1Cau truc ien t cua nguyen t carbonS tao thanh cac lien ket trong hp

chat hu c

Chng 1:

1

1. Cu trc in t1.1. Thuyt t din (Vant Hoff-Le Bel)

C C109o28'

Nguyn t carbon c 4 ha tr.

Bn ha tr hng ra 4 nh ca t din

Tm t din l nguyn t carbon.

Cc gc ha tr tm u bng 109o28

Khi nguyn t lin kt vi 4 nguyn t hay 4 nhm th ng nht th c 1 t din u

2

21.2. Cu trc in t ca nguyn t carbon1.2.1. Trng thi c bn

Cu hnh C

Cn 1 orbital trng (pz)

1.2.2. Trng thi kch thch C*

1s22s22px12py12pz1 = 1s22s12p3

Carbon c 4 in t n c to lin kt. Carbon c ha tr 4. Bn in t kch thch c nng lng khc nhau do cc lin kt phi khc nhau.

1s22s22p2 = 1s22s22px12py1

1s22s22p2

px py pz

3

1s2 2s2 2p2 1s2 2s1 2p3

M hnh khng gian lai ha sp3

1.2.3. Carbon trng thi lai ha

4

3M hnh khng gian lai ha sp2

5

M hnh khng gian lai ha sp

6

42. S to thnh cc lin kt2.1. Lin kt cng ha tr- v - Lin kt hnh thnh do s xen ph cc i ca cc orbital

nguyn t thnh orbital phn t.

- Khi vng xen ph ca cc orbital nguyn t cng ln th linkt c to thnh cng bn v nng lng thot ra hnh thnhlin kt cng ln.

- Xen ph trc: to lin kt

7

- Xen ph bn: to lin kt .

2.2. Lin kt v trong ha hu c2.2.1. Lin kt c to thnh do s xen ph- Orbital s ca nguyn t H vi cc orbital lai ha sp3, sp2 v sp

ca nguyn t C.- Orbital lai ha ca cc nguyn t C vi nhau.- Orbital lai ha (s, p) ca nguyn t O, N vi orbital s ca H

hoc vi cc orbital lai ha ca C to lin kt C-O, C-N hocN-H.

8

59

2.2.2. Lin kt c to thnh do s xen ph- Orbital py hay pz ca nguyn t C xen ph vi nhau tng i

mt to lin kt C=C hoc CC.- Orbital p ca nguyn t O, N vi orbital p ca C to lin kt

C=O hoc C=N hoc C N.

10

6 2.3 Tnh chat cua cac lien ket A. S phan cc cua lien ket:

Khi phan t co dang A-A V du: H-H, Cl-Cl, CH3-CH3

Khi 2 nguyen t lien ket vi nhau khong ong nhat (A-B): cap lien ket se lech ve pha co A ln hn. ay la lien ket cong hoa tr phan cc.S phan cc xay ra ca lien ket va .

: mui ten thang ( ): mui ten cong ( )

Chieu mui ten la chieu chuyen dch ien t.V d C H 3 C l H 3 C C l

-,

H 2 C O11

B. tan:

C. di lin kt:L khong cch gia 2 ht nhn nguyn t lin kt.c o bng cc phng php vt l hin i.- di lin kt (DLK) gia C v 1 nguyn t trong 1 phn

nhm tng theo STT ca nguyn t:C-F < C-Cl < C-Br < C-I

- DLK gia C v 1 nguyn t trong 1 chu k gim khi STT tng:C-C > C-N > C-O > C-F

Lin kt cng ha tr:- t hoc khng tan trong nc-Tan tt trong cc DM HC-Thng khng dn in

Lin kt ion:-d tan trong nc-Khng hoc t tan trong DM HC-Dung dch dn in

12

7C. di lin kt:- DLK cng nh th lin kt cng bn, DLK cng ph thuc

vo:- loi xen ph:- DLK gim khi tng bi ca lin kt (tng orbital ):

C-C > C=C > CCC-O > C=OC-N > C=N > CNN-N > N=N > NN

- A ca nguyn t: khc nhau v A cng ln th DLK cng ngn li.

- DLK gia C v nguyn t khc ph thuc vo trng thi lai ha ca C: t l orbital s trong orbital lai ha cng cao th DLK cng ngn.

Csp3-H > Csp2-H > Csp-H13

alkan u ging nhau.

2.4 Mt s lin kt yu hn lin kt cng ha tr:2.4.1 Lin kt hydro:l lin kt rt yu do sc ht tnh in gia nguyn t H v 1 nguyn t khc c cp in t t do.Nng lng lin kt nh (3-8 kcal/mol).

X-H ... Y-iu kin hnh thnh lin kt hydro:

X c A ln hn H sao cho X-H phn cc.Y c cp in t t do.X, Y thng l F, O, N. Nu l Cl, S th s rt yu.

14Lin kt hydro lin phn t Lin kt hydro ni phn t

O H

N O

O

OCH3

H OCH3

H OCH3

H

O H

HC

OH3C

OHC

OCH3

HOC

O

OCH3

H

8C 2 loi lin kt hydro:

Lin phn t:-Pha long/DM tr: b ct t.

-tn/c, ts:+ Tng

- tan: lin kt hydro lin phn t gia cht tan v DM lm tng tan trong DM phn cc.- bn

Ni phn t:-Pha long: khng nh hng-Lin kt bn khi to thnh vng 5,6 c bit l 7.-tn/c, ts:

+ Khng nh hng- tan: tng tan trong DM khng phn cc.

