1-1 chemistry 121, winter 2016, la tech introduction to organic chemistry and biochemistry...

1-1Chemistry 121, Winter 2016, LA Tech

Introduction to Organic Chemistry and Biochemistry

Instructor Dr. Upali Siriwardane (Ph.D. Ohio State)

E-mail: [email protected]

Office: 311 Carson Taylor Hall ; Phone: 318-257-4941;

Office Hours: MTW 8:00 - 10:00 am;

ThF 9:00 - 10:00 am 1:00 - 2:00 pm.

December 18, 2015: Test 1 (Chapters 12-13)

January 25 , 2016: Test 2 (Chapters 14-16)

February 17, 2016: Test 3 (Chapters 17-19)

February 29, 2016: Test 4 (Chapters 20-22)

March 1 , 2016: Make Up Exam: Chapters 12-22)

Bring Scantron Sheet 882-E

Chemistry 121 Winter 2016

1


Chapter 15: Aldehyde and Ketones

15-1 The Carbonyl Group

15-2 Compounds Containing a Carbonyl Group

15-3 The Aldehyde and Ketone Functional Groups

15-4 Nomenclature for Aldehydes

15-5 Nomenclature for Ketones

15-6 Isomerism for Aldehydes and Ketones

15-7 Selected Common Aldehydes and Ketones

15-8 Physical Properties of Aldehydes and Ketones

15-9 Preparation of Aldehydes and Ketones

15-10Oxidation and Reduction of Aldehydes and Ketones

15-11Reaction of Aldehydes and Ketones with Alcohols

15-12Sulfur-Containing Carbonyl Groups


Carbonyl Group


Simplest Aldehyde


Common Names of Aldehyde and Ketones

Aldehydes: Fomaldehyde: HCHO Acetaldehyde: CH3CHO Propionaldehyde: CH3CH2CHO Butyraldehyde: CH3CH2CH2CHO Valeraldehyde: CH3CH2CH2CH2CHO Ketones: Acetone: CH3COCH3 Methyl ethyl ketone CH3CH2COCH3 Butyl propyl ketone CH3CH2CH2CH2COCH2CH2CH3


IUPAC Nomenclature of Aldehyde and Ketones

The IUPAC system deals with functional groups two different ways.

Modification of the hydrocarbon name to indicate the presence of a functional group.

aldehyde, -CHO use -al ending.Ketones -RCOR’ use -one ending.


Example

C - C - C - C - CHO

Base contains 5 carbon

- aldehyde name is pentane

- remove -e and add -al

C - C - C - C - CO-C-C

Base contains 7 carbon

- aldehyde name is heptane

- remove -e and add -one

3-heptanone


Physical Properties of Aldehydes and ketones

Aldehyde and ketones can only make dipole-dipole attraction.

BP and MP are lower than alcohols ,

higher than hydrocarbons and ether

with comparable carbon numbers


Bonding Characteristics of Aldehydes Ketones

Both aldehydes and ketones contain a carbonyl

functional group. A carbonyl group is an carbon atom

double-bonded to an oxygen atom. The structural

representation for a carbonyl group is

Carbon-oxygen (C=O) and carbon-carbon (C=C) double

bonds differ in a major way. A carbon oxygen double

bond is more polar


Physical properties of aldehydes and ketones.


Nomenclature

H COOHO

COOHO

COOHHO

OHHS

COOHNH2

-al oxo-

Ketone -one oxo-

Alcohol -ol hydroxy-

Amino -amine amino-

3-Oxopropanoic acid

3-Oxobutanoic acid

4-Hydroxybutanoic acid

3-Aminobutanoic acid

Example of When the FunctionalGroup Has a Lower Priority

Sulfhydryl -thiol mercapto- 2-Mercaptoethanol

Functional Group Suffix PrefixCarboxyl -oic acidAldehyde


Name the Aldehyde

2,4-dimethylpentanal


1. Assign the type of organic compound with following general

condensed (structural formula.


2. Names (common/IUPAC)of following aldehydes and

ketones.

a) ____________ b) _______________ c) __________________

d) ____________ e) _______________ f) __________________

g) ____________ h) __________________


Nomenclature

CHO HO CHOCyclopentane-carbaldehyde

trans-4-Hydroxycyclo-hexanecarbaldehyde

14

3-Methylbutanal 2-Propenal(Acrolein)

H

O

(2E)-3,7-Dimethyl-2,6-octadienal(Geranial)

1

2

3

4

5

6

78

1122

33

4 H

O

H

O

2-Methyl-cyclohexanone

5-Methyl-3-hexanone

Benzophenone Acetophenone

OO

O O


3. Draw the condensed formula of

following aldehydes and ketones:

a) acetaldehyde/ ethanal

b) ethyl methyl ketone

c) 3-methyl-2- pentanone

d) isopropyl methyl ketone

e) 2-methylbutanal

f) 5-methyl-3- hexanone

g) benzophenone

h) acetophenone


Important AldehydesMethanal or formaldehydeEthanal or acetaldehyde2-Propanone or acetone2-Butanone or methyl ethyl ketoneOil of almonds or benzaldehydeOil of Cinnamon or cinnamaldehyde Oil of vanilla beans or vanillinMushroom flavoring or 2-octanoneOil of lemongrass or citral:


Preparation of Aldehydes: Partial oxidation of primary alcohols with H2CrO4:

PCC

>


Preapration of ketones: Oxidation of secondary alcohols with KMnO4, or

H2CrO4 (Oxidizing agents)


Bakelite (Polymers)


Chemical Reactions of Aldehydes and Ketone

1) Combustion: Alkenes are very flammable and the combustion products are carbon dioxide and water.

