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1 ALDEHYDES & KETONES (ALKANALS & ALKANONES). alkanealcohol aldehyde ketone carboxylic acid oxidation reduction addition product nucleophilic addition.

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Presentation on theme: "1 ALDEHYDES & KETONES (ALKANALS & ALKANONES). alkanealcohol aldehyde ketone carboxylic acid oxidation reduction addition product nucleophilic addition."— Presentation transcript:

1 1 ALDEHYDES & KETONES (ALKANALS & ALKANONES)

2 alkanealcohol aldehyde ketone carboxylic acid oxidation reduction addition product nucleophilic addition

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

4 Carbon is sp 2 hybridized. C=O bond is shorter, stronger, and more polar than C=C bond in alkenes.

5 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 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 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 More polar, so boiling point higher than corresponding alkane or ether. Absence of H-bond, so boiling point lower than corresponding alcohol.

10 A- 1 0 Alcohol gives aldehydes: CH 3 CH 2 OH C u/ 350 o C CH 3 CHO + H 2 B- Secondary Alcohol gives Ketones: OH O CH3CHCH3 Cu/350 o C CH3CCH3 + H2 A- 1 0 Alcohol gives aldehydes: CH 3 CH 2 OH C u/ 350 o C CH 3 CHO + H 2 B- Secondary Alcohol gives Ketones: OH O CH3CHCH3 Cu/350 o C CH3CCH3 + H2

11 3] Ozonolysis of alkenes:

12

13  A) If dihalogen are terminal:  CH3CHCl2 H2O/NaOH CH3CH(OH)2 H2O CH3CHO acetaldehyde  B) If dihalogen aren’t terminal:  CH3CCl2CH3 H2O/NaOH CH3COCH3 acetone

14  R-CO-Cl H2/Pd R-CHO +HCl  CH3COCl H2/Pd CH3CHO + HCl

15

16 1] Reactions with Grignard reagent:

17 Nucleophilic addition to carbonyl:

18 In presence of dry HCl aldehydes and ketones react with two equivalent of alcohols to form acetals and ketals

19 19 Acetal Formation Acetals are geminal diethers- structurally related to hydrates, which are geminal diols. hydrate (gem-diol) aldehydehemi-acetal acetal (gem-diether) ketonehemi-ketal ketal (gem-diether)

20 4-Reduction of Aldehydes/Ketones Hydrogenation Hydrogenation

21  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 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 The Aldol Condensation base an aldol (  -hydroxyaldehyde) ald + ol H3O+H3O+ - H 2 O ,  -unsaturated aldehyde aldols easily lose water to form a double bond

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

25  1- CH3COCH3 3 I 2 Cl3COCH3 NaOH CHI3 + CH3CO2Na 2- Cannizzaro’s reaction: 2CH2O + NaOH CH3OH + HCOONa

26 Cannizzaro’s reaction

27 Add ammonia solution to AgNO 3 solution until precipitate dissolves. Aldehyde reaction forms a silver mirror.

28 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 29 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  CH 3 — C—OHhydroxyl group or CH 3 COOH carboxyl group

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

31 Carboxylic acid R-COOH Ar-COOH Aliphatic (carboxylic cid) aromatic (benzoic acid) 1) replace ane by -ic acid Nomenclature :CommonIUPACFormula No. C Formic acid Acetic acid Prpionic acid Butyric acid valeric acid Methanoic acid Ethanoic acid Prpanoic acid Butanoic acid Pentanoc acid HCOOH CH 3 COOH CH 3 CH 2 COOH CH 3 (CH 2 ) 2 COOH CH 3 (CH 2 ) 3 COOH 12345

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

33 33 Methanoic acid (formic acid) O ║ H ─ C ─ OH ethanoic acid (acetic acid) O ║ CH 3 ─ C ─ OH

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

35 35 Carboxylic acids  Are strongly polar.  Have two polar groups: hydroxyl ( − OH) and carbonyl (C=O). δ - O ║ δ + δ - δ + CH 3  C  O  H

36 36 The boiling points of carboxylic acids  Are higher than alcohols, ketones, and aldehydes of similar mass.  Are high because they form dimers in which hydrogen bonds form between the polar groups in the two carboxyl groups. O H—O || | CH 3 —C C—CH 3 | || O—H O A dimer of acetic acid

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

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

39 39  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] || CH 3 —CH 2 CH 3 —C—H CH 3 —C—OH ethanol ethanal ethanoic acid (ethyl alcohol) (acetaldehyde) (acetic acid)

40 2] Carbonation of Grignard reagent:

41

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

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

45 5- Reduction: RCO 2 H + LiAlH 4 ; then H +  RCH 2 OH 1 o alcohol 5- Reduction: RCO 2 H + LiAlH 4 ; then H +  RCH 2 OH 1 o alcohol 6- Decarboxylation:( Soda lime) CH3COOH + NaOH/CaO CH4 + Na2CO3 Alkane

46 aldehydeRCOOHketone ROR alkyne alkene RH RX ROH Alcohols are central to organic syntheses

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