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CHAPTER 1.4 Alcohols, Ethers and Thiols Learning Objective: Learn the nomenclature and uses of Alcohols, Ethers and Thiols. Keywords: Alcohol, Primary Alcohol, Secondary Alcohol, Tertiary Alcohol, Phenol, Thiols, Ether 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 Names the following Alcohols IUPAC names for longer chains - number the chain from the end nearest the -OH group. CH3─CH2─CH2─OH OH │ CH3─CH─CH2─CH3 CH3 OH │ │ CH3─CH─CH2─CH2─CH─CH3 6 5 4 3 2 1 4 More Names of Alcohols - Answers 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 5 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 6 Task Name the following compounds. 1. CH3—CH2—CH2—CH2—OH 2. 2 minutes OH CH3 | | CH3—CH—CH—CH2—CH3 OH End 3. 7 Solution 1. CH3—CH2—CH2—CH2—OH OH CH3 | | 2. CH3—CH—CH—CH2—CH3 1-butanol 3-methyl-2-pentanol OH 3. cyclopentanol 8 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 or benzenediol 4-hexylresorcinol 9 Derivatives of Phenol Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint. 10 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 11 Task Write the structure of each of the following. A. 3-pentanol B. ethyl alcohol C. 4-methylphenol 2 minutes End 12 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 13 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 14 Task Classify each alcohol as 1) primary, 2) secondary, or 3) tertiary. OH | A. CH3—CH—CH2—CH3 2 minutes B. CH3—CH2—CH2—OH OH | C. CH3—CH2—C—CH2—CH3 | CH3 End 15 Solution OH | A. CH3—CH—CH2—CH3 secondary B. CH3—CH2—CH2—OH primary OH | C. CH3—CH2—C—CH2—CH3 | CH3 tertiary 16 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 17 Thiols Thiols • often have strong smells. • are used to detect gas leaks. • are found in onions, oysters, and garlic. 18 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 19 Task Write the structure of the following. A. pentyl propyl ether 2 minutes B. diethyl ether End 20 Solution A. pentyl propyl ether B. diethyl ether CH3─CH2─O─CH2─CH3 21 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 22 TASK Answer the questions on the handout. If you don’t finish it in class, do it for homework please 23