1. Alcohols

2. 2 Structure of Water and Methanol Oxygen is sp 3 hybridized and tetrahedral. The H—O—H angle in water is 104.5°. The C—O—H angle in methyl alcohol is 108.9°.

3. 3 Classification of Alcohols Primary: carbon with —OH is bonded to one other carbon. Secondary: carbon with —OH is bonded to two other carbons. Tertiary: carbon with —OH is bonded to three other carbons. Aromatic (phenol): —OH is bonded to a benzene ring.

4. 4 Examples of Classifications CH 3 C CH 3 CH 3 OH * CH 3 CH OH CH 2 CH 3 * CH 3 CH CH 3 CH 2 OH * Primary alcohol Secondary alcohol Tertiary alcohol

5. 5 IUPAC Nomenclature Find the longest carbon chain containing the carbon with the —OH group. Drop the -e from the alkane name, add -ol. Number the chain giving the —OH group the lowest number possible. Number and name all substituents and write them in alphabetical order.

6. 6 Examples of Nomenclature 2-methyl-1-propanol 2-methylpropan-1-ol 2-methyl-2-propanol 2-methylpropan-2-ol 2-butanol butan-2-ol CH 3 C CH 3 CH 3 OH CH 3 CH CH 3 CH 2 OH CH 3 CH OH CH 2 CH 3 3 2 1 1 2 3 4 2 1

7. 7 Alkenols (Enols) Hydroxyl group takes precedence. Assign the carbon with the —OH the lowest number. End the name in –ol, but also specify that there is a double bond by using the ending –ene before -ol 4-penten-2-ol pent-4-ene-2-ol CH 2 CHCH 2 CHCH 3 OH 5 4 3 2 1

8. 8 Naming Priority 1.Acids 2.Esters 3.Aldehydes 4.Ketones 5.Alcohols 6.Amines 7.Alkenes 8.Alkynes 9.Alkanes 10. Ethers 11. Halides Highest ranking Lowest ranking

9. 9 Hydroxy Substituent When —OH is part of a higher priority class of compound, it is named as hydroxy. 4-hydroxybutanoic acid also known as  -hydroxybutyric acid (GHB) CH 2 CH 2 CH 2 COOH OH carboxylic acid 4 3 2 1

10. 10 Common Names Alcohol can be named as alkyl alcohol. Useful only for small alkyl groups. isobutyl alcoholsec-butyl alcohol CH 3 CH CH 3 CH 2 OH CH 3 CH OH CH 2 CH 3

11. 11 Naming Diols Two numbers are needed to locate the two —OH groups. Use -diol as suffix instead of -ol. hexane-1,6- diol 1 2 3 4 5 6

12. 12 Glycols 1, 2-diols (vicinal diols) are called glycols. Common names for glycols use the name of the alkene from which they were made. ethane-1,2- diol ethylene glycol propane-1,2- diol propylene glycol

13. 13 Phenol Nomenclature —OH group is assumed to be on carbon 1. For common names of disubstituted phenols, use ortho- for 1,2; meta- for 1,3; and para- for 1,4. Methyl phenols are cresols. 3-chlorophenol (meta-chlorophenol) 4-methylphenol (para-cresol)

14. 14 Give the systematic (IUPAC) name for the following alcohol. The longest chain contains six carbon atoms, but it does not contain the carbon bonded to the hydroxyl group. The longest chain containing the carbon bonded to the —OH group is the one outlined by the green box, containing five carbon atoms. This chain is numbered from right to left in order to give the hydroxyl-bearing carbon atom the lowest possible number. The correct name for this compound is 3-(iodomethyl)-2-isopropylpentan-1-ol. Solved Problem 1 Solution

15. 15 Physical Properties Alcohols have high boiling points due to hydrogen bonding between molecules. Small alcohols are miscible in water, but solubility decreases as the size of the alkyl group increases.

16. 16 Boiling Points of alcohols Alcohols have higher boiling points than ethers and alkanes because alcohols can form hydrogen bonds. The stronger interaction between alcohol molecules will require more energy to break them resulting in a higher boiling point.

17. 17 Solubility in Water Small alcohols are miscible in water, but solubility decreases as the size of the alkyl group increases.

18. 18 Methanol “Wood alcohol” Industrial production from synthesis gas Common industrial solvent Toxic Dose: 100 mL methanol Used as fuel at Indianapolis 500 – Fire can be extinguished with water – High octane rating – Low emissions – Lower energy content – Invisible flame

19. 19 Ethanol Fermentation of sugar and starches in grains 12–15% alcohol, then yeast cells die Distillation produces “hard” liquors Azeotrope: 95% ethanol, constant boiling Denatured alcohol used as solvent Gasahol: 10% ethanol in gasoline Toxic dose: 200 mL

20. 20 Formation of Alkoxide Ions Ethanol reacts with sodium metal to form sodium ethoxide (NaOCH 2 CH 3 ), a strong base commonly used for elimination reactions. More hindered alcohols like 2-propanol or tert-butanol react faster with potassium than with sodium.

