Nhm : L Th An Bi Th Hng Phm Thanh Phng Nguyn Xun Trng

Nguyn c Khi Bi Th Vinh Hong nh Thin L Don Kin

. nh nghaKhi nguyn t hay nhm nguyn t b tch ra khi mt phn t m khng c s thay th bng nhng nguyn t hay nhm nguyn t khc c gi l phn ng tch k hiu l E (Elimination). Trong loi phn ng ny thng cht ban u tch ra hai thnh phn nh hn gi l hai nhm i ra to sn phm cha lin kt hay . Cht ban u sn phm + thnh phn 1 + thnh phn 2A (R)n B (R)n A B

Tng qut phn ng tch c dng A (R)n B (R)n+ AB

. Nguyn tc phn loi. phn loi phn ng tch ngi ta da vo cc nguyn tc : Theo c ch phn ng tch. Theo v tr tng i ca hai nhm tch ra. Theo mi trng phn ng. Theo sn phm tch. Quan trng v ph bin nht l phn ng tch mt nhm X v nguyn t hidro v tr to ra lin kt bi cacbon cacbon. Do ch yu chng ta xt phn ng tch vi cc c ch E1, E2 sn phm l HX trong mi trng l dung dch.

.S lc v phn ng tch .Phn ng tch hay (1,1) xy ra do hai nguyn t cng mt cacbon tch ra khi phn t cht ban u to hp cht khng no. S tng qut : :B R RCZ R C R + BZ + X Cacben XGiai on chm hnh thnh tiu phn trung gian l cacben (R C:) , nitren (R N:).

Trong B ion OH, Z v X c th l : Z= H Halogen H CO3 X = Halogen Me N2 N2

Halogen Halogen

V d v phn ng tch :

HO + HCCl3HO + HCCl3 - H2O CCl3

Chm

HCOOHCl + :CCl2 - H2O CO

HO

HCOO

(C6H5)2C = CHBr -NH2 (C6H5)2C = CBr

H5C6C CC6H5 + KBr (tc nhn l kali amiua) C H + HCCl HO C H CCl C H CHO6 6 3 6 5 2 6 5

Phn ng thoi phn Hofmann khi cho N-bromamit tc

dng vi baz mnh to thnh nitren : HO R CO NHBr R CO N:

RN=C=O

Phn ng to tnh alen t ihalogenxycloankan :

X Me X ihalogenxycloankan

Tiu phn trung gian

X Alen

IV. Phn ng tch .Phn ng tch hay (1,2) xy ra do hai nguyn t (nhm nguyn t) tch ra hai cacbon cnh nhau to hp cht khng no. Trong hai nhm tch ra , mt nhm l electrophin thng l proton hay H,cn nhm kia l nucleophin thng l Halogen. Sn phm hnh thnh thng cha ni i (CC) hay ni ba (CC).

Dng tng qut ca phn ng tch :

H C C H - HX

CC

(anken)

H CC

- HX

C C (ankin)

X Phn ng tch thng xy ra theo hai c ch : E1, E2.

1. Phn ng tch E2 Tng t nh phn ng

,phn ng tch lng phn E2 l phn ng mt giai on v i qua trng thi chuyn tip hnh thnh phc hot ng do s tng tc gia tc nhn Y v nguyn t H , proton ny tch ra cng vi Y v nhm X ng thi to sn phm cha no. S chung : X C C C = C + X + YH Y H Nhm X c th l : Halogen, OSO R , NR ..2 3

Y l tc nhn nuleophin nh : OH , RO , C2H5O , C6H5 O , NR3 ... - YH Y + HCCX YHC ...CX C=C + X

Hng khng gian ca phn ng tch E2 : Halogen v H b tch ra v tr anti. Anti (ng phng) l v tr m cc lin kt C X , C H v C = C cng nm trn mt mt phng ,cu dng phn t c c im trn cng gi l cu dng anti. c im ng hc ca phn ng E2 : Phng trnh tc : v = k[RX][Y ] ,suy ra E2 l phn

ng bc 2,giai on chm quyt nh tc phn ng. Cht cho cp electron (Y ) c th l anion hay phn t trung ha , nhm i ra (X) cng c th dng anion hay phn t trung ha. [[[jjjjjjjjjjj

