bai_giang_huu_co

8/9/2019 bai_giang_huu_co

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bi ging Ho hc hu c

Mc lc

Trang

A. Mt s phn ng s dng dn xut Halogen.

A.1. Phn ng Wurtz

A.2. Phn ng Correy-House

A.3. Phn ng ankyl ha Haller-Bauer

A.4. Tng hp Williamson

A.5. Phn ng ca hp cht Grignard

A.6. Phn ng Reformasky

A.7. Phn ng lin quan n clorua axitA.8. Phn ng Reimer-Tiemann

A.9. Phn ng Friedel-Crapts

A.10. Mt s phn ng to ra dn xut halogen

B. Mt s phn ng da trn s tn cng ca cacbanion

B.1. Ngng t Claisen.

B.2. Phn ng ngng t Dieckmann

B.3. Phn ng ngng t Perkin

B.4. Phn ng Michael

C. Mt s phn ng lin quan n hp cht cacbonyl

C.1. Phn ng Sommelet

C.2. Phn ng Gattermann

C.3. Phn ng Gattermann-Koch

C.4. Phn ng ClemmensenC.5. Phn ng Wolf-Kisner

C.6. Phn ng Meerwein-Ponndorf-Oppenauer-Verley

C.7. Phn ng Cannizzaro

C.8. Phn ng Baeyer-Villiger

2

2

2

3

4

5

9

1010

12

12

15

15


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D. Bi tp

Nhiu qui tc v phn ng ha hc hu c mang tn tc gi pht hin v

nghin cu chng. Trong c nhng phn ng c nhiu ng dng trong tng

hp, trong phn tch hu c. C nhng phn ng m c ch ca chng c

nghin cu k lng. Sau y l s sp xp bc u mt s phn ng c bn.

A.Mt s phn ng s dng dn xut Halogen.A.1. Phn ng Wurtz: Hai phn t ankyl halogenua di nh hng ca natri

kim loi ghp i li vi nhau thnh ankan. Phn ng Wurtz ch c hiu sut tt

khi iu ch ra ankan c s chn nguyn t cacbon v c cu to i xng xung

quanh lin kt cacbon-cacbon. Ngha l khi ghp hai gc ging ht nhau.

2CnH2n+1X + 2Na CnH2n+1 CnH2n+1 + 2NaCl (1)

C ch phn ng: SN2

CnH2n+1X + 2Na CnH2n+1Na + NaX

CnH2n+1Na + CnH2n+1 X CnH2n+1 CnH2n+1 + NaX+

Phn ng cnh tranh E2:

CnH2n+1Na + CnH2n X

H

CnH2n+2 + CnH2n + NaX

Do hp cht ankylnatri tc dng rt mnh vi ete etylic, do khng dng

ietylete lm dung mi cho phn ng m dng dung mi l hirocacbon.

A.2. Phn ng Correy-House

S phn ng:

2CnH2n+1X CnH2n+1 CmH2m+1[CnH2n+1]2LiCu1. Li2. CuI

CmH2m+1X

Liti iankylcuprat

(2)

trong c th n=m hoc nm.


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Dn xut CmH2m+1X tc dng vi liti iankylcuprat phi l dn xut cha

halogen lin kt vi cacbon bc 1 hoc cacbon bc 2, tc l RCH2X hoc R2CHX,

khng th l dn xut halogen bc 3 R3CX. Trng hp mun ghp vi cacbon

bc 3 th ta chuyn dn xut halogen bc 3 thnh liti iankylcuprat ri cho tc

dng vi dn xut halogen bc 1 hoc bc 2

(CH3)3C Br [(CH3)3C]2LiCu1. Li2. CuI

RCH2Br(CH3)3C CH2 R

Trong trng hp hp cht c kim ni chung, c liti ni ring khng th

iu ch mt cch d dng bng phn ng trc tip gia kim loi v dn xut

halogen, ta nn dng phn ng trao i kim loi-halogen theo s sau:

RX + RKL RKL + RX (3)

Cn bng phn ng (3) chuyn dch theo chiu to sn phm trong kim loilin kt vi gc c m in ln hn. (R c m in ln hn R).

Phn ng xy ra vi hiu sut tt khi X l Br v I. Khng xy ra khi X l Cl v F. Phn ng trao i kim loi-halogen theo s (3) ch yu c dng iu

ch hp cht c liti t dn xut halogen km hot ng nh halogenua aryl,

vinyl, etinyl, v cc dn xut ny kh phn ng trc tip vi liti kim loi

nhng li khng kh khn g khi phn ng vi n-Butyl liti.

Br Cl + CH3 (CH2)3 Li Li Cl + CH3 (CH2)3 Br

A.3. Phn ng ankyl ha Haller-Bauer

Xeton c cha hiro tc dng vi ankyl halogenua khi c mt baz

mnh nh NaNH2, KNH2 to ra xeton c nhm ankyl cacbon .

