12 Hydrocarbon Derivatives I Compounds with carbon-heteroatom single bonds Alkyl halides Alcohols Phenols Ethers Thiols Amines Copyright © Houghton Mifflin Company. All rights reserved. 3–1 12.2 Halogenated Hydrocarbons Halogenated hydrocarbons have halogen atoms (–F, –Cl, –Br, –I) on a hydrocarbon skeleton; R–X H H H H H C C C C Br H H H H 1-bromobutane Copyright © Houghton Mifflin Company. All rights reserved. 3–2 12.2 Naming Halogenated Hydrocarbons Halogens are treated as substituents, like alkyl substituents. The prefixes are fluoro–, chloro–, bromo–, iodo–. H Cl H C C Cl H Cl CH3 H3C C CH3 Br 1,1,1-trichloroethane 2-bromo-2-methylpropane Copyright © Houghton Mifflin Company. All rights reserved. 3–3 12.2 Properties of Halogenated Hydrocarbons Many halogenated hydrocarbons are liquids with densities greater than 1.00 g/mL. Halogenated hydrocarbons are not very polar, and are not soluble in water. They are good solvents for hydrocarbons, and are used to remove grease. Halogenated hydrocarbons are not flammable, and are used in fire extinguishers (halons). Copyright © Houghton Mifflin Company. All rights reserved. 3–4 Common Halogenated Hydrocarbons Some halogenated hydrocarbons are used as inhalation anesthetics. H Cl C Cl Cl F Cl F C C H F Br trichloromethane, a.k.a chloroform 2-bromo-2-chloro-1,1,1-trifluoroethane, a.k.a halothane Copyright © Houghton Mifflin Company. All rights reserved. 3–5 Common Halogenated Hydrocarbons Some halogenated hydrocarbons are used as refrigerants. The chlorofluorocarbons destroy atmospheric ozone. All are greenhouse gases. F Cl C F Cl F H F C C H F F dichlorodifluoromethane, a.k.a. R-12 1,1,1,2-tetrafluoroethane, a.k.a. R-134a Copyright © Houghton Mifflin Company. All rights reserved. 3–6 Common Halogenated Hydrocarbons Several halogenated hydrocarbons have been used as pesticides. Many have adverse environmental effects. Cl Cl H C Cl C Cl Copyright © Houghton Mifflin Company. All rights reserved. Cl 4,4'-(2,2,2-trichloroethane1,1-diyl)bis(chlorobenzene) a.k.a. DDT, dichlorodiphenyltrichloroethane 3–7 12.3 Alcohols Alcohols have a hydroxy(l) group (–OH) on an alkyl chain; R–OH H H H H C C O H H H H C C H H C C C O H H C C C H C H H Ethanol, Ethyl alcohol Copyright © Houghton Mifflin Company. All rights reserved. 3–8 12.3 Naming Alcohols 1. 2. 3. 4. 5. Suffix is “-ol” Find longest chain that bears –OH Number carbons on chain so carbon bearing –OH has lowest possible number Locate –OH by number of carbon Locate and name any other substituents Final “e” on name of hydrocarbon is dropped. Copyright © Houghton Mifflin Company. All rights reserved. 3–9 12.3 Naming Alcohols Name these: H H H H H C C C C OH H H H H CH3 H3C C CH3 OH Draw structures for: 2-methyl-1-propanol Copyright © Houghton Mifflin Company. All rights reserved. 2-butanol 3–10 12.3 Naming Alcohols Name this! O CH3 CH2 C H CH2 CH2 CH3 CH2 CH2 Copyright © Houghton Mifflin Company. All rights reserved. CH2 CH2 CH3 3–11 12.4 Properties of Alcohols Properties are driven by hydrogen bonding and polarity. Alcohols up with up to 6 carbons are at least somewhat soluble in water. Alcohols have higher melting and boiling points than alkanes of similar molar mass. Copyright © Houghton Mifflin Company. All rights reserved. 3–12 12.4 Properties of Alcohols Hydrogen bonding among alcohol molecules Copyright © Houghton Mifflin Company. All rights reserved. 3–13 12.4 Properties of Alcohols Copyright © Houghton Mifflin Company. All rights reserved. 