Chapter 12 Organic Compounds with Oxygen and Sulfur 1
Alcohols An alcohol contains a hydroxyl group ( OH) that replaces a hydrogen atom in a hydrocarbon. A phenol contains a hydroxyl group ( OH) attached to a benzene ring. 2
Naming Alcohols The names of alcohols in the IUPAC system replace the -e with -ol with common names use the name of the alkyl group followed by alcohol Formula IUPAC Common Name CH 4 methane CH 3 OH methanol methyl alcohol CH 3 CH 3 ethane CH 3 CH 2 OH ethanol ethyl alcohol
4 Naming Alcohols
Naming of Alcohols Step 1 Name the longest carbon chain with the OH group. Name an aromatic alcohol as a phenol. CH 3 CH 2 CH 2 OH propanol OH CH 3 CH CH 2 CH 3 butanol CH 3 OH CH 3 CH CH 2 CH 2 CH CH 3 6 5 4 3 2 1 hexanol 5
Naming of Alcohols Step 2 Number the chain starting at the end closer to the OH. CH 3 CH 2 CH 2 OH 1-propanol OH CH 3 CH CH 2 CH 3 2-butanol CH 3 OH CH 3 CH CH 2 CH 2 CH CH 3 6 5 4 3 2 1 2-hexanol 6
Naming of Alcohols Step 3 Give the location and name of each substituent relative to the OH group. CH 3 CH 2 CH 2 OH 1-propanol OH CH 3 CH CH 2 CH 3 2-butanol CH 3 OH CH 3 CH CH 2 CH 2 CH CH 3 6 5 4 3 2 1 5-methyl-2-hexanol 7
Some Typical Alcohols OH Rubbing alcohol CH 3 CH CH 3 2-propanol (isopropyl alcohol) Antifreeze HO CH 2 CH 2 OH 1,2-ethanediol (ethylene glycol) OH Glycerol HO CH 2 CH CH 2 OH 1,2,3-propanetriol 8
Learning Check Name the following compounds: 1. CH 3 CH 2 CH 2 CH 2 OH OH CH 3 2. CH 3 CH CH CH 2 CH 3 3. OH 9
Solution Step 1 Name the longest carbon chain with the OH group. Name an aromatic alcohol as a phenol. 1. CH 3 CH 2 CH 2 CH 2 OH butanol OH CH 3 2. CH 3 CH CH CH 2 CH 3 pentanol OH 3. cyclopentanol 10
Solution Step 2 Number the chain starting at the end closer to the OH. 1. CH 3 CH 2 CH 2 CH 2 OH 1-butanol OH CH 3 2. CH 3 CH CH CH 2 CH 3 2-pentanol OH 3. cyclopentanol 11
Solution Step 3 Give the location and name of each substituent relative to the OH group. 1. CH 3 CH 2 CH 2 CH 2 OH 1-butanol OH CH 3 2. CH 3 CH CH CH 2 CH 3 3-methyl-2-pentanol OH 3. cyclopentanol 12
Phenols in Medicine Phenol is the IUPAC name for benzene with a hydroxyl group used in antiseptics and disinfectants OH OH OH OH OH CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Phenol Resorcinol 4-Hexylresorcinol 13
Derivatives of Phenol Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint. 14
Naming Phenols Step 1 Name the longest carbon chain with the OH group. Name an aromatic alcohol as a phenol. OH OH Cl Br phenol phenol 15
Naming Phenols Step 2 Number the chain starting at the end closer to the OH. OH 1 OH 1 3 Cl Br 4 phenol phenol 16
Naming Phenols Step 3 Give the location and name of each substituent relative to the OH group. OH 1 OH 1 3 Cl Br 4 3-chlorophenol 4-bromophenol 17
Thiols Thiols contain sulfur are similar to alcohols contain a thiol ( SH) group often have strong odors are found in cheese, onions, garlic, and oysters are used to detect gas leaks 18
Thiols Thiols are named in the IUPAC system by adding thiol to the alkane name of the longest carbon chain. 19
Ethers An ether contains an O between two carbon groups has a common name that gives the alkyl names of the attached groups, followed by ether CH 3 O CH 3 CH 3 CH 2 O CH 3 20
Learning Check Write the structure of the following: A. 3-pentanol B. ethanethiol C. diethyl ether 21
Solution OH A. 3-pentanol CH 3 CH 2 CH CH 2 CH 3 B. ethanethiol CH 3 CH 2 SH C. diethyl ether CH 3 CH 2 O CH 2 CH 3 22