21. 21 Formation of Phenoxide Ion The aromatic alcohol phenol is more acidic than aliphatic alcohols due to the ability of aromatic rings to delocalize the negative charge of the oxygen within the carbons of the ring.

22. 22 Synthesis of Alcohols (Review) Alcohols can be synthesized by nucleophilic substitution of alkyl halide. Hydration of alkenes also produce alcohols: – Water in acid solution (suffers from rearragements) – Oxymercuration–demercuration – Hydroboration–oxidation

23. Chapter 1023 Synthesis of Alcohols (Review) Alcohols can be synthesized by nucleophilic substitution of alkyl halide. Hydration of alkenes also produce alcohols:

24. Chapter 1024 Reduction of Carbonyl Reduction of aldehyde yields 1º alcohol. Reduction of ketone yields 2º alcohol. Reagents: – Sodium borohydride, NaBH 4 – Lithium aluminum hydride, LiAlH 4 – Raney nickel

25. Chapter 1025 Sodium Borohydride NaBH 4 is a source of hydrides (H - ) Hydride attacks the carbonyl carbon, forming an alkoxide ion. Then the alkoxide ion is protonated by dilute acid. Only reacts with carbonyl of aldehyde or ketone, not with carbonyls of esters or carboxylic acids.

26. Chapter 1026 Lithium Aluminum Hydride LiAlH 4 is source of hydrides (H - ) Stronger reducing agent than sodium borohydride, but dangerous to work with. Reduces ketones and aldehydes into the corresponding alcohol. Converts esters and carboxylic acids to 1º alcohols.

27. Chapter 1027 Reducing Agents NaBH 4 can reduce aldehydes and ketones but not esters and carboxylic acids. LiAlH 4 is a stronger reducing agent and will reduce all carbonyls.

28. Chapter 1028 Catalytic Hydrogenation Raney nickel is a hydrogen rich nickel powder that is more reactive than Pd or Pt catalysts. This reaction is not commonly used because it will also reduce double and triple bonds that may be present in the molecule. Hydride reagents are more selective so they are used more frequently for carbonyl reductions.

29. Chapter 1129 Alcohol Reactions Dehydration to alkene Oxidation to aldehyde, ketone Substitution to form alkyl halide Reduction to alkane Esterification Williamson synthesis of ether

30. Chapter 1130 Summary Table

31. Chapter 1131 Oxidation States Easy for inorganic salts (reduced, organic oxidized) – CrO 4 2- reduced to Cr 2 O 3 – KMnO 4 reduced to MnO 2 Oxidation: loss of H 2, gain of O, O 2, or X 2 Reduction: gain of H 2 or H -, loss of O, O 2, or X 2 Neither: gain or loss of H +, H 2 O, HX

32. Chapter 1132 1º, 2º, 3º Carbons

33. Chapter 1133 Oxidation of 2° Alcohols 2° alcohol becomes a ketone Reagent is Na 2 Cr 2 O 7 /H 2 SO 4 = H 2 CrO 4 Active reagent probably H 2 CrO 4 Color change: orange to greenish-blue =>

34. Chapter 1134 Oxidation of 1° Alcohols 1° alcohol to aldehyde to carboxylic acid Difficult to stop at aldehyde Use pyridinium chlorochromate (PCC) to limit the oxidation. PCC can also be used to oxidize 2° alcohols to ketones.

35. Chapter 1135 3° Alcohols Don’t Oxidize Cannot lose 2 H’s Basis for chromic acid test

36. Chapter 1136 Reduction of Alcohols Dehydrate with conc. H 2 SO 4, then add H 2

37. Chapter 1137 Reaction with HBr -OH of alcohol is protonated -OH 2 + is good leaving group 3° and 2° alcohols react with Br - via S N 1 1° alcohols react via S N 2

38. Chapter 1138 Reaction with HCl Chloride is a weaker nucleophile than bromide. Add ZnCl 2, which bonds strongly with -OH, to promote the reaction. The chloride product is insoluble. Lucas test: ZnCl 2 in conc. HCl – 1° alcohols react slowly or not at all. – 2  alcohols react in 1-5 minutes. – 3  alcohols react in less than 1 minute.

39. Chapter 1139 Dehydration Reactions Conc. H 2 SO 4 (or H 3 PO 4 ) produces alkene Carbocation intermediate Zaitsev product Bimolecular dehydration produces ether Low temp, 140°C and below, favors ether High temp, 180°C and above, favors alkene

40. Chapter 1140 Esterification Fischer: alcohol + carboxylic acid Nitrate esters Phosphate esters

41. Chapter 1141 Fischer Esterification Acid + Alcohol yields Ester + Water Sulfuric acid is a catalyst. Each step is reversible.

42. End Alcohols