1 2014-1435 Dr Nahed Elsayed. Learning Objectives Chapter eight introduces carbonyl compounds and reactions that involve a nucleophilic attack at the

1

2014-1435

Dr Nahed Elsayed

Learning ObjectivesLearning ObjectivesChapter eight introduces carbonyl compounds and reactions that involve a nucleophilic Chapter eight introduces carbonyl compounds and reactions that involve a nucleophilic attack at the carbonyl carbon in addition to the other topics. attack at the carbonyl carbon in addition to the other topics. By the end of this chapter the student will:By the end of this chapter the student will:

Know the structural differences between aldehydes and ketonesKnow the structural differences between aldehydes and ketonesKnow how to draw aldehydes and ketonesKnow how to draw aldehydes and ketones know the common and IUPAC nomenclature of aldehydes and ketonesknow the common and IUPAC nomenclature of aldehydes and ketones Know the physical properties of aldehydes and ketonesKnow the physical properties of aldehydes and ketonesKnow how to synthesize an aldehyde or a ketone from a compound without thatKnow how to synthesize an aldehyde or a ketone from a compound without that functionality.functionality. Know the different nucleophilic attack reactions at the carbonyl carbon and theKnow the different nucleophilic attack reactions at the carbonyl carbon and the specific products formed in each case.specific products formed in each case.

King Saud University Chemistry Department

ALDEHYDES: STRUCTURE AND NOMENCLATUREALDEHYDES: STRUCTURE AND NOMENCLATURE

General formula: RCHO or Bond line formulaBond line formula

The aldehyde group is always (terminal)at the end of a chain

C=o is polarized group

3145 Chem.

R-C-H

O

R OR H

O


4145 Chem.

Common Nomenclature Of AldehydesCommon Nomenclature Of Aldehydes Common name of aldehydes are derived from the Common name of aldehydes are derived from the common name of the corresponding acidcommon name of the corresponding acidSome aliphatic aldehydes have common names which Some aliphatic aldehydes have common names which have to be memorized. have to be memorized.

Formaldehyde Acetaldehyde Propionaldehyde ButyraldehydeFormaldehyde Acetaldehyde Propionaldehyde Butyraldehyde


Some aromatic aldehydes have common names such as:Some aromatic aldehydes have common names such as:

H

O

H

OOH

H3CO

Salicylaldehyde (Salicylaldehyde (oo-Hydroxybenzaldehyde) Anisaldehyde (-Hydroxybenzaldehyde) Anisaldehyde (pp-methoxybezaldehyde)-methoxybezaldehyde)

IUPAC NomenclatureSelect the longest continuous carbon chain that contains the H-C=O group to get the name of the parent to get the name of the parent hydrocarbon, then replace the ending hydrocarbon, then replace the ending ee by the suffix by the suffix –al–al The CHO group is assigned the locant 1 and takes precedence over other functional groups that may present such as such as C=O(ketone),–OH, C=C, Csuch as C=O(ketone),–OH, C=C, CΞΞC, ORC, OR

For cyclic aldehydes in which the –CHO group is For cyclic aldehydes in which the –CHO group is attached to the ring, the suffix attached to the ring, the suffix carbaldehydecarbaldehyde is used. is used.


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Methanal Ethanal Propanal ButanalMethanal Ethanal Propanal Butanal

3-Chlorobutanal 3-Hydroxypropanal 2-Butenal Cyclohexane carbaldehyde3-Chlorobutanal 3-Hydroxypropanal 2-Butenal Cyclohexane carbaldehyde

Aromatic aldehydes are usually designated as Aromatic aldehydes are usually designated as derivatives of the simplest aromatic aldehyde, derivatives of the simplest aromatic aldehyde, Benzaldehyde.Benzaldehyde.

