Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 641Alcohols, Ethers and Epoxides•Alcohols contain a hydroxy group (OH) bonded to an sp3 hybridized carbon.Introduction—Structure and Bonding2•Compounds having a hydroxy group on a sp2 hybridized carbon—enols and phenols—undergo different reactions than alcohols.•Ethers have two alkyl groups bonded to an oxygen atom.3•Epoxides are ethers having the oxygen atom in a three-membered ring. Epoxides are also called oxiranes.•The C—O—C bond angle for an epoxide must be 60°, a considerable deviation from the tetrahedral bond angle of 109.5°. Thus, epoxides have angle strain, making them more reactive than other ethers.4•The oxygen atom in alcohols, ethers and epoxides is sp3 hybridized. Alcohols and ethers have a bent shape like that in H2O.•The bond angle around the O atom in an alcohol or ether is similar to the tetrahedral bond angle of 109.5°.•Because the O atom is much more electronegative than carbon or hydrogen, the C—O and O—H bonds are all polar.56•When an OH group is bonded to a ring, the ring is numbered beginning with the OH group. •Because the functional group is at C1, the 1 is usually omitted from the name. •The ring is then numbered in a clockwise or counterclockwise fashion to give the next substituent the lowest number.Figure 9.2Examples: Namingcyclic alcohols7•Common names are often used for simple alcohols. To assign a common name:Name all the carbon atoms of the molecule as a single alkyl group.Add the word alcohol, separating the words with a space.8•Compounds with two hydroxy groups are called diols or glycols. Compounds with three hydroxy groups are called triols and so forth.9•Simple ethers are usually assigned common names. To do so: Name both alkyl groups bonded to the oxygen, arrange these names alphabetically, and add the word ether.For symmetrical ethers, name the alkyl group and add the prefix “di-”.Nomenclature of Ethers10•More complex ethers are named using the IUPAC system. One alkyl group is named as a hydrocarbon chain, and the other is named as part of a substituent bonded to that chain:Name the simpler alkyl group as an alkoxy substituent by changing the –yl ending of the alkyl group to –oxy.Name the remaining alkyl group as an alkane, with the alkoxy group as a substituent bonded to this chain.•Cyclic ethers have an O atom in the ring. A common example is tetrahydrofuran (THF).11•Epoxides can be named in three different ways—As epoxyalkanes, oxiranes, or alkene oxides.•To name an epoxide as an epoxyalkane, first name the alkane chain or ring to which the O atom is attached, and use the prefix “epoxy” to name the epoxide as a substituent. Use two numbers to designate the location of the atoms to which the O’s are bonded.Nomenclature of Epoxides12•Epoxides bonded to a chain of carbon atoms can also be named as derivatives of oxirane, the simplest epoxide having two carbons and one oxygen atom in a ring.•The oxirane ring is numbered to put the O atom at position one, and the first substituent at position two. •No number is used for a substituent in a monosubstituted oxirane.13•Epoxides are also named as alkene oxides, since they are often prepared by adding an O atom to an alkene. To name an epoxide in this way:Mentally replace the epoxide oxygen with a double bond.Name the alkene.Add the word oxide.14•Alcohols, ethers and epoxides exhibit dipole-dipole interactions because they have a bent structure with two polar bonds.•Alcohols are capable of intermolecular hydrogen bonding. Thus, alcohols are more polar than ethers and epoxides.Physical Properties•Steric factors affect hydrogen bonding.1516Preparation of Alcohols, Ethers, and Epoxides•Alcohols and ethers are both common products of nucleophilic substitution.•The preparation of ethers by the method shown in the last two equations is called the Williamson ether synthesis.17•In theory, unsymmetrical ethers can be synthesized in two different ways; in practice, one path is usually preferred.18•An alkoxide salt is needed to make an ether.•Alkoxides can be prepared from alcohols by a BrØnsted-Lowry acid—base reaction. For example, sodium ethoxide (NaOCH2CH3) is prepared by treating ethanol with NaH.•NaH is an especially good base for forming alkoxide because the by-product of the reaction, H2, is a gas that just bubbles out of the reaction mixture.19•Organic compounds that contain both a hydroxy group and a halogen atom on adjacent carbons are called halohydrins. •In halohydrins, an intramolecular version of the Williamson ether synthesis can occur to form epoxides.20Reactions of Alcohols•Recall that, unlike alkyl halides in which the halogen atom serves as a good leaving group, the OH group in alcohols is a very poor leaving group.•For an alcohol to undergo nucleophilic substitution, OH must be converted into a better leaving group. By using acid, ¯OH can be converted into H2O, a good leaving group.21Reactions of Alcohols—Dehydration•Dehydration, like dehydrohalogenation, is a elimination reaction in which the elements of OH and H are removed from the and carbon atoms respectively.•Dehydration is typically carried out using H2SO4 and other strong acids, or phosphorus oxychloride (POCl3) in the presence of an amine base.22•Typical acids used for alcohol dehydration are H2SO4 or p-toluenesulfonic acid (TsOH).•More substituted alcohols dehydrate more easily, giving rise to the following order of reactivity.23•When an alcohol has two or three carbons, dehydration is regioselective and follows the Zaitsev rule. •The more substituted alkene is the major product
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