3–14 12.4 Properties of Alcohols As alkyl chain on alcohol gets larger, properties become more alkane-like Copyright © Houghton Mifflin Company. All rights reserved. 3–15 12.4 Properties of Alcohols Melting and Boiling Points of Alkanes and Alcohols 400 Alkane MP, °C Alkane BP, °C Alcohol MP, °C Alcohol BP, °C Temperature, °C 300 200 100 0 -100 -200 0 5 Copyright © Houghton Mifflin Company. All rights reserved. 10 Number of Carbons 15 20 3–16 12.4 Properties of Alcohols Classification of alcohols Primary (1) Secondary (2) R CH2 O H R1 CH O H R2 R1 Tertiary (3) Copyright © Houghton Mifflin Company. All rights reserved. R2 C O R3 H 3–17 12.4 Reactions of Alcohols Alcohols can dehydrate (lose H2O) to produce alkenes. H H3C H H C C H3C O H C H H H2SO4 180o C H3C C C C H3C H H H C H H H H + H H H Major C C H C H H Minor C H + H2O Tertiary alcohols don’t react. Copyright © Houghton Mifflin Company. All rights reserved. 3–18 12.4 Reactions of Alcohols Alcohols can dehydrate to produce ethers H3C CH2 O H3C H + H O CH2 O CH2 CH2 CH3 CH3 + H2SO4 140o C H2O This is most useful with primary alcohols; the alkene may also form. Copyright © Houghton Mifflin Company. All rights reserved. 3–19 12.4 Reactions of Alcohols Alcohols oxidize to form C=O bonds. R1 R2 C O H [O] H R1 C O + H2O R2 The reaction is formally loss of H2. Oxidizing agents: KMnO4, K2Cr2O7 Copyright © Houghton Mifflin Company. All rights reserved. 3–20 12.4 Reactions of Alcohols Different classes of alcohol react differently. Primary alcohols: H R C O H O [O] H R C O [O] H Aldehyde R C H O Carboxylic acid It can be hard to stop at aldehyde stage. Copyright © Houghton Mifflin Company. All rights reserved. 3–21 12.4 Reactions of Alcohols To make aldehyde, use CrO3 in pyridine. Keep water out of the reaction! H H R C C O H H H Copyright © Houghton Mifflin Company. All rights reserved. [O] R O C H 3–22 12.4 Reactions of Alcohols Different classes of alcohol react differently. Secondary alcohols: R1 R2 C O H H O [O] R2 C R1 Ketone Copyright © Houghton Mifflin Company. All rights reserved. 3–23 12.4 Reactions of Alcohols Different classes of alcohol react differently. Tertiary alcohols: R1 R2 C O H [O] No RXN R3 Can’t react, no H on C! Copyright © Houghton Mifflin Company. All rights reserved. 3–24 Common Alcohols Methanol Ethanol CH3–OH Wood alcohol; used as solvent, reactant CH3–CH2–OH Grain alcohol; used as solvent, reactant, beverage! 2-Propanol CH3–CH(OH)–CH3 Isopropanol Rubbing alcohol; used for sterilization of injection sites Copyright © Houghton Mifflin Company. All rights reserved. 3–25 Common Alcohols Ethanediol Ethylene glycol HO–CH2–CH2–OH Antifreeze; poisonous Cholesterol Important biomolecule CH3 CH3 CH3 H H H O Copyright © Houghton Mifflin Company. All rights reserved. 3–26 12.3 a Phenols Alcohols have a hydroxy group on an aromatic ring; –OH H H H C C H H C C C O H H C O C H H C C C C H H C H C H H H Phenol, a.k.a carbolic acid Copyright © Houghton Mifflin Company. All rights reserved. 3–27 12.3 a Naming Phenols Suffix is “phenol” 1. Carbon bearing hydroxyl is #1 2. Number carbons on ring so carbon bearing substituent has lowest possible number O H3C H H O CH3 Cl Copyright © Houghton Mifflin Company. All rights reserved. 3–28 12.3 a Naming Phenols Phenols with several hydroxyls have cool names OH OH HO OH OH OH Catechol Resorcinol OH Hydroquinone OH OH OH OH Pyrogallol HO OH Phloroglucinol Copyright © Houghton Mifflin Company. All rights reserved. HO OH 1,2,4 Benzenetriol 3–29 12.4 a Properties of Phenols Properties are driven by hydrogen bonding, polarity, and aromaticity Most phenols are solids Phenols are weak acids Copyright © Houghton Mifflin Company. All rights reserved. 