2) Addition Reactions: Atoms or group of atoms are added to each a carbon oxygen double bond. Two different

reactants are involved.

a) hemi-acetal or hemi-ketal formation: Addition of Alcohols: -OR group of the R-OH is added to the C atom and H of

the ROH is added to O atom.

b) Aacetal or ketal formation : Substiution of hemi-acetal or -ketal Another or second ROH is reacted in a substitution

reaction to replace the H atom of the -OH group of the hemi-acetal or hemi-ketal and water molecule is produced.

3) Oxidation Reactions: only aldehydes are oxidized to carboxylic acids.

4) Reduction Reactions: both aldehydes and ketones are reduced to alcohols by taking H from the reducing agents.


Addition reactions of als & onesHemiacetal or hemiketal formation


Substitution reactions of hem-acetals/ketalsAcetal or Ketal formation


Hemiacetal form of cyclic sugars


4. Identify each of the following compounds as a hemiacetal, hemiketal,

acetal, or ketal:

a) ____________ b) _______________ c) __________________

d) ____________ e) _______________ f) __________________


Oxidation of alcohol

PCC


Oxidation of alcohol


5) Which alcohol would you oxidize to produce each of the

following compounds?

a)

b)

c)

d)


Oxidation of Alcohols

• to oxidize a 1° alcohol to an aldehyde, use PCC

• PCC oxidation of geraniol gives geranial

Tertiary alcohols are not oxidized by either of these reagents; they are resistant to oxidation

CrO3 HClN N

H

CrO3Cl-

Pyridinium chlorochromate (PCC)

Pyridine

+ ++

OHPCCCH2Cl2 H

O

Geraniol Geranial


6) Preparation of aldehydes and ketones

a) Control oxidation of 1ry alcohol

b) Complete oxidation of 1ry

alcohol


6) Preparation of adehydes and ketones

c) Oxidation of 2ry

alcohol

d) Oxidation of 3ry

alcohol

No Reaction


Chemical Reactions of Aldehydes and Ketone

1) Combustion: Alkenes are very flammable and the combustion products are carbon dioxide and water.

2) Addition Reactions: Atoms or group of atoms are added to each a carbon oxygen double bond. Two different

reactants are involved.

a) hemi-acetal or hemi-ketal formation: Addition of Alcohols: -OR group of the R-OH is added to the C atom and H of

the ROH is added to O atom.

b) Aacetal or ketal formation : Substiution of hemi-acetal or -ketal Another or second ROH is reacted in a substitution

reaction to replace the H atom of the -OH group of the hemi-acetal or hemi-ketal and water molecule is produced.

3) Oxidation Reactions: only aldehydes are oxidized to carboxylic acids.

4) Reduction Reactions: both aldehydes and ketones are reduced to alcohols by taking H from the reducing agents.


Reduction Reactions:

Both aldehydes and ketones are reduced to

alcohols by taking H from the reducing agents.

Reducing Agents

1)

2)

3)


Reduction of als & ones compounds to alcohols:


Aldehyde and Ketone Reduction: To alcohols

H2, Ni

NaBH4 or LiAlH4

then H+

CO

COH

H


7) Complete the following reductions of aldehyde and ketones and identify the type of alcohols (1ry, 2ry

and 3ry) produced.

d)


Formation of Acetals and Ketals.


8) Complete the following formation reactions hemiacetal, hemiketal, acetal, or ketal:


Chemical ReactionsOxidation of aldehyde. Benedict's Test for aldehydes:


Test for Urine Glucose: Benedict’s Test


Oxidation of aldehyde.The commercial manufacture of silver

mirrors uses a similar process.

Tollen's Test:


9) Complete reactions of following aldehydes

and ketones

a) Tollen’s Reagent: Silver mirror test:

b) Benedict's test:


9) Complete reactions of following aldehydes

and ketones

c) Oxidation of aldehyde

d) Cyclic hemi-acetal formation


Addition of HCN and H2O


Aldol Condensation

In biological systems this reaction is catalysed by an enzyme named aldolase.


Keto & Enol tautomersketo form enol from


Keto & Enol tautomers in sugars

aldehyde enol ketone


Formation of Acetals and Ketals.

1-1 chemistry 121, winter 2016, la tech introduction to organic chemistry and biochemistry...

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