Ethers as Anesthetics Anesthetics inhibit pain signals to the brain like diethyl ether, CH 3 CH 2 O CH 2 CH 3, were used for over a century, but caused nausea and were flammable developed by the 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 Ethrane (enflurane) Penthrane 23
Classification of Alcohols Classification of alcohols is determined by the number of alkyl groups attached to the carbon bonded to the hydroxyl primary (1 ), secondary (2 ), or tertiary (3 ) Primary (1 ) Secondary (2 ) Tertiary (3 ) 1 group 2 groups 3 groups H CH 3 CH 3 CH 3 C OH CH 3 C OH CH 3 C OH H H CH 3 24
Solubility of Alcohols in Water Alcohols contain polar OH groups and form hydrogen bonds with other alcohol molecules that have one to three carbons are soluble in water solubility in water decreases with increasing number of carbons 25
Solubility of Ethers in Water Ethers do not have a polar OH group, but have a C O C group do not form hydrogen bonds with less than four carbons are slightly soluble in water with more than four carbons are not soluble in water 26
Solubility of Phenols Phenols are slightly soluble in water have an OH group that can form hydrogen bonds with water can react with water to produce phenoxide ions were once used as antiseptics OH O - + H 2 O + H 3 O + 27
Learning Check Indicate whether each of the following is soluble in water and explain why. A. CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 OH B. CH 3 O CH 2 CH 3 C. CH 3 CH 2 OH 28
Solution Indicate whether each of the following is soluble in water and explain why. A. CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 OH Not soluble Alcohols with long carbon chains (nonpolar) are not soluble. B. CH 3 O CH 2 CH 3 Slightly soluble Ethers with less than four carbons are only slightly soluble in water. C. CH 3 CH 2 OH Soluble Short-chain alcohols form hydrogen bonds with water. 29
Dehydration of Alcohols Alcohols undergo dehydration when heated with an acid catalyst the loss of H and OH from adjacent carbon atoms, producing an alkene H OH H +, heat H C C H H H H H alcohol H C=C H + H 2 O alkene 30
Oxidation of 1 Alcohols Alcohols undergo oxidation, increasing the number of carbon and oxygen bonds. Primary alcohols are oxidized to produce an aldehyde. 1 bond to O 2 bonds to O H OH oxidation H O H C C H H C C H H H H 1 alcohol aldehyde 31
Oxidation of 1 Alcohols Alcohols undergo oxidation, increasing the number of carbon and oxygen bonds. Aldehydes can further oxidize to produce a carboxylic acid. 1 bond to O 2 bonds to O H O H O oxidation H C C H H C C OH H H aldehyde carboxylic acid 32
Oxidation of 2 Alcohols Secondary alcohols are oxidized to produce a ketone. To indicate the process of oxidation, [O] is placed over the reaction arrow. 1 bond to O 2 bonds to O H OH H H O H [O] H C C C H H C C C H H H H H H 2 alcohol ketone 33
Oxidation of Tertiary 3 Alcohols Tertiary (3 ) alcohols do not readily oxidize. OH CH 3 C CH 3 [O] no product CH 3 3 alcohol no H to oxidize no reaction 34
Oxidation and Reduction In an oxidation, there is an increase in the number of C O bonds there is a loss of H In a reduction, there is a decrease in the number of C O bonds there is a gain of H 35