- bn: lm cho ng phn tr nn bn vng hn.

C CH

HC l

C lH

HC CH

HC l

HH

C l

C CH

HO H

O HH

HC CH

HO H

HH

O H

b e n ( a n ti ) s y n

b e n ( s y n )

. . .15

nh hng n mt s tnh cht khc:- Lm thay i mt s vch c trng trong ph IR, UV,

NMR, di lin kt

2.4.2 Lin kt trong phc chuyn in tch:Do s chuyn mt phn mt in t t phn t cho sang

phn t hay ion nhn in t.Phc chuyn in tch do s chuyn dch mt in t

gi l phc .Lin kt trong phc chuyn in tch l lin kt yu.Khi to phc chuyn in tch c s thay i v phn

cc v mu sc ca cht ban u.C H 3 N O 2

N O 2O 2 N

C H 3C H 3

C H 3C H 3

H 3 C

H 3 CN C C N

C NN C16

9Chng 2Cac hieu ng trong hoa hu c

17

H2,1 M IN MT S NGUYN T

C2,5

N3,0

O3,5

F4,0

S2,5

Cl3,0

Br2,8

I2,5

18

m in l kh nng ht in t khi tham gia lin kt

10

I. Cc hiu ng:S phn cc:

Xt nhm

Do AO > AC nn oxi c khuynh hng ht i in t v pha mnh.

Trong lin kt cng ha tr, i in t lin kt khng c phn chia i xng, nguyn t c A ln hn s ko i in t v pha n.

C O

C O -

C O -

H

H 2 N - N H 2

C O H

C ON H 2 - N H 2

19

1. Hiu ng cm ng: I (Inductive effect)-do s phn cc hay s chuyn dch mt in t trong cclin kt .in t phn phi khng u, nguyn t c A ln hn sht e v pha mnh, l hiu ng I. Hiu ng cng quantrng khi s khc bit v A cng ln. phn loi cc nhm nguyn t cm ng, ngi ta quyc nguyn t H lin kt vi C trong C-H c I=0.- nguyn t hay nhm nguyn t c kh nng ht e (C X)mnh hn H th c hiu ng -I, ngc li l +I.* Hiu ng cm ng +I:- Cc nhm alkyl:

H < CH3 < CH3CH2 < (CH3)2CH < (CH3)3CGc cng di, cng phn nhnh th hiu ng +I cng ln.

- Nhm mang in tch m:C- > N- > O-; O- < S- < Se- 20

11

* Hiu ng cm ng I:- Nhng nguyn t c A ln hn C

F > O > N > C (I tng t tri sang phi trong chu k).F > Cl > Br > I (I gim t trn xung di trong nhm)O > S

- Nhm mang in tch dng:O+ > N+ > S+ ; O+R2 > N+R2O+R2 > OR ; S+ > Se+

- Nhm hydrocarbon cha no:CC > C6H6 > C=C > C-CCsp > Csp2 > Csp3CN > C=N > C-N; C=O > C=NCN > CCNO2, SO3H.

Ni chung, A cng tng th I cng ln. 21

* c tnh: - Hiu ng I c tnh thng trc (trng thi tnh).- Hiu ng I truyn trn dy ni (trn mch C) v sc mnh gim dn.

Tm li hiu ng I xy ra trn ni v sinh ra do s khc bit v A.* ng dng: a. mnh ca acid:

Ka: hng s phn lyKa cng ln, pKa cng nh th tnh acid cng mnh.

R C O O H R C O O H+

K a =[ R C O O - ] [ H + ]

[ R C O O H ]p K a = - lg K a

22

12

R CO

O H

Tnh acid cng mnh khi i e lin kt gia O v H cng b ko lch v pha O, H+ d tch ra, tnh acid tng.

Do cc nhm I s lm tng tnh acid.

ClCH2COOH > HCOOH > CH3COOH > CH3CH2COOH

a. mnh ca base:

N HR

R '

NH

HH N

C H 3

HH N

C H 3

HC H 3

N - m e t y l a m in N , N - d i m e t y l a m i n

H 2 N N H 2 H 2 N O H

h y d r a z i n h y d r o x y l a m i n 23

- Mt e trn N cng nhiu th tnh base cng mnh.- Cc nhm +I s lm tng tnh base ca amin.

2. Hiu ng lin hp:2.1 H thng lin hp:- h thng cc lin kt bi (i, ba) lun phin vi cc lin kt n (--).- cc nguyn t c cp e lin kt trc tip vi nguyn t c lin kt bi (p- )

phn t lin hp

24

H2C CH CH CH2 H2C CH C N

NH2C CH Cl

OH

H

13

c im ca h thng lin hp:- Cc nguyn t lun nm trong 1 mt phng.- Trc cc orbital p u song song vi nhau v thng gc

vi mt phng lin kt.- Phn t lin hp c nng lng thp hn phn t khng

lin hp tng ng.

2.2 Hiu ng lin hp: C (Conjugative effect)- l hiu ng sinh ra do s phn cc ca lin kt c lan truyn trong h thng lin hp.

Cng nh I, hiu ng C l dng (+C) nu nhm th cho e v (-C) nu nhm th ht e v pha mnh.* Hiu ng +C:

- Nguyn t c cp e:

- +C cng mnh khi nguyn t cng chu k c in tch ht nhn cng nh (+C gim t tri sang phi).

C > N > O > F ; F > C l > B r > I ; O > S > S e ; N > P

25

- +C gim khi tng bn knh nguyn t trong nhm (+C gim t trn xung di).

