Chng 17

Chng 17-ALCOL V PHENOLAlcol v phenol c xem nh cc dn xut hu c ca nc, trong mt trong hai nguyn t hydrogen ca phn t nc c thay th bi mt nhm hu c: R-O-H v Ar-O-H (so vi H-O-H). Trong thc t, alcol l tn gi ca nhm cc hp cht hu c c nhm OH gn vi nguyn t carbon tp chng sp3, cn phenol l cc hp cht c nhm OH lin kt trc tip vi carbon ca vng thm, trong khi cc hp cht mang nhm OH lin kt vi carbon tp chng sp2 c gi l enol (xem phn enol chng 22).

Alcol hin din rng ri trong t nhin v c nhiu ng dng trong cng nghip v dc phm. V d, methanol l mt trong nhng ha cht quan trng nht ca tt c ha cht cng nghip. Trc y, methanol c sn xut bng cch chng ct g trong iu kin khng c khng kh, v vy cn c tn gi l alcol g. Ngy nay, M c khong 1,3 t galon (1 galon = 3,78541 lt) methanol c sn xut mi nm bng phn ng hon nguyn carbon monoxide bi kh hydrogen.

Methanol gy c i vi ngi, lm m mt ch vi lng nh (15 ml) v lm cht ngi vi lng ln hn (100-250 ml). Methanol c s dng trong cng nghip lm dung mi v lm nguyn liu u sn xut formaldehyde (HCHO) v acid acetic (CH3COOH).Ethanol l mt trong nhng hp cht hu c c con ngi iu ch v tinh ch u tin. T hng ngn nm trc, con ngi bit sn xut ra ethanol bng cch ln men cc loi ng cc v ng, n th k 12, ngi ta bit cch thu ethanol tinh cht bng cch chng ct. Ngy nay, M c khong 4 t galon ethanol c sn xut mi nm bng cch ln men cc nguyn liu nh: bp, la mch,Ethanol, loi khng dng lm ung, c iu ch bi phn ng hydrat ho ethylene vi xc tc acid. C khong 110 triu galon ethanol c sn xut hng nm M lm dung mi hoc ha cht trung gian cho cc ngnh cng nghip khc.

Phenol xut hin rng ri trong t nhin v cng l cc cht trung gian trong qu trnh tng hp cc sn phm cng nghip khc nhau nh cht kt dnh, cht kh trng. Bn thn phenol cng l mt cht ty u c tm thy trong nha than ; methyl salicylate l cht to mi c trong du lc ; v urushiol l cc thnh phn gy d ng ca cy si v dy thng xun. Lu rng t phenol va l tn ring ca hp cht hydroxybenzene v va l tn ca mt nhm hp cht.

17.1. TN GI CA ALCOL V PHENOL17.1.1. Tn gi ca alcolAlcol c phn thnh ba loi: bc mt (1), bc hai (2) v bc ba (3) ty thuc vo s lng cc nhm hu c lin kt vi carbon mang nhm hydroxyl.

Theo h thng IUPAC, gi tn alcol nh tn cc dn xut ca alkane tng ng km theo hu t -ol, bao gm 3 nguyn tc sau:Nguyn tc 1: chn mch carbon di nht c cha nhm hydroxyl lm mch chnh. Xut pht t tn ca alkane mch chnh tng ng, thay -e bi -ol.Nguyn tc 2: nh s mch alkane bt u t pha gn nhm hydroxyl hn.Nguyn tc 3: nh s cc nhm th theo v tr ca chng trong mch, lit k tn gi ca cc nhm th theo th t mu t v ch r v tr m nhm -OH c lin kt.

Mt vi alcol n gin v thng gp c tn gi thng thng c IUPAC chp nhn, tn ca cc alcol ny gm tn ca dy alkyl gn vi nhm -OH v tip theo l t alcol.

Lu v tr ca nhm -OH l s thp nht trong phn t c cha lin kt i C=C, nhm alkyl, hay nguyn t halogen. Th t v u tin trong cch gi tn cc nhm chc cho n chng ny nh sau:

Nu hp cht c cha nhiu hn mt nhm -OH th tn ca alcol c kt thc bng -diol cho hai nhm -OH, -triol cho ba nhm -OH,... Cc vicinal diol l cc diol c cc nhm hydroxyl trn cc carbon cnh nhau. Hai vicinal diol thng gp l 1,2-ethandiol v 1,2-propandiol.

Ethylen glycol v propylen glycol l cc tn gi thng thng cho cc diol ny v l cc tn gi IUPAC c th chp nhn. Tr hai hp cht ny, h thng IUPAC khng s dng t glycol gi tn cc diol.Tn ca cc gc R-O- (hnh thnh bng cch tch nguyn t H ca -OH) l t hp tn ca gc R v hu t oxy-. Th d:

Trng hp R ch cha t 1 n 5 carbon th s dng tn rt gn bng cch b yl. Th d:

i khi tn gi ca cc alcol c gi theo h thng tn gi carbinol. Theo h thng ny, cc alcol c xem nh xut pht t methyl alcol, CH3OH, bng cch thay th mt hay nhiu nguyn t hydro bi cc nhm khc. Mt cch n gin, gi tn cc nhm gn vo carbon mang nhm -OH v sau thm hu t -carbinol bao hm phn C-OH.

17.1.2. Tn gi ca phenolMt tn gi c ca benzene l phene, v dn xut hydroxyl ca n c gi l phenol. Tn gi ny ging nh nhiu tn gi thng thng khc c IUPAC chp nhn. T phenol c s dng nh mt tn ring (hydroxybenzene) v ng thi cng l tn gi ca mt nhm hp cht thm mang nhm th hydroxyl theo cc qui tc gi tn ca hp cht thm. Ch l t -phenol c s dng nh l tn mch chnh thay v t -benzene. Cng nh vy, o-, m- v p-cresol l cc tn gi c chp nhn cho cc dn xut th hydroxyl ca toluen. Nhiu hp cht th nhiu ln c gi tn nh l cc dn xut ca phenol. Vic nh s ca vng bt u t carbon mang nhm hydroxyl v tip din theo hng sao cho cc nhm th mang ch s thp nht, cc nhm th c lit k theo th t mu t.

Ba dn xut dihydroxyl ca benzene c th c gi tn l benzene-l,2-diol, 1,3-diol, v 1,4-diol tng ng, tuy nhin mi dn xut ny c bit di cc tn gi quen thuc tng ng l pyrocatechol, resorcinol v hydroquinon. Dn xut benzene-1,2,3-triol c tn gi thng thng l pyrogallol. Cc tn gi thng thng ny c IUPAC chp nhn.