Methanol Poisoning Methanol is also known as methyl alcohol is highly toxic and found in windshield washer fluid, Sterno, and paint strippers is rapidly absorbed and oxidized to formaldehyde and then formic acid O O [O] [O] CH 3 OH H CH H COH methyl alcohol formaldehyde formic acid 36
Ethanol, CH 3 CH 2 OH Ethanol acts as a depressant and 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 37
38 Effect of Alcohol on the Body
Oxidation of Thiols When thiols undergo oxidation, an H atom is lost from each of two SH groups the product is a disulfide protein in hair is cross-linked by disulfide bonds found in the amino acid cysteine 39
Learning Check Give the primary product for the reaction of 2-propanol when it undergoes A. oxidation B. dehydration 40
Solution OH CH 3 CH CH 3 = 2-propanol = C 3 H 8 O A. oxidation OH 2CH 3 CH CH 3 + 9O 2 [O] O CH 3 C CH 3 + 6CO 2 + 8H 2 O B. dehydration OH CH 3 CH CH 3 H +, heat CH 3 CH=CH 2 + H 2 O 41
Carbonyl Group in Aldehydes and Ketones A carbonyl group consists of a carbon-oxygen polar double bond has a very electronegative oxygen atom has two lone pair electrons on the O atom has partial positive charge on C and partial negative charge on O O C 42
Carbonyl Group in Aldehydes and Ketones A carbonyl group in an aldehyde is attached to at least one H atom in a ketone is attached to two carbon groups 43
Naming Aldehydes An aldehyde has an IUPAC name in which the -e in the alkane name is changed to -al has a common name for the first four aldehydes that use the following prefixes: 1 carbon, form 2 carbons, acet 3 carbons, propion 4 carbons butyr followed by aldehyde 44
45 Naming Aldehydes
46 Naming Aldehydes
Naming Aldehydes Give the IUPAC name for the following aldehydes: O CH 3 CH 2 CH 2 CH C H CH 3 Cl Cl O C H 47
Naming Aldehydes Step 1 Name the longest carbon chain containing the carbonyl group by replacing the e in the alkane name with al. O CH 3 CH 2 CH 2 CH C H CH 3 pentanal Cl Cl O C benzaldehyde H 48
Naming Aldehydes Step 2 Name and number substituents by counting the carbonyl group as carbon 1. O CH 3 CH 2 CH 2 CH C H CH 3 2-methylpentanal Cl Cl O C H 3,4-dichlorobenzaldehyde 49
Aldehydes in Flavorings Several naturally occurring aldehydes are used as flavorings for foods and fragrances. O C H O C H benzaldehyde (almonds) HO OCH 3 O vanillin HC C H C H cinnamaldehyde cinnamon 50
Naming Ketones When naming the following ketones in the IUPAC system, the -e in the alkane name is replaced with -one with a common name, the alkyl groups attached to the carbonyl group are named alphabetically, followed by ketone O O CH 3 C CH 3 CH 3 C CH 2 CH 3 propanone (dimethyl ketone) 2-butanone (ethyl methyl ketone) 51
52 Naming Ketones
Naming Ketones Name the following ketones using the IUPAC system. O O CH 3 CH 2 CH CH 2 C CH 3 CH 3 CH 3 CH 3 53
Naming Ketones Step 1 Name the longest carbon chain that contains the carbonyl group by replacing the e in the alkane name with one. O CH 3 CH 2 CH CH 2 C CH 3 CH 3 hexanone O CH 3 pentanone CH 3 54
Naming Ketones Step 2 Number the carbon chain starting from the end nearer the carbonyl group and indicate its location. O CH 3 CH 2 CH CH 2 C CH 3 CH 3 2-hexanone O CH 3 CH 3 pentanone 55
Naming Ketones Step 3 Name and number any substituents on the carbon chain. O CH 3 CH 2 CH CH 2 C CH 3 CH 3 4-methyl-2-hexanone O CH 3 CH 3 2,3-dimethylcylcopentanone 56
Ketones in Common Use Acetone (propanone) is a solvent used in nail polish remover. 57 Butanedione is the butter flavoring used in margarine.