- Nguyn t mang in tch m:O- > OH, O- > OR > O+R2, NH2 > OR > F; OH- > CH3COO-

* Hiu ng C:- Nhng nhm cha no cha nhng nguyn t c A ln:

C=O, NO2, SO3H, - -C cng mnh nu nguyn t c A cng ln v ln nht

nu nguyn t mang in tch dng.C=O > C=N > C=C ; C=O+ > C=O, C=N+ > C=N- Mt s nhm chc:

NO2 > CN > CCR

C OC l

C OH

C OC H 3

C OO R

C OO H

C ON H 2

C OO

26

14

* c im ca hiu ng C:- Hiu ng C khng gim theo mch C

- Hiu ng lin hp lm thay i trung tm phn ng.

- nh hng ca hiu ng lin hp ch xy ra h thng phng.

H 2 C C H C H C H C H O

27

CO

CH CH

NH2

COH

CH CH

NH2

H+

* ng dng:Cng nh hiu ng I, hiu ng C cng dng

gii thch tnh acid v base.- So snh mnh ca acid:

- So snh mnh ca base:

H 3 C C H 2 O H O H

H 3 C C H 2 N H 2 N H 2

28

15

3. Hiu ng siu lin hp: H (hyperconjugative effect)- l lin hp - gia cc orbital ca nhm alkyl v orbital ca ni i, ba v nhn thm.

Hiu ng H ch c tnh hnh thc, ch khng c lp c H+trong mi trng.

C

H

HH

C H C H 2

C

H

HH

C H C H 2 CHH

C H C H 2H

CHH

H CH

HH CH

HH CH

HH

V d u :

29

* c tnh:- Hiu ng H lm thay i hng cng hp vo ni i.

- Hiu ng H lm nh hng n tnh linh ng ca lin kt C-H trong gc alkyl.

- Ch trng thi ng, trng thi tnh th rt nh hoc khng xut hin.

C

H

HH

C H C H C H 2 H B r+C H 3 H 3 C C H B r C H 2 C H 2 C H 3

+C

H

HH

C H O O H - CHH

C H O + H 2 O

CHH

C H O

30

16

* ng dng: Hiu ng H gii thch+ S thay i di dy ni:V d: C-CH3 trong propen ngn hn ni n bnh thng do c s to thnh ni i.+ bn ca alken mang nhng nhm th alkyl c H.

CH3-CH=CH-CH2-CH3 CH3-CH2-CH2-CH=CH22-penten c 5 H 1-penten c 2 H

i vi 1 hp cht vit c cng nhiu cng thc gii hn th hp cht cng bn.+ bn ca carbocation: C H 3

CH 3 CC H 3

H 3 C C H 2C H

H 3 CC H 3 C H 2 C H 2 C H 2

C a r b o c a t io n b a c I I I b a c I I b a c I

C

CH 3 CC H 3

HHH C

CH 3 CC H 3

HHH

31

Chng 4: Khai niem ve acid-baseI. Khi nim v acid-base:

1. Thuyt Arrhenius:Acid l nhng cht c th phn ly trong dung dch long cho ra proton H+Base l nhng cht trong cng iu kin cho ra OH- ch thch hp cho cc cht v c.

2. Thuyt Bronsted-Lowry:Acid l nhng tiu phn c khuynh hng cho proton.Base l nhng tiu phn c khuynh hng nhn proton.V d: HA A- + H+ (i) y l mt qu trnh thun nghchHA l acid v cho protonA- l base v c th nhn proton to thnh HA. HA l acid lin hp ca base A-hay A- l base lin hp ca HA.

32

17

B + H+ BH+ (ii)(i) & (ii) HA + B A- + BH+

Phn ng ca acid v base l phn ng chuyn dch proton t acid sang base.

- Acid c th khng hoc mang in tch dng (H2SO4, NH4+).

- Base c th khng hoc mang in tch m (CH3O-, NH3).

- Mt s phn ng ha hc c xc tc acid thc ra l s tng tc acid-base.Lu : Mt acid rt mnh th base lin hp ca n rt yu v ngc li.

C H 3 C O O H- H +

C H 3 C O O

C H 3 O H- H +

C H 3 C O -

N H 4 +- H +

N H 3

C H 3 O C H 3- H +

C H 3 O C H 3H

33

3. Thuyt Lewis:- Acid l nhng phn t m in t lp ngoi cng cha y (hay c kh nng kt hp vi cp in t ca base).- Base l nhng phn t c kh nng cung cp in t.Cc base Lewis: ROR, RNH2, ROH, NH3, OH-, RO-

Cc acid Lewis: BF3, AlCl3, FeCl3, ZnCl2Acid Lewis c kh nng to lin kt phi tr vi cc base Lewis.

NH

HH B

F

FF+ N

H

HH B

F

FF

NH

HH B

F

FF

34

18

II. Cc yu t nh hng n tnh acid-base ca hp cht hu c:- Cu trc in t ca phn t- Cc nguyn t hay nhm nguyn t gy cc hiu ng.

Hiu ng -I, -C lm tng tnh acid (tnh base gim)Hiu ng +I, +C lm gim tnh acid (tnh base tng).

35

Chng 3Cau truc phan t hp chat hu cong phan va cau dang

19

ng phn

Hin tng mt cng thc phn t c hai hay nhiu cng thc cu to khc nhau l ng phn.

C 2 loi ng phn:- ng phn mt phng - ng phn lp th.