Cc tn gi thng thng ca hai dn xut monohydroxyl ca naphthalen l 1-naphthol v 2-naphthol, y cng l tn gi c IUPAC cho php, chng cng thng c gi l - v -naphthol tng ng.Cc nhm carboxyl v acyl c th t u tin cao hn nhm hydroxyl phenolic trong vic xc nh tn gi c bn. Trong trng hp ny, nhm hydroxyl c xem nh mt nhm th.

17.2. TNH CHT CA ALCOL V PHENOLDng hnh hc xung quanh nguyn t oxygen trong phn t alcol v phenol tng t nh ca phn t nc. Gc ni R-O-H xp x gc t din (v d trong methanol l 109o) v oxygen mang trng thi tp chng sp3.Cng nh phn t nc, alcol v phenol c nhit si cao do kh nng to lin kt hydrogen. Nguyn t hydrogen phn cc dng trong phn t b i in t t do ca nguyn t oxygen m in trong phn t bn cnh ht v pha mnh to thnh lin kt yu gi cc phn t vi nhau. Cc phn t mun chuyn t trng thi lng sang trng thi hi phi ph v c lin kt lin phn t ny nn nhit si phi tng cao. V d cc phn t: propan-1-ol (MW=60), butane (MW=58) v chloroethane (MW=65), c trng lng phn t gn bng nhau nhng nhit si tng ng khc xa nhau, propan-1-ol si 97 oC, so vi butane l -0,5 oC v chloroethane l 12,5 oC.

Hnh 17.1. Lin kt hydrogen trong alcol v phenol. Sc ht yu gia hydrogen phn cc dng ca nhm -OH v nguyn t oxygen phn cc m gi cc phn t li vi nhau.Bng 17.1. im si v tan trong nc ca mt s alcol v hydrocarbon c trng lng phn t tng ng nhauCng thc hp chtTn giTrng lng phn tim si (C) tan trong nc

CH3OHMethanol3265khng gii hn

CH3CH3Ethan30-89khng tan

CH3CH2OHEthanol4678khng gii hn

CH3OCH3Dimethyl ether46-24khng tan

CH3CH2CH3Propan44-42khng tan

CH3CH2CH2OHPropan-1-ol6097khng gii hn

CH3CH2CH2CH3Butan580khng tan

CH3CH2CH2CH2OHButan-1-ol741178 g/100 g

CH3CH2CH2CH2CH3Pentan7236khng tan

HOCH2CH2CH2CH2OHButan-1,4-diol90230khng gii hn

CH3CH2CH2CH2CH2OHPentan-1-ol881382,3 g/100 g

CH3CH2CH2CH2CH2CH3Hexan8669khng tan

S khc nhau v tnh cht vt l gia cc alcol c trng lng phn t thp v cao l do s khc nhau v lc tng tc gia cc phn t ca chng. Nt c trng cu trc quan trng ca alcohol c trng lng phn t thp l nhm hydroxyl. Ging nh nc, lin kt hydro cc alcol ny c vai tr rt quan trng trong tnh cht vt l ca chng. Kh nng to thnh lin kt hydrogen ca cc alcol ny lm cho chng c im si cao v tan trong nc cao so vi cc alkane c cng trng lng phn t.Hiu qu ca lin kt hydrogen alcol c minh ho mt cch r rng bng cch so snh im si ca ethanol (78C) v ng phn nhm chc ca n, dimethyl ether (-24C). S khc nhau v im si gia hai hp cht ny l do s c mt ca nhm -OH phn cc ca alcol, nhm ny c kh nng to lin kt hydrogen gia cc phn t. Lin kt hydrogen lm tng lc ht gia cc phn t ethanol, do lm cho ethanol c im si cao hn so vi dimethyl ether. Khi phn alkyl ca alcol tng ln v kch thc cng vi s tng trng lng phn t, th phn alkyl ny ca phn t tr nn c nt c trng tri hn, v v mt cu trc, cc alcol ny tng t alkan hn l tng t nc. Do vy, i lc k nc tr nn quan trng hn bt k lin kt hydrogen no, nn im si v tan trong nc ca chng gn tng t alkan.V cc alcol c th tng tc vi nc bng lin kt hydrogen nn chng tan nhiu hn trong nc so vi cc alkan v alken c trng lng phn t tng ng. Methanol, ethanol, v propan-1-ol tan tt trong nc theo bt k t l no. Cc alcol c trng lng phn t cao hn th t tan trong nc hn v s tng kch thc ca phn hydrocarbon ca phn t cc alcol ny.So vi nc, mt tnh cht tng t khc l c alcol v phenol u l cc acid yu v base yu. Nh mt base yu, chng b proton ho thun nghch bi acid mnh to thnh ion oxonium, ROH2+

L mt acid yu, alcol v phenol phn li rt t trong dung dch long trong nc bng cch nhng proton cho nc, to ra H3O+ v ion alkoxide, RO-, hoc ion phenoxide, ArO-:

Nhc li cc tho lun trc y v nng acid (mc 2.7-2.11), lc acid ca mt acid bt k HA trong nc c th c biu th bi hng s acid, Ka

Cc hp cht c Ka nh hn (hoc pKa ln hn) th c tnh acid yu hn, trong khi cc hp cht c Ka ln hn (hay pKa nh hn) th c tnh acid mnh hn. Cc s liu trong bng 17.2 cho thy cc alcol n gin nh methanol v ethanol c tnh acid gn vi nc nhng s khc nhau gia cc nhm th c th c hiu ng ng k. V d: tert-butyl alcol c tnh acid yu hn nhng 2,2,2-trifluoroethanol li c tnh acid mnh hn.Bng 17.2. Hng s acid ca mt s alcol v phenolHp chtpKaAcid yu hn

(CH3)3COH18,00

CH3CH2OH16,00

H-OH (nc)15,74

CH3OH15,54

CF3CH2OH12,43

p-Aminophenol10,46

CH3SH10,30

p-Methylphenol10,17

Phenol 9,89

p-Clorophenol 9,38

p-Bromophenol 9,35Acid mnh hn

p-Nitrophenol 7,15

2,4,6-Trinitrophenol 0,60

B cn tr khng gian nhiu hn v kh solvat ho hnt b cn tr khng gianhn v d dng solvatho hnnh hng ca s th alkyl n tnh acid ca alcol trc ht l do s solvat ho ion alkoxide nhn c t s phn ly. Ion alkoxide cng d dng b solvat ho th cng bn, s to thnh n cng thun li v mt nng lng th tnh acid ca alcol cng mnh. Th d, nguyn t oxygen ca ion alkoxide khng b cn tr khng gian, ging nh ion alkoxide t methanol t b chng ngi lp th nn phn t nc d dng solvat ho. Nguyn t oxygen ca ion alkoxide b cn tr khng gian, nh ion alkoxide t tert-butyl alcol b chng ngi lp th ln, phn t nc kh solvat ho hn v do vy t c n nh hn.

