TAI LIEU ON THI HSG _ LY THUYET + BAI TAP

8/7/2019 TAI LIEU ON THI HSG _ LY THUYET + BAI TAP

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ti liu BI DNG HA THPT I. C s l thuyt v c ch phn ng :1. Phn loi phn ng ho hu c : Phn ng hu c c phn loi theo nhiu cch khc nhau, nhng

nhn chung u ch ti giai on c bn, trong nhng nv phn t tng tc vi nhau v lin kt vi nhau to ra snphm mi. S phn loi da vo mt s c s sau y:a. Phn loi theo s phn ct lin kt:Cc cht tham gia phm ng c phn loi theo kh nng phnct lin kt:

Phn ng d li l nhng phn ng ion:A B+ : -

Phn ng ng li l nhng phn ng gc :

A B:

phn ng khng ch c s phn ct lin kt hnh thnh

ion v gc m ch l s phn b li cc obitan lin kt, chnghn phn ng vng ho.

b. Phn loi da vo thnh phn v cu trc sn phm: Phn ng th (S) Phn ng cng (A) Phn ng tch (E) Phn ng chuyn v.

c. Phn loi theo giai on quyt nh tc phn ng: Phn ng n phn t (1) Phn ng lng phn t (2) Phn ng a phn t (n).

d. Phn loi theo bn cht tc nhn phn ng: Phn ng gc (R) Phn ng electrophin (E)


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Phn ng nucleophin (N).2.Cc c ch phn ng trong ho hu c:

a. C ch S N : thng gp dn xut halogen, ancol, este, axitcacboxylic, bao gm nhiu loi :

C ch S N1: S t lin kt c C-X v to thnh lin kt mi C- Y xy ra khng ng thi, phn ng 2 giai on i qua mtsn phm trung gian ( cacbocation), giai on chm quytnh tc phn ng:

R1R2

R3

X chmC

nhanh

C

R1 R2

R3

+ X

YR1

R2R3

C Y v Y CR1

R2R3

V d :

chmCH 3 C H2O OH

CH 3

CH 3Cl Cl CH 3 C

CH 3

CH 3

nhanhCH 3 C

CH 3

CH 3 C ch S N2 : S t lin kt c C-X v to thnh lin kt mi C-

Y xy ra ng thi, phn ng mt giai on i qua trng thichuyn tip (phc hot ng), to ra sn phm o cuhnh:

X Y C+ Y _

C X

_

Y C + X

trng thi chuyn tip

V d :

C+

_

C

_

C +HO Br HO Br HO Br

b. C ch S E : thng gp cc phn ng th vng thm

+C6H6 NO 2 C6H5chm

NO 2

HC6H5NO 2


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c. C ch S R : thng gp hirocacbon no hoc nhnh no cahirocacbon thm.V d : Clo ho metan (nh sng ) bao gm 3 bc :

Khi mo phn ng :

Cl Cl as 2 Cl .

Pht trin mch :

H + Cl.

CH3 CH3 + HCl.

+Cl Cl.

CH3+ Cl2CH3.

Tt mch :

+ ClCl Cl

. CH3+

CH3

. . Cl2Cl.

.CH3 +

.CH3 CH3 CH3

d. C ch A E : thng gp anken, ankin,

XC chmC

+ XC

CXX

+_ C

C+ X

_

nhanh C

C

X

X (trans)

X

Khi cng hp cc anken khng i xng vi hirohalogenua thphn ng xy ra theo quy tc Maccopnhicop. V d :

CH2+

chmH + _

nhanhR CHCH R CH3+ Cl

_ R CH CH3

Cle. C ch A R : thng gp hirocacbon khng no, khi c mtpeoxit.V d : S cng hp ca hirocacbonua vo propilen trong iukin c ch gc c th xy ra theo 2 hng sau y:

CH 2

.

CHCH 3Br

.Br

CH 2CHCH 3

CH 2CHCH 3 Br

.

.

Br

(a)

(b)


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Thc t hng (b) thng chim u th, bi v gc 1- brompropyl cto ra c li hn v mt nng lng, do bn vng hn. Mt khcgc ny c s cn tr khng gian nh hn so vi gc 2- brompropyl(b). V vy trong trng hp ny sn phm cui cng l 1-

brompropan. y l s cng hp hirohalogenua vo anken bti theo quy tc Kharat ( ngc vi quy tc Maccopnhicop). Ch phn ng A R ch xy ra vi HBr v phn ng cng HBr vo anken lqu trnh pht nhit, nh vy trong s tranh chp gia phn ngAE v AR th phn ng A R chim u th tuyt i :

R

CH 3

CH 2CH

BrAR

AE

H2O2

Tinh khit(khng c peoxit)

R CH 2 CH 2

R CH

Br

quy tc Maccopnhicop

quy tc Kharat

Ch : Phn ng cng HOH khng xy ra theo c ch A R do mun chuyn anken thnh ancol theo hng ngc vi quy tcMaccopnhicop ta c th cng vi HBr theo c ch A R ri thu phndn xut brom, hoc p dng pphn ng hirobo ho nh sau :

