DE1445653C - Process for the preparation of 2 (chloromethyl) 6 chloropyridine and its nuclear chlorinated derivatives - Google Patents

Description

1 2

The invention relates to a process for the preparation. It is also possible that the putative HCl-

of 2- (chloromethyl) -6-chloropyridine and its addition product is a chlorination in the 6-position

nuclear chlorinated derivatives. ■ not allowed. The chorulation of the invention

It is known, «-Picolin with chlorine gas at elevated 2- (Trichlormethy!) - pyridins below the specified

Temperature in the form of its hydrochloride to chloro- 5 conditions that permit the removal of hydrogen chloride

ire. However, only complex genes from the 2- (trichloromethyl) pyridine reaction com-

mix "are obtained, from which alone 2- (trichloro components enable or favor, the

methyl) -3,4,5-trichloropyridine could be isolated. Have an effect, at least part of the reaction

In the case of an improvement in this process, the component had to be brought into the form of the free base.

Water was added, although further nuclear chlorinated conditions would affect the removal or the escape

2- (Trichloromethyl) pyridines were obtained in those of hydrogen chloride from the reaction mixture

the position. 6 was not chlorinated in any case. favor are in the description below

The reaction had to be carefully controlled, illustrated. According to this assumption, the

in order to avoid excessive tar formation and form the free base itself slightly in the 6-position

to obtain reasonably tolerable yields. A 15 can be chlorinated.

Process for the preparation of 2- (trichloromethyl) - It has also been found that chlorination in

6-chloropyridine and its nuclear chlorinated derivatives of the 3-, 4- and / or 5-position of the a-picoline im

however, was not known. general before and not after the termination of

It has now been found that 2- (trichloromethyl) perchlorination of the methyl group occurs. Continue

6-chloropyridine and its nuclear chlorinated derivatives 20 has been found that the introduction of chlorine in

easily and in good yields by chlorination of the 6-position is only possible after the methyl

a-picoline or its chlorination products is perchlorinated by means of a group of the a-picoline molecule.

Chlorine can be produced at elevated temperatures. It is indeed desirable according to the invention. the development

be able. removal of hydrogen chloride. the reaction

The method according to the invention for the production of 25 mixture to favor or promote to a

of 2- (trichloromethyl) -6-chloropyridine and its high hydrogen chloride concentration during the

Nuclear chlorinated derivatives by converting chlorine into the 6-position of the 2- (trichloro

Avoid α-picoline hydrochloride, 2- (trichloromethyl) -pyridine methyl) -pyridine reaction components,

or one of its chlorination products with gas but it has often been found to be advantageous when

form chlorine at elevated temperature is thus 30 hydrogen chloride even during the initial

marked that. Chlorination stage is present, which leads to the nuclear

a) to introduce chlorine into the 6-position of the * i ^s ?, ^{ution dl} \ ^rch ™ ^ΟΤ ? ^nd _A ^{leads to the} perchlorination of the "" -picoline or 2- (trichloromethyl) -pyridine ring methyl group of the "-picoline starting material.

the implementation under anhydrous conditions £ ^ie . ^{s will} ™. explained in more detail below, in a temperature range from 90 to 230 ⁰ C ^{35 Es} ' ^st Sf * ⁰¹ "?"? suitable that the conditions carried out, the gaseous chlorine in excess ^wa ^ ^{rend the} chlorination so that hydrogen chloride excess are applied and thereby developing ^ Z ^{1 "8} the" -Picolm or (from the 2- mono- or hydrogen chloride from the reaction mixture ent-dichloromethyl) -pyndinen, which are present in the reaction removal "mixture, is not removed.

b) given ^ for the introduction of chlorine the * J ^^^^^^^ 3-, 4- and / or 5-position and in the methyl- f. _h . or the chlorination of the solvent is carried out without using a group of «-P.col.ns,
flussigten Ausganpmateriak first .η counter process of the invention may optionally waiting carried out of hydrogen chloride and _{4 fa} ". _{Presence of a kata} , _ysizing light source then after a) weaving process w.rd. _{be guided} through. It is so in many cases of

According to the process of the invention, the chlorination of the 6-position of the 2- (trichloro-

obtained the following compounds: 2- (trichloromethyl) - methyl) pyridines in the presence of radiation, such as

6-chloropyridine; 2- (trichloromethyl) -3,6-dichloropyridine; for example chemically active or ultraviolet

2- (trichloromethyl) -5,6-dichloropyridine; 2- (Trichlorme- 5 ° light, to perform.

thyI) -3,5,6-trichloropyridine and 2- (trichloromethyl) -. An important embodiment of the invention is

