Transcript OXYGEN CONTAINING ORGANIC COMPOUNDS

OXYGEN CONTAINING
ORGANIC COMPOUNDS
Compounds of oxygen
 Carbohydrates,
fats, proteins, nucleic acids
are complex molecules containing oxygen.
 First
is necessary to study simpler organic
compounds:
 Alcohols, phenols, ethers, aldehydes,
ketones, acids, esters.
Electron configuration of oxygen atom:
1s2
2s2
2p4
In organic molecule oxygen is attached covalently
with two pairs of atoms
O
O
 Alcohols
and phenols (hydroxy derivates)
– compounds with the hydroxyl (-OH)
R-O-H

Ethers – compounds with alcoxyl group (-OR)
R-O-R
 Aldehydes
and ketones – carbonyl group
-
C= O
R
C= O
H

R
R
C=O
-
Carboxylic acids – carbonyl + hydroxyl group
R
H -O
-
-
C = O-
Alcohols
Alcohols
Classification
In 1o alcohol, only one carbon atom is attached to the carbon carrying the -OH
group (primary carbon).

In 2o alcohol two carbon atoms are attached to the carbon carrying the -OH
group (secondary carbon).

In 3o alcohol three other carbon atoms are attached to the carbon atom carrying
the -OH group (tertiary carbon).

Alcohols
The number of hydroxyl groups, there are:
Monohydroxyderivatives (monohydroxy alcohols)
Polyhydroxy alcohols




Diols (dihydroxyderivatives,)
Triols (trihydroxyderivatives)
Tetrols (tetrahydroxyderivatives)
Polyols belongs to a group of carbohydrates (sugars)
Phenols -OH attached primary to aromatic ring
Nomenclature of Alcohols
The lower molecular weight alcohols have common names.
Word alcohol is added after the name of the alkyl group to
which the hydroxyl group is attached.
methanol – methyl alcohol
ethanol – ethyl alcohol
1-propanol – propyl alcohol
2-propanol – isopropyl alcohol
1-butanol – n-butyl alcohol
CH3-OH
CH3-CH2-OH
CH3-CH2-CH2-OH
CH3-CH-CH3
OH
CH3-CH2-CH2-CH2-OH
Properties
Low MW alcohols are colorless liquids of specific
odour (unpleasant from C4), narcotic effect, toxic.


Polyhydroxy alcohols have sweet taste.

Higher alcohols (from C12) are solid compounds
H-bonds → solubility in water, higher boiling points
than alkanes.

Reaction of Alcohols
1. Braking the oxygen-hydrogen bond.
H
H
C
C
An acid-base reaction.
O
H
2. Braking the carbon-oxygen bond.
H
H
C
C
A substitution reaction by a nucleophile.
O
H
Reaction of Alcohols
3. Braking both the oxygen-hydrogen bond and the carbonhydrogen bond at the carbon atom bearing the -OH group.
An oxidation reaction.
H
H
C
C
O
H
4. Breaking both the carbon-oxygen bond and the carbonhydrogen bond at a carbon atom adjacent to the carbon atom
bearing the –OH group
H
H
C
C
An elimination reaction.
O
H
Reaction of Alcohols
The –OH group generally makes the alcohol
molecule polar.

The -OH group can form hydrogen bonds to one
another and to other compounds.


Alcohols, like water, act as acids or bases
http://en.wikipedia.org/wiki/Alcohol#Physical_and_chemical_properties
Dehydratation of Alcohols


Alcohols undergo combustion with O2 to produce
CO2 and H2O.
2CH3OH + 3O2
2CO2 + 4H2O + Heat
Dehydration removes H- and -OH from adjacent
carbon atoms by heating with an acid catalyst.
H OH
|
|
H+, heat
H—C—C—H
H—C=C—H + H2O
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|
| |
H H
H H
alcohol
alkene
Dehydratation of Alcohols
Ethers form when dehydration takes place
at low temperature.