R CH2CH H2O2CH23 + BH3

00 C (RCH2CH2)3BNaOH R3 CH2OH

f. C ch A N : thng gp anehit, xeton,

CHH+ OH

CH3 Ochm

HCN + -+ CH3 CH

CN

O

H+nhanh CH3 CH

CN

-

g. C ch E1 : thng gp ancol v dn xut halogen

CH 2

OH

CH 3 CH CH 3H +

nhanh CH 3 CH CH 3

O+

H H

H 2Ochm CH 3 CH CH 3

+

nhanhH +CH 3 CH

h. C ch E2 : thng gp dn xut halogen bc thp v mt s

ancol,

BrCH2-HO + H CH2 HO H CH2 CH2 B - -

CH2 CH2 + H2O + Br-


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Nhn xt : Cc phn ng E1, E2 v S N1, S N2 thng hay i km nhau. Trong tng trng hp c th, mt hay hai trong s 4 phn ng trn schim u th hn cc phn ng cn li. T l gia cc sn phmtch v th (E/S) ph thuc vo nhiu yu t: cu trc ca gc

hirocacbon trong phn t cht phn ng, bn cht v nng ca cc tc nhn nuclophin, bn cht ca dung mi v nhit ca hn hp phn ng, V d: Phn ng ca C 2H5Br vi kim ( c ch lng phn t ) cngd xy ra theo hng E2 ( so vi S N2 ) nu baz cng mnh v dungmi cng t phn cc. Do , khi tin hnh phn ng tch C 2H5- Br

to ra C 2H4, ngi ta khng dng KOH trong nc v khi xy ra phnng th m dng KOH trong ru, hoc tt hn na l dng C 2H5OK trong ru.Phn ng ca C 2H5OH nh H 2SO4 c, khi th cho etilen ( phn ngtch ), khi th cho ete etylic ( phn ng th ) l do nh hng canhit . Phn ng tch thng c nng lng hot ho E a ln hn

phn ng th, nn nhit cao c li cho phn ng tch hn.II. Mt s bi tp v c ch phn ng trong ho huc

Bi tp s 1: Cho s :

C

CH 3CH

Cl 2 askt NaOHB D E

CH 3

,Fe Cl

2, NaOH

t0, pCumen(A)

Cc chui phn ng u din ra theo t l mol 1:1, cc cht ghitrn s u l sn phm chnh. Vit cc phng trnh phnng v cho bit c ch cc phn ng t A B, B C. Gii thchs to thnh sn phm chnh ca 2 phn ng ny.

Gii :


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H

ClH Cl

+

CHCH3CH3

Phc

CHCH3CH3

+

H + FeCl 4 FeCl 3 + HClDo gc (CH 3)2CH- c hiu ng +I l nhm th loi I nn nh h-ng phn ng th tip theo vo v tr ortho v para. Nn giaion to phc c th c hai phc sau :

H Cl

+

CHCH3CH3

(I)(II)

+

CHCH3CH3

H

Cl

Do gc (CH 3)2CH- c s n ng v khng gian nn dn n Cl +

kh tn cng vo v tr ortho nn phn nc (II) kh hnh thnhhn. Cho sn phm chnh l :

Cl

CHCH 3CH 3

C ch phn ng B CPhn ng th theo c ch gc S R, gm cc giai on :

- Khi mo phn ng :

Cl2 Cl2as.

- Pht trin mch :

Cl+.

Cl

CHCH 3CH 3

Cl

CCH 3CH 3

.

+ H Cl

Cl 2

Cl

CCH 3CH 3

.

+

Cl

CCH 3CH 3

Cl

+.

Cl


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C nh vy

- Ngt mch

Cl 2.

+Cl .ClR. + .Cl R ClR. + R

. R R

Cl CCH3

CH3

..

V i gc t do R :

Trong giai on pht trin mch c th sinh ra cc gc sau :

(I) (II)

Cl

CH

CH 2CH 3

Cl

C

CH 3CH 3.

.

Gc (I) bn hn do c hiu ng +C ca vng benzen v hiu ng+H. Gc (II) km bn hn do ch c hiu ng +H.Nn sn phm chnh l :

Cl

CH3

ClC

CH3

Bi tp s 2: a. Cho s sau : ,HClHexin-3 xt t0 C6H12Cl2

Vit c ch phn ng v cu trc ca sn phm to thnh.

b. Butin-2Br2 , 1:1 A

Xc nh cu trc ca A v gi tn.Gii :

a.H Cl2+C CH 2CH 3 CH 2C CH 3 CH 3 CH 2 CCH 2

C

Cl

CH 2CH 3

C ch :


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H ClCCH 3 CH 2C CH 3CH 2 CCH 3 CH 2C CH 3CH 2

H

Cl CCH 3 CH 2C CH 3CH 2

H Cl

CCH 3 CH 2C CH 3CH 2

H

H

Cl

H Cl

Cl CCH3 CH2C CH3CH2

H

H

Cl

Cl

b.Phn ng tun theo quy tc Maccopnhicop v theo hng cng hp

trans.

+CCH 3 C CH 32 Br 2

Br

1:1

cng transCCH 3 C CH 3

Br

trans - (hay E-)2,3 -ibrom-2-buten

CCH 3 C CH 3Br Br CCH 3 C CH 3

BrBr

Br

CCH 3 C CH 3

Br

Bi tp s 3: Vit cng thc cc ng phn lp th khng iquang ( ng phn lp th i-a ) ca 2-clo-1,3-imetylxiclohexanv cho bit cu trc sn phm to thnh khi cho cc ng phn tc dng vi CH 3ONa.