3–30 12.4 a Properties of Phenols O H O H Copyright © Houghton Mifflin Company. All rights reserved. 3–31 12.4 a Reactions of Phenols Phenols are weak acids and undergo acidbase reactions. O H O H Phenoxide anion Copyright © Houghton Mifflin Company. All rights reserved. + H O H Hydronium cation 3–32 12.4 a Reactions of Phenols Dihydroxyphenols oxidize to form quinones. HO OH Hydroquinone [O] O O + H2O Benzoquinone Hydroquinones are antioxidants; they react with oxidizing agents and protect other compounds from oxidation. Copyright © Houghton Mifflin Company. All rights reserved. 3–33 12.4 a Reactions of Phenols Dihydroxyphenols oxidize to form quinones. R HO O O [O] OH O R O + O H2O O Vitamin C (ascorbic acid) acts like hydroquinone. Copyright © Houghton Mifflin Company. All rights reserved. 3–34 Common Phenols Phenol, a.k.a. Carbolic acid O H O C Salicylic acid OH OH Disinfectant, Local anesthetic Analgesic, basis for aspirin and Ben-Gay OH Butylated hydroxytoluene, a.k.a. BHT Copyright © Houghton Mifflin Company. All rights reserved. Preservative, antioxidant 3–35 Common Phenols H3C CH3 HO OH Used in epoxides and polycarbonate plastics, has estrogenic properties Bisphenol-A CH3 OH H H A major component of estrogen HO Estradiol Copyright © Houghton Mifflin Company. All rights reserved. 3–36 12.5 Ethers Ethers have oxygen atoms bonded to two carbon atoms. CH3 CH2 O CH2 CH3 Diethyl ether Copyright © Houghton Mifflin Company. All rights reserved. 3–37 12.5 Naming Ethers Common names of ethers are formed by naming the hydrocarbon group on either side of the oxygen atom and adding the word “ether.” The hydrocarbons are named in alphabetical order. CH3 CH2 O Ethyl phenyl ether Copyright © Houghton Mifflin Company. All rights reserved. CH3 O CH3 Dimethyl ether 3–38 12.5 Naming Ethers Cyclic ethers have interesting names; these turn up in carbohydrates. O H C C H C C H H Furan Copyright © Houghton Mifflin Company. All rights reserved. H H O C H H C H C C H H H Tetrahydrofuran (THF) H H C C O C C C H H H H Pyran 3–39 12.5 Naming Ethers Ethylene oxide and propylene oxide, cyclic ethers with three-membered rings, are important oddities. Such ethers are called epoxides. O ethylene oxide Copyright © Houghton Mifflin Company. All rights reserved. O CH3 propylene oxide 3–40 12.5 Naming Ethers Cyclic di- and tri-ethers: O O O O O O Dioxolane Dioxane Copyright © Houghton Mifflin Company. All rights reserved. O O O Trioxane Dioxepane 3–41 12.5 Properties of Ethers Ethers have boiling points similar to those of hydrocarbons with similar structures. CH3CH2OCH2CH3 CH3CH2CH2CH2CH3 Boiling point 35C Boiling point 36C Like hydrocarbons, they are flammable. Copyright © Houghton Mifflin Company. All rights reserved. 3–42 12.5 Properties of Ethers Ethers have water solubilities similar to those of isomeric alcohols. They are hydrogen bond acceptors. Copyright © Houghton Mifflin Company. All rights reserved. 3–43 12.5 Reactions of Ethers Ethers are not particularly reactive. They are good solvents for certain reactions. Ethers form explosive hydroperoxides in the presence of oxygen. Ethers are treated with antioxidants to prevent this. H H O C H H C H C C H H H + Copyright © Houghton Mifflin Company. All rights reserved. O2 H H O O H C C H O H C C H H H 3–44 12.5 Reactions of Ethers Polymeric ethers are made from ring-opening reactions of epoxides, which are much more reactive than most ethers. CH3 HOCH2CH2OnH HOCH2CHOnH Poly(ethylene glycol) (PEG) Carbowax Poly(propylene glycol) (PPG) Copyright © Houghton Mifflin Company. All rights reserved. 