1. Alcohols

6. Alcohols as Acids

9. resonance in phenols

11. Methanol and ethanol are industrial chemicals: solvents, antifreeze, fuel, antiseptic, social / recreational Isopropyl alcohol is prepared by hydration of propene. All alcohols with four carbons or fewer are readily available. Most alcohols with five or six carbons are readily available. Alcohols

14. Hydration of alkenes Hydroboration-oxidation of alkenes Hydrolysis of alkyl halides Sources of alcohols Reactions discussed in earlier chapters

15. Reduction of aldehydes and ketones Reduction of carboxylic acids Reduction of esters Reaction of Grignard reagents Sources of alcohols New methods:

16. Preparation of Alcohols by Reduction of Aldehydes and Ketones

17. CRHOH H CRH O Reduction of Aldehydes Gives Primary Alcohols

18. Pt, ethanol (92%) Example: Catalytic Hydrogenation CH 3 O CH 2 OH O CH 3 O CH + H2H2H2H2

19. CRHOH R' C R R' O Reduction of Ketones Gives Secondary Alcohols

20. (93-95%) Example: Catalytic Hydrogenation + H2H2H2H2OPt ethanol HOH

21. H:–H:–H:–H:– H:–H:–H:–H:– CRH OHOHOHOH H CRH O CRH OHOHOHOH R' CRR' O Retrosynthetic Analysis

22. Sodium borohydride Lithium aluminum hydride Li+ Na+ – B HHHH – Al HHHH Metal Hydride Reducing Agents act as hydride donors

23. NaBH 4 (82%) Examples: Sodium Borohydride CH 2 OH O CH O2NO2NO2NO2Nmethanol O2NO2NO2NO2N O HOH(84%) NaBH 4 ethanol Aldehyde Ketone

24. Lithium aluminum hydride more reactive than sodium borohydride cannot use water, ethanol, methanol etc. as solvents diethyl ether is most commonly used solvent

25. Examples: Lithium Aluminum Hydride (84%) Aldehyde KetoneO CH 3 (CH 2 ) 5 CH CH 3 (CH 2 ) 5 CH 2 OH 1. LiAlH 4 diethyl ether 2. H 2 O O (C 6 H 5 ) 2 CHCCH 3 1. LiAlH 4 diethyl ether 2. H 2 O (86%)OH (C 6 H 5 ) 2 CHCHCH 3

26. neither NaBH 4 or LiAlH 4 reduces isolated double bonds HOH O 1. LiAlH 4 diethyl ether 2. H 2 O (90%) Selectivity

27. Preparation of Alcohols By Reduction of Carboxylic Acids and Esters

28. lithium aluminum hydride is only effective reducing agent Reduction of Carboxylic Acids Gives Primary Alcohols CRHOH H C R HO O

29. Example: Reduction of a Carboxylic Acid 1. LiAlH 4 diethyl ether 2. H 2 O COH O CH 2 OH (78%)

30. Lithium aluminum hydride preferred for laboratory reductions Sodium borohydride reduction is too slow to be useful Catalytic hydrogenolysis used in industry but conditions difficult or dangerous to duplicate in the laboratory (special catalyst, high temperature, high pressure Reduction of Esters Gives Primary Alcohols

31. Example: Reduction of a Carboxylic Acid 1. LiAlH 4 diethyl ether 2. H 2 O (90%)O COCH 2 CH 3 CH 3 CH 2 OH CH 2 OH +

32. Summary

33. Synthesis of Alcohols Sodium borohydride / Lithium aluminum hydride Reductions