Nucleophilic replacement of a nitro-group in an aromatic compound by chlorine

Tetrahedron Letters No. 32, pp. 2747-2748, 1970.

NuCLEoPHILIC

IWLLCBMBQ

09 A S

Fkinted in Great Britain.

IuAuAuoN4T1ccowamDBTCiiwmHB

P.H.GoRe, 59-p-unur Departmntof

Pergamon Press.

adD.p.C.Horrie

w.3,U.L

~trg,~l~~8i~,~,

(Received in UK 2 June 1970; accepted for publication 11 June 19'70) while displacements of nitro-goapr more umausl

types of replaoemw~te bme

instance of the woleophilic

rkom aotivated aromatio oompounaa are nll reoently been =w=tel+

lQmm,"2

TOdshtor93pO&~iWkp

replaoement ofanaromt3cnitro-groupbyoblori&a

ion: oaQfew

5 examples of this type hare been reoorded. 1,3,5-Triohloro-2,4,64rinitrobensene (A_ 96.9 m2moi’,

illlletbanok206ana300lm;E_4J30aad

respectively)on treatzmt with lithium chloridein aoetom or -1

solutionafforde 1,2,j,5-tetraohloro+6-dinllxobmmw, rydl~coBpama=.p.4241[(~ C, 24.3;H, 0.3; Cl, 45.6;I, 8.9. Caloulatdfor C6041V2C14: C, 23.5;H, 0; Cl, 46.4;I, 9.1s.

LX

in methanol: 208, 3C5 ad 380 1ll;6_ 4,450,233 and 1% m2mo14,

m.p. had been reported ae 636K;7 but idemti~ of the pmduotw

kwwn l-ohloro-3,5-dinitro-2,4,6-tri~bennne,

C24H,804N5C1: Cl, 7.s).

eont%md

reapeatively).

Tim

bynonmion8te*

m-p. 452x (Fauna:Cl, 8.3. mcailateafor

The kinetioa of the roe&ion

in aoetom

were ionwed

epeatrophoto-

metricallyat j8C nm; details are given in the Table. Themactionahaar_keam&iTe

Table.

Kinetic result8 for the reaction of

1,~,w~bhb0-2,4,6-~~~

(0.996mm01dr-3)with Lithiumchloride(1.62rol dm-3)in ACO~OM solutaon.

T

k2

@I

(al&l-'*-',

303.6

1.3 ~003)x109*-'

A

=

0.883

BA

= 53.6+ 3.0 W ml-'

300.6

0.607

ml*

295.5

0.453

289.4

0.293

AS*

= -79 +l Jlc-'nd'

2e4.1

0.168

AC*

= 74.62 4 W ml-'

= 51.12 3.0 w Doi'

k2(2Y8K)= 0.525d&d'

lbarslwpra~nt9~~~ 2747

a-'

l.iDita

2748

No.

8alt&foot, but with a oon8tant initial[UC11 5:1.62 ~1

32

dm-3good reoondorderkinotior

warm obtained. In the triohlorotrinitrobwucne the threerquivalentnitro-group8 oannotb8 ooplanar with the rromtio ring?'2

The 6-complextr8n8ition-atate (I)for th8 reaotionrauldpemt

reliefof rterioorowdingbt

Cl.

Thirwouldrestllt in mor8 ef'feotire oharge-delooalisation intolting the nitro-group8 at C3 and C5,13 and a olowr

Cl Cl 02N5

'4 If ir rpprorohto ooplan8rity of theaenitro-goups.

1 NO2

Cl

L

Cl

therefore.8uggrrted thet the pre8entreaotioninvolve8 a hi&-energyinitialatate,8nd a oompsratirelg &able

a

*O2

energy tran8ition rtate. The remarkablylow motivation may thu8be explained.

(1)

1.

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D.J.Searr and D.Y.Smith, Chem.Corn.,491 (1966). 2. J.I.G.Cadog&n, 3.

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360 (19%).

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P.Caveng, P.B.Fi8Oher, R.Heilbronner, A.I.M.iller and H.Zollinder, Relv.Chin.Acts, z, W

14.

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(1967);

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