JPH01100158A - Production of polychlorinated pyridine - Google Patents

Abstract

PURPOSE:To obtain a mixture of 2,3-dichloro, 2,3,5-trichloro- and 2,3,5,6- tetrachloropyridine, by effecting the reaction of 2-chloropyridine with chlorine lower than a specific temperature. CONSTITUTION:The reaction of 2-chloropyridine hydrochloride with chlorine is carried out lower than 160 deg.C, preferably lower 140 deg.C gives a mixture of 2,3-dichloro-, 2,3,5-trichloro- and 2,3,5,6-tetrachloropyridines. The process according to the present invention is essentially in no need of solvent, and in case of no solvent, the reaction temperature is preferably set over 100 deg.C, relating to the melting point of 2-chloropyridine hydrochloride. 2-Chloropyridine hydrochloride is prepared by blowing a hydrogen chloride gas into 2-chloropyridine. At this time, water markedly inhibits the reaction, and the use of hydrochloric acid is undesirable.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention uses 2-chloropyridine as a raw material to produce 2.3-
The present invention relates to a method for producing dichloropyridine, 2,3.5-trichloropyridine, and 2,3.5.6-titrachloropyridine.

(Prior Art and Problems) Various techniques have been proposed for producing polychlorinated products by chlorinating 2-chloropyridine. For example, a method in which 2-chloropyridine is chlorinated in a liquid phase (U8P3557124, Japanese Patent Publication No. 55-4744) or a method in which 2-chloropyridine is chlorinated in a liquid phase without a catalyst at a concentration of 1000 or more (the inventor's previous method) There is a Japanese Patent Application No. 180714/1983. However, in all of these conventional chlorination reactions using 2-chloropyridine as a starting material, only products obtained by further chlorination of 2,6-dichloropyridine (h) are obtained. That is, using 2-chloropyrinone as a raw material, 2.
There is no known method for producing 3-dichloropyridine or 2,3,5-trichloropyridine.

In particular, no effective method for producing 2,3-dichloropyridine is known.

(Means for solving the problem) The present inventors have developed a method using 2-chloropyridine as a raw material.
-Dichloropyridine and H2,3.5-) 9 As a result of intensive studies on the method for producing chloropyridine,
Quite surprisingly, by reacting the hydrochloride of 2-chloropyridine with chlorine, it selectively reacts with 2,3-dichloropyridine and 2.3.5-)! J dichloropyridine, 2
, 3.5.6-Titrachloropyridine was found to be co-produced, leading to the present invention.

That is, in the present invention, 2-chloropyridine is converted into hydrochloride and chlorine into 1
This is a method for producing a polychlorinated pyridine, characterized by carrying out the reaction at a temperature of 60° C. or lower.

The present inventors discovered that 2-chlorobilinone hydrochloride was heated at 160°C.
It was found that most of the above decomposes, and 16
00°C or less, preferably 140°C or less, 2-
We have discovered that chloropyridine hydrochloride can react with chlorine. When 2-chloropyridine hydrochloride is reacted with chlorine under these temperature conditions, the reaction of 2-chloropyridine hydrochloride proceeds selectively via 2,3-dichloropyridine in a high yield. That is, 2,5-dichloropyridine and 2,6-dichloropyridine are not produced at all.

When the first reaction is conducted without a solvent, it is desirable to carry out the reaction at 100° C. or higher due to the problem of the melting point of the 2-chloropyricin salt a salt, but this is not the case when r is a solvent.

This reaction essentially requires no solvent.

Moreover, its reactivity is extremely high h0. Most preferably, the hydrochloride of 2-chloropyridine is produced by blowing hydrochloric acid gas into 2-chloropyrinone.

Note that the use of hydrochloric acid water is not preferred since the reaction is significantly inhibited by the presence of water.

The amount of chlorine absorbed in the reaction system varies depending on the type or shape of the reaction tank, and the amount of chlorine to be charged can be appropriately determined by measuring the chlorine concentration in the exhaust gas.

(Effect of the invention) 2.3-dichloropyridine, 2.3.5 can be produced in high yield and high selectivity by the reaction of 2-chloropyrinone hydrochloride and chlorine.
-) A mixture of dichloropyridine and 2,3,5,6-titrachloropyridine is co-produced.

Example! 284.9 (2.5 mol) of 2-chloropyridine was added to a 500 ml reactor equipped with a waste gas condenser, a thermometer, a stirrer and a chlorine injection tube.
00#lJ! 40 flasks, and at a temperature of 110° C., chlorine gas was blown in at a rate of 50 liters per hour for 2 hours. After that, the temperature was set to 120℃, and chlorine gas was added every 7 hours.
I injected one at a time for 12 hours.

The composition of the reaction solution at this time was 52 mol of 2-chloropyridine hydrochloride, 16 mol of 2,3-dichloropyridine,
2.3.5-) 10 mol of dichloropyridine, 2.
3.5.6-titraquaropyridine was 22 mol.

The reaction solution was yellowish white, and the presence of -tar was hardly observed.

Comparative Example 1 (Reaction of 2-chloropyridine non-hydrochloride) 2-RIOA viridiy284II (2.5 mol) was charged into the same equipment as in Example 1, and 7 J/hour of chlorine gas was added at a temperature of 120°C.
I infused it for 1.0 hours at a time. However, the reaction solution is 2.
Other than about 1 ton of 6-dichloropyridine, almost no reaction progressed. Therefore, the reaction temperature was set to 15
The temperature was set at 0° C., and chlorine gas was then blown into the tube for 20 hours.

The reaction solution composition was 12% 2,6-dichloropyridine;
．． 3-dichloropyridine 2.5%, 2,3.5-)
2.7% dichloropyridine, 1.2% 2,3.6-drichloropyridine, 2.0% 2.3,5.6-titrachloropyridine and 79.5% unreacted 2-chloropyridine.
Contains a tiger.

Comparative Example 2 After obtaining 2-chloropyridine hydrochloride by the same treatment as in Example 1, the temperature was set to 165°C and chlorine gas was blown at 71°C per hour.
I infused it for 12 hours at a time. The resulting reaction solution contained 7% of 2,6-cyclopyridine, as well as 2,3-dichloropyridine, 2.3.5-)dichloropyridine, 2.
．． Both samples contained about 1 liter of 3.5.6-titraqualohyridine.

Therefore, when the concentration of 2-chloropyridine hydrochloride was measured after heating to t-165°C, it was found that the content was only 3 to 5%.

Patent Applicant: Daicel Chemical Industries, Ltd. Procedural Amendment (Spontaneous) November 19, 1985 Mr. Kunito Ogawa, Commissioner of the Patent Office
1. Indication of the case Patent Application No. 256199 filed in 1988 2. Name of the invention Process for producing pyridine polychloride 3. Person making the amendment Relationship to the case Patent applicant address 1 Teppo-cho, Sakai City, Osaka Prefecture Name (290) Daicel Chemical Industries, Ltd. Representative Yoshifumi Kubota 4, Subject of amendment Column 5 of detailed explanation of the invention in Mei 1III, Contents of amendment (1) “Chlorine gas” on page 4, line 16 of the specification Correct m+ as "hydrochloric acid gas".

Claims (1)

[Claims] A method for producing a pyridine polychloride, which comprises reacting 2-chloropyridine hydrochloride and chlorine at a temperature of 160°C or lower.