CU TRC PHN T HP CHT HU C.

NG PHN

A . Khi nim v ng phn:

ng phn l hin tng cc cht c cng cng thc

phn t, nhng khc nhau v cu to , cu hnh hoc cu

dng nn c nhng tnh cht (vt l, ha hc) khc nhau.

V d: CH3CH2OH v CH3-O-CH3

(cng cng thc phn t l C2H6O)

B . Phn loi ng phn :

+ ng phn cu to (phng)

+ ng phn khng gian (lp th): ng phn cu hnh

( hnh hc , quang hc) v ng phn cu dng

I. ng phn cu to

1. Khi nim: l cc cht c cng cng thc phn t nhng

khc nhau v cu to ha hc

2. Phn loi

ng phn mch cacbon: l ng phn v cch sp xp

mch cacbon theo cch khc nhau: v d C5H12:

ng phn nhm chc: c cng cng thc phn t

nhng c nhm chc khc nhau . V d C2H6O

ng phn v tr nhm chc : c cng nhm chc

nhng v tr nhm chc khc nhau

CH3CH2CH2OH CH3CH(OH)CH3

Propan-1- ol propan -2- ol

ng phn v cch chia mch cacbon khc nhau ca

nhm chc : c cng nhm chc nhng cu to mch

cacbon khc nhau

H-COO-C2H5 CH3-COO-CH3

etyl focmiat metyl axetat

II. ng phn khng gian

1.Cch biu din cu trc khng gian ca phn t

* Cc cng thc:

a. Cng thc phi cnh:

Xen k Che khut

b. Cng thc chiu Niumen (Newman)

H

H

H

H

H

HH H

H

HH

H

Newman

c. Cng thc Fis (Fischer)

CHO

C

H OH

CH2OH

CHO

CH OH

CH2OH

CHO

CH HO

CH2OH

Cng thc phi cnh

2. ng phn hnh hc

1.Khi nim:

l mt loi ng phn cu hnh, trong c s

phn b khc nhau trong khng gian ca cc nhm

th xung quanh b phn cng nhc ca phn t

(mt phng hay vng no)

ng phn hnh hc cn gi l ng phn cis-trans

hay Z- E

ng phn hnh hc

2. iu kin:

- Cn: c b phn cng nhc trong phn t (lin kt i: C=C, C=N, N=N. hoc vng no) lm cn tr s quay t do ca cc nhm th

- : Hai nguyn t hoc nhm nguyn t lin kt vi b phn cng nhc phi c bn cht khc nhau

Xt phn t abC=Cde, trong a b ; d e , nhng a hay b c th ging d hay e.

3. Danh php

a. Danh php cis- trans

a1. Da vo bn cht nhm th Nu hai phi t

( nhm th) ging nhau nm cng mt bn mt

phng tham chiu th ng phn gi l : cis ,

ngc li l ng phn trans;

C C

Cl

H CH3

ClC C

CH3

H Cl

Cl

Cis-1,2-dichloro propen Trans-1,2-dichloro propen

a2 . Da vo mch chnh: nu cc nhm th

nm trn mch chnh cng pha l cis, khc

pha l trans

i vi loi c nhiu ni i

i vi hp cht vng no

CH3 CH3

H3C

CH3

cistrans

b. Cch gi tn theo danh php Z-E :

- p dng qui tc Cahn-Ingold-Prelog: Da vo s

u tin trn s th t trong HTTH. Cc nhm th

c s th t cao hn th c u tin ( hn

cp) ln hn

- ng phn no c hai nhm u tin ln nm v

mt bn ca mt phng qui chiu l : Z, ngc li

l E.

Cch tnh u tin ( hn cp)

Qui tc: Cc nguyn t nh vi Csp2 ca nguyn t c th t

ln hn trong bng HTTH th c hn cp ln hn.