C CH3R'

ONaNH2(-NH3)

CR'

O

CH2

CR'

O

CH2 R X

CR'

O

CH2 RR X

(4)

Phn ng cnh tranh l O-ankyl ha v anion trn c dng cng hng:


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CCH2

R'

O

CR'

O

CH2

Nu dn xut halogen c hot ng ha hc cao th sn phm O-ankyl

l sn phm chnh, cn cc dn xut halogen c ha hc km hn s to ra snphm C-ankyl ha l ch yu.

Ankyl ha theo Haller-Bauer t khi c p dng tng hp dn xut ca

cc xeton n gin, tr khi cn tng hp xeton c nhiu nhm th l cc gc

ankyl m dn xut loi ny iu ch bng cc phng php khc rt kh khn, th

d c th p dng iu ch hexametylaxeton:

C(CH3)3C CH3 + 3CH3I + 3NaNH2

O

C(CH3)3C C(CH3)3 + 3NaI + 3NH3

O

A.4. Tng hp Williamson: ancolat, phenolat tc dng vi dn xut halogen

hoc iankyl sunfat to ra ete.

RONa + R'X ROR' + NaXSN2 (5)

C ch phn ng SN2. Nu dn xut halogen RX trong Rl gc thm th X phi l iot mi cho

hiu sut tt.

Phn ng cnh tranh: ancolat va l baz mnh, va l tc nhn nucleophinmnh, do chng va gy phn ng E2, va gy SN2. Chnh v vy vic chn

cc cht tin hnh tng hp Williamson sao cho gim thiu phn ng E2 l

vic rt quan trng. Cn nh rng nu nhit cng cao, tc nhn c lc baz

cng mnh v km phn cc nh NH2, C2H5O th cng u tin cho phn

ng E2.

Th d:

CH3I + (CH3)2CHO (CH3)2CHCOCH3 + I SN2

CH3O + (CH3)2CHI CH3CH=CH2 + CH3OH + I E2


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t-Butylat kali l baz mnh, c th tch ln, kh tham gia phn ng S N2, n ltc nhn l tng gy phn ng E2.

A.5. Phn ng ca hp cht Grignard: Victor Grignard pht hin v m rng

ng dng hp cht c magie trong tng hp hu c. Nh thnh cng ng c

nhn gii Nobel nm 1912.

A.5.1. Phn ng ca Magie kim loi vi dn xut halogen.

Thng cho phoi bo magie tc dng vi dn xut halogen ca

hidrocacbon trong ete khan:

X + MgR ete (6)MgXR

X c th l Cl, Br, I. Nu X l Cl th phn ng xy ra chm, ngoi ra MgCl2 to ra t tan trong ete,

do dng dn xut halogen vi X l Br, I th tt hn khng nhng l v dn

xut brom, iot c hot cao hn dn xut clo m cn v MgBr2, MgI2 tan tt

trong ete.

Dn xut halogen vinylic phn ng vi Magie kim loi khi dng ete etylic lmdung mi thng xy ra phn ng tch loi v phn ng ngng t. Khi phidng THF lm dung mi mi to ra hp cht Grignard vi hiu sut tt.

Br + MgCHCH2THF

MgBrCHCH2

Dn xut 1,2-ihalogen khi c mt magie to ra sn phm tch:Mg

CHRRCHCHXRRCHX

Dn xut 1,3-ihalogen khi c mt magie to ra dn xut xiclopropan:Mg

CH2RCHX CHXR R R

Dn xut ihalogen trong 2 nguyn t halogen cch nhau xa nh 1,4-, 1,5-,1,6-ihalogen... s to ra hp cht Grignard.

A.5.2. Phn ng ca hp cht Grignard.


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A.5.2.1. Phn ng vi cc cht c hiro linh ng t nhiu nh: xiclopentaien,

ankin-1, amin bc 1, amin bc 2, ancol, H2O, axit to ra hirocacbon:

RMgX + HA RH + MgAX

A.5.2.2. Phn ng vi phi kim oxi, lu hunh, halogen to ra hp cht cha cc

lin kt CO, CS, CX.

MgX + O2R OR O MgXRMgX H3O

2ROH2R OMgX

MgX + S88RH3O

8RSH8R SMgX

RMgX + I2 RI + MgXI

Tuy nhin cc phn ng khng c nhiu ng dng trong tng hp v sn

phm c th iu ch bng cc phng php khc thun li hn. Trong thc tch dng phng php ny iu ch sn phm tng ng khi cc phn ng SN1,

SN2 xy ra chm hoc khng xy ra. Th d iu ch dn xut neopentyl th nn

s dng phng php ny:

CCH3

CH3

CH3

CH2Cl CCH3

CH3

CH3

CH2MgCl CCH3

CH3

CH3

CH2IMg I2

Phn ng ca hp cht c magie vi oxi nhit thp l phng php

tuyt vi iu ch ankyl hiropeoxit:

MgX + O2R OR O MgX-700C

OR O HH+

A.5.2.3. Phn ng vi hp cht c nhm cacbonyl:

Vi CO2:RMgX + CO2 RCOOMgX

Vi anehit:MgX + R'CHOR CHOMgXR

R'