Gin nng lng E2 : Y ...H...C ... C...X E

C=C

HCCX Ta phn ng

V d: Phn ng tch 1-Brom-1,2-iphenylpropan bng kim:CH3 C6H5 H HO CH3 C6H5 CC H Br C2H5OH Chm CC H Br CH3 H C=C + H2O + Br

C2H5OH C6H5 Chm

C6H5 C6H5 Z - Metylstinben CH3 C=C C6H5 + H2O + Br

HHO

C6H5

H C6H5 E - Metylstinben

Mt s phn ng tch E2 in hnh : Loi HX to anken : (CH3)2COK CH3(CH2)5CH2CH2Br CH3(CH2)3CH=CH2 CH3 Cl O CH3 Cl LiCl DMF CH3COONa

CO K 3O CH3

CH2

+

CH3

C6H5CHBrCHBrCOCH3

C6H5CH CHCOCH3

Loi HX to ankin : C6H5CHBrCH2BrNaNH2 , NH3

C6H5CCH (45 52 %)

CH3CCl=CHCH2OH Tch t cc sunfonat:

NaNH2,NH3,NH4Cl

CH3CCCH2OH (C6H5)2C=CH2HCCCH=CHCH3

(C6H5)2CHCH2OSO2C2H5 HCCCH2CH(CH3)OSO2C7H7

CH3ONa

KOH,HOH

OSO2C7H7

(CH3)3COK

Tch t kim amoni bc bn : (CH3)3CCH2CH2N(CI3)3HO (CH3) CN(CH3)3

(CH3)3CCH=CH2H3C CH2

H2O CH3

2. Phn ng tch E1. C ch tch E1 n phn t gm 2 giai on :

Giai on chm to cacbocation. 2. Giai on nhanh cacbocation tch proton to sn phm cha no.1.

HCCX

-X Chm

H C C

Nhanh

C = C + H

Trong X l Cl, Br, I, OSO2R, OH2

Mt s c im ca phn ng E1. Phng trnh tc : v = k[RX] ,l phn ng bc nht,giai

on chm quyt nh tc phn ng. Phn ng c xc tin khi cht ban u c nhm th +I, +C n nh cacbocation. Phn ng cn c nhm i ra d tc l nhm d b ion ha. Dung mi cn c lc ion ha cao. Phn ng thng nhit cao. Phn ng cn c kim mnh.

V d v phn ng tch E2. CH3 OH CH3 C C CH3 H H3-metyl-2-butanol

CH3 H CH3C = CCH32-metyl-2-buten

CH3 H

H CH3

CH3C C=CH2 H C = CCH2CH33-metyl-1-buten 2-metyl-1-buten

3.Hng ca phn ng tch E.

Hng ca phn ng tch E Quy tc Zaixep : trong phn ng tch nucleophin ,nhm b tch ra cng vi proton nguyn t cacbon c bc tng i cao hn,to ra anken c nhiu nhm th hn. '

CH3 CH CH CH CH2CH3 H X H

CH3 CH CH = CH CH3CH3Sn phm chnh

CH3 CH CH2 CH = CH2 CH3Sn phm ph

Hng ca phn ng tch E1 ph thuc vo trng thi

chuyn tip (TTCT) ca cacbocation vi dung mi (S) thnh sn phm : CH3CHCHCH3 X CH3 CHCH CH3 CH3 X

H (CH3)2C CH CH2(A)

S

H(B)

H

S

CH3 C CH CH3

CH3

TTCT (B) c lm bn bi 9 lk CH, c tnh i xng cao. Vi TTCT (A) ch c 7 lk CH v km i xng nn km bn hn TTCT (B). Sn phm chnh c t l t (B) nhiu hn t (A).

Nhn xt : t l sn phm to thnh trong phn ng tch ph thuc vo bn ca TTCT (cacbocation) to nn sn phm , TTCT cng bn,t l sn phm c to thnh t n cng cao.