10

Ion methoxide, CH3O- (pKa = 15,54)

lon tert-butoxide, (CH3)3CO- (pKa= 18,00)

Cc hiu ng cm (mc 16.4) cng c vai tr quan trng trong vic xc nh tnh acid ca alcol. Th d, cc nhm th halogen rt in t lm an nh ion alkoxide bng cch dn tri in tch trn th tch ln hn, do vy lm cho alcol c tnh acid hn. Chng hn khi so snh tnh acid ca ethanol (pKa = 16,00) v 2,2,2-trifluoroethanol (pKa = 12,43), hoc ca tert-butyl alcol (pKa = 18,00) v nonafluoro-tert-butyl alcol (pKa = 5,40).

Cc nhm rt in t lm an nh ion alkoxide V alcol c tnh acid yu hn acid carboxylic hay acid v c nn khng phn ng vi base yu nh amine hoc ion bicarbonate, chng ch phn ng hn ch vi hydroxide kim loi nh NaOH. Tuy nhin, alcol phn ng c vi kim loi kim v vi base mnh nh sodium hydride (NaH), sodium amide (NaNH2) v tc cht Grignard (RMgX). Bn thn cc alkoxide l cc base thng c s dng lm tc cht phn ng trong ho hc hu c. Cc alkoxide c gi theo tn h thng bng cch thm hu t -ate vo tn ca alcol, v d: methanol thnh methanolate. Kh nng phn ng ca cc alcol ROH trong phn ng vi cc kim loi kim gim xung vi s tng mc th. Methanol c kh nng phn ng cao nht v cc alcol bc ba c kh nng phn ng thp nht.

R = CH3 > 1o > 2o > 3o2-Methyl-2-propanol phn ng chm n mc n c th c s dng phn hy an ton lng d kali trong phng th nghim.Vy cc alkoxide l cc tc nhn phn ng hu ch trong tng hp hu c. V d, phn ng ca cc alkoxide cng knh vi cc haloalkan s cho s tch mt phn t HX to alken.

Cc alkoxide phn nhnh t hn tn cng cc haloalkan bng phn ng SN2 cho cc ether.

Phenol c tnh acid mnh hn alcol hng triu ln. Thc vy, mt vi phenol nh 2,4,6-trinitrophenol, c tnh acid vt tri so vi hu ht cc acid carboxylic. Mt bng chng thc t ca tnh acid ny l cc phenol ho tan c trong dung dch NaOH long. Do , phenol thng c th c tch ra khi hn hp mt cch n gin bng cch chit bng base t dung dch nc v sau acid ho thu phenol.

Phenol c tnh acid mnh hn alcol v anion phenoxide c an nh bi hiu ng cng hng ca h thng in t lin hp trong nhn thm. S gii to ca in tch m trn cc v tr ortho v para ca vng thm lm tng bn tng i ca anion phenoxide so vi phenol khng phn li v do lm h thp G ca phn ng phn li.

Cc phenol mang nhm th c tnh acid c th mnh hn hoc yu hn so vi chnh bn thn phenol, ty thuc vo nhm th ny l rt hay y in t (mc 16.4). Cc phenol mang nhm th rt in t lm tng tnh acid do cc nhm ny an nh in tch m, trong khi cc nhm th y in t lm gim tnh acid do chng lm tng mt in tch m.Trong trng hp nhm th rt in t l nitro gn v tr ortho hoc para c nh hng ng k n tnh acid ca phenol.

17.3. CC PHNG PHP TNG HP ALCOLAlcol gi v tr trung tm trong ha hc hu c. T alcol c th bin i thnh nhiu nhm hp cht khc nhau nh: alkene, alkyl halide, aldehyde, ketone, acid carboxylic, ester v ether. Ngc li, cc hp cht cht ny cng c th bin i thnh alcol ban u. Do , alcol ng vai tr trung tm trong s chuyn i qua li ca cc nhm chc hu c.

Hnh 17.2. V tr trung tm ca alcol trong ho hc hu c. Alcol c th c iu ch t nhiu nhm hp cht v chuyn ho thnh nhiu loi hp cht.Cc chng trc cp mt s phng php tng hp alcol, c th nhc li nh sau: alcol c th c iu ch bng cch hydrat ho alken. Nhn chung, phn ng hydrat ho trc tip alken vi dung dch acid l phn ng km hiu qu trong phng th nghim iu ch alcol, nn hai phng php gin tip thng c s dng hn. l s hydrobor ho/oxy ho cho sn phm cng syn v khng theo qui tc Markovnikov (mc 7.5), trong khi s oxymercur ho/hon nguyn cho sn phm hydrat ho tun theo qui tc Markovnikov (mc 7.4).

Cc 1,2-diol c th c iu ch bng cch hydroxyl ho trc tip alkene bi OsO4, tip theo l hon nguyn vi NaHSO3 hoc bng phn ng thy phn epoxide vi xc tc acid (mc 7.8). Phn ng OsO4 xy ra vi ho hc lp th syn cho mt cis diol, v s m vng epoxide xy ra vi ho hc lp th anti cho ra mt trans diol.

Nh cp mc 7.8, cc tin t cis- v trans- s khng r rng khi gi tn diol c ngun gc t 1-methylcyclohexene v trng hp ny trn vng c n 3 nhm th. Ngi ta c th s dng mt nhm th (r) lm tham chiu, trn c s nhm th khc c th l dng cis (c) hoc trans (t) i vi nhm th tham chiu ny. V d, trong 2 ng phn ca 1-methylcyclohexane-1,2-diol, nhm OH C-1 l nhm tham chiu (r-1), v do OH ti C-2 s hoc l cis (c-2) hoc l trans (t-2) i vi nhm OH C-1. V th, ng phn c ngun gc t cis hydroxyl ha c tn l 1-methylcyclohexane-r-1,c-2-diol, cn ng phn c ngun gc bi trans hydroxyl ha th c gi tn l 1-methylcyclohexane-r-1,t-2-diol.17.4. ALCOL T S HON NGUYN HP CHT CARBONYLPhng php chung iu ch cc alcol, c trong phng th nghim v trong c th sng, l bng phn ng hon nguyn hp cht carbonyl. Ging nh s hon nguyn ca mt alkene bng cch cng hydrogen vo lin kt C=C cho alkane (mc 7.7), s hon nguyn hp cht carbonyl bng cch cng hp hydrogen vo lin kt C=O cho ra alcol. Tt c cc hp cht c nhm chc carbonyl u c th c hon nguyn, bao gm aldehyde, ketone, acid carboxylic v ester.