3,4,5,6-tetrachloropyridine. meets the use of a-picoline as a starting point

The new process enables the production of material. This is first converted into a-picoline hydrochloride mass by saturation with a single compound or a selected hydrogen chloride at a temperature of 20 to 70 ° C. It is noteworthy that the compound uses 2- (trichloromethyl) pyridine as starting materials with minimal tar formation and formation. When used rial, good yields can be achieved at temperatures above 135 ° C. and, in particular, at temperatures between 135 and 180 ° C. which do not have a chlorine atom in the 6-position, good yields can be achieved. ⁶ ° But also at temperatures above 180 ⁰ C delivers

It is assumed that aqueous chlorine water chlorination of a-picoline or 2- (trichloromethyl) substance in high concentrations, which results in the pyridine by the process according to the invention from reaction at low temperatures and results shown in the opposite. The introduction of chlorine wart can form water, or more molecularly in the 6-position of 2- (Trich! Ormethyl) pyridine in hydrogen chloride, which in the reaction mixture in the liquid phase can be formed with advantage in the absence of water is or is added at this temperature carried out in the range of 180 to 23O ⁰ C, .Salze or other addition products, but a temperature of 190 results in up with the 2- (trichloromethyl) -pyridine can be formed. 210 ⁰ C higher meneic proportions of 2-CTrichIormethvn-

6-chloropyridine with less formation of undesirable By-products.

2- (Trichloromethyl) -3,4,5,6-tetrachloropyridine is preferably prepared after saturating the a-picoline with hydrogen chloride at low temperatures and before carrying out the perchlorination of the methyl group. This gives mixtures which are rich in 2- (trichloromethyl) -3,4,5,6-tetrachloropyridine heptachloropicoline) and 2- (trichloromethyl) -3,4,5-trichloropyridine (hexachloropicoline) and also some 2- (dichloromethyl) ) -3,4,5-trichloropyridine (pentachloropicolin) contain. The heptachloropicoline and the other components can easily be separated from these mixtures by fractional distillation. Excellent results can be obtained by carrying out the chlorination of a-picoline, at temperatures ranging from 90 to 120 ⁰ C, but temperatures are preferably in the range of 95 to 105 ° C in general.

In this case, the gaseous chlorine is expediently used in an excess of 11.5 to 21.5 parts by weight per part by weight of a-picoline. The yield of the amount of heptachloropicoline can be increased by carrying out the chlorination in the presence of a catalyst. The Leweis acids, such as, for example, AlCl ₃ , FeCl ₃ or PCl _{3, are} among the particularly effective catalysts. In general, it is not necessary to use the catalyst in an amount greater than 5 percent by weight based on the weight of the α-picoline, and amounts of 0.5 to 1 percent by weight are often sufficient to achieve a noticeable increase in the yield to achieve.

2- (trichloromethyl) -3,6-dichloropyridine and 2- (trichloromethyl) -3,6-dichloropyridine can easily be prepared according to the invention by using 2- (trichloromethyl) pyridines as starting material, which are already substituted in the 3- or 5-Stellun * of the nucleus by chlorine. The introduction of the Chlorine in the 6-position of these compounds is advantageously used at a temperature of 110 to 160 ° C. The corresponding 2- (trichloromethyl) -6-chloropyridines, carry the chlorine substituents in any, two or all three of the 3-, 4- and / or 5-positions, can in analogous Mode by using the corresponding chlorine-substituted 2- (trichloromethyl) pyridines as starting materials getting produced.

However, the exact, preferred temperature range will vary depending on the starting material used. For example, 2- (trichloromethyl) -3-chloropyridine, 2- (trichloromethyl) -5-chloropyridine, 2- (trichloromethyl) -3,5-dichloropyridine or 2- (trichloromethyl) -3,4,5-trichloropyridine is used as the starting material so is the particular preferred temperature range for the introduction of chlorine in the 6-position 110 to 120 ° C, 120 to 130 ° C, 135 to 145 ° C or 150 to 16O ⁰ C. in this mode for carrying out the process of gaseous chlorine is preferably used in an amount of 0.5 to 3 moles per mole of 2- (trichloromethyl) pyridine reactant.

The process according to the invention can be carried out continuously by continuously supplying the respective Reactant carried out in a reaction vessel and continuous removal of the chlorinated oc-picoline will.

According to one embodiment of the invention, α-picoline and gaseous chlorine are continuously and simultaneously introduced into a reaction system at points remote from one another, the reaction taking place in the liquid phase with formation of the desired mixture enriched in 2- (trichloromethyl) -6-chloropyridine. In this embodiment, a liquid α-picoline hydrochloride mass is first formed, into which gaseous chlorine is then passed under controlled temperature conditions. By "liquid" picoline hydrochloride mass is meant a homogeneous liquid mixture or solution that is formed when picoline hydrochloride, which is normally a solid substance, is brought into contact with excess hydrogen chloride gas.
In this embodiment of the process according to the invention, chlorine gas is introduced into a suitable, heated liquid system which contains an initiator charge as described below, in order to form gaseous hydrogen chloride in situ, which is fed from this to a cooled system and in countercurrent is contacted with α-picoline to form a liquid α-picoline hydrochloride mass which is returned to the heated liquid system, whereupon it is mixed with gaseous chlorine to form the desired 2- (trichloromethyl) -6- chloropyridine enriched product reacts.

