1、Organic ChemistryAlcoholsand ThiolsStructure-AlcoholsuThe functional group of an alcohol is an-OH group bonded to an sp3 hybridized carbon bond angles about the hydroxyl oxygen atom are approximately 109.5uOxygen is sp3 hybridized two sp3 hybrid orbitals form sigma bonds to carbon and hydrogen the r
2、emaining two sp3 hybrid orbitals each contain an unshared pair of electrons1 10 08 8.9 9 O OC CH HH HH HH HNomenclature-AlcoholsuIUPAC names the parent chain is the longest chain that contains the OH group number the parent chain to give the OH group the lowest possible number change the suffix to u
3、Common names name the alkyl group bonded to oxygen followed by the word Nomenclature-AlcoholsuExamples1 1-P Pr ro op pa an no ol l(P Pr ro op py yl l a al lc co oh ho ol l)2 2-P Pr ro op pa an no ol l(I Is so op pr ro op py yl l a al lc co oh ho ol l)1 1-B Bu ut ta an no ol l(B Bu ut ty yl l a al lc
4、 co oh ho ol l)O O H HO O H HO O H H2 2-B Bu ut ta an no ol l(s se ec c-B Bu ut ty yl l a al lc co oh ho ol l)2 2-M M e et th hy yl l-1 1-p pr ro op pa an no ol l(I Is so ob bu ut ty yl l a al lc co oh ho ol l)2 2-M M e et th hy yl l-2 2-p pr ro op pa an no ol l(t te er rt t-B Bu ut ty yl l a al lc
5、co oh ho ol l)O O H HO O H HO O H Hc ci is s-3 3-M M e et th hy yl lc cy yc cl lo oh he ex xa an no ol lO O H HO O H HB Bi ic cy yc cl lo o 4 4.4 4.0 0 d de ec ca an n-3 3-o ol l1 14 45 58 81 10 09 91 12 22 23 33 34 45 56 67 76 6N N u um m b be er ri in ng g o of f t th he eb bi ic cy yc cl li ic c
6、r ri in ng g t ta ak ke es s p pr re ec ce ed de en nc ce e o ov ve er rt th he e l lo oc ca at ti io on n o of f -O O H HNomenclature of AlcoholsuCompounds containing more than one OH group are named diols,triols,etc.CH3CHCH2HO OHCH2CH2OH OHCH2CHCH2HO HO OH1,2-Ethanediol1,2-Ethanediol(Ethylene glyc
7、ol)(Ethylene glycol)1,2-Propanediol 1,2-Propanediol(Propylene glycol)(Propylene glycol)1,2,3-Propanetriol1,2,3-Propanetriol(Glycerol,Glycerine)(Glycerol,Glycerine)Nomenclature of AlcoholsuUnsaturated alcohols show the double bond by changing the infix from-an-to show the the OH group by the suffix n
8、umber the chain to give OH the lower number1 12 23 34 4 5 56 6 (E E)-2 2-H H e ex xe en ne e-1 1-o ol l(t tr ra an ns s-2 2-H H e ex xe en n-1 1-o ol l)H HO OPhysical PropertiesuAlcohols are polar compounds they interact with themselves and with other polar compounds by dipole-dipole interactions th
9、e attraction between the positive end of one dipole and the negative end of anotherO OH HH HH HC CH H Physical Properties:when the positive end of one dipole is an H bonded to F,O,or N(atoms of high electronegativity)and the other end is F,O,or N the strength of hydrogen bonding in water is approxim
10、ately 21 kJ(5 kcal)/mol hydrogen bonds are considerably weaker than covalent bonds nonetheless,they can have a significant effect on physical propertiesPhysical PropertiesuEthanol and dimethyl ether are constitutional isomers.uTheir boiling points are dramatically different ethanol forms intermolecu
