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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. O. 1s 2. 2s 2. 2p 4. O.

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OXYGEN CONTAINING ORGANIC COMPOUNDS

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  1. OXYGEN CONTAINING ORGANIC COMPOUNDS

  2. 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.

  3. O 1s2 2s2 2p4 O Electron configuration of oxygen atom: In organic molecule oxygen is attached covalentlywithtwo pairs of atoms

  4. R - O - H R - O - R • Alcohols and phenols (hydroxy derivates) – compounds with the hydroxyl (-OH) • Ethers – compoundswith alcoxyl group (-OR)

  5. - - C = O - - - - C = O C = O C = O R R R R O H • Aldehydes and ketones – carbonyl group • Carboxylic acids – carbonyl + hydroxyl group - - - H - -

  6. Alcohols

  7. 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).

  8. 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 -OHattached primary to aromatic ring

  9. 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 CH3-OH ethanol – ethyl alcohol CH3-CH2-OH 1-propanol – propyl alcohol CH3-CH2-CH2-OH 2-propanol – isopropyl alcohol CH3-CH-CH3 OH 1-butanol – n-butyl alcohol CH3-CH2-CH2-CH2-OH

  10. 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.

  11. H H H H C C C C O O H H Reaction of Alcohols 1. Braking the oxygen-hydrogen bond. An acid-base reaction. 2. Braking the carbon-oxygen bond. A substitution reaction by a nucleophile.

  12. H H H H C C C C O O H H Reaction of Alcohols 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 An elimination reaction.

  13. 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

  14. 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 | | | | H H H H alcohol alkene

  15. Dehydratation of Alcohols • Ethers form when dehydration takes place at low temperature. H+ CH3—OH + HO—CH3 CH3—O—CH3 + H2O Two methanol Dimethyl ether

  16. 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 Aldehyde OHO |[O]|| CH3—C—H CH3—C—H + H2O | H Ethanol Ethanal (ethyl alcohol) (acetaldehyde)

  17. [½ O2] Carboxylic acid Aldehyde O || CH3—C—H O || CH3—C—OH [½ O2] Ethanal (acetaldehyde) Acetic acid Oxidation of Primary Alcohols • Aldehydes can easily be oxidized to produce acids

  18. 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 Ketone OH O | [O]|| CH3—C—CH3 CH3—C—CH3 + H2O | H 2-Propanol Propanone (Isopropyl alcohol) (Dimethylketone; Acetone)

  19. 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

  20. 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)

  21. 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)

  22. 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

  23. 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.

  24. CH2 - OH CH - OH CH2 - OH 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) • Present as the backbone of several important biological compounds

  25. 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.

  26. 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.

  27. Glycerol as a Beckbone for Several Bilogical Compounds phosphatidylethanolamine phosphatidylcholine

  28. Phenols • Class of chemical compounds consisting of a hydrohyl group (-OH) bonded directly to an aromatic hydrocarbon group. Phenol

  29. Phenols • Phenols with a single hydroxyl group, meaning mono hydroxylphenols • Phenols with more than one hydroxyl groups in the molecule, meaning poly hydroxyl phenols Dihydroxybenzenes Components of biochemical molecules

  30. 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.

  31. 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 acidis called esterification. • The introduction of acetyl (CH3CO-) group in alcohols or phenols in known as acetylation.

  32. Ethers

  33. Ethers • Derivatives of water • An oxygen atom connected to two alkyl or aryl groups Diethylether CH3-CH2-O-CH2-CH3 Solvent and anestetic

  34. 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.

  35. Aldehydes and Ketones

  36. Aldehydes and Ketones • Aldehydes and ketones have carbonyl group C=O • Aldehydeshave the carbonyl carbon atom bonded to at least one hydrogen atom. • Ketoneshave the carbonyl carbon atom bonded to two other carbons.

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

  38. Formation of Hemiacetals and Hemiketals • An alcohol addition reversibly to an aldehyde or ketoneproduce 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.

  39. The family of aldose The family of ketose

  40. Hemiacetal Formation • The electrons on the alcohol oxygen are used to bond the carbon #1 to make an ether (red oxygen atom). • 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

  41. Hemiketal Formation • The electrons on the alcohol oxygen are used to bond the carbon #2 to make an ether (red oxygen atom). • 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

  42. 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).

  43. Carboxylic Acids

  44. 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.

  45. Stearic acid Octadecanoic acid Formic acid Methanoic acid Acetic acid Ethanoic acid Oleic acid Cis-9-octadecanoic acid Propionic acid Propanoic acid Acrylic acid Propenoic acid Butyric acid Butanoic acid Crotonic acid trans-2-butenoic acid Isobutyric acid Isobutanoic acid Benzoic acid Benzencarboxylic acid Valeric acid Pentanoic acid b-naphtoic acid 2-naphtalenecarboxylic acid Palmitic acid Hexadecanoic acid Examples of monocarboxylic acids

  46. lactic acid malic acid citric 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 Ketoacids Unsaturated acids pyruvic oxaloacetic acid Maleic acid and fumaric acid are geometric isomers a-ketoglutaric acid

  47. 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

  48. Acidic Properties of Carboxylic Acids • Carboxylic acids are week acids. • Partially dissociate into H+ cationts and RCOO- anionts in the water. CH3COOH CH3COO- + H+ CH3COOH + OH− CH3COO− + H2O

  49. Salts of Carboxylic acids • Carboxylic acids react with bases to produce carboxylate salts. • The name of salt is derived from acid name by changing –icending to –ate and preceding the name with the name of the methal ion (sodium acetate or sodium ethanoate).

  50. Acetylation of salicylic acid produces aspirin, which possesses analgesic, anti-inflammatory and antipyretic properties.

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