The "initiator charge" that goes into the primary reaction vessel to initiate the inventive Process is introduced is a liquid material that when brought into contact with gaseous chlorine reacts to form hydrogen chloride.

Although this requirement can be met by innumerable substances, it is for practical reasons an "a-picoline charge" is used ^ and the recommended ones Materials are preformed 2- (trichloromethyl) pyridine or preformed liquid a-picoline hydrochloride mass, which can be prepared by treating picoline with a multiple molar excess of hydrogen chloride. The at Initiator charge used in this way should be a. of solid> a-picoline hydrochloride free liquid medium. In addition, the entire operation can be carried out so that no solid α-picoline hydrochloride or solid tars get into the reaction vessel. The presence of these solids has been found to cause degradation reinforced or the implementation more difficult.

The hydrogen chloride formed in situ is passed to a cooled secondary reaction vessel which is a partial cooler, in which it under set temperature conditions with α-picoline in an atmosphere of excess hydrogen chloride to form a liquid α-picoline hydrochloride mass is brought into contact. At this stage, hydrogen chloride from an external source can be used, but this is not necessary since once the reaction has started there is always a copious amount of hydrogen chloride is formed. In this stage picoline hydrochloride is formed at the beginning, but it does arise a liquid mass in the presence of excess hydrogen chloride. The presence of excess hydrogen chloride ensures the smooth conversion von «-Picolin in liquid α-picoline hydrochloride mass. An Effective Method of Bringing Hydrogen Chloride and Picoline Intimately into Contact consists in a countercurrent mode of operation. The smooth transfer of the liquid α-picoline hydrochloride mass thus obtained to the primary reaction vessel

5 6

can be achieved by changing the temperatures so required time depends on the conditions be controlled that a considerable proportion of the amount used in the system, and can the initial heat of reaction between can easily be determined. Under the above and in the α-Picoline and hydrogen chloride removed, however as much as the following conditions give one Heat is retained so that the formation of a residence time of about 17 to 35 hours is excellent allows liquid mass and the mass on the ere results. Among the preferred workings-dingun-way for the primary reaction vessel in the liquid state, the intended residence time is approximately 17 hours will. Achieving the desired speed.

temperature range can best be achieved by using the successful selective manufacture of a

A reaction vessel of such a size and / or 2-chloro-6- (trichloromethyl) -pyridm-enriched dimensions can be achieved that the temperature range within the temperature of the reaction mixture, ie the temperature of the entire reactor, is achieved by carefully setting the temperature range is taken care of. As that of the primary reaction vessel, facilitated. Relative α-picoline hydrochloride formation exothermic and chlorine- moderately high temperatures should be present in the reaction gas, which should be maintained at all times at excessive temperatures. Within the tar formation, it is useful if the usable temperature range of about 140 the reaction ^{vessel has a relatively large cooling to 230 0} C can have further regulations for the selekfläche or wall, whereby the extent tive control of the desired product-together cooling is easily controlled from the outside can be. Settlement can be made. A suitable temperature range for carrying out 20 fold choice of temperatures, the operation through this stage is between about 20 and about 70 ^° C. can be carried out to 6-chloro-2- (trichloromethyl) -pyridine It is essential that noticeably higher temperatures practically to produce the sole product or to be avoided in order to produce the formation of undesirable compositions, the 3,5-dichloro by-products of the mechanical difficulties, 2- (trichloromethyl) -pyridine and 2- (trichloromethyl) -pydie result from such By-product formation 25 ridin in appreciable but minor amounts to prevent. Temperatures noticeably included. In general, a good half-20 ° C should be avoided in order to eliminate mechanical yields from a mixture, which is caused by 6-chlorine difficulties, which is enriched from a 2- (trichloromethyl) -pyridine. Picoline hydrochloride or the result of the reaction in the temperature range of from chemical difficulties, which is carried out by about 160 to about 200 ^0C . Optimum solid, falling into the primary reaction vessel or in temperatures for the recovery of 6-chloro-2- (trichlordieses run a-picoline hydrochloride caused methyl) -pyridine amount to be from about 180 to about 19O ⁰ C.. An average temperature of about measurable amounts of 3,5-dichloro-2- (trichloromethyl) -5O ⁰ C is suitable. Can pyridin trichloromethyl the introduction of significant pyridine and 2- (by amounts of unchanged "picoline in the primary 35 lowering the reaction temperature, in particular the reaction vessel can be achieved in place of the liquid cooperation to below about 17O ⁰ C, in the product. Reduction leads, as mentioned, usually to low The reaction can in the presence of ultra-

