Lecture 4 Alcohols, Phenols, and Thiols Alcohols, Phenols, and Thiols Alcohols and Phenols An alcohol contains A hydroxyl group ( ) attached to a carbon chain. A phenol contains A hydroxyl group ( ) attached to a benzene ring. 1 2 assification of Alcohols Alcohols are classified By the number of alkyl groups attached to the carbon bonded to the hydroxyl. As primary (1 ), secondary (2 ), or tertiary (3 ). assify each alcohol as (P) primary, (S) secondary, or (T) tertiary. 1. CH 3 CH CH 2 CH 3 Primary (1º) Secondary (2º) Tertiary (3º) 1 group 2 groups 3 groups H CH 3 CH 3 CH 3 C CH 3 C CH 3 C H H CH 3 3 2. CH 3 CH 2 CH 2 3. CH 3 CH 2 C CH 2 CH 3 CH 3 4 1
Naming Alcohols The names of alcohols In the IUPAC system replace -e of alkane name with - ol. that are common names use the name of the alkyl group followed by alcohol. Formula IUPAC Common Name CH 4 methane CH 3 methanol methyl alcohol CH 3 CH 3 ethane CH 3 CH 2 ethanol ethyl alcohol 5 More Names of Alcohols In IUPAC names for longer carbon chains, the chain is numbered from the end nearest the group. CH 3 CH 2 CH 2 CH 3 CH CH 2 CH 3 CH 3 CH 3 CH CH 2 CH 2 CH CH 3 6 5 4 3 2 1 1-propanol 2-butanol 5-methyl-2-hexanol 6 Some Typical Alcohols rubbing alcohol CH 3 CH CH 3 2-propanol (isopropyl alcohol) antifreeze glycerol H CH 2 CH 2 1,2-ethanediol (ethylene glycol) H CH 2 CH CH 2 1,2,3-propanetriol Give the IUPAC name for each of the following: 1. CH 3 CH 2 CH 2 CH 2 CH 3 2. CH 3 CH CH CH 2 CH 3 3. 7 8 2
Write the structure of the following: A. 3-pentanol B. ethyl alcohol Naming Phenols To name a phenol with two substituents, Assign C-1 to the carbon attached to the. Number the ring to give the lowest numbers. Use prefixes o, m, and p for common names. C. 3-methylcyclohexanol Br 9 Phenol 3-chlorophenol 4-bromophenol (m-chlorophenol) (p-bromophenol) 10 Phenols in Medicine Phenol Is the IUPAC name for benzene with a hydroxyl group. Is used in antiseptics and disinfectants. Derivatives of Phenol Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint. CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 phenol resorcinol 4-hexylresorcinol 11 12 3
Write the structure of each of the following: A. 3-pentanol B. ethyl alcohol C. p-methylphenol Thiols Thiols Are carbon compounds that contain a SH group. Are named in the IUPAC system by adding -thiol to the alkane name of the longest carbon chain. 13 14 Naming Thiols In thiols with long carbon chains, the chain is numbered to locate the SH group. CH 3 CH 2 CH 2 SH SH CH 3 CH CH 3 1-propanethiol 2-propanethiol Thiols Thiols ften have strong odors. Are used to detect gas leaks. Are found in onions, oysters, and garlic. 15 16 4
Draw the structure of each compound. A. 2-butanethiol B. 2-methyl-1-butanol Name each of the following compounds: A. CH 3 CH 2 CH CH 3 CH 3 B. CH 3 CH 2 CH CH 2 CH 2 C. CH 3 CH 2 CH 2 SH 17 18 Pause: Group Activity Do the following problems on ALE 4 Problem # 1, parts A to F Problem # 2, parts A to D Ethers Ethers Contain an between two carbon groups. That are simple are named by listing the alkyl names in alphabetical order followed by ether CH 3 CH 3 CH 3 CH 2 CH 3 dimethyl ether ethyl methyl ether 19 20 5
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 CH 3 CH 2 CH 2 CH 3 1 2 3 Numbering the longer alkane gives 1-methoxypropane 21 Ethers as Anesthetics Anesthetics Inhibit pain signals to the brain. Such as ethyl ether CH 3 CH 2 CH 2 CH 3 were used for over a century, but caused nausea and were flammable. Developed by 1960s were nonflammable. F F F H H C C C H H C C C H F F F H F H Ethane(enflurane) Penthrane 22 MTBE Methyl tert-butyl ether CH 3 CH 3 C CH 3 CH 3 Is one of the most produced organic chemicals. Is a fuel additive Is used to improve gasoline combustion. Use is questioned since the discovery that MTBE has contaminated water supplies. Draw the structure of each compound. A. diethyl ether B. ethyl methyl ether C. 2-methoxybutane 23 24 6
Cyclic Ethers Dioxins A cyclic ether Contains an atom in a carbon ring. Is called a heterocyclic compound. Typically has 5 (furan) or 6 atoms (pyran) in the ring. Dioxins are A group of ethers that are highly toxic. Formed during forest fires and as industrial byproducts. ften carcinogenic. furan tetrahydrofuran pyran 1,4-dioxane CH2 C 25 2,4,5-trichlorophenoxyacetic acid (2,4,5-T; agent orange) 2,3,7,8-tetrachlorodibenzodioxin (TTCC, dioxin ) 26 Pause: Group Activity Name each of the following: 1. CH3 Do the following problems on ALE 4 Problem # 1, parts G to I Problem # 2, parts E to F 2. 27 28 7