11、lar hydrogen bonds which increase attractive forces between its molecules resulting in a higher boiling point there is no comparable attractive force between molecules of dimethyl etherbp-24bp-24C CEthanolEthanolbp 78bp 78C CDimethyl etherDimethyl etherCH3CH2OHCH3OCH3Physical PropertiesuIn relation
12、to alkanes of comparable size and molecular weight,alcohols have higher boiling points are more soluble in wateruThe presence of additional-OH groups in a molecule further increases solubility in water and boiling pointPhysical PropertiesStructural Form ul aStructural Form ul aNam eNam e bp bp(C)(C)
13、Sol ubi l i tySol ubi l i tyi n W ateri n W aterM M ethanolethanol32326565I Infi ni tenfi ni teE Ethanethane3030-89-89I Insol ubl ensol ubl eE Ethanolthanol46467878I Infi ni tenfi ni teP Propaneropane4444-42-42I Insol ubl ensol ubl e1-Propanol1-Propanol60609797I Infi ni tenfi ni teButaneButane58580
14、0I Insol ubl ensol ubl e1-Pentanol1-Pentanol88881381382.3 g/100 g2.3 g/100 g1,4-Butanedi ol1,4-Butanedi ol9090230230I Infi ni tenfi ni teH H exaneexane86866969I Insol ubl ensol ubl e8 g/100 g8 g/100 g11711774741-Butanol1-ButanolP Pentaneentane72723636I Insol ubl ensol ubl eC C H H3 3C C H H2 2C C H
15、H2 2O O H HC C H H3 3C C H H2 2C C H H2 2C C H H3 3C C H H3 3O O H HC C H H3 3C C H H3 3C C H H3 3C C H H2 2O O H HC C H H3 3C C H H2 2C C H H3 3C C H H3 3(C CH H2 2)3 3C C H H2 2O O H HH H O O C C H H2 2(C C H H2 2)2 2C C H H2 2O O H HC C H H3 3(C CH H2 2)4 4C C H H3 3C C H H3 3(C CH H2 2)2 2C CH H
16、2 2O O H HC C H H3 3(C CH H2 2)3 3C C H H3 3M M W WAcidity of AlcoholsuIn dilute aqueous solution,alcohols are weakly acidicC CH H3 3O OH H:H HO OH H C CH H3 3O O H H C CH H3 3O O-H H3 3O O+C CH H3 3O O:O OH HH HH H+=1 10 0-1 15 5.5 5p pK Ka a =1 1 5 5.5 5K Ka a =+Acidity of Alcohols(C C H H3 3)3 3C
17、 C O O H H(C C H H3 3)2 2C C H H O O H HC C H H3 3C C H H2 2O O H HH H2 2O OC C H H3 3O O H HC C H H3 3C C O O O O H HH H C Cl l1 15 5.5 51 15 5.7 71 15 5.9 91 17 71 18 84 4.8 8H H y yd dr ro og ge en n c ch hl lo or ri id de eA A c ce et ti ic c a ac ci id dM M e et th ha an no ol lW W a at te er r
18、E Et th ha an no ol l2 2-P Pr ro op pa an no ol l2 2-M M e et th hy yl l-2 2-p pr ro op pa an no ol lS St tr ru uc ct tu ur ra al l F Fo or rm m u ul la aS St tr ro on ng ge er r a ac ci id dW W e ea ak ke er r a ac ci id d*A A l ls so o g gi iv ve en n f fo or r c co om m p pa ar ri is so on n a ar
19、 re e p pK Ka a v va al lu ue es s f fo or r w w a at te er r,a ac ce et ti ic c a ac ci id d,a an nd d h hy yd dr ro og ge en n c ch hl lo or ri id de e.C C o om m p po ou un nd dp pK Ka a-7 7Acidity of AlcoholsuAcidity depends primarily on the degree of stabilization and solvation of the alkoxide
20、ion the negatively charged oxygens of methanol and ethanol are about as accessible as hydroxide ion for solvation;these alcohol are about as acidic as water as the bulk of the alkyl group increases,the ability of water to solvate the alkoxide decreases,the acidity of the alcohol decreases,and the ba