Gii :CH 3

CH 3

Cl

CH 3

ClCH 3

CH 3

Cl

CH 3

CH 3

CH 3

Cl

(I) (II) (III)


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H3CH3C

H3C

CH 3 CH 3CH 3

H

H HH H

ClClCl

C 2 H Cbn cnh utch ra

Khng tch c vH C bn cnh khng ngphng v u vtrcis iv i clo

Chc 1 H l tch c

CH 3CH 3

CH 3CH 3

1,3-imetylxiclohexen

1,3-imetylxiclohexen

H

Quy tc Barton Hassel : Phn ng tch nucleofin vng noch chy tt khi cc nhm th c tch ra v tr axial trans.

Bi tp s 4: Hon thnh cc chui phn ng sau:a. CH3I + (CH3)2CHO- b. CH3O- + (CH 3)2CHIc. (CH3)3CCH2I + C 2H5O-d. (CH3)3Br + CH 3O-

e.

Cl+ (CH 3)3CO-

f.

CH2Br

+ (CH 3)2CHCH2O-

g.

CH2O-

+ (CH 3)2CHCH2BrGii :

a. CH3I + (CH3)2CHO- I- + CH3 CH OCH3

CH3

b. CH3O- + (CH 3)2CHI CH3OH + I - + CH3CH2 CH

c.

CCH 3

CH 3

CH 2

CH 2Kh vvng ny nh km bn

C

CH 3

CH 2ICH 3CH 3

OC

CH 3

CH 3CH 3

CH 2 C2H5

(Ph)

C2H5O-

I-+

+ I-

+ C2H5OH +


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d. (CH3)3CBr + CH3O- CH2 = C (CH3)2 + CH3OH + Br - e.

Cl

+ (CH3)3CO- + (CH3)3COH + Cl-

f.

CH2Br

+ (CH3)2CHCH2O-

CH2OCH2CH(CH3)2

+ Br-

CH3CH2 C

CH3

CH2O-

+ (CH3)2CHCH2Br

CH2CH2CH(CH3)2+ Br-

+CH2OH

+ Br-

g.

Cn l u : :* Phn ng th nucleofin lun i km phn ng tch. Khi bc cagc hirocacbon tng ln, phn ng th gim. Nhit cng cao,kim cng mnh, cng u tin tch loi.

CH 2

C2H5OHH2SO 4

- H 2O C2H5OSO 3H

180 0Ctch

140 0C+C 2H5OH, th

C2H5OC 2H5 H2SO 4

CH 2

monoetyl sunfat+

+ H 2SO 4

* Trong phn ng tng hp ete theo Williamson ( dn xut halogentc dng vi ancolat ) c km theo tch loi. Gc hirocacbon bc 2,3 th thng l phn ng tch loi.Bi tp s 5: Hon thnh cc phn ng sau:

a. C

CH 3

CH 3

CH 3

CH 2BrH2O

SN1, E1

b.

CCH 2CH 3H2O

SN1, E1CH 2

CH 3

CH 3

Br

c.C CHCH 3

H 2 O

S N 1, E1

CH 3

CH 3 Cl

CH 3


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d.CH2 CH CH2Br

H2OSN1, E1

CH2

CH2

CH2 CH CH2BrH2O

CH2

CH2

Gii :`

a.

C

CH 3

CH 3

CH 3

CH 2BrH2O

SN1, E1C

CH 3

CH 3

CH 3

CCH 3

CH 3

CH 2 CH 2 CH 3

CCH 3CH 3

CH 2 CH 3

CCH 3CH 3

CH 2 CH 3

OH

CCH 3CH 3

CH CH3

+ CCH2

CH 3

CH 2 CH 3C

b.

Br

C

CH 3CH 3

H 2 OSN 1, E1

CH 3

CH 2 CH 2 CH 32

CH 2 C

CH 3

CH 2

OH

CH 3CH 3 CH C

CH 3

CH 2 CH 3

CH 3 CH 2 C CH 2CH 2 CH 3

c

C

CH 3

CH 3C

CH 3

CH 3

CHCH 3

Cl

3H2O

SN1, E1CH 3

CH 3

CHCH 3

Chuyn vCH 3 C

CH 3

CHCH 3 CH 3

CH 3

sn phmchnh

C

CH 3

CCH 3 CH 3

CH 3

C

CH 3

CCH 3 CH 3OH CH 3

d.


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CH 2 CH CH 2BrH 2OSN 1, E1

CH 2

CH 2CH 2 CH CH 2

CH 2

CH 2

CH 2 C CH 2

CH 2

CH 2

HChuyn v

hiruaCH 2 C CH 3

CH 2

CH 2

CH 2

CH 2

CH 2

C

OH

CH 3

CH 2 CCH 2

CH 2

CH 2

CH 2 CCH

CH 2

CH 3

CH 2 CH 3

CH 2

CH 2

CH M vng

OH

Bi tp s 6: Hy cho bit sn phm to thnh khi thc hin phnng hirat ho cc cht sau vi xc tc axit H + . Trnh by c

ch phn ng.a. propan-1,2-iol.b. 2-metylpropan-1,2-iol.c. 2-metylbutan-2,3-iol.

