CHEM 3331 1nd Edition Lecture 22Outline of Last Lecture I. HydrogenationII. Addition of X2III. Addition of HXIV. Addition of H2OV. HydroborationVI. KMnO4 oxidation and ozonlysisOutline of Current Lecture I. AlcoholsII. StructureIII. NomenclatureIV. Physical propertiesV. UsesVI. AcidityVII. PreparationCurrent LectureI. AlcoholsAlcohols possess the formula R-OH where R is a hydrocarbon group. Ethanol= CH3CH2OH. Isopropyl alcohol= (CH3)2CHOH. II. StructureIn water oxygen is sp3 hybridized with two lone electron pairs that decrease the angle between the hydrogens to 104.9. The lone pairs compress the hydrogens together. In an alcohol the bondThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.length between oxygen and the R group is 1.4 angstroms and the bond length between H and O is 0.9 angstroms. The angle between the hydrogen and R group bonds is 108.9. Primary alcohols are OH groups connected to a carbon which is connected to only one other carbon. Secondary alcohols have the OH group connected to a carbon attached to two other carbons. A tertiary alcohol has the OH group connected to a carbon that is attached to three other carbons.Primary= CH3OH, CH3CH2OHSecondary= (CH3)2CHOHTertiary= (CH3)3COHBenzene rings with an OH group attached to it are called phenols. III. NomenclatureSimply switch –ane to –anol. The longest chain must contain the OH group. Start numbering from the end closest to the OH group. In order of greatest priority: alcohols> alkenes> alkynes> haloalkanes.CH3OH can be called methanol or methyl alcohol.You can also have more than one OH group. If there are two it is a diol, three is a triol. In this case you keep the –ane and add diol or triol after it. IV. Physical propretiesC1-C12 alcohols are liquids. C13 and on are solids with a waxy texture to them. Hydrogen bonding increases the boiling point. Hydrocarbon C1-C4 are gas and then become liquid at C5.In an alcohol, there is hydrogen bonding and dipole moments. The hydrogen bonding is more important to boiling point than the dipole moment is.Alcohols can hydrogen bond to self and to water. The OH group and the lone pairs make a polar head and the R group makes up a nonpolar tail. The polar head contributes to hydrogen bonding and solubility, but the length of the nonpolar tail determines if it is soluble. With a long enough tail the compound will not be soluble in water. C1-C3 are soluble in water. C4-C7 are less soluble (not fully soluble). C8 are insoluble in water.V. UsesCH3OH is termed wood alcohol because it is produced through the distillation of wood through the process of charcoal. 3C + 4H2O CO + 3H2 +CO2(300-400˚C) CH3OHCO and H2 are synthesis gases and CO2 escapes off into the surroundings. It was a fuel for internal combustion engines and in fuel cell vehicles without combustion.CH3CH2OH is grain alcohol. It is obtained through 2 methods: fermentation of sugarC6H12O6 2CH3CH2OH + 2CO2. After 40-50% concentration it yields organism death. The other method is distillation which yields 96% of the alcohol. Known as an azeotropic mixture. To gain 100% alcohol we have to react with CaO.H2C=CH2(H2O, temp. catalyst, and 100-300 atm) CH3CH2OH.Ethanol is cheap about $4/gal. perfumes use ethanol as a solvent. Ethanol is not meant for human consumption it is denatured and contains impurities that make it smell bad, toxic, or have a yellow color.Methanol poisoning is treated with ethanol by a near lethal dose. The enzyme in our body will process ethanol and ignore the methanol so it can pass through the body and out through urine. We developed this enzyme so we could eat spoiled fruit and not die from it. VI. AcidityAlcohols are acidic and similar to H2O.R-OH + B R-O- +BH+The strength of the base determines the direction in which the reaction will proceed. CH3OH pKa= 15.5C2H5OH=15.9H2O=15.7CCl3CH2OH=14.3 (inductive effect makes the H+ easier to leave)(CH3)3COH=18 (inductive effect makes it harder for H+ to leave)CH3COOH= 4.75HCl= -2.2Phenols are more acidic than alcohols because their conjugate base is more stable.VII. Preparation6 ways to prepare alcohols1) Sn2 reactionCH2CH2CH2CH2Br (HO-) CH3CH2CH2CH2OH2) hydration of alkenesRHC=CH2(H3O+) RH(CH3)COH however, this produces cations which lead to rearrangement.3) oxymercurationRHC=CH2(Hg(OAc)2, H2O, NaSH4) RH(CH3)COH4) hydroborationRHC=CH2 (B2H6, NaOH, H2O2) RCH2CH2OH5) dihydroxylationSyn-addition1-cyclopentene(OsO4, H2O2) cis-1,2- cyclopentanediol6) EpoxidationAnti-addition1-cycopentene (mCPBA, HO-) trans-1,2-cyclopentanediolWe can base our reactions on what we use as reactants or what we produced as products. Alcohols are mostly produced from alkenes. R2C=O + R≡C:- (H2O)