Aldehydes and ketones nucleophilic addition to the carbonyl group
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Aldehydes and Ketones Nucleophilic Addition to the Carbonyl Group. ALDEHYDES AND KETONES “carbonyl” functional group: Aldehydes Ketones. O. O. H. H. O. O. HCCHCH. IUPAC Nomenclature of Aldehydes. 4,4-dimethylpent an al. 5-hex en al or hex-5-en al.

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Aldehydes and Ketones Nucleophilic Addition to the Carbonyl Group

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Aldehydes and ketones nucleophilic addition to the carbonyl group

Aldehydes and KetonesNucleophilic Additionto theCarbonyl Group


Aldehydes and ketones nucleophilic addition to the carbonyl group

ALDEHYDES AND KETONES

“carbonyl” functional group:

Aldehydes Ketones


Iupac nomenclature of aldehydes

O

O

H

H

O

O

HCCHCH

IUPAC Nomenclature of Aldehydes

4,4-dimethylpentanal

5-hexenal

or hex-5-enal

2-phenylpropanedial(keep the -e endingbefore -dial)


Substitutive iupac nomenclature of ketones

O

O

CH3CH2CCH2CH2CH3

CH3CHCH2CCH3

CH3

H3C

O

Substitutive IUPAC Nomenclature of Ketones

Base the name on the chain that contains the carbonyl group and replace -e with -one. Number the chain in the direction that gives the lowest number to the carbonyl carbon.


Substitutive iupac nomenclature of ketones1

O

O

CH3CH2CCH2CH2CH3

CH3CHCH2CCH3

CH3

H3C

O

Substitutive IUPAC Nomenclature of Ketones

3-hexanone

or Hexan-3-one

4-methyl-2-pentanone

or 4-methylpentan-2-one

4-methylcyclohexanone


Aldehydes and ketones nucleophilic addition to the carbonyl group

Special names!


Aldehydes and ketones nucleophilic addition to the carbonyl group

ALDEHYDES AND KETONES

“carbonyl” functional group:

Aldehydes Ketones


Aldehydes and ketones nucleophilic addition to the carbonyl group

Aldehydes, IUPAC nomenclature:

Parent chain = longest continuous carbon chain containing the carbonyl group; alkane, drop –e, add –al. (note: no locant, -CH=O is carbon #1.)

CH3

CH3CH2CH2CH=O CH3CHCH=O

butanal 2-methylpropanal

H2C=OCH3CH=O

methanalethanal


Aldehydes and ketones nucleophilic addition to the carbonyl group

Physical properties:

polar, no hydrogen bonding

mp/bp are relatively moderate for covalent substances

water insoluble

(except: four-carbons or less)


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • Reactions of aldehydes and ketones:

  • oxidation

  • reduction

  • nucleophilic addition

  • Aldehydes are easily oxidized, ketones are not.

  • Aldehydes are more reactive in nucleophilic additions than ketones.


Aldehydes and ketones nucleophilic addition to the carbonyl group

alkane

alcohol

reduction

reduction

aldehyde

ketone

addition

product

nucleophilic

addition

oxidation

carboxylic acid


Aldehydes and ketones nucleophilic addition to the carbonyl group

nucleophilic addition to carbonyl:


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • 1) Oxidation

  • Aldehydes(very easily oxidized!)

  • CH3CH2CH2CH=O + KMnO4, etc.  CH3CH2CH2COOH

  • carboxylic acid

  • CH3CH2CH2CH=O + Ag+ CH3CH2CH2COO- + Ag

  • Tollen’s test for easily oxidized compounds like aldehydes.

  • (AgNO3, NH4OH(aq))

Silver mirror


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • 2) Reduction:

  • To alcohols


Aldehydes and ketones nucleophilic addition to the carbonyl group

5) Addition of alcohols


Aldehydes and ketones nucleophilic addition to the carbonyl group

“The Grignard Song” (sung to the tune of “America the Beautiful”)

Harry Wasserman

The carbonyl is polarized,

the carbon end is plus.

A nucleophile will thus attack

the carbon nucleus.

The Grignard yields an alcohol

of types there are but three.

It makes a bond that corresponds

from “C” to shining “C.”


Aldehydes and ketones nucleophilic addition to the carbonyl group

Dehydration of an alcohol?

CH3 H+

CH3CHCHCH3 yields a mixture of alkenes

OH

CH3 H+

CH3CHCH2CH2-OH yields a mixture of alkenes

E1 mechanism via carbocation!