17.4.1. Hon nguyn aldehyde v ketone Hon nguyn aldehyde cho ra alcol bc mt, trong khi hon nguyn ketone to alcol bc hai.

Hng chc tc nhn c s dng trong phng th nghim hon nguyn aldehyde v ketone ty thuc vo tng trng hp c th, song natri borohydride (NaBH4) thng c chn lm tc nhn hon nguyn aldehyde v ketone do tnh an ton v d vn chuyn. NaBH4 l cht rn kt tinh mu trng, c th cn trong iu kin kh quyn v c s dng trong dung dch nc hoc alcol cho sn phm vi hiu sut cao.

Hon nguyn aldehyde:

Hon nguyn ketone

Litium nhm hydride LiAlH4 cng l mt tc nhn thng s dng hon nguyn aldehyde v ketone. LiAlH4 dng bt mu xm tan trong ether v tetrahydrofuran, LiAlH4 c hot tnh cao hn NaBH4 nhng nguy him hn. N cho phn ng mnh vi nc v phn hy gy n khi un nng trn 120 oC. Nu dng LiAIH4 hay NaBH4 th ch hon nguyn ni i C=O, cn lin kt C=C vn c bo ton.

C ch ca cc phn ng hon nguyn s c trnh by c th chng 19. y, lu rng phn ng bao gm s cng ca ion hydride thn hch (:H-) vo nguyn t carbon phn cc dng v l tm thn in t. Sn phm ban u l mt ion alkoxide c proton ho bng cch thm H3O+ trong bc th hai cho sn phm alcol.

Trong c th sng, hon nguyn aldehyde v ketone c thc hin hoc bng cc coenzyme NADH (nicotinamide adenine dinucleotide, dng hon nguyn) hoc NADPH (nicotinamide adenine dinucleotide phosphate, dng hon nguyn). Mc d cc tc nhn sinh hc c phc tp hn v mt cu trc so vi NaBH4 hoc LiAIH4, song c ch ca cc phn ng trong phng th nghim v trong sinh hc l tng t nhau. Coenzyme hot ng nh cht cho ion hydride, v anion trung gian sau c proton ho bi acid. Th d, s hon nguyn ca acetoacetyl ACP thnh -hydroxybutyryl ACP, mt bc trong sinh tng hp cc cht bo (Hnh 17.3). Ch rng hydrogen pro-R ca NADPH l hydrogen c chuyn trong v d ny. Cc phn ng c xc tc bi enzyme thng xy ra vi tnh c trng cao, mc d thng khng th d on trc c v kt qu ho hc lp th.

Hnh 17.3 S hon nguyn sinh hc ca ketone (acetoacetyl ACP) thnh alcol (-hydroxybutyryl ACP) bng NADPH.17.4.2. Hon nguyn acid carboxylic v esterHon nguyn acid carboxylic v ester cho alcol bc mt:

Cc phn ng ny khng xy ra nhanh nh phn ng hon nguyn aldehyde v ketone. NaBH4 hon nguyn ester rt chm v khng hon nguyn c cc acid carboxylic. V vy, hon nguyn acid carboxylic v ester thng s dng tc nhn mnh hn l LiAIH4. Tt c cc nhm carbonyl, bao gm acid carboxylic, ester, aldehyde, ketone d dng c hon nguyn bng tc nhn ny. Ch rng trong qu trnh hon nguyn aldehyde v ketone ch c mt nguyn t hydrogen c a n nguyn t carbon carbonyl, trong khi hon nguyn acid carboxylic v ester th c n hai nguyn t hydrogen to lin kt vi carbon carbonyl ban u. C ch ca phn ng ny s c cp chng 21.Hon nguyn acid carboxylic:

Hon nguyn ester:

17.5. ALCOL T PHN NG CA HP CHT CARBONYL VI TC CHT GRIGNARDMc 10.7 cho thy cc alkyl, aryl v vinylic halide phn ng vi magne trong ether hay trong tetrahydrofuran sinh ra tc cht Grignard, RMgX, tc nhn ny hot ng nh mt tm thn hch. Cc hp cht c cha lin kt carbon-kim loi nh cht phn ng Grignard v C-Lithi (cht phn ng lithi) c gi l cc hp cht c-kim loi. Cht phn ng Grignard c cha lin kt carbon-magne trong khi cht phn ng lithi li cha lin kt carbon-lithi. Cc hp cht ny phn ng vi hp cht carbonyl s cho alcol theo cch ging nh tc nhn hydride hon nguyn hp cht carbonyl. y l phng php chung tng hp alcol. Phng trnh phn ng chung nh sau:

Phn ng ca tc cht Grignard vi cc hp cht carbonyl khng c phn ng sinh hc trc tip tng ng, do cc hp cht c-magne c tnh base qu mnh trong mi trng nc. Tuy nhin, phn ng sinh hc gin tip xy ra l do s cng hp ca cc tm carbon thn hch bn vo cc hp cht carbonyl c s dng trong hu ht cc con ng trao i cht nh l qu trnh ch yu to thnh cc lin kt carbon-carbon, phn ny s c trnh by chng 23.Alcol bc 1o, 2o v 3o c th c iu ch t phn ng gia tc cht Grignard v carbonyl. Chng hn, tc cht Grignard phn ng vi formaldehyde cho alcol bc mt, vi aldehyde cho alcol bc hai v vi ketone cho alcol bc ba.

Ester phn ng vi tc cht Grignard cho alcol bc ba, trong hai nhm th lin kt vi carbon mang nhm hydroxyl l t tc cht Grignard, ging nh s hon nguyn LiAlH4 ca mt ester cng thm hai hydrogen. Th d di y cho thy trong cng thc alcol bc 3o mang 2 nhm methyl t tc cht Grignard methylmagnesium bromide.

Acid carboxylic khng cho phn ng cng hp vi tc cht Grignard, v hydrogen carboxyl c tnh acid phn ng vi tc cht Grignard c tnh base cho hydrocarbon tng ng v mui ca acid carboxylic. Ta thy phn ng ny nh l s kh ho mt alkyl halide thnh mt alkan.

