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Chapter 12 Organic Compounds with Oxygen and Sulfur 12.1 Alcohols, Ethers, and Thiols Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings 1 Alcohols An alcohol contains a hydroxyl group (—OH) attached to a carbon chain. A phenol contains a hydroxyl group (—OH) attached to a benzene ring. water alcohol phenol Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings 2 Naming Alcohols The names of alcohols • in IUPAC replace the -e with -ol. • with common names use the name of the alkyl group followed by alcohol. Formula IUPAC CH4 methane CH3─OH methanol CH3─CH3 ethane CH3─CH2─OH ethanol Common Name methyl alcohol ethyl alcohol 3 More Names of Alcohols IUPAC names for longer chains number the chain 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 6 5 4 3 2 1 5-methyl-2-hexanol 4 Some Typical Alcohols OH | “rubbing alcohol” CH3—CH—CH3 2-propanol (isopropyl alcohol) antifreeze HO—CH2—CH2—OH 1,2-ethanediol (ethylene glycol) OH | glycerol HO—CH2—CH—CH2—OH 1,2,3-propanetriol 5 Learning Check Name the following compounds. 1. CH3—CH2—CH2—CH2—OH 2. OH CH3 | | CH3—CH—CH—CH2—CH3 OH 3. 6 Solution 1. CH3—CH2—CH2—CH2—OH OH CH3 | | 2. CH3—CH—CH—CH2—CH3 1-butanol 3-methyl-2-pentanol OH 3. cyclopentanol 7 Phenols in Medicine Phenol • is the IUPAC name for benzene with a hydroxyl group. • is used in antiseptics and disinfectants. OH OH OH OH OH CH2CH2CH2CH2CH2CH3 phenol resorcinol 4-hexylresorcinol 8 Derivatives of Phenol Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint. 9 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. OH 1 OH 1 3 Cl 3-chlorophenol 4 Br 4-bromophenol 10 Learning Check Write the structure of each of the following. A. 3-pentanol B. ethyl alcohol C. 4-methylphenol 11 Solution Write the structure of the following. A. 3-pentanol OH | CH3—CH2—CH—CH2—CH3 B. ethyl alcohol CH3—CH2—OH OH C. 4-methylphenol CH3 12 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 (1º) 1 group H | CH3—C—OH | H Secondary (2º) Tertiary (3º) 2 groups 3 groups CH3 | CH3—C—OH | H CH3 | CH3—C—OH | CH3 13 Learning Check Classify each alcohol as 1) primary, 2) secondary, or 3) tertiary. OH | A. CH3—CH—CH2—CH3 B. CH3—CH2—CH2—OH OH | C. CH3—CH2—C—CH2—CH3 | CH3 14 Solution OH | A. CH3—CH—CH2—CH3 secondary B. CH3—CH2—CH2—OH primary OH | C. CH3—CH2—C—CH2—CH3 | CH3 tertiary 15 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. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings 16 Thiols Thiols • often have strong odors. • are used to detect gas leaks. • are found in onions, oysters, and garlic. 17 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. CH3─O─CH3 CH3─CH2─O─CH3 dimethyl ether ethyl methyl ether 18 Learning Check Write the structure of the following. A. 3-pentanol B. diethyl ether 19 Solution A. 3-pentanol B. diethyl ether OH | CH3─CH2─CH─CH2─CH3 CH3─CH2─O─CH2─CH3 20 Ethers as Anesthetics Anesthetics • inhibit pain signals to the brain. • like diethyl ether CH3─CH2─O─CH2─CH3 were used for over a century, but caused nausea and were flammable. • developed by the 1960’s 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 21 MTBE Methyl tert-butyl ether CH3 │ CH3─O─C─CH3 │ CH3 • is second in production of organic chemicals. • is an additive used to improve gasoline performance. • use is questioned since the discovery that MTBE has contaminated water supplies. 22