Xt nguyn t lin kt trc tip vi trung tm cn xc

nh cu hnh (gi l nguyn t lp th nht ca

nhm), ng.t no c stt ln th hn cp ln

Br > Cl > S > P > O > N > C >H

Nu lp th nht nh nhau th xt lp tip n cc

nguyn t lp th 2 (cc nguyn t lin kt trc tip

vi nguyn t lp th nht)

- CH(CH3)2 > -CH2CH3 > -CH3

1H + 2C=13 2H+ 1C=8 3H =3

-Tng t nh vy i vi lp th 3 nu lp th

2 nh nhau

- Cc nguyn t cha lin kt bi th tnh bi ln

-CH=O > -CH2OH; -CN > CH2-NH2

17 10 21 9

- Trong cc ng v , nguyn t c s khi ln

hn th c hn cp ln hn

18O > 16O , 15N > 14N , D > H

F

Cl

H3C

H

Cl

F

H3C

H

(E)-1-Clo-1-flopro-1-en (Z)-1-Clo-1-flopro-1-en

Hy sp xp u tin (hn cp) ca cc nhm th sau:

9 < 1 < 2 < 3 < 5 < 8 < 7 < 4 < 6 < 10 < 11 < 12

4. nh hng ca ng phn hnh hc n

tnh cht ca hp cht

+ Cc ng phn trans thng bn hn cc ng phn Cis

+ Nhit nng chy (mp) ca ng phn cis thng thp hn ng phn trans.

+ Nhit si (bp) ca ng phn cis thng cao hn ng phn trans.

+ T trng v chit xut ca ng phn cis thng ln hn cc ng phn trans.

+ Hot tnh ca ng phn hnh hc c th khc nhau:

Vd: Acid Maleic d b mt nc cho anhydric hn acid fumaric

C

C

CH

H C

OH

OH

O

O

1400c C

C

CH

H C

O

O

O H2O300

0c C

C

CH

C H

OH

O

HO

O

3. ng phn quang hc

Tnh hot ng quang hc ca cht: l kh nng

ca cht lm quay mt phng dao ng ca nh

sng phn cc.

nh sng phn cc

1 2 3 4 5

1-Ngun nh sng, 2-Lng knh Nicol, 3-nh sng phn cc,

4-Cht quang hot, 5-nh sng sau khi i qua cht quang hot

1.Khi nim ng phn quang hc

Nhng hp cht c cng cu to ha hc, c tnh

cht vt l v ha hc ging nhau, nhng do khc

nhau v b tr trong khng gian ca cc nhm th

xung quanh mt b phn chiral (bt i) no

trong phn t , v vy c kh nng lm quay mt

phng nh sng phn cc v tnh cht sinh ha

khc nhau, gi l ng phn quang hc.

ng phn quang hc l mt loi ng phn cu

hnh, xut hin do s b tr trong khng gian khc

nhau ca cc nguyn t hay nhm nguyn t xung

quanh mt b phn chiral (bt i) no ca

phn t.

2 .iu kin c ng phn quang hc

C yu t khng trng vt nh: s cho vt v nh

i xng nhau nhng khng chng kht c

vi nhau

C 2 loi : bt i nguyn t v bt i phn t

+ Nguyn t bt i: l nguyn t lin kt vi 4 nhm

th c bn cht khc nhau ( C*, Si*,S*)

+ Bt i phn t: trong phn t c nhng b phn

hoc nhm th m lm cho 4 nhm th c bn cht

khc nhau b tr trn 2 mt phng vung gc hoc

gn vung gc vi nhau

V d: hp cht c cc lin kt i lin v chn; spiran,

cn quay.

3. Mt s ng phn quang hc thng gp

Phn t c 1 C bt i xng: Nhng nguyn t

cacbon nh vi 4 nguyn t hoc nhm nguyn t

khc nhau gi l cacbon bt i k hiu: C*.

Cc phn t ny c 2 ng phn quang hc to

thnh 1 cp i quang

Phn t c nhiu C bt i : S lng ng phn

quang hc = 2n (n = s lng cacbon bt i).

