<p>Chapter 8 Alcohol and Ether</p><p>Nomenclature of Ethers</p><p>The functional group of ether is an oxygen atom bonded to two carbon atoms</p><p>R—O—R</p><p>◦ The simplest ether is dimethyl ether, CH3OCH3</p><p>◦ The most common ether is diethyl ether CH3CH2OCH2CH3</p><p>Although ethers can be named according to the IUPAC system, chemists almost invariably use common names for low-molecular-weight ethers.</p><p>◦ Common names are derived by listing the alkyl groups bonded to oxygen in alphabetical order and adding the word "ether”.</p><p>◦ Alternatively, name one of the groups on oxygen as an alkoxy group (RO- ).</p><p>CH3</p><p>CH O 3 CH3CH2O CH3CHO CH3CH2CHO H3C CO methoxy ethoxy CH isopropoxy sec-butoxy 3 ter-butoxy E.g Name the following molecule</p><p>O O OH </p><p>E.g Use bond-line to draw </p><p>Isopropyl methyl ether 4-ethoxy-2-methyl-1-hexene</p><p>CHM 201 Dang 1 Substitution of Alcohols (ROH  RX)</p><p>- - CH3Cl + OH  CH3OH + Cl</p><p>- - CH3OH + Cl  CH3Cl + OH </p><p> -OH is strongly basic, unstable, not a good LG</p><p> Must convert into a weaker base, in the protonated form (R OH2 )</p><p>ROH + NaCl  NR (no LG)</p><p>ROH + HCl  RCl + H2O</p><p>ROH + HBr  RBr + H2O</p><p>ROH + HI  RI + H2O </p><p>H Br + CH3 OH + H Br CH3 O H3C Br H2O H SN2</p><p> poor LG weak good LG base</p><p> o o SN1 mechanism (2 and 3 )</p><p>H2O H Br + H Br OH OH Br + H2O</p><p>3o alcohol + Br</p><p> o SN2 mechanism (1 ) Br</p><p>H + H2O + H Br Br OH O H H O 1o alcohol 2</p><p>Explain why (S)-2-butanol forms a racemic mixture when it is heated in aqueous sulfuric acid?</p><p>CHM 201 Dang 2 E.g Predict the product and provide a mechanism </p><p>CH3</p><p>OH + HI</p><p>Elimination reactions of Alcohols</p><p> Aka dehydration of alcohol  lost of H2O</p><p> Required strong acid catalyst</p><p> Formation of alkene follows Zaitsev’s rule: More substituted alkene is the major product</p><p> More stable carbocation will be formed faster</p><p>Benzylic/allylic/3o ROH > 2oROH >> 1oROH</p><p>OSO3H OSO3H E1 mechanism</p><p>HB HA A minor H OSO3H heat O OH H H B + major OSO3H</p><p>CHM 201 Dang 3 E2 mechanism H H O + H2O OH H OSO3H H heat + H2SO4</p><p>OSO3H</p><p>Ether is also obtained; it is the product of a competing SN2 reaction</p><p>H O H OSO H O O OH 3 H H o 1 H O ether HO 2</p><p>E.g Give the major product formed when each of the following alcohols is heated in presence of H2SO4</p><p>OH</p><p>H2SO4</p><p>OH</p><p>H2SO4</p><p>Oxidation of Alcohols</p><p>CHM 201 Dang 4 Oxidation: increases # C-O bonds and decreases the # of C-H bonds</p><p>O O</p><p>CH4 CH3OH HCH HCOH O C O</p><p>Reduction: decreases # C-O bonds and increases the # C-H bonds</p><p>Common reagents: chromic acid, chromate salt, dichromate salt, permanganate</p><p> Oxidation of a 1° alcohol to a carboxylic acid is commonly carried out using potassium </p><p> dichromate, K2Cr2O7, in aqueous sulfuric acid.</p><p>Further oxidation OH O O K2Cr2O7 K2Cr2O7 R C H C C H SO OH H2SO4 R H 2 4 R H 1o alcohol Aldehyde carboxylic</p><p> Or using pyridium chlorochromate (PCC) as the oxidizing agent in an anhydrous solvent OH O PCC R C H C CH2Cl2 R H H 1o alcohol Aldehyde</p><p>◦ Oxidation of a 2° alcohol and cyclic alcohol gives a ketone. OH O K Cr O 2 2 7 C R1 C H R1 R2 H2SO4 R2 Ketone 2o alcohol</p><p>OH O</p><p>K Cr O 2 2 7 CHM 201 Dang 5</p><p>H2SO4</p><p> cyclohexanol cyclohexanone  Tertiary alcohols are resistant to oxidation R H2CrO4 R OH NR</p><p>R</p><p>Consider the following reaction</p><p>OH O LiAlH4 a reaction</p><p> a agent</p><p>Predict the product(s)</p><p>H2CrO4</p><p>OH</p><p>OH</p><p>H2CrO4</p><p>O reagents? alcohol ???? OH</p><p>CHM 201 Dang 6</p>