Alcohols, Phenols, and Thiols General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 13 Alcohols, Phenols, Thiols, and Ethers 13.1 Alcohols, Phenols, and Thiols Lectures © 2013 Pearson Education, Inc.

Alcohols, Phenols, and Thiols An alcohol contains a hydroxyl group (–OH) attached to a carbon chain. A phenol contains a hydroxyl group (–OH) attached to a benzene ring. A thiol contains a thiol group (–SH) attached to a carbon chain. 2

Guide to Naming Alcohols 3

Naming Alcohols The names of alcohols in the IUPAC system, replace -e of the alkane name with -ol. that are common names, use the name of the alkyl group followed by alcohol. Formula IUPAC Common Name CH4 Methane CH3─OH Methanol Methyl alcohol CH3─CH3 Ethane CH3─CH2─OH Ethanol Ethyl alcohol 4

Naming Alcohols In IUPAC names for longer carbon chains, the chain is numbered from the end nearer the –OH group. 5

Naming Alcohols We can also draw skeletal structures for alcohols. CH3─CH2─CH2─OH CH3─CH─CH2─CH3 OH 1-Propanol 2-Butanol 6

Phenols in Medicine Phenol is the IUPAC name for benzene with a hydroxyl group. is used in antiseptics and disinfectants. Phenol Resorcinol 4-Hexylresoricinol 7

Naming Phenols To name a phenol with two substituents, assign C-1 to the carbon attached to the –OH. number the ring to give the substituents the lowest numbers. use prefixes o, m, and p for common names. Phenol 3-chlorophenol 3-methylphenol (m-chlorophenol) (m-cresol) 8

Thiols Thiols are organic compounds that contain a –SH group. are named in the IUPAC system by adding thiol to the alkane name of the longest carbon chain. 9

Naming Thiols In thiols with long carbon chains, the chain is numbered to give the −SH group the lowest possible number. 10

Ethers Ethers consist of an oxygen atom that is connected by single bonds to two carbon groups (alkyl or aromatic). Simple ethers are named by listing the alkyl names in alphabetical order followed by ether CH3─O─CH3 CH3─CH2─O─CH3 methyl methyl ethyl methyl 11

Cyclic Ethers A cyclic ether contains an O atom in a carbon ring. is called a heterocyclic compound. typically has 5 (furan) or 6 atoms (pyran) in the ring. Furan Tetrahydrofuran Pyran 1,4-Dioxane 12

Dioxins Dioxins are a six-atom ring with two oxygen atoms and two double bonds. a group of ethers that are highly toxic and often carcinogenic. formed during forest fires and as industrial by-products. 13

IUPAC Names for Ethers In the IUPAC system, the shorter alkyl group and the oxygen are named as an alkoxy group attached to the longer alkane. Methoxy propane CH3—O—CH2—CH2—CH3 1 2 3 Numbering the longer alkane gives 1-Methoxypropane. 14

Guide to Naming Ethers 15

Classifying Alcohols 16

Boiling Points of Alcohols form hydrogen bonds between alcohol molecules. have higher boiling points than alkanes and ethers of similar mass. 17

Boiling Points of Ethers have an O atom, but no H is attached. cannot form hydrogen bonds between ether molecules. have boiling points similar to alkanes of similar mass. 18

Solubility of Alcohols and Ethers in Water Alcohols and ethers are more soluble in water than are alkanes because the oxygen atom can form hydrogen bonds with water. Alcohol Solubility in H2O 1–3 carbon atoms completely soluble 4 carbon atoms slightly soluble 5 or more carbon atoms insoluble Ethers containing up to 4 carbon atoms are slightly soluble in water. 19

Solubility of Alcohols and Ethers in Water 20

Comparing Solubility and Boiling Points 21

Combustion of Alcohols Combustion is the reaction of an alcohol with O2 to produce CO2, H2O and energy. 22

Dehydration of Alcohols Dehydration of an alcohol occurs when heated with an acid catalyst, H+ with the loss of –H and –OH from adjacent carbon atoms to form water alcohol alkene 23

Saytzeff’s Rule According to Saytzeff’s rule, the dehydration of a secondary alcohol favors the product in which hydrogen is removed from the carbon atom in the chain with the smaller number of H atoms 24

Oxidation and Reduction In the oxidation of an organic compound, there is an increase in the number of C–O bonds. there is a loss of H. In the reduction of an organic compound, there is a decrease in the number of C–O bonds. there is a gain of H. 25

Oxidation and Reduction An alcohol is more oxidized than an alkane; an aldehyde or ketone is more oxidized than an alcohol; a carboxylic acid is more oxidized than an aldehyde. 26

Oxidation of Primary (1) Alcohols Primary alcohols are oxidized to form aldheydes. Ethanol (ethyl alcohol) Ethanal (acetaldehyde) 27

Oxidation of Secondary (2) Alcohols Secondary alcohols are oxidized to form ketones. 2-Propanol (isopropyl alcohol) 2-Propanone(dimethyl ketone, “acetone”) 28

Oxidation of Tertiary (3) Alcohols Tertiary alcohols do not readily oxidize. There is no H on the C–OH to oxidize. 2-Methyl-2-propanol 29