Gii :a.

+CH3CHCH3 CH2

OH OHH CH2 CHO H2O

C ch :

CH

Chuyn vCH3

CH3 CH2OH OH

H CHCH3 CH2OH OH2

. -H2OCH3 CH

OH

CH2

CH

OH

CH2 CH3H- OHC CH2 CH3

CHCH3 CH2OH OH

H CHCH3 CH2OHOH2

. -H2OCHCH3 CH2

OH


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CH

Chuy n vhirua CHCH3

OH

CH2 H CH3CH2 CHO

CCH3

OH

CH3

CH2OH

b. H

-H2O

CH3 CHO

CH3

+ CH3 C

OCH2CH3

CCH3

OH

CH3

OH

c. CH CH3 H-H2O

CH3 C

OCH CH3CH3

+ CH3 C CHO

CH3

CH3(cchtrnh by t ng t cu a.)

(cchtrnh by t ng t cu a.)

Cn lu : Trong trng hp mt nguyn t cacbon COH c hai nhmth khc nhau th nhm no c tnh cht y electron mnh hn sb chuyn dch.

Bi tp s 7: a. Vit phng trnh phn ng khi cho alyl clorua, benzyl clorua tcdng vi dung dch KOH un nng.b. Hp cht hu c X c cu to khng vng c cng thc C 4H7Cl vc cu hnh E. Cho X tc dng vi dung dch NaOH trong iu kinun nng thu c hn hp sn phm bn c cng thc C 4H8O.

Hy cho bit cu trc ca X v cu hnh ca sn phm tothnh.

Gii :

a. CH2 CH2ClCH + KOH CH2 CH2OHCH + KCl+

CH 2Cl+ KOH + KCl

CH 2OH

b. Vi cu hnh E, C 4H7Cl c 3 cu trc sau :


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CH 3C

CH 2ClH

C

CH 3

Cl..

C2H5C C

H Cl..

H

III

CH 3C

H

C

H

III

C4H7Cl t0 C4H8O C 4H7OH:

I v II rt kh thu phn do s lin hp gia cp electron khng linkt ca Cl v ni i. Tho mn iu kin trn l III.

CH2Cl

Cl (-)CH3C

H

CH

CH2

CH3C

H

CH

CH2OH

CH3C

H

CH

OH

*

- chuyn v

OH (-) OH(-)

CH3 CH CH CH2

(Dng E)(Bin thra xemic)

CH3 CH CH CH2

III. Tm tt kin thc c bn v c ch cngelectrophin, iu kin nh h ng n c ch , ccyu t nh h ng.III.1. C ch cng electrophin1. c im c ch

Phn ng gm nhiu giai on; quyt nh tc chung caphn ng l giai on cng tiu phn mang in dng to thnh

sn phm trunggian R + :

XY : Hal2 , Hal Hal, HHal , HOH , HalOH, H2SO4, vv

Trc khi to thnh R + c th to thnh phc gia C=C v XY. Cch AE vo ni ba tng t c ch A E vo ni i.2. Tin trnh lp th

CC chm-Y- X C C

+ nhanh Y -

+

-

YX C C Y+

X


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V mt l thuyt, X v Y c th cng vo cng mt pha cani i, gi l kiu cng cis hay cng syn, hoc cng t hai phakhc nhau- cng trans hay cng anti. Tuy nhin, nu X cng vo trc n ng mt pha, nht l khi to ra cacbocaton vng ni ( trng

hp X l halogen ), Y s i vo pha i lp :

CC

+

CC CCHal Hal

+

Hal

Hal

Hal

.....

Nh vy, phn ng cng eletrophin thng xy ra theo kiu transhay l anti.

3. Dn chng- Cho etilen tc dng vi brom, c mt tc nhn nucleophin Y (thd Cl-, NO3-, CH3OH) thu c sn phm cng hn tp (cha Br v Y -)

CH 2 CH 2

Br CH 2 CH 2 Br

Br CH 2 CH 2 Cl

Br CH 2 CH 2 O CH 3

dung mi NaCl

CH 3OH

iu chng t phn ng nhiu giai on.- Cho xiclohexen tc dng vi HBr trong benzen v trong ete (ete cth b proton ho) thy k ete < k benzen . Th nghim ny cho thy rngnng H + c nh hng n tc phn ng v giai on to R +

trung gian l giai on chm.- (E)-Anken cng XY cho cp eritro, cn (Z)- Ankencho cp treo,iu ny chng minh tin trnh cng anti ca phn ng.III.2. Mt s phn ng cng tiu biu1. Phn ng cng halogenPhn ng xy ra trong iu kin khng chiu sng c xc tc ( thd AlCl3) hoc ch cn dung mi phn cc nhit phng( dung mi cng c th tham gia phn ng ). Tin trnh lp th rtc th ( cng trans ).Ch :- Flo tc dng rt mnh lit, thng gy phn ng hu. C th thchin phn ng cng flo nu dng tc nhn l XeF 2, CoF3 hoc hnhp SF4+PbO 2


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- Clo c th cng vo ni i hoc gy phn ng hu (khi c tiala in hoc chiu sng mnh).- Brom t c dng vo ni i mt cch m du v thun tin nht.- Iot rt km hot ng. Phn ng chm v thun nghch.- Cc hp cht lin halogen Hal-Hal c kh nng phn ng cao hnhalogen tng ng, v c s phn cc v pha Hal m in hn

I2 < IBr < Br 2 < ICl < BrClkt 1 3.10 3 10 4 10 5 4.10 62. Phn ng cng halogenua hiro

Phn ng thng bt u bng s hnh thnh phc . Tnhc th lp th khng cao.

