Aldehydes and Ketones

DrillDraw & name 5 isomers of:

C3H5OF

Aldehydes•Organic compounds with carbonyl groups

on the end carbon

Aldehydes O

R-C

H

Ketones•Organic compounds with carbonyl groups within carbon chains

Ketones

O

R-C-R

Common Aldehydes

Formaldehyde O

H-C

HMethanal

Acetaldehyde O

CH3-C

HEthanal

Propionaldehyde O

CH3-CH2-C

HPropanal

Butyraldehyde O

CH3CH2CH2C

HButanal

Benzaldehyde O

C

HAlmond Extract

Cinnamaldehyde

O

all-trans-retinal

C=OH

all-trans-retinol

4-hydroxy-3-methoxy benzaldehyde

Vanillin

CO

HHO

H3C-O

Draw: acetaldehyde

& benzaldehyde

Common Ketones

Acetone O

CH3-C

CH3Propanone

Methyl ethyl ketone O

CH3CH2C

CH3Butanone

Cyclohexanone

O

Benzophenone

CO

Diphenylmethanone

Muscone

O

General Properties

Polarity•Alcohols > aldehydes

•Aldehydes > ketones

Solubility in Water•Alcohols > aldehydes

•Aldehydes > ketones

Boiling Points•Alcohols > aldehydes

•Aldehydes > ketones

Melting Points•Alcohols > aldehydes

•Aldehydes > ketones

Oxidation State•Alcohols > hydrocarbons

•Aldehydes > alcohols

•Acids > aldehydes

Show all the oxidation steps in

converting butane to 3-butenoic acid

Energy State•Alcohols < hydrocarbons

•Aldehydes < alcohols

•Acids < aldehydes

Chm PE Gradient•Methane: CH4

•Methanol: CH3OH

•Methanal CH2O

•Methanoic A: HCOOH

Chm PE Gradient•Reduced Compounds >•Less reduced•compounds > •Oxidized compounds

Determine MP order•CH3-CH3

•CH3-CH2OH

•CH3-CHO

•CH3-COOH

Drill:Draw & name 5

isomers of:

C3H9NO

Making Aldehydes & Ketones

•Oxidation of primary alcohols

Making Aldehydes

•To oxidize alcohols, Hs must be removed from the OH & the

adjacent carbon

Making Aldehydes

Making Aldehydes OH

R-C-H

H

ox

Making Aldehydes OH

R-C-H

H

ox

Making Aldehydes OH O

R-C-H R-C

H H

ox

Common Oxidizing Agents

Cr2O7-2

MnO4-1

Examples:

K2Cr2O7

KMnO4

•Oxidation of secondary alcohols

Making Ketones

Making Ketones OH

R-C-R

ox

H

Making Ketones OH O

R-C-R R-C

R

ox

H

t-Alcohol Ox OH

R-C-R

R

ox

t-Alcohol Ox OH

R-C-R NR

ox

R

Name reactants & predict & name products

H3C-OHK2Cr2O7

H2SO4

Formaldehyde H

C=O

H Methanal

Name reactants & predict & name products

H2C-OH

H3C

K2Cr2O7

H2SO4

Acetaldehyde H

C=O

H3C Ethanal

Name reactants & predict & name products

OH

H3C-CH-CH3K2Cr2O7

H2SO4

Acetone H3C

C=O

H3C Propanone

Name reactants & predict & name products

K2Cr2O7

H2SO4

OH

Cyclohexanone

O

Name reactants & predict & name products

K2Cr2O7

H2SO4

CH2OH

Benzaldehyde

CHO

Aldehyde Detection Reactions

Detecting Aldehydes•Tollen’s Test

•Benedict’s & Fehling’s Test

•Both distinguish aldehydes from ketones

Tollen’s Reagent AgNO3 Ag+ + NO3

-

Ag+ + 2 NH3

[Ag(NH3)2]+

100 %

Tollen’s Test O

R-C-H + 2[Ag(NH3)2]+ + 2OH-

O

NH4+R-CO- + 2Ag(s)+3NH3 + H2O

Benedict’s Reagent CuSO4 Cu+2 + SO4

-2

NaOH Na+ + OH-

100 %

100 %

Fehling’s Reagent

Benedict’s Test O

R-C-H + 2 Cu+2 + 5 OH-

O

R-C-O- + Cu2O(s) + 3H2O

-Hydroxy Ketones HO O

R-C-C

H RYield positive results in both tests

Drill: Draw-hydroxy-

propanaldehyde

Carbonyl Addition Reactions

Carbonyl Addition Rxns with water O

C + H-OH

CHO OHHydrate

Carbonyl Addition Rxns

O C + H-OH

CHO OH

ChloralHydrate

HCl3C

Chloral ortrichloroacetaldehyde

H CCl3

Carbonyl Addition Rxns

O C + H-OH

HH

Methanal

Carbonyl Addition Rxns

O C + H-OH

CHO OH

Methanediol

HH H H

Carbonyl Addition Rxns with alcohols O

C + R-OH

CRO OH

Example O

C + OHH3C H

CH3C H

HO O

Drill:•Draw & name 4

isomers C5H10O that are either aldehydes

or ketones:

Hemiketal Formation

O

C + R3-OH

CR3-O OH

R1 R2 R1 R2

Hemiketal

Name reactants & draw products O

C + CH3-OH

H3C CH3

O

C + CH3-OH

CH3C-O OH

H3C CH3CH3 CH3

Hemiketal

Hemiacetal Formation

O

C + R3-OH

CR3-O OH

R1 H R1 H

Hemiacetal

Hemiacetal Formation

O

C + R3-OH

CR3-O OH

H3C H CH3 H

Hemiacetal

Hemiacetal Formation

O

C + R3-OH

CR3-O OH

H3C H CH3 H

Hemiacetal

Draw the reactants & products when water

is added to2-butanone

Draw the reactants & products when

methanol is added toacetone

Full Acetals & Ketals

•The second addition of an alcohol to either hemi- acetals or ketals will produce full each

Uses of Aldehydes &

Ketones

1) 1-propanol + KMnO4

2) 2-propanol + K2Cr2O4

3) 2-methyl-2-propanol + K2Cr2O4

4) cyclohexanone + water

5) benzaldehyde + water6) formaldehyde + 1-butanol7) acetone + phenol

8) 5-hydroxypentanaldehyde (addition)

1) ethanol + KMnO4

2) 2-pentanol + K2Cr2O7

3) t-butanol+ K2Cr2O7

4) acetone + water

5) formaldehyde + water6) propanaldehyde + methanol7) 2-butanone + phenol

8) 4-hydroxybutanaldehyde (addition)

Name the following:

OH

H

O

Review

Name the following:

O

H

OH

Draw the following:•3-ethyl-6-methyl-

2-phenoxy-1-sulfhydryl-octa-

4,5-dione

Oxidation of each with KMnO4 or K2Cr2O7:

•1-butanol

•2-butanol

•2-methyl-2-propanol

Carbonyl Addition Rxns:

•2-butanone + water

•Propanaldehyde + water

•Acetone + methanol

•Acetaldehyde + ethanol

Draw the reactants & products when 5-hydroxypentanal reacts with itself

Draw & name 3 isomers of C4H8O

containing carbonyls

Draw & name 10 isomers of

C4H8O