Nhng nu trong phn t c yu t i xng th s

ng phn quang hc nh hn 2n v c xut hin

loi ng phn quang hc khng c tnh quang hot

l ng phn mezo

Axit lactic c 2 i quang l ng phn quay phi v ng phn quay tri, 2 i quang ny chng rt ging nhau nhng khng th chng kht ln nhau c

Hn hp 50% ng phn quay phi v 50% ng phn quay tri gi l hn hp raxemic. Hn hp ny c nng sut quay cc bng 0

Hp cht c nhiu trung tm bt i

Xt phn t: aldotetroz, nu ta gi gc quay ca cacbon bt i th nht l (a), gc quay cacbon th hai l (b) th gc quay ca phn t s bng tng i s ca cc gc quay cc ca tng nguyn t cacbon bt i.

C 4 cu hnh, 4 ng phn quang hc

CHO

HO

HO

H

H

CH2OH

CHO

OHH

H

CH2OH

CHO

HO H

H

CH2OH

CHO

HO

H

H

CH2OH

OH

OH OH

erythro threo

Xt Axit tartric (HOOC CHOHCHOH- COOH), c hai

C* nhng ch c 3 ng phn quang hc. Trong c mt

ng phn meso to thnh do c mt phng i xng

trong phn t,

COOH

H OH

H OH

COOH

Enantiomer

C 3 ng phn quang hc: 2 ng phn hot ng quang hc l

enantiomer v 1 ng phn khng hot ng quang hc gi l

meso

4. Danh php ng phn quang hc

a. Danh php D,L:

gi theo tn ca cht chun l D- v L- glyxerandehit

H

CHO

OH

CH2OH

CHO

H

CH2OH

HO

D- glyxerandehit L- glyxerandehit

b. Danh php R,S ( cu hnh tuyt i)

Quy tc ny da trn c s tng u tin ca nhm th

nh vi trung tm bt i xng theo th t u tin t ln

nht (1) cho n nhm nh nht (4), vi iu kin nhm

nh nht phi xa v tr ngi quan st v sau mt phng

Nu nhn t C bt i n nhm c hn cp (u tin)

nh nht m t abc theo chiu kim ng h l R ,

ngc chiu l S

Kinh nghim: Nu c theo R,S t cng thc Fischer c

nhm th c hn cp nh nht nm trc ngang, t

abc theo kim ng h l S , ngc kim ng h l R

V d: Axit lactic

c. Danh php erythro-threo

phn bit cc ng phn khng i quang trong trng

hp c 2 nguyn t C* ngi ta cn dng danh php erythro

threo (xut pht t hp cht erythro v threo).

Dng erythro l dng trong hai i nhm th tng t

nhau c th a v v tr che khut nhau

Dng threo ch c mt i nhm th tng t nhau c th

a v v tr che khut nhau

D4. ng phn cu dng

1. Khi nim v cu dng v ng phn cu dng

Cu dng l cc dng cu trc khng gian sinh ra khi c tnh

n s quay t do ca cc lin kt n, cc ng phn sinh

ra do s quay t do gi l ng phn cu dng

2. Cu dng ca hp cht hidocacbon no mch h

+ Ca etan : xen k bn

hn che khut

+ Ca n- butan:

bn ca cc dng xen k anti > xen k syn > che khut tng

phn> che khut ton phn

xen ke che khuat?

CH3

CH3

CH3CH3

CH3

CH3CH3

H3C

xen ke anti che khuat tung phn xen ke syn che khuat ton phn?? ?

3 Cu dng ca xiclohexan v dn xut

i vi xiclohexan: gim sc cng Baye: vng khng

phng, gc ha tr t 109028

+Cu dng gh v thuyn vn (xon)bn hn cu dng thuyn

i vi xiclohexan c nhm th: cc nhm th v tr bin

bn hn khi v tr trc

gh thuyn van thuyn

CH3

CH3

p quang hc c vai tr quan trng trong i sng t nhin

Cc cht chuyn ha, cc cht men l cc h thng hp cht quang hot

+ D-(+)-Glucose l ng c tc dng sinh hc lm cht tim truyn, ngc li L-(+)-Glucose khng c tc dng sinh hc.

+ Asparagin dng hu truyn c v ngt, t trin c v ng, racemix khng v.

+ Adrenalin dng t trin tc dng ln thnh mch mu gp 15 ln dng hu truyn.

Tc dng sinh hc ca p quang hc