Th d : DCl cng trans vo metyl xiclopenten-1, nhng li cng cisvo propenylbenzen.

Kh nng phn ng ca HHal tng theo lc axit :HF


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(CH 3 )2 C = CH 2 (CH 3 )3 CCH 2 = C(CH 3 )2

(CH 3 )3 C-CH 2 -C(CH 3 )2

(CH 2 )3 C - CH = C -CH 3 (CH 3 )3 C - CH 2 -C = CH 2

H

CH 3 CH 3

+ + + +- H

+

20% 80%

Dng xc tc l axit Liuyt nh BF 3, SnCl4, AlCl3c th trng hpizobutylen thnh polime. ng ch l phn ng ch bt u khithm mt lng nh nc hay axit v c (lm cht xc tc). V vy khitrng hp khng phi axit Liuyt tc dng m l axit v c sinh ra taxit Liuyt lm xc tcIII.3. Kh nng phn ng v h ng cng eletrophin

1. Kh nng phn ng cng eletrophinKh nng phn ng cng lin quan n tc nhn, v cht xc

tc v c bit l cu trc hp cht cha no. Theo c ch cng eletrophin th giai on quyt nh tc

phn ng l giai on tn cng ca tiu phn mang in tchdng vo ni i, v vy mt electron lin kt bi cng cao

v cacbocation sinh ra cng n nh phn ng cng d xy ra.Nh vy nhng nhm th y electron ( < 0 ) lin kt kp lm

tng kh nng phn ng A E, tri li nhm th ht e ( > 0 ) lmgim kh nng phn ng. Th d k t ca phn ng cng brom :(CH3)2C=CH2 > CH3CH=CH2 > CH2=CH2 > CH2=CHBr > CH 2 =

CHCOOH

5,53 2,03 1,0 0,040,03

Cc quy lut v nh hng ca nhm th n kh nng cngca an ken ni chung cng c th p dng cho cc an kin :

CH 3 CCH CH CH CH> > C-COOH

ng ch l so vi an ken th ankin c kh nng phn ng

electrophin thp hn. Chng hn tc lm mt mu nc bromca axetilen chm hn etilen l 5 ln.


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S khc nhau v kh nng phn ng ca lin kt C C v lin ktC=C ln n mc c th brom ho chn lc ch ring ni i caenyn.

CH CHCH 2 = CH - CH 2 - C + Br BrCH 2 - CHBr - C2

2. Hng cng electrophinPhn ng cng electrophin lun xy ra u tin theo hng hnh thnhcacbocation trung gian tng i bn hn (quy tc Maccopnhicop c khi qut ha).V d:

CH 3CH = CH 2

CH 3CHCH 3 CH 3CHXCH 3

CH 3CH 2CH 2 CH 3CH 2CH 2 X

HXX --

+

+ X-

X -

(sn phm chnh)

(sn phm ph)

(bn hn)

(km bn)

CF3CH = CH 2

F3C - CHCH 3 CF3CHXCH 3

F3C - CH 2CH 2 F3CCH 2CH 2 X

-

+

HX

-

+

(sn phm chn

(sn phm ph)

(bn hn)

(km bn)X

--

XX -

+

+

Theo quy lut trn, cc phn ng cng HCl vo CH 2=CHCl,CH3C CH v CH2= CHCN ln lt cho CH 3CHCl2, CH3CCl = CH2 vClCH2CH2CN.IV. Vn dng gii quyt mt s vn cn thit trongging dy ch ng : an ken ankaien ankin

C ch cng electrophin trong chng trnh ha hc phthng c th tin hnh khi nghin cu cc hirocacbon khng noqu trnh ny c th chia lm 3 giai on :

- Xut hin cc tiu phn hot ng (cc ion v c)- To ra cc ion hu c (cacbocation)- Tng tc gia cc ion to ra cc phn t trung ha

Phn ng cng vo an ken ni ring cng nh hirocacbonkhng no ni chung c xt vi ba tc nhn : Hiro (H 2), halogen(X2) v HX.


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- Nhm 1 : Tc nhn i xng H 2 v X2- Nhm 2 : Tc nhn bt i xng H-X

y ta ch xt c ch cng electrophin vo hiro cacbonkhng no

IV.1. Anken Tnh cht c trng ca an ken l khuynh hng i vo phn

ng cng phn ng ny lin kt b t ra hai nhm mign thm vo v cho mt hp cht no

C =CH

H

H

H+ X - Y H - C - C - H

H X

Y H

Mt c im ni bt ca an ken l mt electron tptrung tng i cao gia hai nguyn t cacbon ca ni i C=C v

tri rng ra theo hai pha ca lin kt . V vy tc nhnelectrophin tc dng c bit d dng vo cc ni i C=C chyu l cng electrophin.1. Cng halogen (Cl 2 , Br 2 ) :

CnH2n + X2 (dd) CCl4 CnH2nX2 V d :

C =CH

H

H

H H - C - C - HH Br

Br H

CCl 4+ Br 2 (dd)

C ch phn ng cng dung dch nc brom : cng electrophin

(ion dng tn cng trc vo cacbocation mang in m) theo haigiai on :

a. Giai on chm (quyt nh tc phn ng) to racacbocation (cation c in tch dng trn nguyn t cacbon).