H

OH

O

H

OH

O OH

H3COO2NBenzaldehyde 4-Nitrobenzaldehyde 2-Hydroxybenzaldehyde 4-Benzaldehyde 4-Nitrobenzaldehyde 2-Hydroxybenzaldehyde 4-MethoxybenzaldehydeMethoxybenzaldehyde


O

H

O

OH

OCl

HO

General formula: RCOR’ (R and R’=alkyl or aryl)

Common names of ketones derived by listing the alkyl derived by listing the alkyl

substituents attached to the carbonyl group in

alphabetical order, followed by the word ketone.

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KETONES:STRUCTUR AND NOMENCLATUREKETONES:STRUCTUR AND NOMENCLATURE

CH3 C CH3

O

CH3 C C6H5

O

CH3 C CH=CH2

O

H5C6 C

O

C6H5

Acetone Acetophenone Benzophenone Acetone Acetophenone Benzophenone Dimethyl ketone Methyl phenyl ketone Methyl vinyl ketone Diphenyl ketoneDimethyl ketone Methyl phenyl ketone Methyl vinyl ketone Diphenyl ketone


In common names carbon atoms attached to the carbonyl group are often designated using Greek

letters (α, ᵝ, ɣ , δ…..) beginning with carbon next to the carbonyl group as α carbon.

In Complex molecules contain more than one of functional group, an order of precedence is used to

determine the name.The functional group priority order in nomenclature system is as following: Acid

and derivatives > aldehyde > ketone > alcohol > amine > alkene > alkyne > ether

With higher priority functional groups, the keto group is named as an oxo substituent

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IUPAC Nomencalture :

Select the longest continuous carbon chain that contains the C=O group to get to get

the name of the parent hydrocarbon, then replace the ending the name of the parent hydrocarbon, then replace the ending ee by the suffix by the suffix –one–one

The chain is numbered in such a way as give the lowest number to the C=O

group.

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Propanone Phenyl ethanone 3-Buten-2-one DiphenylmethanonePropanone Phenyl ethanone 3-Buten-2-one Diphenylmethanone

Cyclopentylpropanone 3-Ethyl-2-hydroxycyclohexanone 5-OxohexanalCyclopentylpropanone 3-Ethyl-2-hydroxycyclohexanone 5-Oxohexanal

C2H5 C

O O

C2H5

CHO

O

OH


Physical Properties OF Aldehydes And Ketones The carbonyl group is polar; with a partial negative charge on oxygen atom, and partial positive charge on The carbonyl group is polar; with a partial negative charge on oxygen atom, and partial positive charge on

carbon atom. carbon atom. Because the polarity of the carbonyl group, aldehydes and ketones are polar compounds. Because the polarity of the carbonyl group, aldehydes and ketones are polar compounds.

A-Boiling and melting pointsA-Boiling and melting points Higher melting and boiling points compared to analogous alkanes due to they show Higher melting and boiling points compared to analogous alkanes due to they show dipole-dipole dipole-dipole

attractions.attractions.

These attractions although important, are not as strong as interactions due to hydrogen bonding as a These attractions although important, are not as strong as interactions due to hydrogen bonding as a result, the result, the boiling points boiling points of of aldehydes and ketones are higher thanaldehydes and ketones are higher than those of non polar those of non polar alkanes,alkanes, but lower than but lower than those of those of alcohols whose alcohols whose molecules are connected together by H-bonds.molecules are connected together by H-bonds.

B-Solubility B-Solubility Lower aldehydes and ketones are are more soluble than alkanes but less soluble than Lower aldehydes and ketones are are more soluble than alkanes but less soluble than

alcohols in aqueous mediaalcohols in aqueous media

C O

H

O

H CO

C O C O

dipole-dipole attaraction

C O

O C


Preparation Of Aldehydes And ketones

1- Oxidation of Alcohols1- Oxidation of Alcohols


Cu/CH3CH2OH H3C CH

or PCC

O

CH3CH2OH H3C C-OH

O

KMnO4

Cu/CH3CHCH3 H3C C-CH3

or KMnO4

OOH

or PCC

PCC =N

, CrO3. HCl Pridinium Chloro chromate

Preparation Of Aldehydes And ketones

2- Ozonolysis of Alkenes; 2- Ozonolysis of Alkenes; results in formation of aldehydes or results in formation of aldehydes or ketones depending on structure of the alkene used.ketones depending on structure of the alkene used.

