Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Alcohols and Phenols Lecture 4 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. Alcohols, Phenols, and Thiols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 1 Classification of Alcohols Learning Check 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°). Primary (1º) 1 group H | CH3—C—OH | H Secondary (2º) Tertiary (3º) 2 groups 3 groups CH3 CH3 | | CH3—C—OH CH3—C—OH | | H CH3 2 Classify each alcohol as (P) primary, (S) secondary, or (T) tertiary. OH | 1. CH3—CH—CH2—CH3 2. CH3—CH2—CH2—OH OH | 3. CH3—CH2—C—CH2—CH3 | CH3 3 4 1 Naming Alcohols More Names of 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 CH4 methane CH3─OH methanol CH3─CH3 ethane CH3─CH2─OH ethanol In IUPAC names for longer carbon chains, the chain is numbered from the end nearest the ─OH group. CH3─CH2─CH2─OH 1-propanol OH │ CH3─CH─CH2─CH3 2-butanol CH3 OH │ │ CH3─CH─CH2─CH2─CH─CH3 methyl alcohol 6 5 4 3 2 5-methyl-2-hexanol 1 ethyl alcohol 5 Some Typical Alcohols “rubbing alcohol” 6 Learning Check OH | CH3—CH—CH3 Give the IUPAC name for each of the following: 1. CH3—CH2—CH2—CH2—OH 2-propanol (isopropyl alcohol) antifreeze HO—CH2—CH2—OH 2. 1,2-ethanediol (ethylene glycol) glycerol OH | HO—CH2—CH—CH2—OH 1,2,3-propanetriol OH CH3 | | CH3—CH—CH—CH2—CH3 OH 3. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 7 8 2 Learning Check 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 lowest numbers. Use prefixes o, m, and p for common names. Write the structure of the following: A. 3-pentanol B. ethyl alcohol C. 3-methylcyclohexanol OH OH OH Cl Br Phenol 9 3-chlorophenol (m-chlorophenol) 4-bromophenol (p-bromophenol) 10 Phenols in Medicine Derivatives of Phenol Phenol Is the IUPAC name for benzene with a hydroxyl group. Is used in antiseptics and disinfectants. Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint. OH OH OH OH OH CH2CH2CH2CH2CH2CH3 phenol resorcinol 4-hexylresorcinol 11 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 12 3 Learning Check Thiols Write the structure of each of the following: Thiols Are carbon compounds that contain a –SH group. A. 3-pentanol B. ethyl alcohol C. p-methylphenol Are named in the IUPAC system by adding -thiol to the alkane name of the longest carbon chain. 13 Naming Thiols Thiols In thiols with long carbon chains, the chain is numbered to locate the –SH group. CH3—CH2—CH2—SH SH | CH3—CH—CH3 14 1-propanethiol 2-propanethiol Thiols Often have strong odors. Are used to detect gas leaks. Are found in onions, oysters, and garlic. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 15 16 4 Learning Check Learning Check Draw the structure of each compound. A. 2-butanethiol Name each of the following compounds: OH | A. CH3—CH2 —CH—CH3 B. 2-methyl-1-butanol CH3 | B. CH3—CH2—CH—CH2—CH2—OH C. CH3—CH2—CH2—SH 17 18 Pause: Group Activity Ethers Do the following problems on ALE 4 Problem # 1, parts A to F Problem # 2, parts A to D Ethers Contain an ─O─ between two carbon groups. That are simple are named by listing the alkyl names in alphabetical order followed by ether CH3─O─CH3 CH3─CH2─O─CH3 dimethyl ether 19 ethyl methyl ether 20 5 Ethers as Anesthetics 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 21 MTBE Anesthetics Inhibit pain signals to the brain. Such as ethyl ether CH3─CH2─O─CH2─CH3 were used for over a century, but caused nausea and were flammable. Developed by 1960s were nonflammable. Cl F F Cl F H │ │ │ │ │ │ H─C─C─O─C─H H─C─C─O─C─H │ │ │ │ │ │ F F F H F H Ethane(enflurane) Penthrane 22 Learning Check Methyl tert-butyl ether CH3 │ CH3─O─C─CH3 │ CH3 Draw the structure of each compound. A. diethyl ether B. ethyl methyl ether Is one of the most produced organic chemicals. C. 2-methoxybutane Is a fuel additive Is used to improve gasoline combustion. Use is questioned since the discovery that MTBE has contaminated water supplies. 23 24 6 Cyclic Ethers Dioxins 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. Dioxins are A group of ethers that are highly toxic. Formed during forest fires and as industrial byproducts. Often carcinogenic. O O furan O tetrahydrofuran O pyran O Cl O Cl Cl O 1,4-dioxane 25 CH2 C OH 2,4,5-trichlorophenoxyacetic acid (2,4,5-T; agent orange) Cl O Cl Cl O Cl 2,3,7,8-tetrachlorodibenzodioxin (TTCC, “dioxin”) Learning Check Pause: Group Activity Name each of the following: Do the following problems on ALE 4 Problem # 1, parts G to I Problem # 2, parts E to F O 1. 