Aldehydes and ketones nucleophilic addition to the carbonyl group

Carboxylic acids:

R-COOH, R-CO2H,

Common names:

HCO2Hformic acidL. formica ant

CH3CO2Hacetic acidL. acetum vinegar

CH3CH2CO2Hpropionic acidG. “first salt”

CH3CH2CH2CO2Hbutyric acidL. butyrum butter

CH3CH2CH2CH2CO2Hvaleric acidL. valerans


Aldehydes and ketones nucleophilic addition to the carbonyl group

5 4 3 2 1

C—C—C—C—C=O

δ γ β αused in common names


Aldehydes and ketones nucleophilic addition to the carbonyl group

special names


Aldehydes and ketones nucleophilic addition to the carbonyl group

IUPAC nomenclature for carboxylic acids:

parent chain = longest, continuous carbon chain that contains the carboxyl group  alkane, drop –e, add –oic acid

HCOOHmethanoic acid

CH3CO2Hethanoic acid

CH3CH2CO2Hpropanoic acid

CH3

CH3CHCOOH2-methylpropanoic acid

Br

CH3CH2CHCO2H2-bromobutanoic acid


Aldehydes and ketones nucleophilic addition to the carbonyl group

dicarboxylic acids:

HOOC-COOHoxalic acid

HO2C-CH2-CO2Hmalonic acid

HO2C-CH2CH2-CO2Hsuccinic acid

HO2C-CH2CH2CH2-CO2Hglutaric acid

HOOC-(CH2)4-COOHadipic acid

HOOC-(CH2)5-COOHpimelic acid

Oh, my! Such good apple pie!


Aldehydes and ketones nucleophilic addition to the carbonyl group

salts of carboxylic acids:

name of cation + name of acid: drop –ic acid, add –ate

CH3CO2Nasodium acetate or sodium ethanoate

CH3CH2CH2CO2NH4 ammonium butyrate

ammonium butanoate

(CH3CH2COO)2Mg magnesium propionate

magnesium propanoate


Aldehydes and ketones nucleophilic addition to the carbonyl group

physical properties:

polar + hydrogen bond  relatively high mp/bp

water insoluble

exceptions: four carbons or less

acidic turn blue litmus  red

soluble in 5% NaOH

RCO2H + NaOH  RCO2-Na+ + H2O

stronger stronger weaker weaker

acid base base acid


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • RCO2HRCO2-

  • covalentionic

  • water insolublewater soluble

  • Carboxylic acids are insoluble in water, but soluble in 5% NaOH.

  • Identification.

  • Separation of carboxylic acids from basic/neutral organic compounds.

  • The carboxylic acid can be extracted with aq. NaOH and then regenerated by the addition of strong acid.


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • Carboxylic acids, syntheses:

  • oxidation of primary alcohols

  • RCH2OH + K2Cr2O7 RCOOH

  • 2.oxidation of arenes

  • ArR + KMnO4, heat  ArCOOH


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • oxidation of 1o alcohols:

  • CH3CH2CH2CH2-OH + CrO3 CH3CH2CH2CO2H

  • n-butyl alcohol butyric acid

  • 1-butanol butanoic acid

  • CH3 CH3

  • CH3CHCH2-OH + KMnO4  CH3CHCOOH

  • isobutyl alcohol isobutyric acid

  • 2-methyl-1-propanol` 2-methylpropanoic acid


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • oxidation of arenes: Remember for Benzaldehyde!!

note: aromatic acids only!


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • carboxylic acids, reactions:

  • as acids

  • conversion into functional derivatives

  • a)  acid chlorides (Never Mind! But use SOCl2 if needed)

  • b)  esters (use an alcohol and name!)

  • c)  amides (following chapter, 16!)


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • as acids:

  • with active metals

  • RCO2H + Na  RCO2-Na+ + H2(g)

  • with bases

  • RCO2H + NaOH  RCO2-Na+ + H2O

  • relative acid strength?

  • CH4 < NH3 < HCCH < ROH < HOH < H2CO3 < RCO2H < HF


Aldehydes and ketones nucleophilic addition to the carbonyl group

Resonance stabilization of the carboxylate ion decreases the ΔH, shifts the ionization in water to the right, increases the Ka, and results in carboxylic acids being stronger acids.


Aldehydes and ketones nucleophilic addition to the carbonyl group

  •  esters

  • “direct” esterification: H+

  • RCOOH + R´OH  RCO2R´ + H2O

  • -reversible and often does not favor the ester

  • -use an excess of the alcohol or acid to shift equilibrium

  • -or remove the products to shift equilibrium to completion

  • “indirect” esterification:

  • RCOOH + PCl3 RCOCl + R´OH  RCO2R´

  • -convert the acid into the acid chloride first; not reversible


Aldehydes and ketones nucleophilic addition to the carbonyl group

  •  amides

  • “indirect” only!

  • RCOOH + SOCl2 RCOCl + NH3  RCONH2

  • amide

  • Directly reacting ammonia with a carboxylic acid results in an ammonium salt:

  • RCOOH + NH3 RCOO-NH4+

  • acid base


Aldehydes and ketones nucleophilic addition to the carbonyl group

  • Reduction:

  • RCO2H + LiAlH4; then H+ RCH2OH

  • 1o alcohol

  • Carboxylic acids resist catalytic reduction under normal conditions.

  • RCOOH + H2, Ni  NR


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