alcohols alcohols r o h

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Alcohols R-O-H Classification CH3, 1o, 2o, 3o Nomenclature: Common names: “alkyl alcohol” IUPAC: parent = longest continuous carbon chain containing the –OH group alkane drop -e, add –ol prefix locant for –OH (lower number for OH) CH3 CH3CHCH2CHCH3 OH 4-methyl-2-pentanol 2o CH3 CH3CCH3 OH tert-butyl alcohol 2-methyl-2-propanol 3o CH3 HO-CHCH2CH3 CH3CH2CH2-OH sec-butyl alcohol 2-butanol 2o n-propyl alcohol 1-propanol 1o Physical properties of alcohols: polar + hydrogen bonding relatively higher mp/bp water insoluble! (except for alcohols of three carbons or less) CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2-OH hydrophobic hydrophilic Oldest known organic synthesis: “fermentation” Sugar + yeast  Grape juice => “wine” Barley => “beer” Honey => “mead” Rice => “sake” ~5-11% ethanol ethyl alcohol + CO2 Distillation of fermented beverages to produce “distilled spirits” with a greater percentage of ethyl alcohol (bp 78.3 oC) Ethyl alcohol forms a binary azeotrope with water: 95% ethanol + 5% water (bp 78.15oC) Diluted with water => “vodka” 40% ethyl alcohol in water “proof”: when aqueous alcohol is placed on a sample of gunpowder and ignited, the gunpowder will burn at a minimum concentration of 50% alcohol This is called “100-proof” (proof = * alcohol percent) Add oil of juniper => gin Add peat smoke => scotch Age in a burned barrel => whiskey Add peppermint => schnapps Etc Ethyl alcohol is a poison LD50 = ~10g/Kg orally in mice Nausea, vomiting, flushing, mental excitement or depression, drowsiness, impaired perception, loss of coordination, stupor, coma, death may occur (intoxication) Alcohols, synthesis: Hydrolysis of alkyl halides (CH3 or 1o) R-H R-X R-OH Acids NR NR  Bases NR some Active metals NR   Oxidation NR NR 1o/2o Reduction NR  NR Halogens NR NR NR  Alcohols, reactions: R-|-OH With HX With PX3 (later) RO-|-H As acids Ester formation Oxidation Reaction of alcohols with HX: (#1 synthesis of RX) R-OH + a) HX: HX  R-X + H2 O HI > HBr > HCl b) ROH: 3o > 2o > CH3 > 1o c) May be acid catalyzed d) Rearrangements are possible except with most 1o alcohols Most 1o? If large steric requirement… CH3 CH3CCH2-OH + CH3 neopentyl alcohol HBr CH3  CH3CCH2CH3 Br 2-bromo-2-methylbutane  CH3 CH3CCH2-OH2+  CH3  CH3 CH3CCH2+  CH3 1o carbocation CH3 CH3CCH2CH3 + 3o carbocation [1,2-CH3] With PX3 ROH + PX3  RX a) PX3 = PCl3, PBr3, P + I2 b) No rearrangements  c) ROH: CH3 > 1o > 2o CH3 CH3CCH2-OH CH3 neopentyl alcohol + PBr3  CH3 CH3CCH2-Br CH3 2,2-dimethyl-1-bromopropane Dehydration (later) 4) As acids a) With active metals: ROH + Na  RONa + ½ H2  b) With bases: ROH + NaOH  NR! CH4 < NH3 < ROH < H2O < HF CH3CH2OH + WA +  SB + NaNH2 SB + CH3CH2ONa SA CH3MgBr SA SA H2O WB CH3CH2OH