Yields and often uncontrollable mixtures. violet light. It did, however The exact feed rate of the chlorine in found that in contrast to many chlorination gas Primary reaction vessel depends on the particular reactions no benefit is achieved thereby. Will Operating size, shape of the reaction vessel, whether the reaction is carried out in the presence of light, mechanical mixing is used or not, the light source can also serve as a heat source, and the like. For effective operation it is useful - The thus obtained, 6-chloro-2- (trichloroiethyl)

moderately, a sufficiently rapid stream of chlorine gas pyridine-enriched mixture should be provided to ensure rapid conversion of the "-picolin- 45 liquid and small amounts of 3,5-dichlorohydrochloride to the desired mass- 2- (trichloromethyl) - pyridine and 2- (trichloromethyl) -pyridines to maintain good movement and contain contini- idin. The process can also be modified with the addition of hydrogen chloride from the reaction vessel to remove substantially pure 6-chloro-2- (trichloromethylene). Appropriate speeds to produce pyridine as the only product.
In a modification according to the invention, the speed of the a-picoline reaction component can be expressed in terms of the one method for continuously obtaining reaction system. As such 6-chloro-2- (trichloromethyl) -pyridine as a practically pure rate is concerned with a ratio of chlorine to product, the chlorination in the reaca-picoline is from about 1: 1 to about 2: 1 on weighting vessel, such as set out above, preferably viewed at a base. A typical example of a reactor temperature in the range from about 190 to about an appropriate rate is about 1.8 to 3.2 kg of 210 ^° C. carried out. The resulting mixture is discharged (4 to 7 pounds) of chlorine per hour with an α-picoline directly from the reaction vessel and introduced into the feed rate of about 0.9 to 3.2 kg in the center of a distillation column which (2 to 7 pounds) per hour when introduced into a at a bubble or vessel temperature in the range 24-1 reaction vessel (6.4 gallon), which is about 17 1 (4.5 gal- 60 from 180 to 190 ⁰ C, at a temperature at the upper ion ) Contains reaction mixture. The residence time depends on the end of the column in the range from 125 to 130 ⁰ C on the volume of the reaction mixture and the and at a pressure of about 8 to 10 mm Hg abs. to maintain a steady state works, whereupon a smaller proportion of the required a-picoline feed rate of more volatile 2- (trichloromethyl) -pyridine preferentially off. Under "steady state" the state 65 distilled and preserved in the passing fraction is meant, which is reached when the composition is and the less volatile 6-chloro-2- (trichlorous reaction mixture is no longer noticeably methyl) -pyridine and by-products as Backlog changes. The fraction to be obtained to achieve a steady state. The residue fraction

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can be withdrawn at the vessel temperature or without the process according to the invention can be introduced into the center of a second distillation continuous low-temperature chlorination process column by cooling, which at about 20 to ren high yields of highly chlorinated 22 mm Hg abs. Pressure and at a temperature «-Picoline compounds can be achieved, the ^{product at the top of the column of about 150 0} C and 5 being enriched in S ^ Sjo-tetrachlor ^ -ttrichlormethyty-pyr at a vessel temperature in the range of about idin. The mixture obtained contains 200 to 220 ⁰ C works in order to distill over practically pure 6-chloro two more highly chlorinated "-Picoline in 2- (trichloromethyl) -pyridine and win as significant, but easily separable amounts and transferring fraction and is smaller to obtain practically free from isomeric impurities, amounts of by-products in the higher-boiling, lower-chlorinated compounds and decomposition residue fraction. The products thus obtained. The product usually contains 3,4,5-tri-6-chloro-2- (trichloromethyl) -pyridine is a water-white chloro-2- (trichloromethyl) -pyridine and 3,4,5-trichloro liquid, which on cooling on room temperature 2- (dichloromethyl) pyridine than the other main temperature as a white crystalline solid from the components. This process not only allows the F. = 60.7 to 62 ° C to be deposited without recrystallization. The 2- (trichloromethyl) pyridine, which is obtained as passing yields and in a slightly from the smaller fraction in the first distillation, amounts of lower chlorinated by-products can be separated into the reaction vessel for further chlorination, but the By-products are freely recycled to 6-chloro-2- (trichloromethyl) -pyridine from tarry decomposition products, which is why they are used. 20 use as starting materials for production

The process according to the invention can, if desired, other chemical intermediates and, if necessary, can be modified to make significant and / or products possible. The method according to the invention recoverable amounts of 3,5-dichloro-2- (trichloromethyl) - provides a method for the first time to generate pyridine. In some operations this is used as a preparative method for highly chlorinated a product is desired which is rich in 6-chloro-2- (tri- 25 (trichloromethyl-pyridine compounds) chloromethyl) pyridine is and subordinate, but and which is also a useful technical promissory amounts of 3,5-dichloro-2- (trichloromethyl) - is a production method.

contains pyridine. To make such assemblies, the initial charge used in this case

The chlorination described above is preferably a highly chlorinated «picoline addition

in a temperature range of about 140 to about 30 composition with a density of 1.65 to 1.8.