Lecture 4 13.3 Physical Properties of Alcohols, Phenols, and Ethers Boiling Points of Alcohols Alcohols Contain a strongly electronegative in the groups. Form hydrogen bonds between alcohol molecules. Have higher boiling points than alkanes and ethers of similar mass. 29 30 Boiling Points of Ethers Ethers Have an atom, but no H is attached. Cannot form hydrogen bonds between ether molecules. Solubility of Alcohols and Ethers in Water Alcohols and ethers are more soluble in water than alkanes because the oxygen atom hydrogen bonds with water. Alcohols with 1-4 C atoms are soluble, but alcohols with 5 or more C atoms are not. 31 32 8
Comparing Solubility and Boiling Points Compound Molar Boiling Soluble Mass Point ( C) in Water? Alkane CH 3 CH 2 CH 3 44-42 No Ether CH 3 CH 3 46-23 Yes Alcohol CH 3 CH 2 46 78 Yes Solubility of Phenol Phenol Is soluble in water. Has a hydroxyl group that ionizes slightly (weak acid). Is corrosive and irritating to the skin. - + H 2 + H 3 + 33 34 Which compound would have the higher boiling point? Explain. ethyl methyl ether or 1-propanol Which compound would be more soluble in water? Explain. ethanol or 2-pentanol 35 36 9
Pause: Group Activity Do the following problems on ALE 4 Problem # 3 Problem # 4 Lecture 4 13.4 Reactions of Alcohols and Thiols 37 38 Combustion of Alcohols Combustion is the reaction of an alcohol with 2 to produce C 2 and H 2. 2CH 3 + 3 2 2C 2 + 4H 2 + Heat Dehydration of Alcohols Dehydration of an alcohol occurs When heated with an acid catalyst. With the loss of H and from adjacent carbon atoms. H H +, heat H C C H H H H H H C=C H + H 2 39 alcohol alkene 40 10
Write the equations for the reactions when 2-propanol undergoes: 1. combustion 2. dehydration Formation of Ethers Ethers form when dehydration takes place at low temperature. H + CH 3 + H CH 3 CH 3 CH 3 + H 2 two methanol dimethyl ether 41 42 xidation and Reduction xidation and Reduction In the oxidation of an organic compound There is an increase in the number of C bonds. There is a loss of H. In the reduction of an organic compound There is an decrease in the number of C bonds. There is a gain of H. 43 44 11
xidation of Primary (1 ) Alcohols When a primary alcohol is oxidized [], ne H is removed from the. Another H is removed from the carbon bonded to the. An aldehyde is produced. [] Primary alcohol Aldehyde [] CH 3 C H CH 3 C H + H 2 H Ethanol Ethanal (ethyl alcohol) (acetaldehyde) 45 xidation of Secondary (2 ) Alcohols When a secondary alcohol is oxidized [], ne H is removed from the. Another H is removed from the carbon bonded to the. A ketone is produced. [] secondary alcohol ketone [] CH 3 C CH 3 CH 3 C CH 3 + H 2 H 2-propanol (isopropyl alcohol) 2-propanone(dimethyl ketone, acetone ) 46 xidation of Tertiary (3) Alcohols Tertiary alcohols do not readily oxidize. [] Tertiary alcohol no reaction [] CH 3 C CH 3 no product CH 3 no H on the C- to oxidize 2-methyl-2-propanol Select the compound that would result for each reaction of CH 3 CH 2 CH 2. 1) CH 3 CH=CH 2 2) C 2 + H 2 3) CH 3 CH 2 C H A. H +, heat B. [] 47 C. 2, heat 48 12
xidation of Ethanol in the Body Ethanol CH 3 CH 2 In the body, Ethanol is oxidized by enzymes in the liver. Aldehyde product impairs coordination. CH 3 CH 2 CH 3 C H CH 3 C ethyl alcohol acetaldehyde acetic acid 2C 2 + H 2 Ethanol Acts as a depressant. Kills or disables more people than any other drug. Is metabolized at a rate of 12-15 mg/dl per hour by a social drinker. Is metabolized at a rate of 30 mg/dl per hour by an alcoholic. 49 50 Effect of Alcohol on the Body TABLE 13.2 Select the product for the oxidation of [] CH 3 CH CH 2 CH 3 51 52 1) CH 3 CH=CH CH 3 2) CH 3 C CH 2 CH 3 3) C 2 + H 2 4) CH 3 CH CH 2 CH 3 13
xidation of Thiols When thiols undergo oxidation, An H atom is lost from each of two SH groups. The product is a disulfide. [] CH 3 SH + HS CH 3 CH 3 S S CH 3 + H 2 Pause: Group Activity Do the following problems on ALE 4 Problem # 5 53 54 14