CH3OH  NaOH SB CH4 + MgBr(OCH2CH3) WA  NH3 WA + WB CH3ONa WB Ester formation CH3CH2-OH + CH3CO2H, H+ CH3CH2-OH + CH3COCl CH3-OH CH3SO2Cl +  Esters are alkyl “salts” of acids   CH3CO2CH2CH3 CH3CO2CH2CH3 CH3SO3CH3 + HCl + + H2 O HCl O R C OH O R C ONa O R C OR' ester carboxylic acid sodium salt O R S OH O O R S OK O sulfonic acid potassium salt O HO P OH OH O HO P OR OH O HO P OR OR monoester diester phosphoric acid O R S OR' O ester O RO P OR OR triester "Lasso" chemistry O + R C O H O CH3C O H acetic acid H-O-R' + H+ O + R C O R' CH3 H-O CHCH3 isopropyl alcohol H+ H2O O + H2O CH3C CH3 O CHCH3 isopropyl acetate acid chloride + alcohol > ester O R C Cl O CH3C Cl + H-O-R' + H+ O + R C O R' CH3 H-O CHCH3 acetyl chloride isopropyl alcohol H+ HCl O + HCl CH3C CH3 O CHCH3 isopropyl acetate O R S Cl O sulfonyl chloride + H-O-R alcohol O R S O-R + HCl O sulfonate ester oxidation states of carbon - oxidation  CH4 CH3OH CH2O -4 -2  reduction - HCO2H CO2 +2 +4 Oxidation Oxidizing agents: KMnO4, K2Cr2O7, CrO3, NaOCl, etc Primary alcohols: CH3CH2CH2-OH + KMnO4, etc  CH3CH2CO2H carboxylic acid Secondary alcohols: OH CH3CH2CHCH3 O + K2Cr2O7, etc  CH3CH2CCH3 ketone Teriary alcohols: no reaction Primary alcohols can also be oxidized to aldehydes: CH3CH2CH2-OH + C5H5NHCrO3Cl  pyridinium chlorochromate CH3CH2CHO aldehyde or CH3CH2CH2-OH + K2Cr2O7, special conditions  Alcohols, synthesis: Hydrolysis of alkyl halides (CH3 or 1o) Alcohols, reactions: R-|-OH With HX With PX3 (later) RO-|-H As acids Ester formation Oxidation [...]... CH3COCl CH3-OH CH3SO2Cl +  Esters are alkyl “salts” of acids   CH3CO2CH2CH3 CH3CO2CH2CH3 CH3SO3CH3 + HCl + + H2 O HCl O R C OH O R C ONa O R C OR' ester carboxylic acid sodium salt O R S OH O O R S OK O sulfonic acid potassium salt O HO P OH OH O HO P OR OH O HO P OR OR monoester diester phosphoric acid O R S OR' O ester O RO P OR OR triester "Lasso" chemistry O + R C O H O CH3C O H acetic acid H -O -R' ... H+ O + R C O R' CH3 H -O CHCH3 isopropyl alcohol H+ H 2O O + H 2O CH3C CH3 O CHCH3 isopropyl acetate acid chloride + alcohol > ester O R C Cl O CH3C Cl + H -O -R' + H+ O + R C O R' CH3 H -O CHCH3 acetyl chloride isopropyl alcohol H+ HCl O + HCl CH3C CH3 O CHCH3 isopropyl acetate O R S Cl O sulfonyl chloride + H -O -R alcohol O R S O -R + HCl O sulfonate ester oxidation states of carbon - oxidation  CH4 CH3OH... with most 1o alcohols) : CH3 CH3CHCHCH3 + HBr  OH Br ↑  CH3 CH3CHCHCH3 OH2+ CH3 CH3CCH2CH3  Br- CH3 [1,2 -H] CH3 CH3CHCHCH3  CH3CCH2CH3 + + 2o carbocation 3o carbocation In the reaction of most 1o alcohols with HX you don't have to worry about the possibility of rearrangements The mechanism is SN2 and does not involve carbocations CH3CH2CH2CH2CH2-OH + HBr, H+ , heat 1-pentanol CH3CH2CH2CH2CH2-Br 1o. .. CH3OH CH 2O -4 -2 0  reduction - HCO 