Vi Xeton:


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MgX + R'R C

O

R" CR

R'

OMgX

R"

Vi este:MgX + CH3R C

O

OEtCR

CH3

O CR

CH3

OMgX

RRMgX

Vi clorua axit:MgX + CH3R C

O

ClCR

CH3

O CR

CH3

OMgX

RRMgX

Cn nh:

R2CuLi + R' CO

ClCR

R'

O

RMgCl + CdCl2 RCdCl + MgCl2

R' C

O

ClCRR'

ORCdClMgCl

2+

Vi amit c 2 nhm th nit ch theo t l 1:1 to ra xeton:R' C

O

N(CH3)2CR

R'

N(CH3)2

OMgX

RMgXHCl, H2O+ CR' R + (CH3)2NH2Cl

O

A.5.2.4. Phn ng ca hp cht Grignard vi mt s cht khc:

Vi etylenoxit, trimetylen oxit:RMgX + (CH2)2O RCH2CH2OMgX

RMgX + (CH2)3O RCH2CH2CH2OMgX

Vi nitrin:


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C C C O

+

MgX + R'R C N C N

R

R'MgX CR R'

OH3O

+

Phn ng trao i: Tng t nh phn ng Wurtz+

Cl + R'R MgX R R' + MgXCl SN2

Tuy nhin phn ng loi ny ch xy ra i vi dn xut halogen hot ng nh

alyl halogenua CH2=CHCH2X hoc iankyl sunfat, ankyl sunfonat v -cloeste,

tc l cc dn xut c kh nng cao trong khuynh hng tham gia phn ng SN2.

Hn hp gm hp cht Grignard v ankyl halogenua iu kin thng l

h bn, tc l chng khng phn ng vi nhau, nu thm vo hn hp lng nhCoCl2 th xy ra phn ng ngng t trn, bn cnh c c RR c to ra

do phn ng:

2R' MgX R' R'CoCl2

Phn ng vi cc anehit, xeton, este , -khng no:tng t nh ankaien-1,3 c cc phn ng cng 1,2 v cng 1,4.

Cc este ca axit , -khng no khi phn ng vi hp cht Grignard cho

sn phm cng 1,4:

C C C O

OR'+

+ R MgX C C C OMgX

OR'R

C CH C O

OR'RH3O

+

S cnh tranh gia phn ng cng 1,2 v cng 1,4 chu s chi phi rt

mnh ca hiu ng khng gian. Nu cacbon

ca anehit

,

-khng no c t

nht mt nhm th th c phn ng cng 1,2 tc l phn ng vo nhm C=O:

CH3 CH CH CO

HCH3 CH CH CH CH2 CH3

OH

+ C2H5MgBr

i vi penten-3-on-2 th t l sn phm phn ng cng 1,4 v 1,2 l 3:1


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CH3 CH CH C

O

CH3 + C2H5MgBr CH3 CH CH2 C CH3

C2H5

O

CH3 CH CH C C2H5

CH3

OH

+

75% 25%

Nu c thm mt nhm CH3 cacbon , tc l trong trng hp 4-

metylpenten-3-on-2 th hon ton ch c sn phm cng 1,2 tc l ch xy ra

phn ng ca hp cht Grignard vi xeton:

CH3C CH C

O

CH3CH3

+ C2H5MgBrCH3

C CH C

OH

CH3CH3 C2H5

A.6. Phn ng Reformasky-Bromeste tc dng vi anehit hoc xeton khi c mt km kim loi to

ra -hiroxieste, dn xut ny c th hirat ha to ra este , -khng no.

Dung mi hay dng l benzen-toluen. i khi cn dng thm mt t tinh th I2

hoc HgBr2 hay CuBr2 hot ha km.

R C O

R'

+ Br CH

R1

CO2R2 + Zn R C

R1

CH

OH

R1

CO2R2 (7)

Ban u to ra hp cht c km, sau cht ny phn ng vi anehit,

xeton tng t hp cht Grignard. Nhng khng th dng Mg v hp cht c

magie s phn ng vi nhm cacbonyl ca phn t este khc, hp cht c km

khng c phn ng .

Br CH

CH3

CO2C2H5 + ZnC6H6 C7H8

BrZn CH

CH3

CO2C2H5

BrZn CH

CH3

CO2C2H5 CH3 C CH3

O

+ C

OZnBr

CHCO2C2H5

CH3CH3

CH3

H3O+

C

OH

CHCO2C2H5CH3CH3

CH3H2SO4

C CCO2C2H5

CH3CH3

CH3


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A.7. Phn ng lin quan n clorua axit

A.7.1. Phn ng kh Rosenmund: Chuyn axit thnh clorua axit ri kh clorua

axit bng cch hiro ha trn xc tc paladi c mt lu hunh iu ch

anehit:

R CO

Cl+ H2

Pd(S)+ HClR C

O

H(8)( = 90%)

A.7.2. Tng hp Arndt-Eister: Chuyn axit thnh clorua axit ri cho tc dng vi

iazometan, phn hy sn phm bng cch un nng vi bc oxit to ra xeten,

cho xeten tc dng vi H2O c ng ng k tip ca axit ban u:

( = 92%)

( = 80%)

R CO

Cl+ 2CH2N2 + CH3Cl + N2R C

O

CHN2

CH2N2R CO

ClCH2 C

O

OHR (9)

R C

O

CHN2Ag

2O

- N2 R CH C O R CH2 CO2HH2O

A.7.3. Thoi bin Curtius: iu ch amin bc 1 tng t thoi bin Hoffmann v

thoi bin Schmidt.