Phn ng Grignard tuy rt thng dng nhng cng c mt vi hn ch. Tc cht Grignard khng th iu ch t dn xut halide c nhm chc khc c kh nng phn ng trong cng mt phn t. Chng hn, mt hp cht c c nhm alkyl halide v nhm keton khng th c to thnh tc cht Grignard v xy ra phn ng Grignard ni phn t. Tng t, hp cht c c nhm alkyl halide v nhm acid carboxylic, alcol, hay amin cng khng th c to thnh tc cht Grignard v cc hydrogen hin din trong cng phn t RCOOH, ROH hay RNH2 s phn ng nhanh vi tc cht Grignard c tnh base khi n c to thnh. Ni chung tc cht Grignard khng th iu ch t cc alkyl halide c cha cc nhm chc sau y ( y, FG = nhm chc, Functional Group):

Tc cht Grignard cng vo cc nhm nyTc cht Grignard b proton ho bi cc nhm nyXt v c ch phn ng, cn ch l tc cht Grignard th hin nh mt carbon anion thn hch hoc carbanion (:R-), v s cng hp ca tc cht Grignard vo hp cht carbonyl tng t nh s cng hp ca ion hydride. Ion trung gian alkoxide b proton ho bc tip theo bng H30+ cho alcol:

17.6. PHN NG CA ALCOL Cc phn ng ca alcol c th c chia thnh hai loi: phn ng t ni C-O v phn ng t ni O-H.

Phn ng t ni O-H

Phn ng t ni C-O

17.6.1. Chuyn ha alcol thnh alkyl halogenurAlcol bc 3 phn ng d dng vi HCl hoc HBr 0 oC theo c ch SN1 thng qua trung gian carbocation. Tuy nhin, alcol bc 2 v bc 1 c tnh khng acid mnh nn chuyn ha cc alcol ny thnh halogenur cch tt nht l s dng SOCl2 hoc PBr3, trong trng hp ny phn ng theo c ch SN2.Phn ng ca alcol bc 3 vi HX din ra theo c ch SN1, u tin acid s proton ha nguyn t oxygen ca nhm OH, sau loi b phn t nc cho ra ion carbocation v ion ny phn ng vi halogenur thn hch cho ra sn phm halogenur alkyl.

Phn ng ca alcol bc 1 v bc 2 vi SOCl2 hoc PBr3 xy ra theo c ch SN2. Bn thn nhm hydroxide l nhm xut rt km bi tc nhn thn hch trong phn ng SN2, tuy nhin phn ng ca alcol vi SOCl2 hoc PBr3 s chuyn i nhm OH thnh nhm xut d dng hn, sau nhm chlorosulfite(-OSOCl) hoc dibromophosphite (-OPBr2) nhanh chng c loi b bi nhm th thn hch tc kch t pha sau.

17.6.2. Chuyn ha alcol thnh tosylateAlcol phn ng vi p-toluenesulfonyl chloride (tosyl chlorie, p-TosCl) trong dung mi pyridine cho ra alkyl tosylate, ROTos (mc 11.1). Phn ng ny ch lm t ni O-H ca alcol m thi, cn ni C-O vn cn nguyn vn, do khng xy ra s thay i cu hnh nu oxygen c gn vi tm th tnh. Qu trnh to ra sn phm alkyl tosylate cng tng t nh alkyl halide u tri qua c hai phn ng th SN1 v SN2.

Thun li c bit ca cc ester sulfonate l ch thng qua vic s dng chng, mt nhm hydroxyl, l nhm rt kh b th, c th c bin i thnh mt nhm tosylate (-OTS) hay mesylate (-OMs). C hai nhm ny u l nhm xut tt, d dng c thay th bng nhm th thn hch.Mt trong nhng l do quan trng ca vic s dng tosylate trong cc phn ng SN2 l ha hc lp th. Phn ng SN2 ca alcol i qua alkyl halide xy ra hai ln nghch chuyn cu hnh, mt ln trong phn ng to ra halide t alcol v mt ln trong phn ng thay th halide, v do sn phm c cng cu hnh vi alcol ban u. Tuy nhin, phn ng SN2 ca alcol i qua tosylate ch xy ra mt ln nghch chuyn cu hnh nn sn phm c cu hnh ngc vi alcol ban u. Hnh 17.4 cho thy cc phn ng trn i phn R ca octan-2-ol v minh ha mi quan h ha hc lp th tng ng.

Hnh 17.4. Kt qu ha hc lp th ca phn ng SN2 trong hp cht (R)-octan-2-ol. S thay th i qua halide cho sn phm c cng ha hc lp th vi alcol ban u; s thay th i qua tosylate to sn phm c ha hc lp th ngc vi alcol ban u.

17.6.3. Phn ng kh nc ca alcol thnh alkenePhn ng quan trng th ba ca alcol l s kh nc cho ra alkene, l mt trong nhng phng php c s dng to alkene c trong phng th nghim v trong cc con ng sinh hc. Phn ng ny c s t ni lin kt C-O v C-H k cn hnh thnh lin kt ca alkene.

Phn ng kh nc

Do s tin li ca phn ng nn rt nhiu cch c ra thc hin s kh nc. V nhm hydroxyl -OH l mt nhm xut km, nn cn chuyn nhm ny thnh nhm H2O+ l mt nhm xut tt hn. Thay v s dng cc acid c tnh thn hch HBr v HI (do base lin hp c tnh thn hch mnh), th cc acid khng c tnh thn hch, nh H3PO4 hoc H2SO4, c s dng. y l mt phng php c bit tt i vi alcol bc ba iu ch alkene (mc 7.1). Th d, khi un nh 1-methylcyclohexanol vi dung dch H2SO4 trong dung mi THF s thu c 1-methylcyclohexene do s mt mt phn t nc ca alcol.