180 ⁰ C made and the mixture obtained. Such a starting material still contains reactive

by continuously withdrawing from the reactive hydrogen atoms, but he avoids the inclusion

vessel can be obtained without distillation. Introduction of foreign matter. Once the procedure

Product which started about 10 to 30 mole percent 3,5-dichloro becomes a chlorinated «picoline mixture

2- (trichloromethyl) pyridine can be available after this 35 as initiator charge. When

Process modification can be obtained. If no chlorinated «picoline is available, one can

notes that the product obtained in this way continuously small amount of-picoline, diluted with an inert

can be distilled off to use the components, low-boiling solvents,

d. H. 6-chloro-2- (trichloromethyl) -pyridine as overgrowth whereby the solvent from the product after it

existing fraction and 3,5-dichloro-2- (trichloromethyl) - 40 recovery is easily removable. It is common

pyridine expediently by further distillation of the heavy, in this case several equivalents

Winning faction. anhydrous hydrogen chloride before adding the chlorine

To be introduced as a further modification of the invention. Otherwise, solid -Picolin process can use the chlorination to achieve good monohydrochloride, which impairs good yields. Yields of 6-chloro-2- (trichloromethyl) pyridine at 45 The exact feed rate of chlorine at a lower temperature than that specified above the primary reaction vessel depends on the particular optimum temperature to be carried out, the size of the operation, the shape of the reaction vessel, whether the chlorination is carried out in two stages, mechanical mixing is used or not, with two reaction vessels connected in series and the like. For effective operation of this Verwerden and the chlorination mixture obtained of the 50 driving a molar excess of about the first reaction vessel in the second reaction vessel should / about 80 to 85 ° ₀ of chlorine during the entire time in and be present in this under similar Bedingun- your reaction vessel In order not only to achieve a rapid conversion of the "6-chloro-2- (trichloromethyl) pyridine" -picoline hydrochloride-enriched mixture is chlorinated Hydrogen chloride is recovered from the reaction vessel or the distillation columns are flushed. The appropriate rate can be fed in. When using the two-stage - based on the feed rate of the a-picoline chlorination, lower temperatures can be used. in order to obtain high yields of the desired pressure kt. As such speed, a product will be obtained with no waste of management. 60 ratio of chlorine to -picoline of about 11.5: 1 However, good yields can also be viewed at lower to about 21.5: 1 on a weight basis. Temperatures without using a two-step purification for a convenient rate is chlorination can be achieved by using a distillation of about 1.8 to 2.7 kg (4 to 6 pounds) as part of the operating process, chlorine per hour with an α-picoline feed where the passing fraction consisting primarily of 2- (trichloromethyl) - 65 at a rate of 0.13 to 0.16 kg (0.28 to 0.35 pyridine) per hour when fed into a 24 -1 reactor process is recycled. (6.4 gallon), which is about 17 1 (4.5 gallon) reaction

In another significant embodiment, it contains mixed. The residence time depends on the volume

of the reaction mixture and the α-picoline feed rate required to maintain steady state. The time required to reach steady state depends on the conditions applied to the system and can easily be determined. The steady state density of the reaction mixture is usually from about 1.2 to 1.4 g / cm ³ (10 to 12 pounds / gallon) with an average of about 1.3 g / cm ³ (11 pounds / gallon). This density is an average density of the total mixture in the reactor in that a liquid two-phase system of practically determined proportions with the above average densities develops when the reaction reaches a steady state. The upper liquid phase is a liquid hydrochloride composition which contains -picoline hydrochloride and low-chlorinated oc-picoline hydrochloride in excess hydrogen chloride, and the lower liquid phase contains a highly chlorinated mixture which contains 3,4,5,6-tetrachloro-2 - (trichlormethyi) -pyridine is enriched. Assuming a reactor feed composition as given above, an α-picoline feed rate of about 0.14 kg (0.3 pounds) per hour, and an average molecular weight of the product of 300, the residence time would be 50 hours.

In this method of selectively preparing a mixture enriched in 3,4,5,6-tetrachloro-2- (trichloromethyl) pyridine, better results can be obtained by carefully adjusting the temperature of the reaction mixture, ie the temperature in the primary reaction vessel. In particular, the temperature should not be allowed to remain above 120 ^° C. for any appreciable period of time. A convenient temperature range is from about 95 to about 110 ⁰ C. Equally good results were achieved at 100 ⁰ C.

Although the reaction can be carried out in the absence of a catalytically active light source, however, the use of light is preferred.

