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ALDEHYDES & KETONES (ALKANALS & ALKANONES)

ALDEHYDES & KETONES (ALKANALS & ALKANONES). alkane. alcohol. reduction. reduction. aldehyde ketone. addition product. nucleophilic addition. oxidation. carboxylic acid. Aldehydes and Ketones. Aldehydes and ketones are characterized by the the carbonyl functional group (C=O).

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ALDEHYDES & KETONES (ALKANALS & ALKANONES)

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  1. ALDEHYDES & KETONES (ALKANALS & ALKANONES)

  2. alkane alcohol reduction reduction aldehyde ketone addition product nucleophilic addition oxidation carboxylic acid

  3. Aldehydes and Ketones Aldehydes and ketones are characterized by the the carbonyl functional group (C=O). Some common classes of carbonyl compounds

  4. Carbonyl Structure Carbon is sp2hybridized. C=O bond is shorter, stronger, and more polar than C=C bond in alkenes.

  5. Naming Aldehydes and Ketones Aldehydes are named by replacing the terminal -e of the corresponding alkane name with –al The parent chain must contain the CHO group The CHO carbon is numbered possible minimum number.

  6. Naming Ketones Replace the terminal -e of the alkane name with –one Parent chain is the longest one that contains the ketone group Numbering begins at the end nearer the carbonyl carbon

  7. Solubility Good solvent for alcohols. Lone pair of electrons on oxygen of carbonyl can accept a hydrogen bond from O-H or N-H. Acetone and acetaldehyde are miscible in water.

  8. Preparation of Aldehydes & ketones 1] Oxidation of 1& 2 alcohol : C2H5OH [O] CH3CHO [O] CH3COOH CH3CHOHCH3 [O] CH3COCH3 isopropanol

  9. Physical Properties Boiling Points More polar, so boiling point higher than corresponding alkane or ether. Absence of H-bond, so boiling point lower than corresponding alcohol.

  10. 2- Dehydrogenation A- 10 Alcohol gives aldehydes: CH3CH2OH Cu/ 350 oCCH3CHO + H2 B- Secondary Alcohol gives Ketones: OH O CH3CHCH3 Cu/350oC CH3CCH3 + H2

  11. 3] Ozonolysis of alkenes:

  12. 4- Hydration of Alkynes

  13. 5- Hydrolysis of gem-dihalides by the action of base: • A) If dihalogen are terminal: • CH3CHCl2 H2O/NaOHCH3CH(OH)2 H2O CH3CHO acetaldehyde • B) If dihalogen aren’t terminal: • CH3CCl2CH3 H2O/NaOHCH3COCH3 acetone

  14. 6-From Acid Chlorides:Rosenmund reduction • R-CO-ClH2/Pd R-CHO +HCl • CH3COCl H2/Pd CH3CHO + HCl

  15. Chemical Reactions

  16. 1] Reactions with Grignard reagent:

  17. Nucleophilic addition to carbonyl:

  18. Addition of Alcohol In presence of dry HClaldehydes and ketones react with two equivalent of alcohols to form acetals and ketals

  19. Acetal Formation Acetals are geminaldiethers- structurally related to hydrates, which are geminaldiols. hydrate (gem-diol) acetal (gem-diether) aldehyde hemi-acetal ketal (gem-diether) ketone hemi-ketal

  20. 4-Reduction of Aldehydes/Ketones • Hydrogenation

  21. B- Condensation reaction: • 1- Hydroxylamine: • -C=O + NH2OH -C=NOH + H2O (oxime) • CH3COCH3 + NH2OH CH3-C=NOH • CH3 • 2- Hydrazine: • -C=O + H2N-NH2 -C=N-NH2 + H2O (hydrazone) CH3CHO +H2N-NH2 CH3CH=N.NH2+H2O

  22. 3-Aldol Condensation Aldol Condensation - Under the influence of dilute base or dilute acid two molecules of an aldehyde or a ketone may combine to form b-hydroxaldehyde or b-hydroxyketone. This reaction is called aldol condensation.

  23. ald + ol an aldol (b-hydroxyaldehyde) The Aldol Condensation base H3O+ - H2O aldols easily lose water to form a double bond a,b-unsaturated aldehyde

  24. Aldol Condensation -- Mechanism fast enolate ion slow forms new C-C bond fast

  25. C- Substitution reaction: 1-Haloform reaction: • 1- • CH3COCH3 3I2 Cl3COCH3 NaOHCHI3 + CH3CO2Na • 2- Cannizzaro’s reaction: • 2CH2O + NaOH CH3OH + HCOONa

  26. Cannizzaro’s reaction

  27. Tollens Test Add ammonia solution to AgNO3 solution until precipitate dissolves. Aldehyde reaction forms a silver mirror.