Phn ng kh nc ca alcol bi xc tc acid thng tun theo qui tc Zaitsev (mc 11.7) v alkene bn hn s l sn phm chnh. V th, phn ng kh nc ca alcol 2-methylbutan-2-ol cho sn phm chnh l 2-methylbut-2-ene (cha lin kt i mang 3 nhm th) v sn phm ph l 2-methylbut-1-ene (lin kt i mang 2 nhm th)

Phn ng kh nc ca 1-methylcyclohexanol xy ra theo c ch E1 v tri qua 3 bc (xem hnh 17.5). Ging nh cc phn ng theo c ch E1 thng thng (mc 11.10), ch cc alcol bc ba mi d dng b kh nc vi acid. Alcol bc hai cng c th phn ng c, nhng vi iu kin khc khe hn (H2SO4 75%, 100C) v cc phn t km bn th khng tn ti. Cn phn ng ca alcol bc 1 thm ch cn km hn c alcol bc 2 v iu kin phn ng ht sc khc nghit cho s kh nc (H2SO4 95%, 150C). Do , th t v kh nng phn ng kh nc vi xc tc acid nh sau:

1. Hai in t t nguyn t oxygen lin kt vi H+ to ra alcol trung gian b proton ha ho.3. Hai in t ca lin kt C-H bn cnh to thnh lin kt alkene, v tch H+ (proton)2. t ni C-O, v hai in t lin kt i cng oxygen, li trung gian carbocation.321

Hnh 17.5 C ch phn ng kh nc to alken ca alcol bi xc tc acid. Qu trnh l phn ng kh E1 bao gm mt trung gian carbocation. C th hiu r th t kh nng phn ng kh nc ca alcol khi xem xt c ch phn ng kh E1 bao gm 3 bc. Trc tin l proton ho oxygen ca alcol, sau mt phn t nc to trung gian carbocation v cui cng l s mt H+ t nguyn t carbon bn cnh to alkene. Cc alcol bc ba lun phn ng nhanh nht trong phn ng ny do s to thnh trung gian carbocation bc ba c an nh cao. trnh vic s dng acid mnh v phn ng kh nc ca alcol bc hai vn thc hin c, nhiu tc cht phn ng c pht trin v mang li hiu qu iu kin base. Th d nh tc cht phosphorus oxychloride (POCl3) trong dung mi pyridine (c vai tr l mt amin base), v tc cht ny c th kh nc cc alcol bc hai v bc ba kh hiu qu 0C.

Phn ng kh nc ca alcol thc hin vi POCl3 trong pyridine xy ra theo c ch E2 (xem hnh 17.6). Do ion hydroxide l nhm xut km, nn s tch H2O t alcol bng phn ng kh E2 trc tip s khng xy ra. Tuy nhin, phn ng vi POCl3, nhm -OH c chuyn ho thnh dichlorophosphate (-OPOCl2), y l nhm xut tt v phn ng kh E2 din ra nhanh chng. Pyridin ng vai tr va l dung mi phn ng va l base loi b proton bn cnh trong bc kh E2.

2. Sau s kh E2 xy ra theo c ch mt bc thng thng, base amin (pyridine) tch proton t carbon bn cnh ng thi nhm dichlorophosphate b tch ra cng lc.1. Nhm hydroxyl alcol phn ng vi POCl3 to thnh trung gian dichlorophosphate.Hnh 17.6 C ch phn ng kh nc ca alcol bc hai v bc ba bng phn ng vi POCl3 trong pyridine. Phn ng theo c ch E2.

Nh c lu trong mc 11.10, s kh nc sinh hc cng ph bin v thng xy ra theo c ch ElcB trn cht nn, trong nhm -OH nm cch nhm carbonyl 2 nguyn t carbon. Ly v d s kh nc xy ra trong qu trnh sinh tng hp amino acid thm tyrosine. u tin, base tch proton t carbon lin k vi nhm carbonyl, sau trung gian anion va trc xut nhm -OH va proton ha ng thi bng acid (HA) to thnh nc.

17.6.4. Chuyn ha alcol thnh esterAlcol phn ng vi acid carboxylic to thnh ester l phn ng rt ph bin c trong phng th nghim v c th sng. Trong phng th nghim, phn ng c th tin hnh ch vi mt bc nu dng acid mnh lm xc tc. D vy, kh nng phn ng ca acid carboxylic s tng ln bng cch chuyn n thnh chloride ca acid carboxylic trc ri mi cho phn ng vi alcol. C ch phn ng chi tit ca cc phn ng s c cp chng 21.

Trong c th sng cng xy ra qu trnh tng t, mc d thioester hoc acyl adenosyl phosphate l cht nn ch khng phi chloride acid carboxylic.

17.7. OXID HA ALCOLC l mt trong cc phn ng c gi tr nht ca alcol l s oxid ho ca chng thnh hp cht carbonyl qu trnh ngc li ca phn ng hon nguyn hp cht carbonyl thnh alcol. Oxid ha alcol bc mt cho ra aldehyde hoc acid carboxylic, alcol bc hai thnh ketone, cn alcol bc ba khng phn ng theo cch thng thng vi hu ht cc tc nhn oxid ho.

S oxy ho alcol bc mt v bc hai c th c thc hin vi nhiu tc cht oxid ho nh: KMnO4, CrO3 v Na2Cr2O7. Cht oxid ho no c s dng trong tng trng hp c th ty thuc vo cc yu t nh gi c, s tin li, hiu sut phn ng, v kh nng phn ng ca alcol. Th d, oxy ho mt lng ln alcol n gin v khng t tin nh cyclohexanol th tt nht s dng cht oxid ho r tin nh Na2Cr2O7. Mt khc, s oxid ho d qui m nh cc alcol a chc t tin v tinh t cng phi thc hin trong iu kin tt nht vi tc cht phn ng nh nhng cho hiu sut cao v bt chp gi c.Oxid ha alcol bc mt cho ra aldehyde hoc acid carboxylic ty thuc vo tc nhn oxid ha s dng v iu kin thc hin phn ng. Mt trong nhng phng php tt nht iu ch aldehyde t alcol bc mt qui m phng th nghim l s dng pyridium chlorochromate (PCC, C6H5NCrO3Cl) trong dung mi dichloromethane lm tc nhn oxid ha.

Hu ht cc tc nhn oxid ho khc, nh chromium trioxide (CrO3) trong dung dch acid, oxid ho alcol bc mt n acid carboxylic. Aldehyde l sn phm trung gian trong phn ng ny nhng khng th c lp c v phn ng oxid ha xy ra qu nhanh.

Alcohol bc hai b oxid ho d dng cho ra ketone vi hiu sut cao. Khi oxid ho lng ln, c th s dng cht oxid ho r tin nh Na2Cr2O7 trong dung dch acid acetic long. Tuy nhin, vi nhng alcol qu v d phn hy th thng dng pyridinium chlorochromate oxid ha do phn ng m du v xy ra nhit thp.