Hng ca phn ng tch E2 ph thuc vo n nh ca TTCT gia ion Y (OH ) vi cht phn ng. Sn phm tch l anken th t l cu hnh cis/trans hay Z/E ph thuc vo bn cht ca nhm ra i (X) v cu trc ca dn xut (RX). Tng t nh phn ng E1, TTCT E2 cng n nh khi s lin kt CH gii ta, phn tn in tch cng nhiu. Quy tc Hopman trong phn ng E2: khi X l nhm th mang in tch dng v kh b tch hoc cng knh nh NR3,SR2, SO2R nhm X s u tin tch cng nguyn t hir cacbon bc thp hn,tri vi quy tc Zaixep. Hiu xut ca sn phm Hopman ni chung tng theo kch thc nhm X.

H H

OH

H

H C CH CH C H H Br H TTCT (B) n nh hn nh 6 lk CH CH3 CH = CH CH3 (81%)

+ OH

+ OH CH3 CH CH CH2 CH3 C CH CH2 H Br H H Br TTCT (A) km bn ch c 2 lk CH CH3 CH2 CH = CH2 (19%)

H

H

OH

V d v quy tc Hopman : CH3 CH CH2 CH3

OH E2

CH3 CH = CH CH3 Sn phm ph OH E2

+ CH2 = CH CH2 CH3 Sn phm chnh

N(CH3)3

CH3 CH CH2 CH2 CH3

CH3CH = CHCH2CH3 + CH2 = CHCH2CH2CH3 Sn phm ph Sn phm chnh

SO2CH3

4.Mt s phn ng tch khc. Phn ng tch lin hp 1,4.

Cc hp cht thuc loi sau s tch 1,4 : HCC=CCX C=CC=C Phn ng tch cc nhm khc hyr. Phn ng tch , - ibrom vi kim loai c tnh kh mnh nh Zn, Mg trong dung mi axitaxetic : R1R2C CR3R4 ZnBr R1R2C = CR3R4 + Br

Zn

Br Br

Phn ng tch vi h M C C X vi M l nhm

mang in tch dng, X l nhm m in hn,sn phm tch cho anken. Tng t vi cc hp cht c - Sn,Si.

M CH2 CH2 OH

H

MOH + CH2 = CH2

5. Quan h gia phn ng th v phn ng tchCc yu t nh hng Phn ng tch E Phn ng th S Tc S2 gim i. Tc S1 gim i. Cu trc gc hidrocabon Tc E2 tng ln. (tng phn nhnh ca Tc E1 t thay i. gc ankyl)

Kt lun : t l E/S tng khi tng phn nhnh ca ankyl. Tc nhn nucleophin Y (tng mnh v nng bazo) Tc E2 tng. Tc E1 ni chung l tng Tc S2 gim. Tc S1 t thay i.

Kt lun : t l E/S tng khi tng mnh v nng bazo. Nhit (tng nhit ) Tc E tng . Tc S gim.

Kt lun : nng lng hot ha ca phn ng tch ln hn phn ng th. Tc E2 gim nhiu. Tc E1 tng. Tc S2 ni chung l gim t . Tc S1 tng.

Dung mi (tng phn cc)

6.Mt s phn ng tch thng gp.1) Phn ng ehidrohalogen ha : CC H X 2) Phn ng ehidrat ha ancol.H2SO4 CC hay Al2O3 ,100C H OH 3) Phn ng ehidroxianua ha. Bazo C=C - HCN H CN

OH Ancol

C=C

C=C

C =C

4) Phn ng ehidrohalogenua ca axyl halogenua v sunfonyl halogenua. R R R3N RCC=O RC=C=O H X RCH2CH2SO2Cl [RCH=SO2] RCH=CHR + sunfen 5) Phn ng phn ct ete cho olefin. CC H ORRNa

C = C + RONa + RH

6) Phn ng phn tch hydoxit tetraankylamoni. C C NR3 HO 7) Phn tch toluen p sunfonylhidrazon. C=C + NR3 + H2O

(- Ts : gc toluen)CC H N NH Ts 8) Phn ng tch hp cht sunfoni ,sunfoxit. CCHO (1 -3) RLi -2 H2O

