DE1545984C - Process for the production of pentachloropyridine - Google Patents

Description

1 2

The invention relates to a method of using earth or silica / alumina. It is

Production of pentachloropyridine by chlorination is particularly preferred, using microspheroidal silica

in the vapor phase. 'Use physical properties that are relevant for the

The accessibility of poly chlorinated pyridines fluidized bed processes are suitable.

is so far due to the relative difficulty and 5 expedient residence times of the mixture in the

Ineffectiveness of the known methods for one reaction zone are, for example, between 2

. result from more than 2 chlorine atoms as substituents and 20 seconds, but with higher and lower

been confined to the pyridine ring. Residence times can also be used.

Aas the essay by Wib au t and Nicolei [cf. It is also preferred to turn off the feed.

Itec. trav. chim. 58 (1939), p. 709] it is known, io chlorine and the charge of pyridine or substi-

preheat that pyridine in the vapor phase at 250 ° C separately to tuierter pyridine. In which

2-chloro- and 2,6-dichloropyridine are chlorinated in fluidized bed operation, it is expedient to use the entire

can. However, the authors mentioned indicate that or a part of the chlorine charge is separated into

at temperatures above 300 ° C introduce the chlorination of the fluidized bed, so that the mixing

Pyridines with much greater violence are made by chlorine with the pyridine or substituted

than the bromination and there will be a charring of the pyridine in the bed.

Pnedokts comes with experiments in which pumice stone The pyridine or substituted pyridine is

or glass wool used as the contact mass was moderately in a stream of water vapor

uffld "in which the molar ratio of chlorine to evaporate, both as a diluent as

Pyridine was from 0.8 / 1 to 1.6 / 1, the ao also serves as a carrier gas.

Main products from monochloropyridines and dichloro- The pyridine or substituted pyridine can be used in

pyridines, with only small amounts of more highly pure form or in the form of mixtures with

chlorinated products, namely trichloropyridines, one or more of the desired starting

have been received. fabrics are used.

According to the above work, pentachloropyridine can also be reported from the reaction products

denHeitog and Wibaut [cf. Rec. Trav. chim. 51 th in a known manner, such as fractional distillation,

(1932), p. 387] that the gas phase conversion between solvent extraction or combinations of the

Schea chlorine and pyridine can be isolated at temperatures via similar procedures.

30GPC runs very violently, and that when used, the invention is illustrated by the following examples

dung -ran 2MoI chlorine per mole of pyridine with a 30 explained.

Temperature of 250 ⁰ C in the presence of asbestos Example 1

the GesanaSasre yield of chlorinated pyridines is low

and only small amounts of polychlorinated pyridine is evaporated in a stream of nitrogen

Pyridines could be isolated. and continuously with preheated, gaseous

Polychlorinated pyridines are so far obtained 35 chlorine in a fluidized bed of 110 g microspherical

been carried out in steady-phase reactions using silica with a particle size of 100 to

formation of excess phosphorus pentachloride, 300 μ and a surface area of about 500 m ² / g

however, the mixing reaction times have been very long. The temperature of the bed is at 500 ° C

The yields were low and such were kept while the reaction mixture was off

Do not practice for large-scale 4 ° 8.1 moles of chlorine and 1.7 moles of nitrogen per mole of pyridine

Executions were suitable. through the bed at a speed equivalent

It has now been found that a high rate of chlorine of 1.6 moles per

beutes of pentachloropyridine can be obtained hour, is passed.