Cho clorua axit tc dng vi natri azit Na N N N , sau un nng ti

70-1000C c isoxianat, thy phn cht sau cng thu c amin bc 1:

R CO

Cl+ NaN3 + NaCl

NaN3R C

O

ClNH2R (10)

R C

O

N R NH2

ete

R C

O

N N N R N C OH2O

+ CO270-1000C

- N2

R C

O

N N N


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A.8. Phn ng Reimer-Tiemann:

iu ch anehit thm c nhm -OH v tr ortho so vi nhm -CHO. Cho

phenol tc dng vi clorofom trong mi trng kim, un nng:

OH

+ CHCl3NaOH, H2O

60-700C

OH

CHO(11)

(Phn ng cng nghip sn xut Salixylanehit)

A.9. Phn ng Friedel-Crapts:ankyl ha v axyl ha vng thm dng ankyl

halogenua, clorua axit c xc tc l axit lewis, hay dng nht l AlCl3 khan.

A.9.1. Ankyl ha:

+ CH3 CH2 BrAlCl3

CH2 CH3(12)+ HBr

Mun thu c sn phm monoankyl phi dng d rt nhiu hirocacbonthm v sn phm to ra c kh nng phn ng cao hn rt nhiu so vi aren

ban u do thng to ra sn phm th nhiu ln.

V phn ng tri qua giai on to ra cacbocation, m cacbocation d bchuyn v do to ra sn phm do s chuyn v ca cacbocation:

CH3 CH2 CH2 Cl + AlCl3 CH3 CH2 CH2 AlCl4

CH3 CH2 CH2 CH3 CH CH3

AlCl3(CH2)2 CH3

+ HClCH CH3

CH3+CH3CH2 CH2Cl+

Sn phm phn ng ankyl ha c th b ng phn ha hoc tham gia phn

ng phn b li, c bit khi dng lng ln xc tc HF-BF3:

Th d o- v p-xylen b chuyn thnh ng phn m-xylen:


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CH3

CH3

CH3

CH3

HF BF3

Etylbenzen b phn b li thnh benzen v 1,3-ietylbenzen.

CH2CH3

C2H5

C2H5

HF BF3+2

A.9.2. Axyl ha bng clorua axit thng tin hnh trong dung mi l CS2 hoc

nitrobenzen, thng phi dng lng xc tc nhiu hn so vi ankyl ha do xetonto phc vi xc tc:

AlCl3 + HCl

C R

ORCOCl+ (13)

Phn ng dng li giai on to ra sn phm th 1 ln. Do c ng

dng iu ch monoankylaren, v c th kh xeton thnh hirocacbon bng

hn hng km trong axit clohiric.

A.10. Mt s phn ng to ra dn xut halogen:

A.10.1. Hiu ng Kharasch v Mayo (1933): Phn ng ngc qui tc

Maccopnhicop:

(14)CHCH3 CH2 + HBr CH2CH3 CH2 Brh hoc peoxit

nhanh

Ch xy ra vi HBr, i khi vi HCl. Khng xy ra vi HF v HI. C ch:


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H = +35kcal

+ HBrROH + Br

ROBr + H

H = -23kcal

H = +39kcal

CHCH3 CH2 + Br CHCH3 CH2 Br H = -5kcalH = -11kcal+ HBr CH2CH3 CH2BrCHCH3 CH2Br

RO

R O O R 2ROtoC

+ Br

A.10.2. Phn ng Wohl-Ziegler: Brom ha anken dng NBS, cn chiu sng hoc

c mt peoxit, hoc xc tc khc, iu ch dn xut alyl halogenua. C ch gc

t do dy chuyn:

hN Br

O

O

N

O

O

+ Br

N

O

O

H

+ + N

O

O

H

+ N Br

O

O

Br

N

O

O

+ (15)

A.10.3. Phn ng Hunsdiecker: iu ch dn xut ankyl clorua hoc bromua

bng cch ecacboxyl ha mui bc ca axit cacboxylic trong s c mt ca clo

hoc brom.

(16)+ Br2CCl4, 76

0CRCO2Ag RBr + AgBr + CO2

Phn ng c s kh khn l i hi phi c mui bc tinh khit v khan. Loi

mui nh th rt kh iu ch.

Trong mt s trng hp kt qu thu c rt tuyt vi khi cho axitcacboxylic tc dng vi lng d oxit HgO trong dung mi CCl4, trong

bng ti v nhit khong 760C.