Tt c cc phn ng oxy ho ny xy ra theo con ng gn vi phn ng E2 (mc 11.8). Trc tin, alcol phn ng vi Cr(VI) to thnh trung gian chromate, tip theo l tch nhm chromium (nh mt nhm xut) cho sn phm carbonyl. Mc d phn ng E2 thng c cho l phn ng to thnh lin kt i carbon-carbon bng cch tch nhm xut halide, phn ng trn cng to ra lin kt i carbon-oxygen bng s tch ra ca kim loi b kh nh l nhm xut. C ch trn c tm tt nh sau:

Qu trnh oxid ha cc phn t alcol sinh hc hon ton ngc li qu trnh hon nguyn carbonyl sinh hc v c thc hin bi cc coenzyme NAD+ v NADP+. Base s ly proton ca nhm -OH, v ion alkoxide chuyn ion hydride vo kt hp vi coenzyme NAD+. Th d, qu trnh oxid ha sn-glycerol 3-phosphate to thnh dihydroxyacetone phosphate, mt bc trong qu trnh chuyn ha sinh hc ca cht bo (hnh 17.7). Lu , vic thm ch xy ra trn phn Re ca vng NAD+, thm mt hydrogen vi ha hc lp th pro-R.

Hnh 17.7 Qu trnh oxid ha sinh hc ca alcol (sn-glycerol 3-phosphate) cho ra ketone (dihydroxyacetone phosphate). C ch ny hon ton ngc li vi s hon nguyn ketone hnh 17.3.17.8. BO V ALCOLVn thng xy ra trong tng hp hu c nht l nhng phn t phc tp cha nhiu nhm chc, l mt nhm chc trong phn t gy tr ngi cho phn ng d kin ca mt nhm chc khc u trong cng phn t. Mt v d d thy trong chng ny l tc cht Grignard khng th c iu ch t haloalcol bi v lin kt C-Mg khng th tn ti ng thi vi nhm -OH c tnh acid trong cng mt phn t.

Khi kiu khng tng thch gia cc nhm chc trong cng phn t xy ra, i khi cn phi bo v nhm chc gy tr ngi. Vic bo v bao gm 3 bc:1. Gn nhm bo v vo v hiu ha nhm chc gy tr ngi,2. Tin hnh phn ng mong mun,3. Tho b nhm bo v.Mt trong nhng phng php thng thng bo v alcol l cho alcol phn ng vi chlorotrialkylsilane, Cl-SiR3, cho ra trialkylsilyl ether, R-O-SiR3. Chlorotrimethylsilane thng c s dng v tin hnh phn ng vi s c mt ca base chng hn nh triethylamine. Base ng vai tr gip to thnh anion alkoxide t alcol v trung ha lng HCl to ra trong qu trnh phn ng.

Bc to thnh ether ca phn ng trn ging nh phn ng SN2 ca ion alkoxide trn nguyn t silic, ng thi mt anion chloride. Khng ging nh cc phn ng SN2 thng thng, phn ng ny din ra ti mt tm tam cp- silic mang 3 nhm th. Phn ng xy ra c l do silic, nguyn t thuc chu k 3, c bn knh ln hn carbon v dng lin kt di hn. V vy, ba nhm th methyl gn vi nguyn t silic t chng ngi lp th hn khi phn ng so vi tert-butyl chloride.

Ging nh hu ht cc ether khc (s cp chng 18), ether TMS hu nh khng phn ng. Ether TMS khng cha hydrogen c tnh acid v khng phn ng vi cc tc nhn oxid ho, tc nhn hon nguyn hay tc cht Grignard. Tuy nhin, chng phn ng vi dung dch acid hoc vi ion fluoride ti to alcol.

gii quyt vn t ra phn u ca mc 17.8, c th s dng halo alcol trong phn ng Grignard bng cch thc hin th t bo v nh v d trong hnh 17.8

Hnh 17.8 S dng TMS bo v alcol trong phn ng Grignard.

17.9. PHENOL V NG DNGTrong lch s, khi chin tranh th gii th nht bng n to iu kin kch thch ngnh cng nghip tng hp phenol pht trin, phc v cho nhu cu s dng phenol lm nguyn liu th sn xut thuc n, acid picric (2,4,6-trinitrophenol). Ngy nay, c khong 8 triu tn phenol c sn xut trn ton th gii mi nm s dng trong cc sn phm nh nha Bakelite v keo dn vn p.Phenol c sn xut trong nhiu nm theo trnh Dow, trong qui trnh ny chlorobenzene phn ng vi dung dch NaOH nhit v p sut cao (mc 16.8). Tuy nhin, hin nay mt qui trnh tng hp khc i t isopropylbenzene (cumene) c p dng. Phn ng gia cumene vi khng kh nhit cao to thnh cumene hydroperoxide do phn ng oxid ha benzylic theo c ch gc t do, cht ny sau khi x l vi acid s chuyn thnh phenol v acetone. y l mt qu trnh c bit hiu qu v hai ha cht c gi tr c iu ch cng lc.

Hnh 17.9 C ch to thnh phenol bi phn ng chuyn v cumene hydroperoxide vi xc tc acid.

Nh trong hnh 17.9, phn ng xy ra bi s proton ha oxygen, sau nhm phenyl chuyn di t carbon n oxygen ng thi mt i phn t nc. Phn t nc li tip tc tc kch cho ra trung gian c tn gi l hemiacetal - hp cht c cha mt nhm -OR v mt nhm -OH lin kt trn cng carbon, thy gii hp cht ny trong mi trng acid cho ra ng thi phenol v acetone.Ngoi vic s dng lm nha v keo dn, phenol cng l nguyn u cho qu trnh tng hp cc hp cht phenol gn clo v cc cht bo qun thc phm BHT (butylated hydroxytoluene) v BHA (butylated hydroxyanisole). Pentachlorophenol, mt cht bo qun g c s dng rng ri, c iu ch bng phn ng ca phenol vi lng d Cl2. Thuc dit c 2,4D (acid 2,4dichlorophenoxyacetic) c iu ch t 2,4-dichlorophenol, v cht kh trng s dng trong cc bnh vin hexachlorophene c iu ch t 2,4,5-trichlorophenol.

Cht bo qun thc phm BHT c iu ch bi phn ng alkyl ha Friedel-Crafts p-methylphenol (p-cresol) vi 2-methylpropene c mt xc tc acid. Cn BHA cng c iu ch tng t bi phn ng alkyl ha vi p-methoxyphenol.

17.10. PHN NG CA PHENOL 17.10.1. Phn ng th thn in t trn nhn hng phng:Nhm OH trong phenol l nhm tng hot v nh hng ortho- v para- trong phn ng th thn in t trn nhn hng phng (mc 16.4). Do , phenol c phn ng cao vi cc tc nhn thn in t v d cho phn ng halogen ha, nitro ha, sulfon ha v Friedel-Crafts.

