AU450077B2 - Halogenated pyridine derivatives - Google Patents

Description

31.44 9

This invention relates to chloropyridine derivatives and

more particularly to a novel chloro-derivative of 4-cyanopyridine.

In the specification of our U.K. Patent No. 1,0.1,906 there

is described a process for the manufacture of substituted pyridines

containing one or more chlorine atoms as substituents in the

pyridine ring which comprises interacting pyridine or a

substituted pyridine with chlorine in the vapour phase, the

proportion of chlorine in the reactants being more than two moles

of chlorine per mole of pyridine or substituted pyridine.

We have now found that a novel cyanochloropyridine may be

obtained when 4-cyanopyridine is used as the starting material

in the said process, namely 4-cyano-2,3,6-trichloropyridine.

Thus according to a further aspect of the present invention,

there is provided a process for the manufacture of 4-cyano-2,3,6-

2 450.077

3144 9 M: triohloropyridine which comprises Interacting 4-yano-pyLidine

with chlorine in the vapour phase at an elevated temperature,

the proportion of chlorine in the reaotants being more than

two moles of chlorine per mole of 4-cyanopyridine.

It is preferred to use three to ten moles of chlorine for

each mole of 4-cyanopy ridine.

The reaction between 4-cyanopyridine and chlorine may be

carried out over a wide range of temperatures, and preferably

0 the range in the range from 300 C to 6000c. A temperature in

400*0 to 500*C is especially preferred. It is preferred to

preheat separately the feed of chlorine and the feed of

4-cyanopyridine.

The reactants may be diluted with inorganic diluents, for

example nitrogen ane/or steam, or with organic diluents,

preferably inert towards chlorine, for example carbon tetrachloride.

When a gaseous or volatile diluent is used, 4-cyanopyridine may be

vaporised in a stream of diluent vapour which serves as a carrier

gas; when a liquid diluent is used, 4-cyanopyridine may be

dissolved in the liquid diluent and the resulting solution may

then be vaporised as a whole. If the diluent is reactive

towards chlorine, for example chloroform, an appropriate amount

of chlorine may be used to allow for its reaction with both

4-cyanopyridine. and the diluent.

The reaction may be carried out in the absence of a catalyst,

but a catalyst may be present if desired, for example a porous

material comprising silica, alumina (or a mixture or composition

of silica and alumina) or carbon.

3 450.077

31,44 9 7 Convenient residence times of the mixture in the reaction

zone are, for example, between 2 and 20 seconds, but higher or

lower residence times may also be used.

4-cyano-2,3,6-trichloropyridine may be used as a chemical

intermediate in the preparation of fungicidal, pesticidal or

herbicidal compositions.

The invention is illustrated but not limited by the

following Examples

A solution of 4-cyanopyridine (25 g) in carbon tetrachloride

(250 ml) was fed at a rate of 1.0 mi/minute to a packed vaporiser

maintained at a temperature of 300C. The issuing vapours were

passed to a vertical glass tubular reactor of 1-inch bore held at 0 a temperature of 4800C (1 20 C) where they were mixed with chlorine

fed at the rate of 0.2 litre/minute (measured at

corresponding to molar ratios of 4-cyanopyridine:carbon tetra-

chloride:chlorine of 1:10.8;9.2). The residence time was 14.9

seconds. The .gaseous reactor effluent was condensed and colleotod

in cooled carbon totrachloride. The resulting carbon tetrachloride

solution was distilled to remove carbon tetrachloride, and the

residual solid was recrystallised from acetic acid. There was 2 then obtained 4-cyano- ,3,6-trichloropyridine (18 which was

identified by the following spectral and physical datas

Melting Point 810C-82°C

I.R. vmax (Nujol) 1550, 1510, 1325, 1300, 1200, 1140, 910, 880 -1 and 8 cm a0

N.M.R. Z(CCl 4 2.48 1.S. Ii/e 206 with characteristic C13 isotope pattern

(C6 H22 35c3 gas M/ 206). 4 500 77

Claims (1)

1. -3a 44 9171 The claims defining the invention are. as follows:

   1. 4-cyanod2,3,6-trichloropyridine. 2. A process for the manufacture of 4-yao-2,3,6-trichloro-

   pyridine which comprises interacting 4-crano-pyridino with chlorine in the vapour phase at an elevated temperature,

   the proportion of chlorine in the reactants being more than two moles of chlorine per mole of 4-cyanopyridine.

   3. A process as claimed in claim 2 wherein the proportion of

   chlorine is three to ten moles of chlorine per mole of

   4-cyanopyridine.

   4. A process as claimed in claim 2 or claim 3 wherein the

   reaction temperature is in the range 300C to 6000C.

   A process as claimed in claim 4 wherein the reaction 0 temperature is in the range 400 C to 5000C.

   6. A process as claimed in any of claims 2 to 5 wherein the

   reaction is carried out in the presence of a diluent.

   7. A process as claimed in claim 6 wherein the diluent is carbon tetrachloride. 2 8. A process for the manufacture of 4-cyano- ,3,6-trichloro-

   pyridino substantially as described in the Example.

   9. 4-cyano-2,3,6-trichloropyridine whenever made by a process

   claimed in any of claims i to 8.

   DATED: 9th July, 1971 PHILLIPS ORMIDE AND FITZPATRICK Attorneys for: IMPBRIAL CMICALI INDUSTRIES LIMITED

   B. TUNNICLIFFE) AGENT FOR THE APPLICANTS 450,077