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

Ethers – compounds with alcoxyl group (-OR)

Alcohols and phenols (hydroxy derivates) – compounds with the hydroxyl (-OH)

R - O - H

R - O - R

C = OR

OH ----

-

Carboxylic acids – carbonyl + hydroxyl group

Aldehydes and ketones – carbonyl group

C = OR

H

-- C = O

R

R --

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).

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

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 CH3-OHethanol – ethyl alcohol CH3-CH2-OH1-propanol – propyl alcohol CH3-CH2-CH2-OH2-propanol – isopropyl alcohol CH3-CH-CH3

OH1-butanol – n-butyl alcohol CH3-CH2-CH2-CH2-OH

Nomenclature of Alcohols

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.

Properties

Reaction of Alcohols

C C O H

HH An acid-base reaction.

C C O H

HH

1. Braking the oxygen-hydrogen bond.

2. Braking the carbon-oxygen bond.

A substitution reaction by a nucleophile.

Reaction of Alcohols

C C O H

HH

3. Braking both the oxygen-hydrogen bond and the carbon-hydrogen bond at the carbon atom bearing the -OH group.

An oxidation reaction.

4. Breaking both the carbon-oxygen bond and the carbon-hydrogen bond at a carbon atom adjacent to the carbon atom bearing the –OH group

C C O H

HH An elimination reaction.

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

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+, heatH—C—C—H H—C=C—H + H2O

| | | | H H H H

alcohol alkene

Dehydratation of Alcohols

H+

CH3—OH + HO—CH3 CH3—O—CH3 + H2O Two methanol Dimethyl ether

Dehydratation of Alcohols

Ethers form when dehydration takes place at low temperature.

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 Aldehyde

OH O | [O] ||

CH3—C—H CH3—C—H + H2O |

H Ethanol Ethanal (ethyl alcohol) (acetaldehyde)

Oxidation of Primary Alcohols

Oxidation of Primary Alcohols

O ||

CH3—C—H

O ||

CH3—C—OH

Aldehyde Carboxylic acid[½ O2]

[½ O2]

Ethanal(acetaldehyde)

Acetic acid

Aldehydes can easily be oxidized to produce acids

The oxidation of a secondary alcohol removes one H from –OH and another H from the carbon bonded to the –OH.

[O] Secondary alcohol Ketone OH O

| [O] || CH3—C—CH3 CH3—C—CH3 + H2O |

H 2-Propanol Propanone (Isopropyl alcohol) (Dimethylketone; Acetone)

Oxidation of Secondary Alcohols

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

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)

Production

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

Acts as a depressant. Lethal dose is 6-8 g/kg ( 1 L of vodka)

Production

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

Oxidation of Alcohol in the Body

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.

Ethanol – An Antidote for Methanol Poisoning

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 with a single hydroxyl group, meaning mono hydroxyl phenols Phenols with more than one hydroxyl groups in the molecule, meaning poly hydroxyl phenols

Phenols

Dihydroxybenzenes

Components of biochemical molecules

polar, can form hydrogen bond water insoluble stronger acids than water and will dissolve in 5% NaOH weaker acids than carbonic acid

Physical Properties of Phenols

Methyl derivatives - cresols are used to dissolve other chemicals, as disinfectants and deodorizers, and to make specific chemicals that kill insect pests.

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.

Reactivity of Alcohols and Phenols

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.

R C H

O

R C R

O

aldehyde ketone

FormaldehydeMethanal

AcetaldehydeEthanal

PropionaldehydePropanal

AkrylaldehydePropenal

Acetonepropanone

Ethylmethyl ketoneButanone

Cyclohexanone

GlyoxalEthandial

Benzaldehyde

Cinnamaldehyde 3-phenyl propenal

AcetophenoneMethylphenyl ketone

BenzophenoneDiphenyl 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 ketose

The family of aldose

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).

Hemiacetal Formation

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

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.

R-COOH

Examples of monocarboxylic acids

Formic acidMethanoic acid

Acetic acidEthanoic acid

Propionic acidPropanoic acid

Butyric acidButanoic acid

Isobutyric acidIsobutanoic acid

Valeric acidPentanoic acid

Palmitic acidHexadecanoic acid

Stearic acidOctadecanoic acid

Oleic acidCis-9-octadecanoic acid

Acrylic acidPropenoic acid

Crotonic acidtrans-2-butenoic acid

Benzoic acidBenzencarboxylic acid

-naphtoic acid2-naphtalenecarboxylic acid

Examples of Polyfunctional Carboxylic 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

lactic acid

malic acid

citric acid

Dicarboxylic acids

-OH group containing acids

Maleic acid and fumaric acid are geometric isomerspyruvic oxaloacetic acid

Unsaturated acids

-ketoglutaric acid

Ketoacids

The liquid carboxylic acids The liquid carboxylic acids (low molecular (low molecular weight) weight) have sharp and unpleasant odors (have sharp and unpleasant odors (butyric butyric

acid occurs in ranciacid occurs in rancidd butter and aged cheese butter and aged cheese).). Liquid at room temperature.Liquid at room temperature.

The high molecular weight acids (myristic, The high molecular weight acids (myristic, palmytic, stearic) are known as fatty acids.palmytic, stearic) are known as fatty acids. Wax-like solidsWax-like solids

Properties

Acidic Properties of Carboxylic Acids

Carboxylic acids are week acids. Carboxylic acids are week acids.

Partially dissociate into HPartially dissociate into H++ cationts and RCOO cationts and RCOO-- anionts in the water.anionts in the water.

CH3COOH CH3COO - + H+

CHCH33COOH + OHCOOH + OH−− CH CH33COOCOO−− + H + H22O O

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