H+
CH3—OH + HO—CH3
Two methanol
CH3—O—CH3 + H2O
Dimethyl ether
Oxidation of Primary Alcohols

In the oxidation [O] of a primary alcohol, one H is
lost from the –OH and another H from the carbon
bonded to the OH.
[O]
Primary alcohol
OH
|
CH3—C—H
|
H
Ethanol
(ethyl alcohol)
Aldehyde
[O]
O
||
CH3—C—H + H2O
Ethanal
(acetaldehyde)
Oxidation of Primary Alcohols
Aldehydes can easily be oxidized to produce
acids

[½ O2]
Aldehyde
Carboxylic acid
O
O
||
CH3—C—H
Ethanal
(acetaldehyde)
[½ O2]
||
CH3—C—OH
Acetic acid
Oxidation of Secondary Alcohols

The oxidation of a secondary alcohol removes one
H from –OH and another H from the carbon
bonded to the –OH.
[O]
Secondary alcohol
OH
|
CH3—C—CH3
|
H
2-Propanol
(Isopropyl alcohol)
Ketone
[O]
O
||
CH3—C—CH3 + H2O
Propanone
(Dimethylketone; Acetone)
Oxidation of Tertiary Alcohols

Tertiary alcohols are resistant to oxidation.
[O]
Tertiary alcohols
no reaction
OH
|
[O]
CH3—C—CH3
no product
|
CH3 no H on the C-OH to oxidize
2-Methyl-2-propanol
Production

Methanol

Obtained by heating wood to a high
temperature in the absence of air.
Toxic substance, temporary blindness (15 ml),
permanent blindness or death (30 ml)
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Production
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Ethanol (spiritus, alcohol)
Obtained by fermentation from sugar juices
 Fermentation from sugar from the hydrolysis of
starch in the presence of yeast and temperature
of less than 37°C

C6H12O6 (hexose)
2 CH3CH2OH + 2H2O
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Acts as a depressant.

Lethal dose is 6-8 g/kg ( 1 L of vodka)
Oxidation of Alcohol in the Body


Enzymes in the liver oxidize ethanol to acetaldehyde
The aldehyde produces impaired coordination.
Ethanol
acetaldehyde
acetic acid
Oxidation of methanol in the liver produces formaldehyde
CH3OH
H2C=O
Ethanol – An Antidote for Methanol Poisoning
Formaldehyde reacts very rapidly with proteins.
 Enzymes loss of the function.
 Ethanol competes for the oxidative enzymes
and tends to prevent the oxidation of the methanol
to formaldehyde.

Polyhydroxy Alcohols
Ethylene glycol - ethane-1,2-diol
HO–CH2–CH2–OH


Used as a radiator and automobile antifreez
toxic: 50 mL, lethal: 100 mL
Glycerol - propane-1,2,3-triol (glycerin)
CH2 - OH
CH - OH
CH2 - OH
 Present as the backbone of several important biological
compounds
Glycerol


Oxidation of glycerol arises glyceraldehyde – major
metabolite.
Reaction with acid esters formed - with nitric acid
arises glyceroltrinitrate – nitroglycerin. Nitroglycerin
is administered as a treatment for heart disease.
Glycerol


The phosphoric acid esterifies primary –OH group
to form 1-glycerophosphate acid.
1-glycerophosphate acid is an important
metabolite and a structural component of complex
lipids.
Glycerol as a Beckbone for Several
Bilogical Compounds
phosphatidylcholine
phosphatidylethanolamine
Phenols
Class of chemical compounds consisting of a
hydrohyl group (-OH) bonded directly to an
aromatic hydrocarbon group.

Phenol
Phenols
Phenols with a single hydroxyl group,
meaning mono hydroxyl phenols
 Phenols with more than one hydroxyl groups
in the molecule, meaning poly hydroxyl
phenols

Dihydroxybenzenes
Components of biochemical molecules
Physical Properties of Phenols
polar, can form hydrogen bond
 water insoluble
 stronger acids than water and will dissolve in
5% NaOH
 weaker acids than carbonic acid

Methyl derivatives - cresols are used to dissolve other chemicals, as
disinfectants and deodorizers, and to make specific chemicals that kill
insect pests.
Reactivity of Alcohols and Phenols
Reaction with carboxylic acids, acid chlorides
and acid anhydrides to form esters.

Reaction of primary or secondary alcohol in the
presence of a catalyst (commonly concentrated
sulfuric acid) with carboxylic acid is called
esterification.

The introduction of acetyl (CH3CO-) group in
alcohols or phenols in known as acetylation.

Ethers
Ethers
Derivatives of water
 An oxygen atom connected to two alkyl or aryl
groups

Diethylether
CH3-CH2-O-CH2-CH3
Solvent and anestetic
Properties
Ether molecules cannot form hydrogen bonds
amongst each other, resulting in a relatively low
boiling point compared to that of the analogous
alcohols.
 Ethers are slightly polar.

Aldehydes and Ketones
Aldehydes and Ketones

Aldehydes and ketones have carbonyl group
C=O
Aldehydes have the carbonyl carbon atom bonded to
at least one hydrogen atom.