1. ng phn mt phng

Cc ng phn khc nhau v v tr v th t lin kt gia cc nguyn t to thnh phn t.

1.1 ng phn mch carbon:

H 3 C C H 2 C H 2 C H 3 H 3 C C H C H 3

C H 3

H 3 C C H 2 C H 2 C H 2 H 3 C C H C H 2

C H 3

H 3 C C C H 3

C H 3

C H 3 C H 3

C H 3n - b u t a n is o b u t a n

n - p e n t a n is o p e n t a n n e o p e n t a n

20

1.2 ng phn v tr nhm chc:

1.3 ng phn nhm chc:

H 3 C C H 2 C H 2 C H 2 O H H 3 C C H 2 C H 2 C H 3O H

H 3 C C O H

C H 3

C H 3

1 - b u t a n o l 2 - b u t a n o l 2 - m e t y l - 2 - p r o p a n o l

H 3 C C H 2 C H 2 C H 2 H 3 C C H 2 C H 2 C H 3

1 - b u t e n 2 - b u t e n

H 3 C C H 2 C O O H H 3 C C O O C H 3

A c i d p r o p a n o i c M e t y l a c e t a t

H 3 C C H 2 C H O H 3 C C H 3CO

A l d e h y d p r o p a n o i c A c e t o n

1.4 ng phn lin kt:

CH2=CH-CH=CH2 CH2=C=CH2-CH3 CH3-CH2-CCH CH3-CC-CH3

1,3-butadien 1,2-butadien 1-butyn 2-butyn

1.5. S h bin: hin tng 1 cht c th tn ti 2 dngkhc nhau trong nhng iu kin xc nh v chng cth thay i cho nhau to hn hp cn bng.

- Dng h bin ceton-enol:

H 3 C C H 2 C H 2 C H 2

1 - b u t e n

H 2 C

H 2 C C H 2

C H 2

C y c l o b u t a n

O OH

H 3 C CO

C H 2 C O O C 2 H 5 H 3 C CO H

C H C O O C 2 H 5

C y c l o h e x a n o nE t y l a c e t o a c e t a t

21

2. ng phn lp th - ng phn khng gian

S phn b trong khng gian ca cc nguyn t hay cc nhm nguyn t trong phn t.

Cc loi ng phn khng gian:- ng phn cu dng.- ng phn hnh hc- ng phn quang hc

R CO

NH R' R COH

N R'

- Dng h bin Amido-Imidol:

- Dng h bin nitroso-oximo:

R CH2N=O R CH N OH

2.1 Cu dng: ch cc dng cu trc khng gian c th hnh thnh khi cc

nhm th quay t do quanh lin kt n.Mt cht hu c c th biu din theo:

- Cng thc t din- Cng thc chiu Fisher- Cng thc phi cnh- Cng thc Newman.

V d: biu din phn t etan

H HH

HHH

H

HH

H

H

HH

HH

HHH

H

HHH

H H

C T t d i e n C T c h i e u F i s h e r C T p h o i c a n h C T N e w m a n

22

- Cng thc phi cnh:M t khng gian 3 chiuLin kt theo ng cho t tri sang phi v xa dn ngi quan

st.C 2 dng: xen k v che khut.

- ng m nt (): lin kt hng v pha trc mt phng- ng t qung (----): lin kt hng v pha sau mt phng- ng nht nt (): lin kt nm trong mt phng.

Cu dng xen k bn hn cu dng che khut.

Z

ZY

YXX Z

Z

Y

YX

X

D a n g x e n k e D a n g c h e k h u a t

A

DBC

- Cng thc Newman:Nhn phn t theo trc lin kt C1-C2C1 tmC2 b che khut bng vng trn

Z

ZY

YXX

D a n g x e n k e

Z

YXZ

X Y1

2

C T N e w m a n

Z

Z

Y

YX

X

D a n g c h e k h u a t C T N e w m a n

Z

Y

Z

YXX

1

2

23

- Cng thc chiu Fisher:Chuyn cu dng xen k sang cu dng che khut.

Z

Z 'X

X '

Y

Y ' Z 'X ' Y '

ZYX

Z

Z '

Y

Y 'X 'X

Z

Z 'X

Y '

Y

XZ '

Y ' X '

ZYX

C T c h i e u F i s h e rC T c a u d a n g

A

DBC

A

B C

D

- Cu dng ca cyclohexan: cu dng gh: cc nguyn t H 2 C k cn phn b xen k. cu dng thuyn: cc nguyn t H 2 C k cn phn b che khut. cu dng gh bn hn cu dng thuyn.

H H

H

H

H

H

H

H

H

H

H

H

H

H

H

HH

H

H

H

H

H

HH

C a u d a n g g h e C a u d a n g th u y e n

24

2.2 ng phn hnh hc:Cc nguyn t C khng th quay t do xung quanh lin kt c v s cn tr ca mt phng .S phn b v 2 pha ca mt phng cng thng gp tronghp cht vng. PHH l nhng hp cht c cng CTPT nhng v trkhng gian ca cc nguyn t hay nhm nguyn t khcnhau i vi mt phng hay mt phng ca vng.2.2.1 ng phn ca hp cht c ni i C=C:

P cis: ch 2 nguyn t hay nhm nguyn t ging nhau cng mt pha vi mp hay mp vng.

P trans: ch 2 nguyn t hay nhm nguyn t gingnhau khc pha vi mp hay mp vng.