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+ Br2HgO, CCl4

760CCO2H + HBr+ CO2Br

A.10.4. Phn ng Sandmeyer v phn ng Schiemann: Phn hy mui iazoni

ca amin thm bc 1 bng cch un nng dung dch mui trong s c mt ca

ng (I) halogenua tan trong lng d axit halogenhiric tng ng l mt trong

nhng phng php hiu qu iu ch dn xut halogen thm. Phn ng ny l

mt trng hp ca phn ng Sandmeyer.

ArN2X Ar X + N2 (17)CuX, HX

CH3NH2

HCl, NaNO2, H2O0-50C

CH3N2Cl (CuCl), HCl

600C

CH3Cl

(74-79%)

CH3

NH2

H2SO4, NaNO2, H2O

15-200C

CH3

N2HSO4

HBr, (CuBr)1000C

CH3

Br

(70-73%)

C ch phn ng: Mui iazoni phn ng to ra gc thm t do, sau trong qu

trnh oxi ha-kh tip theo to ra dn xut halogen. Trong phn ng ny lc u

ng l cht kh sau ng vai tr l cht oxi ha.

C6H5 N N + [CuCl2] + N2C6H5 + Cu Cl2+2

+ Cu Cl2C6H5 C6H5 Cl + CuCl

Trng hp iu ch dn xut it th khng nht thit phi dng hp cht cang (I), v bn thn anion I gy nn s phn hy mui iazoni, trongtrng hp ny c to ra mt lng I2 ng k.

ArN2X Ar I + N2 (18)KI, H2O


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NH2 I1. HNO2, H2O2. KI, H2O

(53%)

Khi iu ch dn xut ca flo, qui trnh tin hnh c s iu chnh nh sau:cho mui iazoni tc dng vi HBF4 hoc NaBF4 to ra kt ta iazoni

floroborat. Lc ly kt ta ny, lm sch, lm kh ri un nng t t cho ti

khi bt u phn hy gii phng nit v to ra bo triflorua:

ArN2BF4 Ar F + N2 + BF3 (19)t0

C6H5N2 BF4 + N2C6H5F + BF3t0C

iu ch dn xut thm ca flo nh trn gi l phn ng Schiemann

V d:

1. NaNO2, H2SO42. HBF4

(97%)

NH2

Br

N2BF4

Br

150-1550C

F

Br

Phn ng Schiemann xy ra qua giai on to cacbocation thm. Bngchng cho c ch ny l s to ra 3-nitroiphenyl bn cnh flobenzen khi phn

hy phenyliazoni floroborat trong nitrobenzen:

+ BF3

N2 BF4

F

NO2

NO2

BF4

-N2

B.Mt s phn ng da trn s tn cng ca cacbanionB.1. Ngng t Claisen.


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Phn ng gia hai phn t este c hiro cacbon , di nh hng ca baz,

to ra -xetoeste. Phn ng khng c li v mt nhit ng v c H=6 kcal/mol.

S :

(20)R C OR'

O

CH C OR2

O

R1

H CH C OR2

O

R1

C

O

R+ + R'OHbaz

Baz thng dng l ancolat natri ca ancol to ra este. C ch phn ng:

CH3 C OC2H5

O

C2H5O+ CH2 C OC2H5

O-C2H5OH

CH3 C OC2H5

O

+ CH2 C OC2H5

O

CH2 C OC2H5

O

CCH3

OC2H5

O

CH2 C OC2H5

O

CCH3

O-C2H5O

Cc giai on u xy ra thun nghch, do phi chng ct loi b ancol

chuyn dch cn bng. Qu trnh tch b ancol s gp kh khn nu este ban

u c im si thp hn ancol, khi thng phi dng d ancolat chuyn

-xetoeste thnh dng mui ca enol:

CH3 C CH2COC2H5

O O

C2H5O+ CH3 C CHCOC2H5

O O

CH3 C CHCOC2H5

O O-C2H5OH

(21)

V ancol c lc axit yu hn enol. ng nhin thu c sn phm th

sau khi tin hnh phn ng ngng t phi cho dung dch axit long, lnh vo hn

hp sau phn ng.

V mt l thuyt ch cn este c t nht mt nguyn t hiro cacbon ,nhng thc t nu dng ancolat th nhng este c mt hiro khng t ngngt to ra -xetoeste, v nh trn nhc, phn ng khng thun li v mt

nhit ng, khi ch c mt H th khng to ra enolat theo phng trnh (21).


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2H3C CH COC2H5

CH3

O

C C COOC2H5

CH3

CH3

O

CHCH3

CH3

C2H5ONa+ C2H5OH

Trong nhng trng hp ny phi dng d baz mnh hn rt nhiu so vi

ancolat loi b ht ancol to ra. Mt trong nhng baz l triphenylmetyl

natri.