Ketones have the carbonyl carbon atom bonded to
two other carbons.

O
O
R C H
R C R
aldehyde
ketone
Formaldehyde
Methanal
Glyoxal
Ethandial
Acetaldehyde
Ethanal
Benzaldehyde
Propionaldehyde
Propanal
Akrylaldehyde
Propenal
Cinnamaldehyde
3-phenyl propenal
Acetone
propanone
Acetophenone
Methylphenyl ketone
Ethylmethyl ketone
Butanone
Cyclohexanone
Benzophenone
Diphenyl ketone
Formation of Hemiacetals and Hemiketals
 An
alcohol addition reversibly to an aldehyde or
ketone produce hemiacetal or hemiketal and –OH
group and OR1 group are attached to the same
carbon.
Hemiacetal hydroxyl
Hemiacetals are unstable.
 Sugars contain both –OH and C=O groups that undergo
these reactions.

The family of aldose
The family of ketose
Hemiacetal Formation
1. The electrons on the alcohol oxygen are used to bond the carbon #1 to
make an ether (red oxygen atom).
2. The hydrogen (green) is transferred to the carbonyl oxygen (green) to
make a new alcohol group (green).
http://www.elmhurst.edu/~chm/vchembook/700carbonyls.html
Hemiketal Formation
1. The electrons on the alcohol oxygen are used to bond the carbon #2 to
make an ether (red oxygen atom).
2. The hydrogen (green) is transferred to the carbonyl oxygen (green) to make
a new alcohol group (green).
http://www.elmhurst.edu/~chm/vchembook/700carbonyls.html
Reactions of Aldehydes and Ketones with
Amines
Aldehydes and ketones react with primary amines to form
imines, or Schiff bases (sugars with proteins, neenzymatic
glycation in diabetes).
Carboxylic Acids
Carboxylic Acids
R-COOH

Functional group is carboxyl group.
R – can be alifatic chain (CH3CH2-), cyclic
molecule (including heterocycle) or aromatic
molecule, exceptionally hydrogen (HCOOH).


Involved in many vital function.

Cleavage of H+ allows the formation of salts.
Examples of monocarboxylic acids
Formic acid
Methanoic acid
Stearic acid
Octadecanoic acid
Acetic acid
Ethanoic acid
Oleic acid
Cis-9-octadecanoic acid
Propionic acid
Propanoic acid
Butyric acid
Butanoic acid
Isobutyric acid
Isobutanoic acid
Valeric acid
Pentanoic acid
Palmitic acid
Hexadecanoic acid
Acrylic acid
Propenoic acid
Crotonic acid
trans-2-butenoic acid
Benzoic acid
Benzencarboxylic acid
b-naphtoic acid
2-naphtalenecarboxylic acid
Examples of Polyfunctional Carboxylic Acids
Dicarboxylic acids
HOOC-COOH – oxalic acid
HOOC-CH2-COOH – malonic acid
HOOC-CH2-CH2-COOH – succinic acid (citric cycle)
HCCO-CH2-CH2-CH2-COOH – glutaric acid
-OH group containing acids
lactic acid
malic acid
citric acid
Ketoacids
Unsaturated acids
pyruvic
Maleic acid and fumaric acid are geometric isomers
oxaloacetic acid
a-ketoglutaric acid
Properties
The liquid carboxylic acids (low molecular
weight) have sharp and unpleasant odors (butyric
acid occurs in rancid butter and aged cheese).
 Liquid at room temperature.

The high molecular weight acids (myristic,
palmytic, stearic) are known as fatty acids.
 Wax-like solids

Acidic Properties of Carboxylic Acids

Carboxylic acids are week acids.
Partially dissociate into H+ cationts and RCOOanionts in the water.

CH3COOH CH3COO - + H+
CH3COOH + OH−  CH3COO− + H2O
Salts of Carboxylic acids
Carboxylic acids react with bases to produce
carboxylate salts.

The name of salt is derived from acid name by
changing –ic ending to –ate and preceding the name
with the name of the methal ion (sodium acetate or
sodium ethanoate).

Acetylation of salicylic acid produces aspirin,
which possesses analgesic, anti-inflammatory
and antipyretic properties.
Esters of Carboxylic Acids
Carboxylic acids can react with an alcohol to form
an esters
Esters have a pleasant odor.
 The aroma of many flowers, fruits, and
perfumes are due to a mixture of esters.

Esters Used as Flavoring Agents