Dng chungabC=CabacC=Cab

C CH

H 3 C C H 3

HC C

H

H 3 C H

C H 3c i s - 2 - b u t e n t r a n s - 2 - b u t e n

C CH O O C

H H

C H 3C C

H O O C

H C H 3

Hc is - i s o c r o t o n ic a c i d t r a n s - c r o t o n i c a c i d

C 3 hay 4 nhm th khc Hydro: abC=Ccd ng phn E-Za, b, c, d l nhng nguyn t hay nhm nguyn t khc

nhau v ln.Gi s a > b v c > d

Cch xc nh ln theo quy tc Cahn-Ingold-Prelog- Nguyn t c s th t trong bng tun hon cng ln th ln ca n cng ln.

I > Br > Cl > S > P > F > O > N > C > H-CH2Cl > -CH2OH > -CH2CH3

C Cb

a c

d

C a u h n h Z ( c i s ) C a u h n h E ( tra n s )

a b C = C c d

C Cb

a d

c

25

- Nu trong mt nhm nguyn t c mt lin kt i hay ba th xem nh nguyn t c 2, 3 ln lin kt vi nguyn t kia.

-So snh ln nhm th theo tng tng lin ktHp cht c nhiu ni i th s ng phn hnh hc s tng ln.

V d: 1,4-diphenyl-1,3-butadien

C OH

CH O

O CC C H C C H

CC

C C

C CH 3 C

H C l

C H 3( E ) - 2 - c h l o ro - 2 - b u t e n

C CH 3 C

H C H 3

C l( Z ) - 2 - c h l o ro - 2 - b u te n

;

C 6 H 5

H

H

H C 6 H 5

HC 6 H 5

H

H

H H

C 6 H 5H

C 6 H 5

H

H H

C 6 H 5

t r a n s - t r a n s t r a n s - c i s c i s - c i s

2.2.2 ng phn hnh hc trong cc hp cht vng:

Cc lin kt trong vng cyclohexan c 2 hng th:- hng thng gc vi mp trung bnh -hng trc a. - hng song song vi mp trung bnh- hng xch o e.

Cc lin kt theo hng e s bn hn do hng e i ra xa phn t.

H

C O O H

H

H

H

C O O H

t r a n s - 1 , 2 - d ic a r b o x y l c y c l o p r o p a nae

a

e

a

a

e

e

a

e

a

e

CH3

CH3

CH3CH3

CH3

CH3

CH3

CH3

trans(a,a)-1,2-dimethylcyclohexan trans(e,e)-1,2-dimethylcyclohexan

cis(e,a)-1,2-dimethylcyclohexan cis(a,e)-1,2-dimethylcyclohexan

26

2.2.3 ng phn hnh hc trong hp cht c ni i:

N NC 6 H 5

N NC 6 H 5

C 6 H 5C 6 H 5

s y n - a z o b e n z e n a n t i - a z o b e n z e n

C NO H

C 6 H 5

HC N

O H

H

C 6 H 5s y n - b e n z a l o x i m a n t i - b e n z a l o x i m

* Tnh cht ha hc:ng phn cis d tham gia cc phn ng loi nc, ng vng.V d:

C O O HH

H C O O H

1 8 0 o C CC

OH

H

CO

CO

C O O HH

H O O C H

C O O N aO H

HH H +

O O

A c i d m a l e i c A c i d f u m a r i c

c i s - h y d r o x y c i n n a m ic c o u m a r i n

27

2.3 ng phn quang hc:L nhng cht c tc dng lm quay mt phng nh sngphn cc.Mt phng nh sng phn cc l mt phng vung gc viphng dao ng ca nh sng phn cc.Cht lm quay mt phng nh sng phn cc l cht quanghot.Kh nng quang hot ca mt hp cht c c trngbng i lng quay cc ring hay gi l nng sut quaycc, k hiu l []

2.3.1 Phn t c nguyn t C khng i xng:a. Phn t c 1 nguyn t C bt i xng.- Cc cht c tnh quang hot l do s bt i xng trong phn t, ngha l phn t khng th chng kht ln nh ca n qua gng phng.Hay phn t bt i xng l phn t khng c mt phng i xng, trc i xng hay tm i xng.

V d:H

CC O O HH OH 3 C

H

CH O O C O HC H 3

( + ) - l a c t i c a c i d ( - ) - l a c t i c a c i d

**

H O

H

C O O H

C H 3 H 3 C

H

C O O H

O H

C T c h i e u F i s h e r

Vt nh

28

- Vt v nh qua gng l 2 ng phn quang hc-i quang.- ng nht v t/nh cht vt l.- Mt quay phi (+)-hu truyn- d (dextrogyre), mt quay tri (-)-t truyn- l (levogyre). - Trn 1 lng bng nhau ca 2 cht i quang mt hn hp khng quay mt phng nh sng phn cc. Gi l bin th racemic.

b. Phn t c nhiu nguyn t C bt i.Nu phn t c nhiu C bt i (C*) th s ng phn quang hc tng ln.Nu c n nguyn t C bt i xng th s ng phn quang hc c th l 2n.

V d 1:

- Threonin c 2 C bt i xng: c 4 ng phn quang hc- I v II, III v IV: cc i quang- I v III, II v III, I v IV, II v IV: ng phn quang hc khng i quang vi nhau (ng phn dias).