CH 2 = CH 2 + Br Br CH 2 - CH 2 - Br + + +- -

b. Giai on nhanh :

+ -CH 2 - CH 2 - Br + Br CH 2 - CH 2Br

Br


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Phn ng ny dng nhn bit an ken nh s mt mu nu ca dung dch nc brom.2. Cng HX (X : halogen, OH, OSO 3H)Quy tc Maccopnhicop : Khi cng mt anken bt i vi mt tc

nhn bt i HX th sn phm chnh c to thnh do phn dngca tc nhn ( H +) gn vo C ca ni i mang in m (C cnhiu nguyn t hiro hn) v phn m ca tc nhn (X) gnvo cacbon ca ni i mang din dng (C c t nguyn t hirohn)

CH3

- CH = CH2

+ HClCH3 - CH2 - CH2 - Cl (sn phm ph)

CH3 - CH - CH 3 (sn phm chnh)Cl

Gii thch quy tc : Phn ng xy ra theo c ch cng electrophindo giai on chm u tin to ra cacbocation bn vng hn(in tch dng ca cacbocation c gii ta khp phn t).

( + -

-CH 3 - CH = CH 2 + HCl CH 3 - CH 2 - CH 2 + Cl

CH 3 - CH - CH 3 + Cl(A)

(B)

)

( +)

Cacbocation (A) bn hn (B) v in tch dng nm ixng nn gii to trn ton b phn t.Cng c th gii thch : do gc ankyl y electron lm cho lin kt b phn cc, nn ion dng d gn vo cacbon mang in mv ngc li.- Kh nng cng : HI > HBr >HCl > HF- Phn ng cng H 2O : etylen ru etylic

ng ng ru bc 2 hoc bc 3

CH2 = CH2 + HOH H+ CH3CH2OH

CH 3-CH=CH 2 + HOH CH 3-CH-CH 3OH

H +


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CH 3- C = CH 2 + HOH CH 3 - C - CH 3

CH 3

OH

H +CH 3

- Phn ng cng H 2SO4

CH 3-CH=CH 2 + H-OSO 3H CH 3-CH-CH 3OSO 3H iso propyl hirosunfat( )

IV.2. AnkaienAnkaien lin hp to thnh do hai ni i C=C xen k bng mt nin C-C.Cc hp cht c ni i C=C quan trng l:- Butaien 1,3 hay ivinyl : CH 2=CH-CH=CH2

2-Metyl butaien-1,3 hay isopren CH2 = C-CH =CH 2

CH3

- :

Butaien 1,3 c th coi l cht in hnh cho cc ien lin hp.Butaien -1,3 cho cc phn ng thng thng ca an ken, nhng xyra d dng hn nhiu so vi a s cc anken hoc cc ien c nii cch xa. Mt khc bn cnh cng hp 1,2 cn xy ra cng hp1,4.Chng hn :Ankaien c th cng ti a theo t l s mol 1:2CH2=CH-CH=CH 2 + Br 2 CH2-CH-CH-CH2

Br Br Br Br2

(Tetra brom butan)

Nu phn ng cng theo t l 1:1 th s cho 2 sn phm theokiu cng 1,2 v cng 1,4

(1,2)

(1,4)

CH 2=CH-CH=CH 2 + Br 2

CH 2-CH-CH=CH 2

CH 2-CH-CH=CH 2Br Br

BrBr (20%)

80%)(

CH 2=CH-CH=CH 2 + HCl

(1,2)

(1,4)

CH 3 -CH-CH=CH 2

CH 3-CH=CH-CH 2-Cl

Cl

i vi isopren, phn ng cng vi HCl theo t l 1:1 c th cho ti

a 7 sn phm cng, nhng trong thc t ch c 2 sn phm chnhsau :


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CH 2=C-CH=CH 2 + HCl

CH 3-C-CH=CH 2

CH 3-C=CH-CH 2

CH 3 ClCH 3

Cl

CH 3(1,2)

(1,4)

IV.3. Ankin Trong phn t c mt ni ba C C vi nguyn t C lai ho sp nnphn t c cu to thng, gc ho tr 180 0.Lin kt C=C bao gm mt lin kt km bn. Tuy nhin ni trong C C hi bn hn so vi ni trong C=C nn phn ng cngvo ni ba xy ra kh hn cng vo ni i.1. Cng halogen X 2( X : Cl, Br )

Phn ng xy ra qua hai giai on (giai on 1 cng trans)CnH2n-2 +X2 CnH2n-2 X2 +X2 CnH2n-2 X4V d :

CH CHBr2 CH=CH

Br

Br

CH - CHBr Br

Br Br

Br2+ +

trans-1,2- ibrometen 1,1,2,2-TetrabrometanGiai on sau xy ra kh hn giai on trc. Ni chung cc ankinlm mt mu dung dch nc brom chm hn anken.2. Cng HX( X : Cl, Br, I )Phn ng ny cng xy ra hai giai on v giai on sau kh khnhn giai on trc.