i) O3

ii) Zn / H2O

CH3CH2CHO + CH3CHO

i) O3

ii) Zn / H2O

O

O

Diketone

two aldehydes

1] O3

2]Zn/ H2O

A

A

A

A

OA

AO

A

A+


3- Hydration Of Alkynes3- Hydration Of Alkynes

Friedel Crafts AcylationFriedel Crafts AcylationN.B: -COR group is m-director and deactivating towards

electrophiles

+ R

O

Cl

AlCl3 R

O

H2SO4,HgSO4C C C

H

OH

an enol unstable

C

H

H

carbonyl more stableO

H2O,

HC CHH2SO4,HgSO4H2O,

H

O

C CHH2SO4,HgSO4H2O,

O

H3C


Reactions Of Aldehydes And Reactions Of Aldehydes And Ketones (Nucleophilic addition Ketones (Nucleophilic addition

reactions)reactions)1- Reduction : Formation Of Alcohols1- Reduction : Formation Of AlcoholsThe reduction by NaBH4 , LiAlH4 ; the

hydride ion H- is serve as nucleophile.

H

O

O

NaBH4

or LiAlH4

or H2 / Pb

NaBH4

or LiAlH4

or H2 / Pb

OH

OH


2-Nucleophilic addition of Grignard reagent 2-Nucleophilic addition of Grignard reagent (formation of alcohols)(formation of alcohols)

Addition of RMgX to formaldehyde gives 1Addition of RMgX to formaldehyde gives 1◦◦ alc. alc. Addition of RMgX to any other aldehyde gives 2Addition of RMgX to any other aldehyde gives 2 ◦◦ alc. alc. Addition of RMgX to ketones gives 3Addition of RMgX to ketones gives 3◦◦ alc. alc.

, dry ether+

2] H3O+

O CH3MgXCH3

OH1]

3- Oxidation reactionOnly aldehydes can be oxidized ketones resist

oxidation

KMnO4

R

O

Hor

or K2Cr2O7Ar

O

H R

O

OHor

Ar

O

OH


5-Addition of Hydrogen Cyanide: Formation Of 5-Addition of Hydrogen Cyanide: Formation Of CynohydrinsCynohydrins

+OHO

HCN CN

+ HCN

O

H

CN

OHBenzaldehyde cyanohydrin

R+ HCN

O

R'R

OH

R'

CNcyanohydrin


6- Addition Of Alcohols:6- Addition Of Alcohols:


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7- Addition of Ammonia and Ammonia Derivatives

145 Chem.

H3C

O

H

Aldehyde

NH2NH2

PhNHNH2

NH2OH

NH3

H3C

N

H

NH2

hydrazone

H3C

N

H

NHPh

phenylhydrazone

H3C

N

H

OH

Oxime

H3C

NH

H imine


Exercise

s1- The correct name of the following compound is: H

O

OH A) 3-hydroxyhexanalB) 3-hydroxy-4-hexenalC) 4-hydroxy-5-hexenalD)3-hydroxy-1-hexenal

2- The structure of Acetal is:

OC2H5

OH

OC2H5

OH

OH

OC2H5

OC2H5

OC2H5

OC2H5

A) B)

C) D)H

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3- Reaction of phenyhydrazine with carbonyl compounds (aldyhydes or ketones) gives:

A) Oxime B) Phenylhydrazone C) Imine D) Hemiacetal

4 - Which of the following compounds has the highest boiling point?

O

H

O OH OCH3A) B) C) D)


Questions?

Documents

1 2014-1435 Dr Nahed Elsayed. Learning Objectives Chapter eight introduces carbonyl compounds and reactions that involve a nucleophilic attack at the