Physical Properties The polar carbonyl group provides dipole-dipole interactions. + - + - C=O C=O Because the electronegative oxygen atom forms hydrogen bonds with water molecules, aldehydes and ketones with one to four carbons are very soluble. 58
59 Solubility of Aldehydes and Ketones in Water
Solubility in Water The electronegative O atom of the carbonyl group of aldehydes and ketones forms hydrogen bonds with water. 60
Oxidation of Aldehydes Primary alcohols can be oxidized to aldehydes, which can be easily oxidized to carboxylic acids. Secondary alcohols can be oxidized to ketones, which cannot be further oxidized. 61
Tollens Test In Tollens test, Tollens reagent, which contains Ag +, oxidizes aldehydes but not ketones. Ag + is reduced to metallic Ag, which appears as a mirror in the test tube. 62
63 Tollens Test
Benedict s Test In Benedict s test, Benedict s reagent, which contains Cu 2+, reacts with aldehydes that have an adjacent OH group. Monosaccharide sugars typically have this aldehyde adjacent hydroxide arrangement. 64
Benedict s Test In Benedict s test, an aldehyde is oxidized to a carboxylic acid, while Cu 2+ is reduced to give red Cu 2 O(s). The blue Cu 2+ in Benedict s solution forms a brick-red solid of Cu 2 O in a positive test for many sugars and aldehydes with adjacent hydroxyl groups. 65
Reduction of Aldehydes and Ketones Aldehydes and ketones can be reduced by sodium borohydride, NaBH 4, or H 2. The reduction of aldehydes and ketones decreases the number of carbon oxygen bonds by addition of hydrogen or loss of oxygen. 66
Isomers Molecules are structural isomers when they have the same molecular formula, but different bonding arrangements. 67
Stereoisomers Stereoisomers have identical molecular formulas, but they are not structural isomers. In stereoisomers, the atoms are bonded in the same sequence but differ in the way they are arranged in space. When stereoisomers have mirror images that are different, they are said to have handedness. 68
Chiral Molecules Have Handedness Chiral molecules have the same number of atoms arranged differently in space have one or more chiral carbon atoms, each of which is bonded to four different groups are like your hands Try to superimpose your thumbs, palms, back of hands, and little fingers. 69
70 Some Everyday Chiral and Achiral Objects
Chiral Carbon Atoms Are Mirror Images The mirror images of chiral compounds cannot be superimposed. When the H and I atoms are aligned, the Cl and Br atoms are on opposite sides. 71
Achiral Structures Are Superimposable When the mirror image of an achiral structure is rotated, the structure can be aligned with the initial structure. Thus this mirror image is superimposable. 72
Learning Check Identify each as a chiral or an achiral compound. H C l C C H 3 C H 2 C H 3 C l H C C H 3 H C l H C C H 3 B r A. B. C. 73
Solution Identify each as a chiral or an achiral compound. H C l C C H 3 C H 2 C H 3 C l H C C H 3 H C l H C C H 3 B r A. B. C. chiral achiral chiral 74
Fischer Projections A Fischer projection is a two-dimensional representation of a three-dimensional molecule places the most oxidized group at the top uses vertical lines in place of dashes for bonds that go back uses horizontal lines in place of wedges for bonds that come forward 75
76 Drawing Fischer Projections
D and L Notations By convention, the letter L is assigned to the structure with the OH on the left. The letter D is assigned to the structure with the OH on the right. 77
Learning Check Indicate whether each pair is a mirror image that cannot be superimposed (enantiomers). CH 2 OH CH 2 OH A. H C CH 3 and CH 3 C H Br Br Cl Cl B. H C CH 3 and CH 3 C H H H 78
Solution Indicate whether each pair is a mirror image that cannot be superimposed (enantiomers). A. CH 2 OH H C CH 3 and CH 3 CH 2 OH C H Yes Br Br Cl Cl No B. H C CH 3 and CH 3 C H H H 79
Concept Map Organic Molecules with O and S 80