CH CH HCl CH2=CH-Cl CH 3-CHCl2HClaxetilen Vinyl clorua 1,1- iclo etan

Trong k thut, vinylclorua c iu ch bng cch cho hn hpcng s mol C 2H2 v HCl i qua cht xc tc HgCl 2 150-200 0C.

CH CH CH2=CH-Cl

HgCl2150-200 C0

+ HCl


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CH2=CH-Clnxt,t o,p -CH2-CH-

Cln

Phn ng cng cc ng ng axetilen tun theo quy tc

Maccopnhicop.3. Cng HOH (hirat ha)

Axetilen Anehit axeticng ng Xeton

CH CH + HOH HgSO480 C0

CH2=CH

OH

CH3-CHOAnehit axetic

km bn

0tR1 - CH=C - R 2

OH

R1 - C =C- R 2 + HOH R1 -CH2-C - R2,pxt

Okm bn Xeton

4. Cng axit CH 3COOHAxetilen v cc ankin-1c kh nng tham gia phn ng cng vi

axit axetic

CH CH + CH 3COOH CH2=CH-O-C-CH 3

OZnCH3COO)2

0t5. Cng hiroxianua :

CH CH + H-CN CuCl2/NH3 CH2=CH-C NIV.4. Bi tp p dngBi 1 : Hon thnh cc phng trnh phn ng sau ( vit sn phmchnh):

a. CH2 = CH2 + HBr ? b. CH3- CH = CH2 + HI ?c. ? + ? CH3- CHBr- CHBrCH3


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d. ? + ? CH3- CHBr- CH(CH3)2Bi gii

a. CH2 = CH2 + HBr CH3-CH2Brb. CH3- CH = CH2 + HI CH3- CHI- CH3

c. CH3- CH = CHCH3 + Br 2 dungmi tr CH3- CHBr- CHBrCH3d. CH2= CH- CH(CH3)2 + HBr CH3- CHBr- CH(CH3)2

Bi 2 : Vit sn phm v gii thch c ch phn ng ca etilenvi :a, Br 2 trong CCl 4 b, Br2 trong H 2O c, Br2 trong ncc pha NaClBi gii a,

C =CH

H

H

H H - C - C - HH Br

Br H

CCl 4+ Br 2(dd)

C ch : Giai on chm (quyt nh tc phn ng) to ra

cacbocation. CH2= CH 2 + Br Br CH 2 - CH2 - Br + + +- -

Giai on nhanh :

+ -CH2 - CH2 - Br + Br CH2 - CH2Br

Br

b, Trong dung mi nc c sn phm Br-CH 2-CH2-OH(etilenbromhirin) theo c ch phn ng :

Br2 + H 2O HBr + HOBr {H+ , Br-, HOBr}

CH 2=CH 2 + Br - OH CH 2-CH 2 + OH CH 2-CH 2

Br

OH

Br

-++ -

Ngoi ra c th c :


26/30

CH 2-CH 2

Br+

+ Br - CH 2 - CH 2Br

Br

c, Tng t nh b, nhng cn c :

CH 2-CH 2 CH 2-CH 2

BrBr

+ -+ ClCl

Khng to ra 1,2 - icloetan do khng c tc nhn Cl +Nh vy : Mun cho phn ng ch to ra BrCH 2-CH2Br phi tin hnhphn ng trong dung mi tr ( v d : CCl 4)Bi 3 : Propen phn ng vi nc brom c ho tan mt lng nh NaI cth to thnh bao nhiu sn phm ? Vit phng trnh phn ng.

Gii thch?C ch :Giai on chm : Tc nhn eletrophin Br + cng vo C - to racacbocation :

CH 3-CH=CH 2 + Br 2

CH 3-CH-CH 2Br + Br

CH 3-CH 2Br-CH 2 + Br

(+)

(+)

-

-

Giai on nhanh : Cacbocation kt hp vi Br -, I-, OH- to ra 5 snphm gm :

CH 3-CH=CH 2 + Br 2 CH 3-CH-CH 2

BrBr(1)

CH 3-CH=CH 2 + Br 2 + I-

CH 3-CHI-CH 2Br + Br

CH 3-CHBr-CH 2 I + Br

-

-

(2)

(3)

CH 3-CH=CH 2 + Br 2

CH 3-CHOH-CH 2Br + HBr

CH 3-CHBr-CH 2OH + HBr

(4)

(5)

+ H O 2

Bi 4 : So snh s chn lc v tr ca phn ng gia HBr vi :

a, CF3CH=CH2 b, BrCH=CH2 c, CH3-O-CH=CHCH3


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Bi gii a, Ba nguyn t F lin kt vi C c t nguyn t hiro c khuynh h-

ng ko cp electron v pha n gy ra phn ng cng ngc quytc Maccopnhicop. Do sn phm chnh l CF 3CH2CH2Br :

-C - CH = CH 2 + HBr CF 3CH 2 - CH 2Br

FF

F

+

b, Vi Br hiu ng ht electron b b qua bi s bt nh x tri

rng ca mt cp electron cha lin kt t Br n C + , bng cch

y lm bn vng cation R + ( hiu ng cng hng p- ) :

+Br....: CH CH 3 Br..:

+CH CH 3

v sn phm Maccopnhicop c to thnh :

BrCH = CH 2 + HBr Br - CH - CH 3

Br

c, Tng t b, xy ra hin tng cng hng p- gia cp electron p

t do cha lin kt ca oxi vi electron :

.. ..+

CH3 - O - CH = CH - CH3 CH3 - O = CH - CH2 - CH3H+..