If vapor phase chlorination is successful, 611.5 g

is obtained using more than 6 moles of a crude solid product. The raw product

CMor per mole of pyridine or substituted pyridine. is dissolved in chloroform and the solution filtered;

The invention accordingly relates to a method for the filtrate is made with sodium bicarbonate solution and the production of pentachloropyridine, whereby pyri-water is washed and then dried over anhydrous fin, a methylpyridine or a chloropyridine with sodium sulfate. The chloroform is less than 5 chlorine atoms with chlorine in the steam 50 removed by distillation until a small volume phase ^{remains at 400 to 550 0} C in the presence of a porous solution and then ethanol (11) reacts to material and the proportion is added .

aa chlorine more than 6 moles of chlorine per mole of pyridine or a practically pure one separated from the solution

substituted pyridine. Pentachloropyridine (446 g with melting point

The reactants can with inorganic 55 from 126 to 127 ° C) and an impure second fraction

cal diluents, for example nitrogen ion in pentachloropyridine (17.5 g) are used in the

and / or steam, or with organic evaporation of part of the solvent from the

dänmingsmittel, which, preferably against chlorine, contain mother liquor,

are inert, for example carbon tetrachloride,

be d & mt. 60 Example 2

The porous material can, for example, be made from 2-methylpyridine in a stream of nitrogen.

TOBCTde, silica or coal. It's steaming and continuously with preheated chlorine in

particularly preferred, the reaction in the presence of a fluidized bed of the same amount and composition

of silica, alumina or a mixture of der- composition as in Example 1 mixed. The tempe-

to make sdben. 65 temperature of the bed is kept at 500 ° C while

The porous material can either be in the form of a reaction mixture, composed of 10 moles of chlorine and

rubenden bed or a fluidized bed applied 1.8 moles of nitrogen per mole of 2-methylpyridine, through

threw. It is preferred to have a fluidized bed of pebbles - the bed at one speed - equivalent

a flow rate of chlorine of 1.8 mol per hour - is directed. ·

After an hour of operation, 76 g of a crude solid are obtained. The crude product is dissolved in chloroform, washed with sodium bicarbonate solution and water, and then dried over anhydrous sodium sulfate. The chloroform is removed from the dried solution by distillation and the residue is then recrystallized from ethanol. This gives 38 g of practically pure pentachloropyridine (melting point 126 ^° C.).

Example 3

2-Chloropyridine is evaporated in a stream of nitrogen and continuously with preheated chlorine in a fluidized bed of the same amount and composition as in the previous examples mixed. The temperature of the bed is kept at 500 ° C while the reaction mixture is off 8.5 moles of chlorine and 1.3 moles of nitrogen! per mole of ao 2-chloropyridine is passed through the bed, with one Rate - equivalent to a flow rate of chlorine - of 1.7 moles per hour.

The crude product, which is obtained after throughput for 5 hours, is as described in Example 2, as treated and gives 176 g of practically pure pentachloropyridine.

Example 4

A mixture of pyridine and carbon tetrachloride is evaporated in a stream of nitrogen and continuously mixed with preheated chlorine in a fluidized bed with the same amount and composition as in the previous examples. The temperature of the bed is at 500 ° C held while the reaction mixture of 9 moles of chlorine, 2 moles of carbon tetrachloride and 1 mole Nitrogen per mole of pyridine through the bed at a rate - equivalent to a flow rate of chlorine - of 1.5 moles per hour - is passed through.

The crude product obtained after 3 hours of operation is treated as described in Example 2 and gives 98.5 g of practically pure pentachloropyridine.

Claims (6)

Patent claims: 1. A process for the preparation of pentachloropyridine by vapor phase chlorination of pyridine, a methylpyridine or a chloropyridine containing fewer than 5 chlorine atoms in the presence of a porous material, characterized in that the vapor phase ^{chlorination is carried out at a temperature of 400 to 550 0} C and the proportion of chlorine is more than 6 moles of chlorine per mole of pyridine or substituted pyridine. 2. The method according to claim 1, characterized in that the method in the presence a diluent is carried out. 3. The method according to claim 1 and 2, characterized in that as a diluent Nitrogen or carbon tetrachloride is used. 4. The method according to claim 1, characterized in that the porous material consists of silica, alumina or a mixture thereof. 5. The method according to any one of the preceding claims, characterized in that the Carries out reaction in a fluidized bed. 6. The method according to claim 5, characterized in that the reaction is carried out in one Performs fluidized bed of microspheroid silica.