C O O H

C H 3

N H 2H

H O H

2 - a m i n o - 3 - h y d r o x y b u t a n o i c a c i d ( t h r e o n i n e )

C O O H

C H 3

H 2 N H

HH O

C O O H

C H 3

N H 2H

H O H

C O O H

C H 3

H 2 N H

O HH

( I ) ( I I ) ( I I I ) ( I V )

H 3 C C H C HO H

C O O HN H 2

**

29

V d 2:

- I v II: i quang.- III v IV: ng phn meso (c mt phng i xng trong phn t, III v IV l mt).

C O O H

C O O H

O HH

H O H

C O O H

C O O H

H O H

O HH

C O O H

C O O H

O HH

H O H

C O O H

C O O H

H O H

HH O

2 R , 3 R 2 S , 3 S 2 R ,3 S 2 S ,3 R

a c id t a r t a r ic

H O O C - C H O H - C H O H - C O O H* *

m a t p h a n g o i x n g

( I ) ( I I ) ( I I I ) ( I V )

2.3.2 Danh php ng phn quang hc: k hiu cu hnh cc nguyn t C bt i.C 2 loi danh php: - danh php D, L

- danh php R, S a. Danh php D, L:- chia cht quang hot thnh 2 dy.- ch c tnh cht so snh.- dng cu hnh aldehyd glyceric lm chun.

C H O

C H 2 O HHH O

C H O

H O H 2 CH

O H

C H O

H

C H 2 O H

O H

C H O

H O

C H 2 O H

H

D - ( + ) - a l d e h y d g ly c e r ic L - ( - ) - a l d e h y d g ly c e r i c

C H 2 O H - C H O H - C H O*

( I ) ( I I )

30

- Cng thc I: nhm OH bn phi cu hnh D- Cng thc II: nhm OH bn tri cu hnh L.- Nhng hp cht c C bt i s th t cao nht c cu hnh ging D aldehyde glyceric th thuc dy D v ngc li.- Du (+) v (-): ch chiu quay ca mt phng nh sng phn cc.

- Danh php D,L cng p dng cho acid amin vi cu hnh chun l glycin (CH3-CHNH2-COOH).

CHOOHHHHOOHHOHH

CH2OH

CHOHHOOHHHHOHHO

CH2OH

D-(+)-glucose L-(-)-glucose

1

5

CH2OH-CHOH-CHOH-CHOH-CHOH-CHO* * * *

b. Danh php R, S: (danh php Cahn-Ingold-Prelog)Danh php D, L c hn ch:

- khng bit c cu hnh ca nguyn t trong phn t.- c tnh cht so snh.

* Phng php xc nh cu hnh R, S theo cu hnh Fisher:R: Latin rectus; S: Latin sinister

- Chuyn v hnh chiu Fisher.- Xt ln ca 4 nhm th gn vo C bt i- a nhm th b nht v pha di.- Xt chiu theo th t gim dn ln cc nhm th. Nucc nhm th theo chiu kim ng h ta c cu hnh R vngc li l S.Qui tc: nu thay i v tr nhm th 1 ln th cu hnh thayi, nu thay i v tr 2 ln th cu hnh khng thay i.

31

V d:

* Phng php xc nh R,S trong khng gian:

C H O

H O HC H 2 O H

C H O

H O

H

C H 2 O H1

2

3

( R ) - a l d e h y d e g l y c e r i c

C H O

H O HC H 2 O H

C H O

H

C H 2 O H

O H 1

2

3

C H O

H O H 2 C

H

O H

o i v tr 1 l a n SR

c. Danh php Erythro v threo: phn bit cc ng phn quang hp cht c 2 C bt i.Dng erythreo: i quang c 2 nhm th tng t cng mt pha.

Dng threo: i quang c 2 nhm th tng t khc pha.

C H 3

C H 3

O HH

H P h

C H 3

C H 3

H O H

HP h

C H 3

C H 3

HH O

H P h

C H 3

C H 3

H O H

HP h

e r y t h r o t h r e o

32

2.3.3 Cc ng phn quang hc khng c C bt i:Mt s hp cht do s cn quay lm cho phn t tr thnh bt i nn phn t c tnh quang hot.

C C Ca

b d

cR

R' R'"

R" O

O

R

R'

(CH2)n

Allen Diphenyl Paracyclophan Spiran

2.4 ngha ng phn lp th:Tc dng sinh hc

Thm ha Thalidomid

64

33

Chng 5

Cac loai phan ng trong hoa hu c

Khai niem ve c che phan ng

Cc loi phn ng trong trong ha hu c

C nhiu phng php phn loi phn ng nh:- Theo s phn ct lin kt- Theo hng phn ng- Theo giai on quyt nh tc phn ng- Theo bn cht tc nhn phn ng

C cc loi phn ng nh sau:1. Phn ng th: (Substitution)

L phn ng trong mt nguyn t hay mt nhmnguyn t trong phn t c thay th bngnguyn t hay nhm nguyn t khc.Tng qut: R-X + Y R-Y + X

X: nhm b thY: nhm th

34

Mt s phn ng th thng dng: halogen ha, nitro ha, sulfonic ha, alkyl ha, aryl ha, acyl ha.Mt s phn ng th km theo s loi nc, alcol, amoniac .. cn gi l phn ng ngng t.