17.10.2. Phn ng oxid ha phenol to thnh quinone:Do phenol khng c nguyn t hydrogen gn vi carbon mang nhm hydroxyl, nn phenol khng b oxid ha ging nh kiu oxid ha alcol. Thay vo , phn ng ca phenol vi tc nhn oxid ha mnh cho ra cyclohexa-2,5-diene-1,4-dione, hay quinon. Nhiu tc nhn oxid ha khc nhau s tham gia thc hin phn ng, v d vi cc phenol n gin th la chn ph bin l dng Na2Cr2O7, cn kali nitrosodisulfonate [(KSO3)2NO], mui Fremy, c s dng trong cc trng hp phc tp hn. Phn ng din ra m du v theo c ch gc t do.

Do va c tnh oxid ha va c tnh hon nguyn, nn quinone l nhm hp cht th v v c nhiu gi tr. Chng c th hon nguyn d dng thnh hydroquinone (p-dihydroxybenzene) bng cc tc nhn NaBH4, SnCl2, v cng d dng oxid ha tr li thnh quinone bi Na2Cr2O7.

Tnh cht va oxid ha va hon nguyn ca cc quinone ng vai tr quan trng i vi cc hot ng sng ca t bo, trong cc hp cht c gi l ubiquinone hot ng nh tc nhn oxid ha sinh ha, lm trung gian trong cc qu trnh vn chuyn in t lin quan n sn xut nng lng. Ubiquinone cn c gi l coenzyme Q, l thnh phn ca cc t bo trong tt c sinh vt hiu kh, t vi khun n gin nht cho n con ngi. S d c tn gi Ubiquinone nh vy l do chng xy ra khp ni trong t nhin.

Ubiquinone thc hin chc nng trong ty th ca t bo l lm trung gian cho qu trnh h hp, trong cc electron c vn chuyn t tc cht kh sinh hc NADH n phn t oxygen. Thng qua mt lot cc bc phc tp, kt qu cui cng l mt chu trnh phn ng, trong chu trnh ny NADH b oxid ha thnh NAD+, O2 b kh thnh nc v nng lng c to ra. Ubiquinone ch hot ng nh mt trung gian v bn thn n khng b bin i.

17.10. PH CA ALCOL V PHENOL 17.10.2. Ph IRDao ng dn ca ni ho tr C-O trong alcol hp thu mnh khong 1050 cm-1 v dao ng dn c trng ca ni O-H hp thu s sng t 3300 n 3600 cm-1.V tr chnh xc ca dao ng dn O-H ph thuc vo mc to thnh lin kt hydrogen trong phn t.Cc alcol khng lin kt cho mi hp thu kh sc khong 3600 cm-1, trong khi cc alcol c lin kt hydrogen cho mi bu rng trong vng 3300-3400 cm-1. V d trn ph IR ca cyclohexanol (hnh 17.10), nhm hydroxyl c lin kt hydrogen hp thu 3350 cm-1.

Hnh 17.10 Ph IR ca cyclohexanol ch r dao ng dn c trng ca C-O v O-HCc phenol cng cho hp thu IR c trng bi mi bu rng ca nhm OH ti 3500 cm-1, cng nh cc di hp thu c trng ca nhn thm trong vng t 1500-1600 cm-1 (hnh 17.11). Trong bn thn vng thm, c th thy r mi hp thu c trng ca nhn thm n hon 690 v 760 cm-1.

Hnh 17.11 Ph IR ca phenol17.10.2. Ph NMRNguyn t carbon lin kt vi nhm -OH rt in t nn b gim chn v s cng hng t trng thp hn so vi carbon alkane cng kiu tng ng trn ph 13C-NMR. Hu ht cc carbon ca alcol c chuyn di ha hc trong vng C 50-80 ppm, ly d liu minh ha trong trng hp cyclohexanol nh sau:

Ph 1H-NMR cng ch r cc v tr cng hng c trng ca alcol. Cc hydrogen gn vi nguyn t carbon mang oxygen b gim chn do hiu ng rt in t ca nguyn t oxygen gn , v v tr cng hng xut hin trong khong H 3,4-4,5 ppm. Tuy nhin, thng khng quan st c s ghp spin-spin gia proton ca nhm O-H ca alcol v proton ca carbon k cn. Hu ht cc mu c cha mt lng nh tp cht acid, do acid s xc tc cho s trao i proton ca nhm O-H trong khong thi gian rt nhanh, s trao i ny nhanh n mc hiu ng ghp spin-spin b loi b. Hiu ng trao i proton nhanh ny thng c p dng xc nh v tr cng hng ca proton thuc nhm O-H. C th thm mt lng nh (1-2 git) D2O vo ng cha mu NMR, nu trong hp cht c cha nhm OH th proton ca nhm O-H s trao i nhanh vi deuterium, khi o li ph 1H-NMR mt ln na th tn hiu cng hng ca proton ny s bin mt trn ph 1H-NMR thu c.

C th thy r s phn tch spin-spin c trng gia cc proton gn trn carbon mang oxygen vi cc proton methylene bn cnh. Th d, tn hiu ca hai proton oxymethylene (-CH2O-) trong propan-l-ol b ch thnh mt mi ba do s ghp cp vi cc proton methylene (-CH2-) bn cnh. (Hnh 17.12)

Hnh 17.12 Ph 1H-NMR ca propan-1-ol. Proton oxymethylene b ch thnh mi ba cng hng ti H 3,58Phenol cho tn hiu cng hng trn ph 1H-NMR khong H 7-8 ppm, cng ging nh v tr cng hng ca cc proton nhn thm (mc 15.8). Thm vo , proton ca nhm O-H phenol cng hng H 3-8 ppm. Do cc loi proton khc cng cng hng trong vng ny nn khng th dng cc gi tr cng hng trong vng ny nhn bit phenol.17.10.3. Ph MSNh lu trong mc 12.3, cc alcol b phn mnh trong khi ph theo hai cch c trng: t ni v kh nc. Theo hng t ni , lin kt C-C gn nhm hydroxyl nht b ct t, to thnh gc t do trung ha v cation cha oxygen c an nh bi hiu ng cng hng.

Trong cch kh nc, nc c tch ra, cho gc t do alkene mang in tch dng.

C hai phng thc phn mnh u thy r trn khi ph ca butan-l-ol. Pic (hnh 17.13). Mi m/z =56 l do s mtphn t nc t ion phn t, v mi m/z =31 l do t ni .

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