21、sicity of the alkoxide ion increasesReaction with MetalsuAlcohols react with Li,Na,K,and other active metals to liberate hydrogen gas and form metal alkoxidesuAlcohols are also converted to metal alkoxides by reaction with bases stronger than the alkoxide ion one such base is sodium hydride2 2C CH H
22、3 3O O H H2 2N N a a2 2C CH H3 3O O-N Na a+H H2 2S So od di iu um m m m e et th ho ox xi id de e(M M e eO O-N N a a+)+C CH H3 3C CH H2 2O O H HN Na a+H H-C CH H3 3C CH H2 2O O-N N a a+H H2 2E Et th ha an no ol lS So od di iu um mh hy yd dr ri id de eS So od di iu um m e et th ho ox xi id de e+Reacti
23、on with HX 3 alcohols react very rapidly with HCl,HBr,and HI low-molecular-weight 1 and 2 alcohols are unreactive under these conditions 1 and 2 alcohols require concentrated HBr and HI to form alkyl bromides and iodidesr re ef fl lu ux x1 1-B Br ro om m o ob bu ut ta an ne e1 1-B Bu ut ta an no ol
24、l+H H B B r rH H2 2O OH H2 2O OO O H HB B r rO OH H+H H2 2O O+H HC Cl l2 25 5 C CC Cl l2 2-M M e et th hy yl l-2 2-p pr ro op pa an no ol l2 2-C C h hl lo or ro o-2 2-m m e et th hy yl lp pr ro op pa an ne eReaction with HX with HBr and HI,2 alcohols generally give some rearranged product 1 alcohols
25、 with extensive -branching give large amounts of rearranged product2-Brom opentane2-Brom opentane3-Brom opentane3-Brom opentane(m ajor product)(m ajor product)3-Pentanol3-Pentanolheatheat+H H B B r r+H H2 2O OO O H HB B r rB B r ra product ofa product ofrearrangem entrearrangem ent 2 2-B Br ro om m
26、o o-2 2-m m e et th hy yl lb bu ut ta an ne e(a a p pr ro od du uc ct t o of f r re ea ar rr ra an ng ge em m e en nt t)2 2,2 2-D D i im m e et th hy yl l-1 1-p pr ro op pa an no ol l+H HB Br rH H2 2O OO O H HB Br rReaction with HXuBased on the relative ease of reaction of alcohols with HX(3 2 1)and
27、 the occurrence of rearrangements,uChemists propose that reaction of 2 and 3 alcohols with HX occurs by an SN1 mechanism,and involves a carbocation intermediateReaction with HX-SN1Step 1:proton transfer to the OH group gives an oxonium ionStep 2:loss of H2O gives a carbocation intermediateC C H H3 3
28、C C H H3 3C C H H3 3-C C-O O H H:H HH HH HO OO OH HH HC C H H3 3-C CC C H H3 3C C H H3 3:H HH HO O+r ra ap pi id d a an nd dr re ev ve er rs si ib bl le e+O OH HH HC C H H3 3-C CC C H H3 3C C H H3 3C C H H3 3C C H H3 3C C H H3 3-C C+:H HH HO O+A A 3 3 c ca ar rb bo oc ca at ti io on n i in nt te er
29、rm m e ed di ia at te es sl lo ow w,r ra at te ed de et te er rm m i in ni in ng gS SN N1 1+Reaction with HX-SN1Step 3:reaction of the carbocation intermediate(an electrophile)with halide ion(a nucleophile)gives the productC C H H3 3C C H H3 3C C H H3 3-C C+:C Cl lC C H H3 3-C C-C C l lC CH H3 3C CH
30、 H3 32 2-C C h hl lo or ro o-2 2-m m e et th hy yl lp pr ro op pa an ne e (t te er rt t-B Bu ut ty yl l c ch hl lo or ri id de e)f fa as st t+Reaction with HX-SN2u1 alcohols react with HX by an SN2 mechanismStep 1:rapid and reversible proton transferStep 2:displacement of HOH by halide ionR RC CH H2