V d: R-CHO + H2NR R-CH=NR + H2ORCOOC2H5 + CH3COC6H5 RCOCH2COC6H5 + C2H5OHCc loi phn ng th:a. Phn ng th i nhn SN:

R-X + Y- R-Y + X- Y-: tc nhn i nhnV d: CH3Cl + OH- CH3OH + Cl-

b. Phn ng th gc t do SR:R-X + Y. R-Y + X. Y.: gc t do.V d: SO2Cl2 + .C6H5 C6H5Cl + .SO2Cl

c. Phn ng th i in t SE:R-X + E+ R-E + X+ E+: tc nhn i in t.V d: Ar-H + +NO2 Ar-NO2 + H+

2. Phn ng cng hp: (Addition)L phn ng trong hai phn t (hoc ion) kt hp vi nhau thnh mt phn t (ion) mi.Thng xy ra cc hp cht c ni i, ni ba. Phn ng xy ra c s thay i trng thi lai ha ca nguyn t C.

CH3-CCH + H2O CH3-CO-CH3CH2=CH2 + HBr CH3-CH2Br

Cc loi phn ng cng hp:

a. Phn ng cng hp i in t AE:CH3-CH2-CH=CH2 + H2O CH3-CH2-CHOH-CH3

b. Phn ng cng hp i nhn AN:CH3-CH=O + HCN CH3-CH(CN)-OH

c. Phn ng cng hp gc AR:

+ C l. C l

.

35

3. Phn ng tch loi (Elimination)Phn ng lm 2 nguyn t hay nhm nguyn t tch ra khi mt phn t.Phn ng lm thay i trng thi lai ha ca nguyn t C.CH3-CH2-OH CH2=CH2 + H2OBr-CH2-CH2-Br + Zn CH2=CH2 + ZnBr2.

4. Phn ng chuyn v:Trong phn ng c s chuyn ch mt hay nhm nguyn t gi l s chuyn v.Phn ng c s chuyn v trong phn t gi l phn ng chuyn v.

CR

RR

C H 2 X CR

RR

C H 2- X -c h u y e n v CR

RC H 2 R

Khi nim v c ch phn ng

1. S ct t lin kt v cc tiu phn ca phn ng:Ty theo bn cht lin kt c th b ct t theo kiu d ly hoc ng ly.a. S ct t d ly:

A|B A+ + B- hoc A|B A- + B+A+, B+: carbocation, A-, B-: carbanionCarbocation v carbanion tham gia cc phn ng th, tch loi v cng hp.

b. S ct t ng ly:AB A. + B.

A., B. cc gc t do, tham gia phn ng theo c ch gc.

36

2. Cu to v tnh cht ca cc tiu phn.a. Carbocation: (R+)Nhng cation m trung tm in tch dng nguyn t C (trn orbital p khng c e-orbital trng).Hnh thnh khi ct t d li lin kt cng ha tr hoc cng hp proton H+ vo ni i, ba.

CH3CH=CH2 + H+ CH3CH+CH3Carbocation c cu trc phng.

C H 3

H 3 C H

C a u tru c p h a n g c u a C H 3 C H+ C H 3

b. Carbanion: (R-)Nhng anion m in tch m tp trung ch yu nguyn t C (trn orbital p c 2 e).Hnh thnh do ct t d ly lin kt cng ha tr.

H-CH2-CHO + HO- -CH2CHO + H2O.Carbanion c cu trc hnh thp.

OHC

HH

37

c. Gc t do (R.)Nhng tiu phn c cha 1 e t do (khng cp i) nguyn t C (trn orbital p c 1 e).Gc t do to thnh do s ct t ng ly lin kt cng ha tr di tc dng ca nh sng hoc nhit.Gc t do c cu trc phng.

C H 3

H 3 C H

C a u tru c p h a n g c u a C H 3 C H. C H 3

d. Carben (RRC:): Nhng tiu phn c 2 e khng lin kt lp ngoi cng ca nguyn t C.Nu 2 e phn phi trn 2 orbital p, carben c dng lng gc.Nu 2 e trn cng 1 orbital p v c 1 orbital p trng, carben c dng ion dng.

H

H

H H

Ion dng Lng gc

Cu trc ca carben H2C:

38

e. bn cc tiu phn: bn ca cc tiu phn ph thuc vo cu trc e.Mt in tch trn carbocation v carbanion cng gim th nng lng ca chng cng thp v chng cng bn (d tn ti trong qu trnh phn ng).- Carbocation bn vng khi in tch dng c gii ta. Cc hiu ng +I v +C c tc dng lm carbocation bn vng hn.V d: CH3+ < CH3CH2+ < (CH3)2CH+ < (CH3)3C+

CH3+ < C6H5CH2+ < (C6H5)2CH+ < (C6H5)3C+- Carbanion bn vng khi c nhm ht e. Hiu ng I v C lm tng bn ca carbanion.V d: CH3- < (CF3)2CH- < (C6H5)2CH-

CH3CH2CH2- < CH2=CH-CH2- < (CH2=CH)2CH-- Cc gc t do bn khi gn vi cc nhm alkyl, aryl. Cc nhm th c hiu ng I, C v H v tr para trong p-XC6H4CH2 lm tng bn ca gc.V d: CH3. < CH3CH2. < (CH3)2CH. < (CH3)3C.

CH3. < C6H5CH2. < (C6H5)2CH. < (C6H5)3C.

3. C ch phn ng th: (Substitution)a. Phn ng th i nhn SN: Theo 2 c ch:

- Lng phn t SN2- n phn t SN1

- C ch SN2:Tc phn ng c nng ca 2 cht phn ng.Phn ng xy ra mt giai on.Trng thi chuyn tip gia cht phn ng v tc nhn i nhn Y--y l giai on quyt nh tc phn ng.V d: CH3Cl + HO- CH3OH + Cl-Phng trnh tc phn ng: = k [CH3OH][HO-]Sn phm c s thay i cu hnh.