The reaction can also be carried out in the presence or absence of a catalyst will. One of highly chlorinated <x-picoline compounds, in particular 3,4,5,6-tetrachloromethyl-2- (trichloromethyl) pyridine Enriched mixture can be used in good yields in the absence of a catalyst can be obtained. This is especially true if the product obtained by this method has passed through Using known chlorination methods, the products obtained are compared. It did, however found that by using Lewis acid catalysts in the process of the invention the yield of the desired product can be markedly increased. The preferred method to produce a mixture enriched in 3,4,5,6-tetrachloro-2- (trichloromethyl) -pyridine is therefore the use of a Lewis acid catalyst is advantageous. Any Lewis acid catalyst can be used. Aluminum chloride, phosphorus trichloride and ferric chloride are particularly useful. The others include stannous chloride, antimony trichloride, thionyl chloride, sulfuryl chloride, phosphorus pentachloride, Calcium chloride, iodine and red phosphorus. Likewise, salts of polyvalent metals can be used in the lower valence level as well as free metals are used. If the latter are used, so

they are evidently easily converted into the corresponding one by the hydrogen chloride formed in the reaction mixture Metal chloride transferred. The catalyst is advantageously used in an amount of no more than 5 percent by weight of the alpha-picoline feed used. Preferred amounts are from 0.5 to 1 percent by weight.

The mixture obtained in this way, enriched in 3,4,5,6-tetrachloro-2- (trichloromethyl) pyridine, is water-white, has a practically constant density, contains only small amounts of low-chlorinated oc-picolines and is practically free of hydrogen chloride. This product mixture forms a lower liquid phase in the reaction vessel, while the less chlorinated «picoline, dissolved in hydrogen chloride, the lighter one; forms upper liquid phase. The exact composition of the mixture to be removed from the reaction vessel in the steady state can easily be determined analytically by vapor phase chromatography of samples or estimated by density comparison with a predetermined density-composition relationship. The average densities of the j to 3,4,5,6-tetrachloro-2- (trichloromethyl) - \\ pyridin-enriched 3,4,5-trichloro-2- (trichloromethyl) pyridine and 3,4,5-trichloro- Products containing 2- (dichloromethyl) pyridine as main components vary from 1.68 to 1.78 and are usually about 1.73. The product can be withdrawn from the reactor by customary methods and, if necessary, separated into its components by fractional distillation.

According to another preferred embodiment of the invention, 6-chloro-2- (trichloromethyl) pyridine compounds can be prepared easily and in good yields by a method in which a 2- (trichloromethyl) pyridine compound the general formula

X-i

CCl ₃

in which X is either a hydrogen or chlorine atom, heated to a liquid state and / or is kept in liquid form and gaseous chlorine is passed through. The reaction can be caused by the the following equation can be reproduced:

-A-x

+ Cl ₂

-CCl ₃

X— 1 Cl

-X + HCl CCl ₃

The selective chlorination reaction proceeds smoothly; quickly and in good yields with little or none Formation of by-products and without formation of unwanted tar materials, if for an effective one Contact between the appropriate 2- (trichloromethyl) pyridine reactant in the liquid state and gaseous chlorine.

When carrying out the reaction, the rate of the reaction can be increased by moderately increasing it the temperature can be increased above that temperature which is necessary for the reaction medium

in the liquid state, but in order to achieve selectivity in the chlorination it is important that harsh temperature conditions are not used. The upper temperature limit suitable for achieving the desired selective chlorination is about 160 ° C. The lower limit will of course be determined by the particular starting material, but although the reaction can be carried out in the vicinity of room temperature, a practical lower limit will be a temperature of about 100 ° C viewed. The preferred temperatures for conducting the reaction vary to some extent depending upon the particular connection to be established and are within the range of about 110 to about 16O ⁰ C. With the exception of 2- (trichloromethyl) -pyridine itself, preferably at temperatures of about 135 ⁰ C. is chlorinated to 6-chloro-2- (trichloromethyl) pyridine, it appears that the less chlorinated reactants have optimal reaction temperatures at the lower end of the overall preferred range, while the more highly chlorinated reactants have preferred reaction temperatures at the upper end of the preferred range. For example, seems to be the chlorination of 3-chloro-2- (trichloromethyl) pyridine to 3,5-dichloro-2- (trichloromethyl) pyridine best run at temperatures between about 110 and 120 ⁰ C. Similarly, the chlorination of 5-chloro-2- (trichloromethyl) pyridine to 5,6-dichloro-2- (trichloromethyl) pyridine best run at temperatures in the range of about 120 to 130 ⁰ C appears. On the other hand, the chlorination of 3,4,5-trichloro-2- (trichloromethyl) pyridine to give 3,4,5,6-tetrachloro-2- (trichloromethyl) pyridine appears to be best at temperatures in the range from about 150 to 160 ^° C to run. The preferred range of about 135 to 145 ° C. for the chlorination of 3,5-dichloro-2- (trichloromethyl) pyridine to give 3,5,6-trichloro-2- (trichloromethyl) pyridine is typical of an intermediate optimum range.