2CH3 CH COC2H5CH3

O

C C COOC2H5

CH3

CH3

O

CHCH3

CH3

+ C2H5OH

+ C2H5OH(C6H5)3CNa (C6H5)3CH + C2H5ONa

2CH3 CH COC2H5CH3

O+ (C6H5)3CNa C C COOC2H5

CH3

CH3

OCHCH3CH3

+ C2H5ONa

+ (C6H5)3CH

Ngng t Claisen c th xy ra gia hai loi este khc nhau, khi to ra hnhp 4 loi -xetoeste. Nu 1 trong 2 loi este khng c H th phn ng xy ra

thun li v phc tp hn. Cc este khng c H thng dng l este ca

axit benzoic, axit fomic, axit cacbonic, axit oxalic.

Khi dng este ca axit fomic ta thu c -anehiteste:

1. C2H5O

2. H3O+C6H5 CH2 COC2H5

O

H COC2H5

O

+ C6H5 CH COC2H5

CHO

O

(90%)

Khi dng ietyl oxalat thu c -etosalixyleste, este loi ny khi b un nng

mnh s tch phn t oxit cacbon CO to ra este ca axit malonic:


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18

1. C2H5O

2. H3O+CH3CH2 CH2 COC2H5

O

+(CO2C2H5)2 CH3CH2 CH COC2H5

O

COCOOC2H5

t0C CH3CH2 CH COC2H5

O

COOC2H5

+ CO

-etosalixylbutirat etyl

ietyl -etylmalonat

Ngng t Claisen c th xy ra gia 1 xeton c H v 1 este, khi xeton tora cacbanion v xeton c lc axit ln hn cc este n gin, phn ng t

ngng t gia 2 phn t xeton theo kiu anol ha rt kh xy ra. Dn xut

oxaxyl to ra cng b tch CO khi un nng:

1. C2H5ONa

2. H3O++(CO2C2H5)2

O O

COCOC2H5

O

+ C2H5OH

O

COCOC2H5

O

1500C

O

COC2H5

O

+ CO

Phn ng ngng t Claisen cng c th xy ra gia 1 anehit hoc 1 xeton

khng c H vi 1 este c H, khi to ra este , -khng no:

C2H5ONa+ CH2(CO2C2H5)2CHO CHCH(COC2H5)2

OOH

+ H2OCH=C(COC2H5)2

O

B.2. Phn ng ngng t Dieckmann: l phn ng Claisen ni phn t este ca

iaxit c cha 6 hoc 7 nguyn t cacbon to ra -xetoeste mch vng 5 hoc 6

cnh:


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19

C C C O

+

CH2CH2

CH2CH2

COOC2H5

COOC2H5

O

COOC2H5

C2H5ONa + C2H5OH (22)

B.3. Phn ng ngng t Perkin: xy ra gia mt anehit thm vi anhirit axit

c H khi c mt mui vi kim loi kim ca axit ng vi anhirit axit:

+ CH3COONaC O C

O

CH3CH3

O

C O C

O

CH3Na CH2

O

+ CH3COOH

C O C

O

CH3CH2

O

CH3COOH, t0C

C

O

H CH-CH2C

OO

O CCH3

O

+

CH=CH COOH

(23)

Phn ng to ra axit , -khng no. Mui ca kim loi kim ng vai tr

ca baz to ra cacbanion, do c th thay n bng mt baz khc, hay dng

nht l K2CO3 khan.

B.4. Phn ng Michael: l phn ng cng ca tc nhn nucleophin vo lin kt

i cacbon-cacbon c nhm ht electron mnh (lin kt i hot ha) nh dn

xut axit , -khng no, anehit , -khng no, xeton , -khng no, hay nitrin,

nitro..., -khng no vi k hiu chung l:

in hnh l phn ng cng cacbanion vo h thng trn theo s :

CH2(COOC2H5)2 + B CH(COOC2H5)2 + BH

C C C O CH(COOC2H5)2+ C C C O

CH(COOC2H5)2

C CH C O

CH(COOC2H5)2

BH+


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Trong B l 1 baz.

Th d 1:

CH2(COOC2H5)2+C6H5CH CH COOC2H5 C6H5CH CH2 COOC2H5

CH(COOC2H5)2

C2H5ONa

Ngoi este ca axit malonic, cc cht khc c th to ra cacbanion tng i bn

nh malononitrin, este ca axit axetoaxetic, este ca axit xianoaxetic...

Th d 2:

Phn ng Michael thng c dng tng hp vng 6 cnh, ban u to

ra enolat hoc cacbanion, sau cc tc nhn ny phn ng vi xeton , -khng

no, cui cng to ra xeton vng:

O

O CH3O

OH OObaz

O C

O CH3

+baz

OOCH2

O O

-H2O

;

Cc enamin rt d tham gia phn ng cng Michael:


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21

N N

CH2 C COOCH3

CH3H

CCH2

CH3

CO

OCH3

+ DMFt0C

N

CH2 CH COOCH3

HCH3

O

CH2 CH COOCH3

CH3H2O, H

+

Cc enamin c th iu ch c bng phn ng ca xeton, anehit c H vi

amin bc 2 khi c xc tc axit v lin tc chng ct loi nc:

+

O

HNN + H2O

H+

piroliin

Nh rng cc enamin rt d c phn ng C-ankyl ha vi cc dn xut

halogen hot ng nh allyl halogenua hoc -halogeneste, sau thy phn s

thu c dn xut mi ca hp cht cacbonyl ban u:

N+ Br CH2COOC2H5

N

CH2COOC2H5

Br H2O

O

CH2COOC2H5

BrH2N+

Phn ng Michael bao gm c phn ng cng 1,4 ca hp cht c magievo h lin kt i hot ha (xem A.5.2.4)

C.Mt s phn ng lin quan n hp cht cacbonyl


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C.1. Phn ng Sommelet: Oxi ha nhm CH2Cl lin kt vi vng thm thnh

nhm CHO bng hexametylentetramin trong dung mi CH3COOH/H2O nhit

si, sau phn hy sn phm trong mi trng axit c pH=36,5. Ban u

to ra mui amoni bc 4, sau phn hy ra anehit:

CH2Cl

+ N N

N

N

CH3CO2H, H2Ot0 si

CH2 N Cl CHO

pH=3 : 6,5(25)

Dn xut ArCH2Cl d dng iu ch bng phn ng clometyl ha aren. Cho

hirocacbon thm tc dng vi anehit fomic v hiroclorua trong s c mt ca

ZnCl2 khan:

C6H6 + HCHO + HCl C6HCH2Cl + H2OZnCl2

C ch phn ng clometyl ha tng t nh phn ng Friedel-Crafts:

CHO

H+ HCl C ClH

H

OH

C ClH

H

HO ZnCl2ZnCl2

+ ZnCl2 + H2OC ClH

H

HO ZnCl2

+

H

CH2Cl+ HOZnCl2

CH2Cl

C.2. Phn ng Gattermann: L phn ng fomyl ha hp cht thm c kh nng

phn ng cao trong phn ng SE nh phenol, ete ca phenol v hirocacbon thm

khc. Tc nhn c s dng l hiroxianua, hiroclorua v xc tc l ZnCl 2 hay

AlCl3 khan hoc ci tin bng cch dng km xianua v hiroclorua. Thy phn

cc sn phm s to ra anehit.

(26)OH

+ HCN + HClOH

CHO

+ NH4Cl1. ZnCl2, ete2. H2O


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C.3. Phn ng Gattermann-Koch: L phn ng iu ch aneht thm bng

cch cho oxit cacbon CO tc dng vi hirocacbon thm khi c mt hiroclorua

v AlCl3 khan. Phn ng xy ra p sut thng th cn dng thm CuCl, nu

p sut cao th khng cn dng CuCl.

(CH3)2CH + CO (CH3)2CH CHOHCl, AlCl335at, 25-300C

(27)

(60%)

+ COHCl, AlCl3Cu2Cl2, 35-40

0C

(73%)

CHO

C.4. Phn ng Clemmensen: Kh anehit, xeton thnh hirocacbon di tc

dng ca hn hng Zn trong axit HCl.

Zn/Hg, HClC

O

CH2COOC2H5 CH2 CH2COOC2H5(28)

Phn ng Clemmensen p dng khi anehit, xeton c cc nhm bn trong mi

trng axit, km bn trong mi trng kim.

C.5. Phn ng Wolf-Kisner: Kh anhit, xeton thnh hirocacbon do tc dng

ca hirazin trong mi trng kim, dng dung mi phn cc c im si cao

nh etilenglicol, khi un nng.

+ H2N NH2O+ N2 + H2O

KOH, 1500

(CH2OH)2

(29)

Phn ng ny p dng cho hp cht cacbonyl bn trong mi trng kim,

km bn trong mi trng axit. Phn ng xy ra n cng nu lin tc chng ct

loi b nc to ra.

Cn ch rng: Nu anehit v xeton km bn c trong mi trng kim

v mi trung axit, tc l khng th dng phn ng Clemmensen v phn ng


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Wolf-Kisner, hoc dng cc phng php khc cho hiu sut thp th phi

chuyn hp cht cacbonyl thnh thioxetal, ri kh bng hiro ha xc tc Niken-

Raney.

Th d:

O

O

COOC2H5C2H5OOC COOC2H5C2H5OOC

S

(CH2)3S

S

(CH2)3S

HS (CH2)3 SH

H+

H2/Ni COOC2H5C2H5OOC

(70%)

C.6. Phn ng Meerwein-Ponndorf-Oppenauer-Verley: L phn ng kh

anhit, xeton thnh ancol bng nhm isopropylat.

Nhm isopropylat [(CH3)2CHO]3Al l cht rn c im chy thp (1180C), c th

chng ct nhit 140-1500C/12mmHg.

3R2CO + [(CH3)2CHO]3Al 3(CH3)2CO + (R2CHO)3Al (30)

Phn ng xy ra n cng khi chng ct axeton lin tc ra khi hn hp phnng. Thy phn axit sn phm s thu c ancol.