31、 2-O O H H:H HH HH HO OR RC C H H2 2-O OH HH H:H HH HO O+r ra ap pi id d a an nd dr re ev ve er rs si ib bl le e+B Br r:-R R C C H H2 2-O OH HH HR RC CH H2 2-B Br r:H HH HO O+S SN N2 2+s sl lo ow w,r ra at te ed de et te er rm m i in ni in ng gReaction with HXuFor 1 alcohols with extensive -branchin
32、g SN1 is not possible because this pathway would require a 1 carbocation SN2 is not possible because of steric hindrance created by the -branching uThese alcohols react by a concerted loss of HOH and migration of an alkyl group Step 1:proton transfer gives an oxonium ion Step 2:concerted elimination
33、 of HOH and migration of a methyl group gives a 3 carbocation+O OH HO OH HH HH H+r ra ap pi id d a an nd d r re ev ve er rs si ib bl le e+O OH HH H2 2,2 2-D D i im m e et th hy yl l-1 1-p pr ro op pa an no ol lA A n n o ox xo on ni iu um m i io on nO OH HH H+O OH HH Hs sl lo ow w a an nd dr ra at te
34、 e d de et te er rm m i in ni in ng g (c co on nc ce er rt te ed d)O OH HH H+A A 3 3 c ca ar rb bo oc ca at ti io on ni in nt te er rm m e ed di ia at te eReaction with HXStep 3:reaction of the carbocation intermediate(an electrophile)with halide ion(a nucleophile)gives the product2 2-C Ch hl lo or
35、ro o-2 2-m m e et th hy yl lb bu ut ta an ne eC Cl l-+f fa as st tC Cl lReaction with PBr3uAn alternative method for the synthesis of 1 and 2 bromoalkanes is reaction of an alcohol with phosphorus tribromide this method gives less rearrangement than with HBrP PB B r r3 3H H3 3P PO O3 30 0 P Ph ho os
36、 sp ph ho or ro ou us sa ac ci id d+2 2-M M e et th hy yl l-1 1-p pr ro op pa an no ol l(I Is so ob bu ut ty yl l a al lc co oh ho ol l)P Ph ho os sp ph ho or ru us s t tr ri ib br ro om m i id de e1 1-B Br ro om m o o-2 2-m m e et th hy yl lp pr ro op pa an ne e(I Is so ob bu ut ty yl l b br ro om
37、m i id de e)O O H HB Br rReaction with PBr3Step 1:formation of a protonated dibromophosphite converts H2O,a poor leaving group,to a good leaving groupStep 2:displacement by bromide ion gives the alkyl bromideB Br rO O P PB Br r2 2R R-C CH H2 2H HP PB Br rB Br rB Br rR R-C CH H2 2-O O-H H+a a g go oo
38、 od d l le ea av vi in ng g g gr ro ou up p+Br -O O P PB Br r2 2R R-C CH H2 2H HR-CH2-BrHO-PBr2+SN2 Reaction with SOCl2uThionyl chloride is the most widely used reagent for the conversion of 1 and 2 alcohols to alkyl chlorides a base,most commonly pyridine or triethylamine,is added to catalyze the r
39、eaction and to neutralize the HClO O H HS SO O C C l l2 2C C l lS SO O2 2H H C C l lThionylThionylchloridechloride1-H eptanol1-H eptanol1-C hloroheptane1-C hloroheptanepyridinepyridine+Reaction with SOCl2uReaction of an alcohol with SOCl2 in the presence of a 3 amine is stereoselective it occurs wit
40、h inversion of configurationO O H HS SO O C Cl l2 2C Cl lS SO O2 2H HC Cl l+3 3 a am m i in ne e+(S S)-2 2-O O c ct ta an no ol lT Th hi io on ny yl lc ch hl lo or ri id de e(R R)-2 2-C Ch hl l o or ro oo oc ct ta an ne eReaction with SOCl2Step 1:formation of an alkyl chlorosulfiteStep 2:nucleophili
