH22))22CH(O(CHCH(O(CH22))22CHCH33)(OH) + )(OH) +

CHCH33CHCH22CHCH22OH –H+OH –H+

CHCH33(CH(CH22))22CH(O(CHCH(O(CH22))22CHCH33))22 + H + H22

PracticePractice

React 2-pentanone with ethanol (str, cond) React 2-pentanone with ethanol (str, cond)