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: 1s 2 2s 2 2p 4 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 = O R O H  Carboxylic acids – carbonyl + hydroxyl group  Aldehydes and ketones – carbonyl group C = O R H - - R R

Alcohols

Classification  In 1 o alcohol, only one carbon atom is attached to the carbon carrying the -OH group (primary carbon).  In 2 o alcohol two carbon atoms are attached to the carbon carrying the -OH group (secondary carbon).  In 3 o 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 alcoholCH 3 -OH ethanol – ethyl alcohol CH 3 -CH 2 -OH 1-propanol – propyl alcoholCH 3 -CH 2 -CH 2 -OH 2-propanol – isopropyl alcohol CH 3 -CH-CH 3 OH 1-butanol – n-butyl alcoholCH 3 -CH 2 -CH 2 -CH 2 -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 CCOH HH An acid-base reaction. CCOH HH 1. Braking the oxygen-hydrogen bond. 2. Braking the carbon-oxygen bond. A substitution reaction by a nucleophile.

Reaction of Alcohols CCOH 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 CCOH 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

Alcohols undergo combustion with O 2 to produce CO 2 and H 2 O. 2CH 3 OH + 3O 2 2CO 2 + 4H 2 O + 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 + H 2 O | | | | H H H H alcohol alkene Dehydratation of Alcohols

H + CH 3 —OH + HO—CH 3 CH 3 —O—CH 3 + H 2 O 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] || CH 3 —C—H CH 3 —C—H + H 2 O | H Ethanol Ethanal (ethyl alcohol) (acetaldehyde) Oxidation of Primary Alcohols

O || CH 3 —C—H O || CH 3 —C—OH Aldehyde Carboxylic acid [½ O 2 ] 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] || CH 3 —C—CH 3 CH 3 —C—CH 3 + H 2 O | H 2-Propanol Propanone (Isopropyl alcohol) (Dimethylketone; Acetone) Oxidation of Secondary Alcohols

Oxidation of Tertiary Alcohols  Tertiary alcohols are resistant to oxidation. [O] Tertiary alcoholsno reaction OH | [O] CH 3 —C—CH 3 no product | CH 3 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 C 6 H 12 O 6 (hexose)2 CH 3 CH 2 OH + 2H 2 O  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. Ethanolacetaldehydeacetic acid Oxidation of methanol in the liver produces formaldehyde CH 3 OHH 2 C=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–CH 2 –CH 2 –OH  Used as a radiator and automobile antifreez  toxic: 50 mL, lethal: 100 mL Glycerol - propane-1,2,3-triol (glycerin) CH 2 - OH CH - OH CH 2 - 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 (CH 3 CO - ) group in alcohols or phenols in known as acetylation. Reactivity of Alcohols and Phenols

Ethers

 Derivatives of water  An oxygen atom connected to two alkyl or aryl groups DiethyletherCH 3 -CH 2 -O-CH 2 -CH 3 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 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.

Formaldehyde Methanal Acetaldehyde Ethanal Propionaldehyde Propanal Akrylaldehyde Propenal Acetone propanone Ethylmethyl ketone Butanone Cyclohexanone Glyoxal Ethandial Benzaldehyde Cinnamaldehyde 3-phenyl propenal Acetophenone Methylphenyl ketone 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 OR 1 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

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).

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

 Functional group is carboxyl group.  R – can be alifatic chain (CH 3 CH 2 -), 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 acid Methanoic acid Acetic acid Ethanoic acid Propionic acid Propanoic acid Butyric acid Butanoic acid Isobutyric acid Isobutanoic acid Valeric acid Pentanoic acid Palmitic acid Hexadecanoic acid Stearic acid Octadecanoic acid Oleic acid Cis-9-octadecanoic acid Acrylic acid Propenoic acid Crotonic acid trans-2-butenoic acid Benzoic acid Benzencarboxylic acid  -naphtoic acid 2-naphtalenecarboxylic acid

Examples of Polyfunctional Carboxylic Acids HOOC-COOH – oxalic acidHOOC-CH 2 -COOH – malonic acid HOOC-CH 2 -CH 2 -COOH – succinic acid (citric cycle)HCCO-CH 2 -CH 2 -CH 2 -COOH – glutaric acid lactic acid malic acid citric acid Dicarboxylic acids -OH group containing acids Maleic acid and fumaric acid are geometric isomers pyruvic oxaloacetic acid Unsaturated acids  -ketoglutaric acid Ketoacids

 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 Properties

Acidic Properties of Carboxylic Acids  Carboxylic acids are week acids.  Partially dissociate into H + cationts and RCOO - anionts in the water. CH 3 COOH  CH 3 COO - + H + CH 3 COOH + OH −  CH 3 COO − + H 2 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