41、c displacement of this leaving group by chloride ion gives the chloroalkaneC CR R1 1H HR R2 2O OS SO OC Cl lC Cl l+C CR R1 1H HR R2 2C Cl l+C Cl l+O OS SO OS SN N2 2C CR R1 1H HR R2 2O O H HC Cl l-S S-C Cl lO OC CR R1 1H HR R2 2O OS SO OC Cl lH H-C Cl l+A A n n a al lk ky yl lc ch hl lo or ro os su
42、ul lf fi it te eAlkyl SulfonatesuSulfonyl chlorides are derived from sulfonic acids sulfonic acids,like sulfuric acid,are strong acidsA A sulfonyl sulfonylchloridechlorideA sulfonate anionA sulfonate anion(a very weak base and(a very weak base and stable anion;a verystable anion;a verygood leaving g
43、roupgood leaving groupA sulfonic acidA sulfonic acid(a very strong acid)(a very strong acid)R-S-OHR-S-O-R-S-ClOOOOOOAlkyl SulfonatesuA commonly used sulfonyl chloride is p-toluenesulfonyl chloride(Ts-Cl)+p-p-ToluenesulfonylToluenesulfonylchloridechloridepyridinepyridineEthyl Ethyl p-p-toluenesulfona
44、tetoluenesulfonate(Ethyl tosylate)(Ethyl tosylate)+EthanolEthanolO OO OC C l l-S SC C H H3 3C C H H3 3C C H H2 2O O H HH H C C l lC C H H3 3C C H H2 2O O-S SO OO OC C H H3 3Alkyl SulfonatesuAnother commonly used sulfonyl chloride is methanesulfonyl chloride(Ms-Cl)M M ethanesulfonylethanesulfonylchlo
45、ridechloride+pyridinepyridine+C yclohexyl C yclohexyl m ethanesulfonatem ethanesulfonate(C yclohexyl m esylate)(C yclohexyl m esylate)C yclohexanolC yclohexanolO O H HC C l l-S S-C C H H3 3O O-S S-C C H H3 3H H C C l lO OO OO OO OAlkyl SulfonatesuSulfonate anions are very weak bases(the conjugate ba
46、se of a strong acid)and are very good leaving groups for SN2 reactionsuConversion of an alcohol to a sulfonate ester converts HOH,a very poor leaving group,into a sulfonic ester,a very good leaving groupAlkyl SulfonatesuThis two-step procedure converts(S)-2-octanol to(R)-2-octyl acetateStep 1:format
47、ion of a p-toluenesulfonate(Ts)esterStep 2:nucleophilic displacement of tosylateO O H HT Ts sC Cl lO O T Ts sH HC Cl l(S S)-2 2-O O c ct ta an no ol l(S S)-2 2-O O c ct ty yl l t to os sy yl la at te e+p py yr ri id di in ne e+T To os sy yl lc ch hl lo or ri id de eO O-N N a a+O OO O T Ts sO OO ON N
48、 a a+O O T Ts s-(S S)-2 2-O O c ct ty yl l t to os sy yl la at te e+S So od di iu um ma ac ce et ta at te ee et th ha an no ol lS SN N2 2+(R R)-2 2-O O c ct ty yl l a ac ce et ta at te eDehydration of ROHuAn alcohol can be converted to an alkene by acid-catalyzed dehydration(a type of -elimination)1
49、 alcohols must be heated at high temperature in the presence of an acid catalyst,such as H2SO4 or H3PO4 2 alcohols undergo dehydration at somewhat lower temperatures 3 alcohols often require temperatures at or slightly above room temperature Dehydration of ROH180180C CCH3CH2OHH2SO4CH2=CH2 +H2O140140
50、C CCyclohexanolCyclohexanolCyclohexeneCyclohexeneOH+H2OH2SO4CH3COHCH3CH3H2SO4CH3C=CH2CH3+H2O5050C C2-Methyl-2-propanol2-Methyl-2-propanol(tert-tert-Butyl alcohol)Butyl alcohol)2-Methylpropene2-Methylpropene(Isobutylene)(Isobutylene)Dehydration of ROH where isomeric alkenes are possible,the alkene ha