2H CO2 +2 +4 6 Oxidation Oxidizing agents: KMnO4, K2Cr 2O7 , CrO3, NaOCl, etc Primary alcohols: CH3CH2CH2-OH + KMnO4, etc  CH3CH2CO 2H carboxylic acid Secondary alcohols: OH CH3CH2CHCH3 O + K2Cr 2O7 , etc  CH3CH2CCH3 ketone Teriary alcohols: no reaction Primary alcohols can also be oxidized to aldehydes: CH3CH2CH2-OH + C 5H5 NHCrO3Cl  pyridinium chlorochromate CH3CH2CHO...CH3CH2CH2CH2-OH + NaBr, H2 SO4, heat  CH3CH2CH2CH2-Br n-butyl alcohol n-butyl bromide 1-butanol 1-bromobutane CH3 CH3C-OH CH3 + HCl  CH3 CH3C-Cl CH3 (room temperature) tert-butyl alcohol tert-butyl chloride 2-methyl-2-propanol 2-chloro-2-methylpropane CH3CH2-OH + HI, H+ , heat  CH3CH2-I ethyl alcohol ethyl iodide ethanol iodoethane Mechanism? CH3-OH and most 1o alcohols react with HX via SN2 mechanism... alcohol + PBr3  CH3 CH3CCH2-Br CH3 2,2-dimethyl-1-bromopropane 3 Dehydration (later) 4) As acids a) With active metals: ROH + Na  RONa + ½ H2  b) With bases: ROH + NaOH  NR! CH4 < NH3 < ROH < H 2O < HF CH3CH2OH + WA +  SB + NaNH2 SB + CH3CH2ONa SA CH3MgBr SA SA H 2O WB CH3CH2OH CH3OH  NaOH SB CH4 + MgBr(OCH2CH3) WA  NH3 WA + WB CH3ONa WB 5 Ester formation CH3CH2-OH + CH3CO 2H, H+ CH3CH2-OH + CH3COCl... 3o and 2o react with HX via SN1 mechanism Both mechanisms include an additional, first step, protonation of the alcohol oxygen: R- OH + H+  R- OH2+ “oxonium ion” Whenever an oxygen containing compound is placed into an acidic solution, the oxygen will be protonated, forming an oxonium ion Mechanism for reaction of an alcohol with HX: CH3OH or 1o alcohols: SN2 1) 2) R- OH X + + R- OH2 HX R- OH2 RDS R- X... 1o alcohol: No rearrangement, SN2 1-bromopentane Most 1o? If large steric requirement… CH3 CH3CCH2-OH + CH3 neopentyl alcohol HBr CH3  CH3CCH2CH3 Br 2-bromo-2-methylbutane  CH3 CH3CCH2-OH2+  CH3  CH3 CH3CCH2+  CH3 1o carbocation CH3 CH3CCH2CH3 + 3o carbocation [1,2-CH3] 2 With PX3 ROH + PX3  RX a) PX3 = PCl3, PBr3, P + I2 b) No rearrangements  c) ROH: CH3 > 1o > 2o CH3 CH3CCH2-OH CH3 neopentyl... + X H 2O Mechanism for reaction of an alcohol with HX: 2o or 3o alcohols: SN1 1) R- OH 2) R- OH2 3) R + + HX RDS X R- OH2 R R-X + H 2O + X May be catalyzed by acid SN2 rate = k [ ROH2+ ] [ X- ] SN1 rate = k [ ROH2+ ] Acid protonates the -OH, converting it into a better leaving group (H 2O) , increasing the concentration of the oxonium ion, and increasing the rate of the reaction Rearrangements are possible... oxidized to aldehydes: CH3CH2CH2-OH + C 5H5 NHCrO3Cl  pyridinium chlorochromate CH3CH2CHO aldehyde or CH3CH2CH2-OH + K2Cr 2O7 , special conditions  Alcohols, synthesis: 1 2 3 4 Hydrolysis of alkyl halides (CH3 or 1o) 5 6 7 8 Alcohols, reactions: R- |-OH 1 With HX 2 With PX3 3 (later) RO-| -H 4 As acids 5 Ester formation 6 Oxidation
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