The reaction is preferably carried out in the presence of actinic radiation such as ultraviolet Light, carried out. A light with a wavelength of about 2000 to 5000 Å, in particular A light source emitting from about 3000 to about 4000 Å is suitable. When the reaction is in the presence a light source is carried out, the light source can also serve as a heat source. In trade available sunlamps are suitable for such use.

The reaction is preferably carried out in the absence of a solvent or diluent. While certain solvents or diluents can be used, this has usually of no practical value as good results can be obtained without using them. If a solvent or diluent is used, the type of solvent should be used and its boiling point should be respected. This is how low-boiling solvents set the reaction temperatures and, if used, would cause a reduction in reaction efficiency or require significant changes to the equipment. Solvents with reactive groups, such as for example water, could cause side reactions. Suitable solvents are chlorinated Solvents such as hexachlorobutadiene. Also note that better results can be achieved if water, which is often added in some chlorination processes, is rigorous is excluded.

The rate of the flow of chlorine and the total time of delivery of the same become in part determined by chemical and partly by mechanical requirements. Too in determining the factors to be considered include size and / or shape of the vessel, mechanical Entrainment of the product in flue gases, reaction temperature, mechanical aids for the contact effectiveness, application of the countercurrent principle, application of packed columns, Single pass of gas or recycle and the like. Generally good results can be obtained when the rate of chlorine stream is from about 0.5 to about 3 moles of chlorine per mole of 2- (trichloromethyl) pyridine reactant per hour, however, higher or lower speeds can also be used with good success depending on the specific circumstances and conditions may be applied. The higher flow velocities can sometimes or can lead to excessive reaction and by-product formation cause the product to be physically entrained and lost in the flue gas stream. Lower flow rates can reduce the reaction rate to such an extent reduce the need for additional external heating. It should be noted that the heat source partly an inner, d. H. Heat of reaction, and partly an external, d. H. Light and thermal radiation, is.

When the reaction temperatures approach the upper limit, a very large excess should be used Chlorine should be avoided in order to reduce side reactions to a minimum.

After the reaction has ended, the reaction mixture can be cooled to room temperature leave to recover the 6-chloro-2- (trichloromethyl) pyridine product as a solid. Preferably the reaction mixture is distilled before cooling to obtain a practically pure product. Possibly further purification processes, such as fractional distillation and / or recrystallization, be applied.

The following examples illustrate the invention without restricting it.

B e i s ρ i e 1 1

One operation was carried out in an apparatus which, as the primary reaction vessel, was a vessel of 17 1 capacity (A), a water-cooled column with an internal diameter of 50 mm (2 inches) and a length of 914 mm (36 inches) (B) and a cooler (C) consisting of a Water cooled column 50 mm (2 inches) in diameter and 355 mm in length (14 inches) consisted.

The primary reactor was charged with 60 pounds of a mixture of partially chlorinated Λ-picoline from an earlier run as an initiator charge. The temperature of the loaded reactor was then raised to 21O ⁰ C, and chlorine gas was introduced in an amount of about 2.5 to 3 kg (5.5 to 6.6 pounds) per hour. The gaseous chlorine reacted with the partially chlorinated α-picoline in the initiator charge to form hydrogen chloride which was released from the mixture and passed into column (B). a-picoline

13 14

was fed into column (B) in an amount of about one of 3,4,5,6-tetrachloro-2- (trichloromethyl) pyridine 0.5 to 0.55 kg (1.1 to 1.2 pounds) each Hour to form the product mixture submitted. After that leads. The a-picoline introduced in this way came when the steady state was reached, the product gaseous hydrogen chloride was continuously removed from the primary reaction vessel in countercurrent. Contact and react with it to form 5 It weighed 59 kg (130 pounds). The analysis of the α-picoline hydrochloride, which in the presence of excess 3,4,5,6-tetrachloro-2- (trichloromethyl) pyridine accumulated gaseous hydrogen chloride, formed a liquid safe product by vapor phase chromatography oc-picoline hydrochloride mass which shows, downwards, that the mixture was also entering the primary reaction vessel, 3,4,5-Trichloro. The liquid cc-picoline hydro-die introduced into the reaction vessel containing 2- (trichloromethyl) pyridine and 3,4,5-trichloro-2- (dilich in the chlorination medium in the primary io chloromethyl) pyridine as main components in this way Composition of the product in mole percent chloride mass reacted with the gaseous chlorine, was the following: 30 ° / ₀ 3,4,5,6-tetrachloro-2- (trichlorodas continuously introduced for 17 hours methyl) -pyridm, 32% 3, 4,5-Trichloro-2- (trichloromethyl) was added to a product mixture enriched in 6-chloro-2- (trichloromethyl) -pyridine pyridine, 16% 3,4,5-trichloro-2- (dichloromethyl) -pyridine to build. Upon reaching about 6% 3,5-dichloro-2- (trichloromethyl) pyridine, about reaching steady state, the product was 7% 3,5,6-trichloro-2- (trichloromethyl) pyridine and about mixed with a degree of purity of about 80 ° / ₀ 4 ° / "SS.-dichloro ^ dichloromethyl-pyridine.
continuously from the reaction vessel at a rate of about 1.36 kg (3 pounds) each can be easily separated by fractional distillation.
Hour removed without distillation; the product 20

