Structures of Alcohols, Phenols, Thiols and EthersSlide 2Naming AlcoholsNomenclatureClassification of AlcoholsNaming PhenolsSlide 7Naming ThiolsSlide 9Thiols - NomenclatureNaming EthersSlide 12Naming Cyclic EthersNaming ExamplesPhysical Properties of Alcohols, Phenols, Thiols and EthersSlide 16Slide 17Physical PropertiesAcidity and Basicity of Alcohols and PhenolsCombustion Reactions of Alcohols and EthersDehydration of Alcohols to Form AlkenesMechanism of Acid-Catalyzed Dehydration of an AlcoholStructures of Alcohols, Phenols, Thiols and Ethers•Alcohols, phenols, thiols and ethers consist of a hydrocarbon singly bonded to an oxygen or a sulfur•Alcohols have an -OH group attached to an alkane, phenols have an -OH group attached to a benzene, thiols have an -SH group attached to an alkane and ethers have an O bonded to two C’sOHSHOHOAlchol PhenolThiol EtherNaming Alcohols•Parent name ends in -ol•Find longest chain containing the C to which the OH group is attached•Number C’s starting at end nearest OH group•Locate and number substituents and give full name- use a number to indicate position of OH group- cyclic alcohols have cyclo- before the parent name; numbering begins at the OH group, going in direction that gives substituents lowest possible numbers- use a prefix (di-, tri-) to indicate multiple OH groups in a compoundNomenclatureEthanol(Ethyl alcohol)1-Propanol(Propyl alcohol)2-Propanol(Isopropyl alcohol)1-Butanol(Butyl alcohol)OHOHOHOH2-Butanol(sec-Butyl alcohol)2-Methyl-1-propanol(Isobutyl alcohol)2-Methyl-2-propanol(tert-Butyl alcohol)OHCyclohexanol(Cyclohexyl alcohol)OHOHOHClassification of Alcohols•Alcohols can be classified as methyl, primary, secondary or tertiary•Classification is based on the number of alkyl groups attached to the carbon to which the OH group is attached•If OH is attached to a 1 C, it’s a 1 alcohol, etc.C OHHHHC OHHH3CHC OHCH3H3CHC OHCH3H3CCH3Methyl Primary Secondary TertiaryNaming Phenols•Phenol is the common name for an OH group attached to a benzene, and is accepted by IUPAC•Compounds with additional substituents are named as substituted phenols•Ortho, meta and para are used when there is only one other substituent•If there are two or more additional substituents, each must be numbered, beginning at the OH and going in direction that gives substituents lowest numbers (or alphabetical if same in both directions)Many phenols have pleasant odors, and some are bioactive- Euganol (from cloves) is a topical anesthetic- Thymol (from thyme) is an antisepticNaming Thiols•Parent name ends in -thiol•Find longest chain containing the C to which the SH group is attached•Number C’s starting at end nearest SH group•Parent name is alkane name of carbon portion of longest chain, followed by thiol•Locate and number substituents and give full name- use a number to indicate position of SH group- cyclic thiols have cyclo- before the parent name; numbering begins at the SH group, going in direction that gives substituents lowest possible numbers- use a prefix (di-, tri-) to indicate multiple SH groups in a compoundThiols - Nomenclature•Common names for simple thiols are derived by naming the alkyl group bonded to -SH and adding the word "mercaptanmercaptan" CH3CH2SHCH3CH3CHCH2SHEthanethiol(Ethyl mercaptan)2-Methyl-1-propanethiol(Isobutyl mercaptan)Naming Ethers•Simple ethers are named by their common names•For common names: name each alkyl group attached to the oxygen followed by ether•For complex ethers IUPAC names are used•For IUPAC names:1. Name as an alkane, with larger alkyl group being the parent chain2. The smaller alkyl group and the O are named together as an alkoxy group (replace -yl with -oxy)3. Number chain starting at end nearest alkoxy group4. Use a number to give location of alkoxy groupOCH3CH3CH2OCH2CH3Cyclohexyl methyl ether(Methoxycyclohexane)Diethyl etherNaming Cyclic Ethers•Cyclic ethers are generally named by their common names (we will not study the IUPAC names)•A cyclic ether containing two carbons is called ethylene oxide (generally known as epoxides)•A cyclic ether containing 4 carbons (with 2 double bonds) is called a furan•A cyclic ether containing 5 carbons (with 2 double bonds) is called a pyran•A cyclic ether containing 4 carbons and 2 oxygens is called a dioxaneOOfuranO OO1,4-dioxaneOOethylene oxide tetrahydrofuranpyrantetrahydropyranNaming ExamplesOHSHOHOHCH3OHBrBrOOOO2-propanol 2-ethyl-4-methylcyclopentanol propanethiol ortho-methylphenol2,4-dibromophenoldiethyl etherfuran1,4-dioxanePhysical Properties of Alcohols, Phenols, Thiols and Ethers •All of these types of compounds have a bent geometry around the O or the S, and are polar compounds•Alcohols and phenols contain a very polarized O-H bond, and they can H-bond with themselves and with other alcohols or water- Small alcohols (4 or less C’s) are soluble in water- Phenol is soluble in water (even with 6 C’s) because it partially ionizes in water (it’s a weak acid)- Alcohols and phenols have relatively high boiling points•Thiols are much less polar than alcohols because the electronegativity of S is the same as that of C (2.5), much less than that of O (3.5), so C-S and S-H bonds are not polar- thiols do not H-bond and have relatively low boiling points•Ethers do not H-bond with themselves, so have boiling points similar to hydrocarbons-ethers are only slightly soluble in water and are highly flammablePhysical Properties–bp increases as MW increases–solubility in water decreases as MW increasesCH3CH2CH2OHCH3CH2CH2CH3CH3OHCH3CH3CH3CH2OHCH3CH2CH3CH3CH2CH2CH2OHCH3CH2CH2CH2CH3Structural Formula NameMolecularWeightbp(°C)Solubilityin Watermethanol 32 65 infiniteethane 30 -89 insolubleethanol4678infinitepropane44 -42 insoluble1-propanol60 97infinitebutane 58 0 insoluble8 g/100 g117741-butanolpentane72 36 insolubleAcidity and Basicity of Alcohols and Phenols•Alcohols and phenols, like water, can act as either weak acids or weak bases (although phenol is more acidic)•Phenols are more acidic because the anion that forms upon loss of the proton is stabilized by resonanceOH+HClOHH+ClOH+NH3O+ NH4OH+H2OO+ H3OOOOOCombustion Reactions of Alcohols and Ethers•Both alcohols and ethers can burn with oxygen to produce water, carbon dioxide and heat (just like hydrocarbons)•However, ethers are much more flammable than alcohols and care should be taken when working with ethers in the laboratory (just a