H

C l

HH

H O -

H

H H

C lH O- -

+

H

H O

HH

C l -+

39

C ch SN1:Phng trnh tc phn ng ch c nng ca cht phn ng.Phn ng xy ra 2 giai onGiai on to carbocation R+ l giai on chm quyt nh tc phn ng.V d: HO- + (CH3)3C-Br (CH3)3C-OH + Br-

Phng trnh tc phn ng = k [(CH3)3C-Br]Giai on chm: (CH3)3C-Br (CH3)3C+ + Br-

Giai on nhanh: (CH3)3C+ + HO- (CH3)3-OHPhn ng theo c ch SN1 c s racemic ha.

C H 3

C +

H 3 C C H 3

H O -H O - H 3 C

O H

H 3 CH 3 C

C H 3

H O

C H 3C H 3

C a rb o c a ti o n

* Trong R-X, nu X gn trc tip vo C bc nht RCH2-X th phn ng xy ra ch yu theo SN2.* Trong R-X, nu X gn trc tip vo C bc ba R3C-X th phn ng xy ra ch yu theo SN1.* Trong R-X, nu X gn trc tip vo C bc hai R2CH-X th phn ng xy ra theo SN1 hay SN2 ty thuc vo cu trc hoc dung mi.* Dung mi nh hng n c ch phn ng.

- DM phn cc u tin theo SN1.- DM khng/t phn cc u tin theo SN2.

b. Phn ng th i in t SE:- Ch yu xy ra cc hydrocarbon thm v d vng thm.- Tc nhn i in t Y+ l nhng tc nhn c orbital trng nh cc ion dng (+NO2, Br+) hoc nhng hp cht c orbital cha cht y (SO3, CO2).

40

Phn ng th i in t xy ra nhiu giai on:- Giai on tng tc gia E+ v Ar-H to phc .- Giai on chuyn t phc sang phc .- Giai on to sn phm cui cng.

c. C ch phn ng th gc t do SR:Phn ng th theo gc t do l phn ng dy chuyn c 3 giai on.

- Giai on khi mo.- Giai on pht trin mch v to sn phm.- Giai on tt mch v kt thc phn ng.

E ++H

E +HE

HE

E+ H +

P h c P h c

V d: Phn ng cloro ha alkan:- Khi mo: Cl-Cl Cl. + Cl.- Pht trin mch: R-H + Cl. R. + HCl

R. + Cl-Cl Cl. + R-Cl

- Tt mch v kt thc phn ng: R. + R. R-RCl.+ Cl. Cl-Cl

Giai on quyt nh tc phn ng l giai on pht trin mch.Gc t do c cu trc phng, sn phm c s racemic ha.

4. C ch phn ng cng hp: (Addition)a. Phn ng cng hp i in t AE:

Hp cht c lin kt i, ba + E-YQua cc giai on:- Giai on to tc nhn i in t E+ (t E-Y)- Tng tc ca E+ vi cht phn ng to carbocation R+- Tng tc gia carbocation R+ v Y- to sn phm.

41

* Giai on chm quyt nh tc phn ng l giai on E+tng tc vi cht phn ng.Dung mi v cu to phn t E-Y nh hng n quyt nh s hnh thnh tc nhn i in t E+.V d: Phn ng cng HBr vo propylen:

CH3-CH=CH2 + HBr H-Br H+ + Br-

b. Phn ng cng hp i nhn AN:- thng xy ra gia tc nhn i nhn Y- vi cc hp cht c ni i C=O, C=N

C H 3 - C H = C H 2 + H +C H 3 - C H + - C H 3

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

H

H 3 C+

c h a m

n h a n h

h o a c

C H 3 - C H + - C H 3 + B r - C H 3 - C H B r - C H 3

C H 3 - C H 2 - C H 2 + + B r - C H 3 - C H 2 - C H 2 B r

Cc giai on ca phn ng:- Tc nhn Y- tn cng vo trung tm mang in tch dng trn C ca nhm carbonyl (C=O +C-O-) to thnh ion mang in tch m trn O.

R-CH=O + Y- R-CHY-O-

- Ion m s kt hp vi ion dng (H+) to sn phm cui cng.

R-CHY-O- + H+ R-CHY-OHin tch dng trn nguyn t C cng ln th kh nng phn ng cng cao.

OCR Cl

OCR O C

O

ROCR O H

OCR O R'

OCR O-> > > >

42

5. C ch phn ng tch loi:Theo 2 c ch:

- Lng phn t E2- n phn t E1a. Tch loi E2:Cc giai on:

- Tng tc ca mt base mnh vi cht phn ng to trng thi chuyn tip

- S tch loi xy ra v to sn phm c lin kt i.

V d: Phn ng tch loi HBr t etylbromid.

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

T ra n g th a i c h u y e n ti e p

Br-+

H H

H Br

H3C H

C2H5O-+

H H

H Br

H3C H

C2H5O

H3C H

HH+ C2H5OH

b. Tch loi E1:Cc giai on:- Cht phn ng to carbocation R+ l giai on chm- Tch H+ v to ni i l giai on nhanh.

V d: Tch HBr ca 2-bromo-2,3-dimeylbutan.

H C C X H C C X -+

H C C C C + H +

c h a m

n h a n h

H CC H 3

C H 3C B rC H 3

C H 3- B r - H C

C H 3

C H 3CC H 3

C H 3H +

CH 3 C

H 3 CC

C H 3

C H 3

C a r b o c a t i o n