  28. Identification of aldehydes Tollen’s test Fehling’s test Schiff’s test Schiff's Test for aldehydes. Use 2 mL Schiff's reagent + 3 drops unknown. Positive test showing a magenta color after ten minutes.

  29. Carboxylic Acids A carboxylic acid • Contains a carboxyl group, which is a carbonyl group (C=O) attached to a hydroxyl group (—OH). • Has the carboxyl group on carbon 1. carbonyl group O  CH3 —C—OHhydroxyl group or CH3COOH carboxyl group

  30. IUPAC Names The IUPAC names of carboxylic acids • Replace the -e in the alkane name with -oic acid. CH4 methane HCOOH methanoicacid CH3—CH3 ethane CH3—COOH ethanoic acid • Number substituents from the carboxyl carbon 1. CH3 O | ║ CH3—CH—CH2—C—OH 4 3 2 1 3-methylbutanoic acid

  31. Carboxylic acid R-COOHAr-COOH Aliphatic(carboxylic cid)aromatic (benzoic acid) Nomenclature : 1) replace ane by -ic acid

  32. 2) Longest continuous chain CH3CH2CHCH2CH2COOH 4-Methyl hexanoic acid CH3   C-C-C-C-C-COOH CH3CH2CHCH2CH2COOH γ-Methyl hexenoic acid CH3 commmone: -- Dimethyl butyric acid IUPAC: 2,3-Dimethyl butanoic a CH3-CHBr-CHCl-CO2H 3-Bromo-2-chlorobutnoic acid

  33. Common Carboxylic Acids Methanoic acid (formic acid) O ║ H─C─OH ethanoic acid (acetic acid) O ║ CH3─C─OH

  34. Physical properties: 1] They form hydrogen 2] comp. 1-7 soli in H2O . 3] mor than 7 carbon less soli. (bec. R increased) 4] Aromatic acids insoluble. In H2O 5] BP. Acid > Alcohol

  35. Polarity of Carboxylic Acids Carboxylic acids • Are strongly polar. • Have two polar groups: hydroxyl (−OH) and carbonyl (C=O). δ- O ║δ+δ- δ+ CH3CO H

  36. Boiling Points of Carboxylic Acids The boiling points of carboxylic acids • Are higher than alcohols, ketones, and aldehydes of similar mass. • Are high because they formdimersin which hydrogen bonds form between the polar groups in the two carboxyl groups. O H—O || | CH3—C C—CH3 | || O—H O A dimer of acetic acid

  37. Solubility in Water Carboxylic acids • Form hydrogen bonds with many water molecules. • With 1-4 carbon atoms are very soluble in water. Water molecules 37

  38. Preparation of carboxylic acid 1] Oxidation a) 1 alcohols & Aldehydes

  39. Preparation of Carboxylic Acids • Carboxylic acids can be prepared by oxidizing primary alcohols or aldehydes. • The oxidation of ethanol produces ethanoic acid (acetic acid). OH O O | [O] || [O] || CH3—CH2 CH3—C—HCH3—C—OH ethanol ethanalethanoic acid (ethyl alcohol) (acetaldehyde) (acetic acid)

  40. 2] Carbonation of Grignard reagent:

  41. Chemical Reaction

  42. Reactions of acids 1)Salt formation: it react with strong base & we can use Ca or K It reacts with weak base Sodium bicarb. Can be used to distinguish between carboxylic acid and phenols

  43. 2) Formation of Ester: nucleophilic substitution H+ + + H2O carboxylic acid ester alcohol condensation reaction reverse = hydrolysis H+ + carboxylic acid alcohol ester + H2O

  44. 2) Formation of Ester: 3) Formation of acid chloride: 4) Formation of acid anhydride: 2RCOOH + P2O5 (RCO)2O + H2O 2CH3COOH + P2O5 (CH3CO)2O + H2O

  45. 5- Reduction: RCO2H + LiAlH4; then H+ RCH2OH1oalcohol 6- Decarboxylation:( Soda lime) CH3COOH + NaOH/CaO CH4 + Na2CO3 Alkane

  46. ketone aldehyde RCOOH ROH ROR alkene Alcohols are central to organic syntheses RX RH alkyne

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