3–45 Common Ethers Diethyl ether and chloroform were used as anesthetics in the 1840’s. Fluorinated ethers are not flammable and have fewer side effects than either of these. F F F H F C C C O F F Cl F Cl F H F C C C O F F F Enflurane Isoflurane Copyright © Houghton Mifflin Company. All rights reserved. F H F H F C C C O F F F Desflurane F F F C H H H F C C C O F F F Sevoflurane 3–46 Common Ethers Diethyl ether and tetrahydrofuran (THF) are very useful solvents. Unlike most ethers, THF is freely soluble in water. CH3 CH2 O CH2 Diethyl ether Copyright © Houghton Mifflin Company. All rights reserved. CH3 H H O C H H C H C C H H H Tetrahydrofuran (THF) 3–47 Common Ethers Bisphenol-A diglycidyl ether (BADGE) is the “resin’ in most epoxy glues. H3C CH3 O O O Copyright © Houghton Mifflin Company. All rights reserved. O 3–48 12.6 Thiols Thiols are the sulfur analogs of alcohols. The SH is called a sulfhydryl group. R O H Alcohol R S H Thiol Another name for thiols is mercaptans, from “mercury capture.” Thiols and sulfide ions react with heavy metals. Copyright © Houghton Mifflin Company. All rights reserved. 3–49 12.6 NamingThiols Thiols are named like alcohols. The suffix for the sulfhydryl group is “-thiol.” The -e at the end of the alkane name is retained. CH3 CH2 CH CH3 OH CH3 CH2 CH CH3 OH 2-butanol 2-butanethiol Copyright © Houghton Mifflin Company. All rights reserved. 3–50 12.6 Properties of Thiols Thiols are polar, but are not capable of hydrogen bonding. Boiling points of thiols are lower than those of analogous alcohols. Small thiols are often have strong odors. Copyright © Houghton Mifflin Company. All rights reserved. 3–51 12.6 Properties of Thiols 1-butanethiol is added to natural gas as an odorant, so leaks can be detected. Skunk odor is due to thiols. Copyright © Houghton Mifflin Company. All rights reserved. 3–52 12.6 Reactions of Thiols Thiols are weak acids and undergo acid-base reactions. CH3 CH2 S H + H2O CH3 CH2 S H + OH1Р ethanethiol Copyright © Houghton Mifflin Company. All rights reserved. CH3 CH2 S + H3O CH3 CH2 S + H2O thiolate anion 3–53 12.6 Reactions of Thiols Thiols undergo oxidative coupling to form disulfides. R S H + H S R thiols [O] R S S R + H2O disulfide This reaction is important in protein chemistry. Copyright © Houghton Mifflin Company. All rights reserved. 3–54 12.6 Reactions of Thiols Oxidative coupling is reversible. Reducing agents, [H2], restore the thiols. R S S R [H2] disulfide R S H + H S R thiols These reactions are involved in “permanents” and straightening agents for hair. Copyright © Houghton Mifflin Company. All rights reserved. 3–55 12.7 Amines Amines contain nitrogen. They are organic derivatives of ammonia. Copyright © Houghton Mifflin Company. All rights reserved. 3–56 12.7 Naming Amines Common names of amines are formed by naming the alkyl groups attached to the nitrogen in alphabetical order and adding the suffix “amine.” CH3 CH2 NH2 ethylamine CH3 CH2 N CH2 CH3 H diethylamine CH3 N CH2 CH3 ethylmethylphenylamine Copyright © Houghton Mifflin Company. All rights reserved. 3–57 12.7 Naming Amines Aromatic amines are called anilines. H N H aniline H N CH2 CH3 N-ethylaniline H3C N CH3 N,N-dimethylaniline The prefix “N-” locates alkyl groups on nitrogen. Copyright © Houghton Mifflin Company. All rights reserved. 