Phn ng kh nh trn cng cho hiu sut rt tt khi trong gc R c cha linkt bi (khng no) hoc c cha halogen.

C ch phn ng: Ban u nguyn t oxi cacbonyl kt hp vi nhm, tip theo c

s dch chuyn anion hirua trong phc hot ng mch vng sang nguyn tcacbon-cacbonyl to ra ancol:

R CH

O

H C(CH3)2O

Al[OCH(CH3)2]2 OAl[OCH(CH3)2]2

CR

H

H + (CH3)2C=O


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C.7. Phn ng Cannizzaro: L phn ng t oxi ha t kh ca anehit khng

c H di nh hng ca kim mnh.

(31)

R C

H

O HCR

O

OH+ OH-

R CH

O R C

O

O+ RCH2OH

Phn ng Cannizzaro c th xy ra gia 2 anehit khc nhau, khi

anehit no c nhm CHO d b anion OH- tn cng hn (in tch dng

cacbon cao hn; nhm CHO t b n ng khng gian) s b oxi ha thnh axit.

(CH3)3C CH

O

OH-H CH

O

(CH3)3CCH2OH ++ H COH

O

Nu anehit c hiro cacbon th ban u xy ra phn ng andol ha n ht

H, cui cng s xy ra phn ng Cannizzaro.

CH3 CH

O

OH-4H C

H

O+ H C

OH

OCH2 CHO CH2OH

CH2OH

CH2OH

+

C.8. Phn ng Baeyer-Villiger: L phn ng ca xeton vi peaxit to ra este.

Ban u peaxit to ra oxi nguyn t, sau oxi kt hp vi cacbon trong nhm

cacbonyl xeton to ra este.

phe C

O

phe phe C

O

O pheC6H5CO3H

O

(32)

O

CH2

OC6H5CO3H

Nu 2 gc ca xeton khc nhau th to ra hn hp 2 este:

R C

O

R' R C

O

O R'C6H5CO3H R'C

O

OR+


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D.Bi tp1. Hp cht no di y khng th iu ch bng phn ng Wurtz vi hiu sut

tt? Gii thch.

(CH3)2CHCH2CH(CH3)2 (A) (CH3)2CHCH2CH2CH(CH3)2 (B)

CH3CH2C(CH3)2CH2CH3 (C) (CH3)3CCH2CH2CH3 (D)

2. T E-2-buten hy iu ch CH3CHBrCHBrCH2CH2CHBrCHBrCH3 (G). Hydng cc k hiu R, S cho bit cc ng phn lp th no ca G c to ra.

Nu i t Z-2-buten th G c nhng ng phn lp th no?

3. T Cumen hy iu ch Cumarin.4. Cho phenol tc dng vi clorofom v NaOH c G. Li cho G tc dng vi

etanol (c xc tc axit), ri ly sn phm cho phn ng vi alyl bromua khi c

mt kim, c cht K. un nng K ti 2000C sau thy phn axit. Vit cc

phng trnh phn ng v cho bit s dng cc phn ng no mang tn

ngi.

5. Vit cc phng trnh phn ng theo cc giai on sau, cho bit cc phn ngmang tn ngi (nu c):

1. Butaien-1,3 tc dng vi metyl metacrilat c cht (O).2. Oxi ha (O) bng KMnO4/H2SO4 un nng, ri cho sn phm tc dng

vi CH2N2 d c (P).

3. P + CH3ONa, ri thy phn axit v un nng, tch ra CO2 c (R).4. R + CH2N2 S5. S + BrCH2CO2CH3 + Zn T U + H2O6. U + H2 V7. V + CH3ONa X. Thy phn X trong mi trng axit, un nng,

tch CO2 c Y

8. Y+ NaNH2 + CH3I d 1-Metyl-2-oxo-3,3-imetyl Bixiclo[2.2.1]heptan


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CH3

O

H3C

O

OCO2CH3

CH3

O1

2

34

5

6

6. Cho axetanehit tc dng vi lng d fomanehit khi c mt NaOH ccht A. Cho A tc dng vi lng d dung dch NaBr bo ha v H 2SO4 c

c B. un nng B vi bt Zn c C (C5H8). Vit cc phng trnh phn

ng.

7. Cho 1-penten-5-ol tc dng vi Br2/CCl4 thu c cht X (C5H9OBr). Cho Xchuyn ha qua cc bc sau:

B1: phn ng vi Mg/ete B4: tc dng vi iazometan

B2: phn ng vi CO2 ri thy phn axit B5: un nng vi Ag2OB3: phn ng vi thionyl clorua B6: tc dng vi H2O

Vit cng thc cu to ca sn phm trong tng bc chuyn ha.

8. Vit cng thc cu to sn phm ca dy chuyn ha sau:(CH2CO)2NH + LiAlH4 A

A + xiclohexanon c xc tc axit B

B + CH3COCl C, sau thu phn to ra D

D + CuCl2 E

9. T Metylvinylxeton v hy iu ch ra

10.T cc hp cht cha 1 nguyn t cacbon v cc cht v c cn thit, hyiu ch hp cht

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