+.. CH 3 - O - CH - CH 2 - CH 3CH 3 - O - CH -CH 2 - CH 3

+ Br -..

Br

Nhn xt : Khi c nhm ht electron cn c 1cp electron p trnnguyn t gn vo cacbon ni i th c hin tng cng hng p - v phn ng cng theo quy tc Maccopnhicop.Bi 5 : Vit cc phng trnh phn ng theo t l s mol 1:1 cacc cht sau y vi dung dch Br 2 trong CCl 4. Gii thch s nhhng phn ng :a, CH2= CH- CH2- C CH b, CH2= CH- C CHc, (CH3)2C= CH- CH2- CH= CH2 d, CH3- CH= CH- CH2- CH= CHBr

Bi gii a, CH2= CH- CH2- C CH + Br 2 CH2Br- CHBr- C CH


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Kh nng phn ng cng electrophin ca lin kt i (C sp 2 ) cao

hn lin kt ba (C sp) do m in C sp > C sp 2 nn kh nng gieletron ca C sp bn hn.b,

CH 2Br-CH=C = CHBr

CH 2=CH-CBr = CHBr

CH 2Br-CHBr-C = CH

CH 2 = CH - C = CH1 32 4 + Br 2

1,4

3,4

1,2

C 3 sn phm cng : cng 1,4 ; cng1,2 ; cng 3,4 do c s

lin hp gia cc lin kt

ca lin kt i v lin kt ba.c, (CH3)2C = CH - CH 2- CH = CH 2 + Br 2 (CH3)2CBr- CHBr - CH 2 -CH = CH 2

6 5 4 3 2 1

Do C 5 c hai nhm CH 3 y electron v pha lin kt i nn mt electron lin kt C 5 = C 4 cao hn lin kt C 2 = C 1 nn kh nngphn ng electrophin ca C 5 = C 4

6 5 4 3 2 1

CH3-CH = CH - CH 2 -CH = CHBr + Br 2CH

3CHBr - CHBr - CH

2- CH = CH

2d,

Kh nng cng A E ca lin kt C 5 = C 4 cao hn lin kt C 2 = C 1 do C5 = C 4 cnhm CH 3 y electron lm tng mt electron, cn C 2 = C 1 cBr ht electronlm gim mt electron.

Bi 6 : Khi cho iso-butilen vo dung dch HCl c ha tan NaCl,CH3OH c th to ra nhng hp cht g ? Gii thch.

Bi giiSn phm phn ng l hn hp gm :

CH 3 - CBr - CH 3

CH 3 - CCl - CH 3 CH 3 - C- O-CH 3

CH 3CH 3 - C - CH 3

OH

CH 3

CH3

OH

CH 3

v

;

Gii thch da vo c ch phn ng


29/30

- Trong dung dch c cc qu trnh phn li :HBr H+ + Br -

NaCl Na+ + Cl -

Do trong dung dch c 4 tc nhn l Br -, Cl-, H2O v

CH3OH c kh nng kt hp vi cacbocation. Phn ng theo cch cng electrophin (A E).

Trc ht tc nhn electrophin(H + ) tn cng vo C - to cacbocation (giai on chm) :

CH 3 C CH 2 + H CH 3 - C - CH 3

CH 3CH 3

++ + - chm

Sau l qu trnh kt hp cacbocation vi cc tc nhnBr-, Cl-, H2O v CH3OH to thnh sn phm (giai onnhanh) :

+

CH 3CH 3 - C (+)

OHBr CH 3 - C - Br

CH 3

- nhanhCH 3

+ nhanhCH 3

CH 3 - C (+)OH

Cl - CH 3 - C - ClCH 3

CH 3

nhanh CH 3 - C - OH + HCH 3

CH 3+

CH 3CH 3 - C (+)

OHHOH

nhanh CH 3 - C - O - CH 3 + HCH 3

CH 3+

CH 3CH 3 - C (+)

OHCH 3OH

Bi 7 : Cho bit sn phm phn ng ca isobutilen vi H 2S trongH2SO4 c. Ti sao phn ng khng xy ra nu khng c H 2SO4c.

Bi gii

Phn ng :


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CH3 - C = CH 2 + H 2S CH3 - C - S - HCH3

CH3

CH3

H2SO4 mc

Gii thch : H2S l axit yu khng th bt u phn ng bng

cch cng H+

vo C=C to cacbocation (CH 3)3C+

, sau linkt vi S ca H 2S to axit lin hp ca (CH 3)CSH2+ v tr li H +

cho HSO4 - to sn phm cui cng.

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