3–58 12.7 Naming Amines Cyclic aromatic amines with nitrogen in the ring are common in biological molecules. N N N pyridine N N pyrimidine N N pyrazine triazine H N H N pyrrole N imidazole Copyright © Houghton Mifflin Company. All rights reserved. N 3–59 12.7 Naming Amines Fused aromatic rings that contain nitrogen are also common. N N N quinoline Copyright © Houghton Mifflin Company. All rights reserved. H N N purine 3–60 12.7 Naming Amines Aliphatic rings that contain nitrogen are also common. H N H N H N O piperidine N H piperazine morpholine H N pyrrolidine N CH3 HO Copyright © Houghton Mifflin Company. All rights reserved. O morphine OH 3–61 12.8 Structures of Amines Aliphatic amines have tetrahedral electronic geometry and trigonal pyramidal molecular geometry at the nitrogen atom. R1 Copyright © Houghton Mifflin Company. All rights reserved. N R 3 R2 3–62 12.8 Structures of Amines Aromatic amines have trigonal planar electronic geometry and trigonal planar or angular molecular geometry at the nitrogen atom. N H N The lone pair on pyrrole’s nitrogen is part of the aromatic electron system. Copyright © Houghton Mifflin Company. All rights reserved. 3–63 12.8 Properties of Amines Amines are polar molecules. 1 and 2 amines are hydrogen-bond donors. 3 amines are hydrogen-bond acceptors. Copyright © Houghton Mifflin Company. All rights reserved. 3–64 12.8 Properties of Amines Nitrogen is less electronegative than oxygen, so amines are less polar than alcohols. Melting points and boiling points are lower than those of alcohols of similar structure. BP, C Name Formula Methylamine H3C NH2 -6.3 Methanol H3C OH 65 Ethylamine H3C CH2 NH2 17 Ethanol H3C CH2 OH 78 Copyright © Houghton Mifflin Company. All rights reserved. 3–65 12.8 Properties of Amines Aromatic amines follow the same trends. MP, C BP, C C6H5 NH2 -6 184 C6H5 OH 41 182 Name Formula Aniline Phenol Amines with 6 or fewer carbon atoms are at least somewhat water-soluble. Copyright © Houghton Mifflin Company. All rights reserved. 3–66 12.8 Properties of Amines Odors are prominent and unpleasant. Small amines smell like ammonia. Slightly larger amines smell like dead fish. H2N CH2 CH2 CH2 CH2 NH2 putrescine H2N CH2 CH2 CH2 CH2 CH2 NH2 cadaverine Copyright © Houghton Mifflin Company. All rights reserved. 3–67 12.8 Reactions of Amines Amines are weak bases and undergo acid-base reactions. R 1 N R3 R2 + R 1 N R3 + R2 H2O H3O1+ R1 H N R3 R2 + OH1 R1 H N R3 R2 + H2O ammonium ion Copyright © Houghton Mifflin Company. All rights reserved. 3–68 12.8 Reactions of Amines Amines undergo alkylation when reacted with alkyl halides. R1 N R3 R2 + R4Cl R1 R4 N R3 R2 + Cl1 Even tertiary amines do this. The products are called quaternary amine or ammonium salts or just “quats.” Copyright © Houghton Mifflin Company. All rights reserved. 3–69 Common Amines Simple alkyl amines, e.g. methylamine, have already been mentioned. Amines from plants are called “alkaloids” because they are basic. They often have physiological effects. OH H3C H N CH3 N Nicotine, a stimulant from tobacco Copyright © Houghton Mifflin Company. All rights reserved. O N CH3 N N N CH3 Caffeine, a stimulant from coffee and tea 3–70 Common Amines The “bases” in DNA and RNA are amines. They interact by hydrogen bonding. Adenine O H H N N H N N N sugar N CH3 Guanine H N O Thymine Copyright © Houghton Mifflin Company. All rights reserved. H N O sugar N N sugar N N N H N sugar O H Cytosine N H 3–71