Aldehydes and Ketones Nucleophilic Addition to the Carbonyl Group

1. Aldehydes and KetonesNucleophilic Additionto theCarbonyl Group

2. ALDEHYDES AND KETONES “carbonyl” functional group: Aldehydes Ketones

3. O O H H O O HCCHCH IUPAC Nomenclature of Aldehydes 4,4-dimethylpentanal 5-hexenal or hex-5-enal 2-phenylpropanedial(keep the -e endingbefore -dial)

4. O O CH3CH2CCH2CH2CH3 CH3CHCH2CCH3 CH3 H3C O Substitutive IUPAC Nomenclature of Ketones Base the name on the chain that contains the carbonyl group and replace -e with -one. Number the chain in the direction that gives the lowest number to the carbonyl carbon.

5. O O CH3CH2CCH2CH2CH3 CH3CHCH2CCH3 CH3 H3C O Substitutive IUPAC Nomenclature of Ketones 3-hexanone or Hexan-3-one 4-methyl-2-pentanone or 4-methylpentan-2-one 4-methylcyclohexanone

6. Special names!

7. ALDEHYDES AND KETONES “carbonyl” functional group: Aldehydes Ketones

8. Aldehydes, IUPAC nomenclature: Parent chain = longest continuous carbon chain containing the carbonyl group; alkane, drop –e, add –al. (note: no locant, -CH=O is carbon #1.) CH3 CH3CH2CH2CH=O CH3CHCH=O butanal 2-methylpropanal H2C=O CH3CH=O methanal ethanal

9. Physical properties: polar, no hydrogen bonding mp/bp are relatively moderate for covalent substances water insoluble (except: four-carbons or less)

10. Reactions of aldehydes and ketones: • oxidation • reduction • nucleophilic addition • Aldehydes are easily oxidized, ketones are not. • Aldehydes are more reactive in nucleophilic additions than ketones.

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

12. nucleophilic addition to carbonyl:

13. 1) Oxidation • Aldehydes(very easily oxidized!) • CH3CH2CH2CH=O + KMnO4, etc.  CH3CH2CH2COOH • carboxylic acid • CH3CH2CH2CH=O + Ag+ CH3CH2CH2COO- + Ag • Tollen’s test for easily oxidized compounds like aldehydes. • (AgNO3, NH4OH(aq)) Silver mirror

14. 2) Reduction: • To alcohols

17. 5) Addition of alcohols

21. “The Grignard Song” (sung to the tune of “America the Beautiful”) Harry Wasserman The carbonyl is polarized, the carbon end is plus. A nucleophile will thus attack the carbon nucleus. The Grignard yields an alcohol of types there are but three. It makes a bond that corresponds from “C” to shining “C.”

22. Dehydration of an alcohol? CH3 H+ CH3CHCHCH3 yields a mixture of alkenes OH CH3 H+ CH3CHCH2CH2-OH yields a mixture of alkenes E1 mechanism via carbocation!

23. Carboxylic acids: R-COOH, R-CO2H, Common names: HCO2H formic acid L. formica ant CH3CO2H acetic acid L. acetum vinegar CH3CH2CO2H propionic acid G. “first salt” CH3CH2CH2CO2H butyric acid L. butyrum butter CH3CH2CH2CH2CO2H valeric acid L. valerans

24. 5 4 3 2 1 C—C—C—C—C=O δ γ β α used in common names

25. special names

26. IUPAC nomenclature for carboxylic acids: parent chain = longest, continuous carbon chain that contains the carboxyl group  alkane, drop –e, add –oic acid HCOOH methanoic acid CH3CO2H ethanoic acid CH3CH2CO2H propanoic acid CH3 CH3CHCOOH 2-methylpropanoic acid Br CH3CH2CHCO2H 2-bromobutanoic acid

27. dicarboxylic acids: HOOC-COOH oxalic acid HO2C-CH2-CO2H malonic acid HO2C-CH2CH2-CO2H succinic acid HO2C-CH2CH2CH2-CO2H glutaric acid HOOC-(CH2)4-COOH adipic acid HOOC-(CH2)5-COOH pimelic acid Oh, my! Such good apple pie!

29. salts of carboxylic acids: name of cation + name of acid: drop –ic acid, add –ate CH3CO2Na sodium acetate or sodium ethanoate CH3CH2CH2CO2NH4 ammonium butyrate ammonium butanoate (CH3CH2COO)2Mg magnesium propionate magnesium propanoate

30. physical properties: polar + hydrogen bond  relatively high mp/bp water insoluble exceptions: four carbons or less acidic turn blue litmus  red soluble in 5% NaOH RCO2H + NaOH  RCO2-Na+ + H2O stronger stronger weaker weaker acid base base acid

31. RCO2H RCO2- • covalent ionic • water insoluble water soluble • Carboxylic acids are insoluble in water, but soluble in 5% NaOH. • Identification. • Separation of carboxylic acids from basic/neutral organic compounds. • The carboxylic acid can be extracted with aq. NaOH and then regenerated by the addition of strong acid.

32. Carboxylic acids, syntheses: • oxidation of primary alcohols • RCH2OH + K2Cr2O7 RCOOH • 2. oxidation of arenes • ArR + KMnO4, heat  ArCOOH

33. oxidation of 1o alcohols: • CH3CH2CH2CH2-OH + CrO3 CH3CH2CH2CO2H • n-butyl alcohol butyric acid • 1-butanol butanoic acid • CH3 CH3 • CH3CHCH2-OH + KMnO4  CH3CHCOOH • isobutyl alcohol isobutyric acid • 2-methyl-1-propanol` 2-methylpropanoic acid

34. oxidation of arenes: Remember for Benzaldehyde!! note: aromatic acids only!

37. carboxylic acids, reactions: • as acids • conversion into functional derivatives • a)  acid chlorides (Never Mind! But use SOCl2 if needed) • b)  esters (use an alcohol and name!) • c)  amides (following chapter, 16!)

38. as acids: • with active metals • RCO2H + Na  RCO2-Na+ + H2(g) • with bases • RCO2H + NaOH  RCO2-Na+ + H2O • relative acid strength? • CH4 < NH3 < HCCH < ROH < HOH < H2CO3 < RCO2H < HF

39. Resonance stabilization of the carboxylate ion decreases the ΔH, shifts the ionization in water to the right, increases the Ka, and results in carboxylic acids being stronger acids.

40.  esters • “direct” esterification: H+ • RCOOH + R´OH  RCO2R´ + H2O • -reversible and often does not favor the ester • -use an excess of the alcohol or acid to shift equilibrium • -or remove the products to shift equilibrium to completion • “indirect” esterification: • RCOOH + PCl3 RCOCl + R´OH  RCO2R´ • -convert the acid into the acid chloride first; not reversible

42.  amides • “indirect” only! • RCOOH + SOCl2 RCOCl + NH3  RCONH2 • amide • Directly reacting ammonia with a carboxylic acid results in an ammonium salt: • RCOOH + NH3 RCOO-NH4+ • acid base

44. Reduction: • RCO2H + LiAlH4; then H+ RCH2OH • 1o alcohol • Carboxylic acids resist catalytic reduction under normal conditions. • RCOOH + H2, Ni  NR