1. Chapter 13 Alcohols, Phenols, and Ethers Spencer L. Seager Michael R. Slabaugh www.cengage.com/chemistry/seager Jennifer P. Harris

2. ALCOHOLS, PHENOLS, & ETHERS A hydroxy group is the –OH functional group. An alcohol has an –OH group attached to an aliphatic carbon. General formula: R-OH A phenol has an –OH group on a benzene ring. An ether has the functional group: General formula: R-O-R’

3. ALCOHOL EXAMPLES

4. NAMING ALCOHOLS Step 1: Name the longest chain to which the –OH group is attached. Use the hydrocarbon name of the chain, drop the final –e, and replace it with –ol. Step 2: Number the longest chain to give the lowest number to the carbon with the attached –OH. Step 3: Locate the –OH position. Example: CH 3 —CH 2 —CH 2 —CH—CH 2 —CH 3 6 5 4 3 2 1 OH | 3-hexanol

5. NAMING ALCOHOLS (continued) Step 4: Locate and name any other groups attached to the longest chain. Step 5: Combine the name and location of other groups, the location of the –OH, and the longest chain into the final name. Example: Note: Alcohols containing two –OH groups are diols, three –OH groups are triols. The IUPAC names for these compounds have endings of –diol and –triol rather than –ol. CH 3 —CH 2 —CH—CH—CH—CH 3 6 5 4 3 2 1 OH | 2,4-dimethyl-3-hexanol CH 3 | CH 3 |

6. NAMING PHENOLS Substituted phenols are usually named as derivatives of the parent compound phenol. Examples:

7. CLASSIFICATION OF ALCOHOLS

8. PHYSICAL PROPERTIES OF ALCOHOLS The –OH group is polar and capable of hydrogen bonding. This makes low molecular weight alcohols highly soluble in water. Hydrogen bonding in a water-methanol solution:

9. PHYSICAL PROPERTIES OF ALCOHOLS (continued) Larger alkanes have greater hydrophobic regions and are less soluble or insoluble in water. Water interacts only with the –OH group of 1-heptanol:

10. PHYSICAL PROPERTIES OF ALCOHOLS (continued)

11. The –OH group can hydrogen bond between alcohol molecules leading to relatively high boiling points. Hydrogen bonding in pure ethanol:

12. PHYSICAL PROPERTIES OF ALCOHOLS (continued)

13. ALCOHOL REACTIONS The removal of water (dehydration) from an alcohol at 180°C is an elimination reaction that produces an alkene.

14. ALCOHOL DEHYDRATION TO ALKENE EXAMPLES

15. DEHYDRATION OF AN ALCOHOL Protonation of alcohol Formation of carbocation and water Formation of double bond and regeneration of catalyst

16. ALCOHOL REACTIONS (continued) Under slightly different conditions (140°C), a dehydration reaction can occur between two alcohol molecules to produce an ether.

17. ALCOHOL DEHYDRATION TO ETHER EXAMPLE

18. ALCOHOL REACTIONS (continued) Oxidation – the removal of hydrogen atoms Alcohol oxidations with an oxidizing (O) agent, such as K 2 Cr 2 O 7 and KMnO 4 : Primary alcohols → aldehyde → carboxylic acid Secondary alcohols → ketone Tertiary alcohols → no reaction

19. ALCOHOL REACTIONS (continued) Primary alcohol oxidation Secondary alcohol oxidation

20. ALCOHOL REACTIONS (continued) Tertiary alcohol oxidation

21. ALCOHOL OXIDATION EXAMPLES (1) The tube on the left contains orange K 2 Cr 2 O 7 and is next to the colorless ethanol. (2) After mixing, the ethanol is oxidized, and chromium is reduced, forming a grayish green precipitate.

22. ALCOHOL REACTIONS (continued)

23. MULTISTEP REACTIONS