2. CH3 26 O O 27 28 7 Lecture 4 Boiling Points of Alcohols Alcohols Contain a strongly electronegative O in the OH groups. Form hydrogen bonds between alcohol molecules. Have higher boiling points than alkanes and ethers of similar mass. 13.3 Physical Properties of Alcohols, Phenols, and Ethers Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 29 30 Solubility of Alcohols and Ethers in Water Boiling Points of Ethers Ethers Have an O atom, but no H is attached. Cannot form hydrogen bonds between ether molecules. 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. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 31 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 32 8 Comparing Solubility and Boiling Points Compound Alkane CH3─CH2─CH3 Molar Boiling Mass Point (°C) 44 -42 Soluble in Water? No Ether CH3─O─CH3 46 -23 Yes 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. OH Alcohol CH3─CH2─OH O- + H2O + H3O+ 33 34 Learning Check Learning Check Which compound would have the higher boiling point? Explain. Which compound would be more soluble in water? Explain. ethyl methyl ether or 1-propanol ethanol or 2-pentanol 35 36 9 Pause: Group Activity Lecture 4 Do the following problems on ALE 4 Problem # 3 Problem # 4 13.4 Reactions of Alcohols and Thiols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 37 38 Combustion of Alcohols Dehydration of Alcohols Combustion is the reaction of an alcohol with O2 to produce CO2 and H2O. 2CO2 + 4H2O + Heat 2CH3OH + 3O2 Dehydration of an alcohol occurs When heated with an acid catalyst. With the loss of —H and —OH from adjacent carbon atoms. H OH | | H+, heat H—C—C—H H—C=C—H + H2O | | | | H H H H alcohol alkene Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 39 40 10 Learning Check Formation of Ethers Write the equations for the reactions when 2-propanol undergoes: 1. combustion Ethers form when dehydration takes place at low temperature. H+ CH3—OH + HO—CH3 CH3—O—CH3 + H2O two methanol dimethyl ether 2. dehydration 41 Oxidation and Reduction 42 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 an decrease in the number of C—O bonds. There is a gain of H. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 43 44 11 Oxidation of Primary (1°) Alcohols Oxidation of Secondary (2°) Alcohols When a primary alcohol is oxidized [O], One H is removed from the –OH. Another H is removed from the carbon bonded to the OH. An aldehyde is produced. [O] Primary alcohol Aldehyde OH O | [O] || CH3—C—H CH3—C—H + H2O | H Ethanol (ethyl alcohol) Ethanal (acetaldehyde) When a secondary alcohol is oxidized [O], One H is removed from the –OH. Another H is removed from the carbon bonded to the OH. A ketone is produced. [O] secondary alcohol ketone OH O │ [O] ║ CH3—C—CH3 CH3—C—CH3 + H2O │ H 2-propanol (isopropyl alcohol) 45 Oxidation of Tertiary (3)°Alcohols Tertiary alcohols do not readily oxidize. [O] Tertiary alcohol no reaction OH │ [O] no product CH3─C─CH3 │ no H on the C-OH to oxidize CH3 2-propanone(dimethyl ketone, “acetone”) 46 Learning Check Select the compound that would result for each reaction of CH3—CH2—CH2—OH. 1) CH3—CH=CH2 A. H+, heat B. 2-methyl-2-propanol 47 2) CO2 + H2O O || 3) CH3—CH2—C—H [O] C. O2, heat 48 12 Oxidation of Ethanol in the Body Ethanol CH3─CH2─OH In the body, Ethanol is oxidized by enzymes in the liver. Aldehyde product impairs coordination. O O ║ ║ CH3─CH2─OH CH3─C─H CH3─C─OH ethyl alcohol acetaldehyde acetic acid 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. 2CO2 + H2O Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 49 Effect of Alcohol on the Body 50 Learning Check Select the product for the oxidation of OH │ [O] CH3—CH—CH2—CH3 TABLE 13.2 1) CH3—CH=CH—CH3 3) CO2 + H2O Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 51 O ║ 2) CH3—C—CH2 —CH3 OH │ 4) CH3—CH—CH2—CH3 52 13 Oxidation of Thiols Pause: Group Activity When thiols undergo oxidation, An H atom is lost from each of two –SH groups. The product is a disulfide. [O] CH3—SH + HS—CH3 CH3—S—S—CH3 + H2O Do the following problems on ALE 4 Problem # 5 53 54 14