C = C + Ts + N2 H

C = C + SR2 + H2O

H SR2

Phn ng trn cng xy ra tng t vi cp tc nhn : [Br, (C6H5)3CNa] .Cc sunfon v sunfonit c H tch khi c ankoxit : CC C = C + RSO + ROH H SO R RO CC C = C + RSO2 + ROH H SO2 R 9) Phn ng ehalogen ha ca 1,2 ihalogen. Zn CC C=C X X Thng dng cc tc nhn nh Zn, Mg, I cng nh cc tc nhn khc nh phenylliti ,phenylhydrazin , CrCl3, NH NH , LiAlH .RO

i vi clorua axit th halogen cng tch cho xecten khi c tc nhn l km hay triphenylphotphin : R R Zn RCC=O RC=C=O X X Phn ng tch ete th halogen khi c mt tc nhn Zn, Mg, Na, hay cc kim loi c tnh kh mnh khc : Zn CC C=C X OR Nhn xt : cc hp cht loi XCCZ tch c khi Z l OCOR, Ots, NR2, SR hay OH nhng X ch gii hn Br v I.

10) Phn ng eoxy ha cc iol. 2CH3Li CC CC THF HO OH O O 11) Phn ng tch ca boran.

K2WCl2 THF

C=C

[R2CHCH2]3B + 3 CH3(CH2)5CH=CH2 [CH3(CH2)6CH2]3B + 3 R2CH=CH2 Phn ng ny dng iu ch anken c ni i u mch cacbon. Vi ankin cng tng t nh trn nhng phn ng khng thun nghch : (R2CHCH2)3B + RCCR 3 R2CH=CH2 + (RCH=CH)2B

12) Phn ng chuyn ha anken thnh ankin. Cc anken c nhm metyl ni i c th tham gia phn ng chuyn ha thnh ankin :CH3 CH3 C = C CH2R HNaNO2 CH3COOH.H2O

CH3 C C CH2R + CO2

13) Phn ng nhit phn cc ankyl axetat v ankyl xantogenat cho anken.R CH2 CH2 OCOCH3 R CH2 CH2 OCSSRtt

R CH = CH2 + CH3COOH R CH = CH2 + COS + RSH

14) Phn ng chuyn ha ihidrazon thnh akin . 1,2 ihidrazon tc dng vi HgO, AgO, CuCl2O2 pyridine v vi tc nhn khc s mt i 2 mol nit cho ankin: RC C R RCCR

NNH2 NNH2 R, R ch l ankyl v aryl ,phn ng ny cng dng tng hp xicloankan mnh vng ln. 15) Phn ng chuyn ha 1,2-initro thnh anken.

Khi c mt hn hng canxi Ca-Hg , c s chuyn ha :R R RCCR R R

Ca-Hg

RC=CR

16) Phn ng chuyn ha epoxi v episunfua thnh olefin. Cc hp cht epoxi chuyn thnh olefin khi tc dng vi triphenyl photphin hay trietylphotphit : C C + (C6H5)3P C = C + (C6H5)3PO O Phn ng cng dng tc nhn diphenylphotphit (C6H5)2PLi, Li trong THF, TsOH, trimetylsilyl iotua, ddimetyl iazomalonat, PI3 . Cc episunfua cng chuyn thnh anken tng t nh epoxi:

C C + P(OC2H5)3metyl iotua.

C = C + S= P(OC2H5)3

Phn ng cng dng tc nhn (C4H9)3SnH, LiAlH4,

17) Phn ng hidrat ha amit. Amit khng th c th ehidrat ha khi c mt cc tc nhn nh P2O5, POCl3, PCl3, PCl5, CCl4-P(C6H5)3, HMPA, CH3COOCNSO2N(C2H5)3, SOCl2 R C NH2 O Vi hp cht nitro : RCH2 NO2PCl5 pyridin P2O5

RCN

RCN

Cn rt nhiu cc loi phn ng tch khc trong thc t , trn y l cc phn ng tch thng gp v c nhiu ng dng nht.

Ngun ti liu : Bi ging ha hu c phn 1 TS. PHM XUN NI TS. TNG TH THANH HNG TS. BI TH L THY C ch v phn ng ha hc hu c PGS.TS. THI DON TNH.

Chn thnh cm n qu thy c v cc bn ch theo di!Thank you so much !