weighed about 22.7 kg (50 pounds). One from example 3

Methylene chloride-pentane crystallized sample of the. ,

Product had a melting point of 62.5 to 62.9 ° C 6-chloro-2- (trichloromethyl) pyndine

on. 39 g (0.2 mol) of 2- (trichloromethyl) pyridine were in

Analysis: ² 5 ^eme tubular apparatus was introduced and the

Calculated ... C 31.20, H 1.31, Cl 61.1, N 6.05 ° / ₀ ; ?: ^e _u ^aktionskom P ^on ^ ⁿ _c ^te "™ ^urde _U1 ^with <T ^ine 5. ^Re ^ ^ek _u ^to , ^r :

Found ... C 31.23, H 1.32, Cl 61.22, N 5.99%. high altitude sun (type RS-4) irradiated and heated. As soon as

the temperature of the reaction component about

Another sample recrystallized from pentane at 135 ° C was a stream of gaseous chlorine

a 30 exhibited a slightly lower melting point at a rate of about 0.45 moles per hour

Infrared spectrum, which practically passed through with that of one for 1.5 hours, whereby the ge

Authentic 6-chloro-2- (trichloromethyl) pyridine produced by an independent system was obtained

table sample from the F. = 64 to 65 ⁰ C was identical, was. Analysis of the product by vapor phase

and a purity of 98% chromatography chromatography showed that 71 mole percent off

shear analysis compared to the pure sample. 35 6-chloro-2- (trichloromethyl) pyridine and the rest from

unconverted starting material passed.
Example2

An operation was in the Working Example 1 ^J ^

written apparatus carried out. 6-chloro-2- (chloromethyl) pyridine

The primary reaction vessel was charged with 1.45 kg (3.2 40 pounds) of a partially chlorinated α-picoline gaseous chlorine at a rate of mixing from a previous batch as an initia- 5 moles per hour into 58.0 g (0.295 moles) of heated gate charge. The temperature of the irradiated 2- (trichloromethyl) pyridine, sent reactor was then increased to 100 ° C. The supply of gaseous chlorine was continued for 7.5 hours and gaseous chlorine was continued in an amount of 45 while the temperature of the reaction introduced about 4 kg (9 pounds) per hour. The gas medium in the range of 120 to 135 ⁰ C-shaped kept chlorine reacted with the partially chlorinated was to give the desired 6-chloro-2 was formed (trichlora-picoline in the initiator feed to form methyl) -pyridine. After the reaction mixture, which had escaped from the mixture, had cooled, the product crystallized as and was passed into column (B). α-Picoline 50 solid substance from the F. = 65 to 66 ⁰ C from. Infrared was fed into the column (B) in a speed spectral analysis indicated that the product was introduced with it at 0.318 kg (0.7 pounds) per hour. The melting point of pure 6-chloro-2- (trichloromethyl) -pyriso -picoline came in the gaseous din was. The yield of the product was 64 g or countercurrent hydrogen chloride in contact and 94% of theory,
reacted with this to form «-Picoline- 55 Example 5
hydrochloride, which in the presence of gaseous " _r ^. ,. - /, · ,,, _ts
Excess hydrogen chloride creates a liquid "-Pico-3,6-dichloro-2- (trichloromethyl) - _Py ndin
lin hydrochloride mass formed, which passed down into the gaseous primary reactor. 227 grams (0.5 pounds) of aluminum chlorine in an amount of 0.4 moles per hour in 46 grams of chloride catalyst (about 1 percent by weight, based on 60 (0.20 moles) of 3-chloro-2- (trichloromethyl) pyridine the entire used a-picoline) were passed into the irradiating and introduced to a temperature of about a liquid-picoline hydrocblorid mass, which was heated to 13O ⁰ C 120. The passage of chlorine exited column (B) and continued with it for about 5.75 hours, bringing 48.4 g of the primary reaction vessel. The so continuously crude 3,6-dichloro-2- (trichloromethyl) pyridine obtained in the chlorination medium of the primary reaction 65 were. The analysis of the crude product through a vapor vessel introduced liquid α-picoline hydrochloride phase chromatography showed that 79.6% of the mass reacted with gaseous chlorine, the continuously desired 3,6-dichloro-2- (trichloromethyl) -pyridine reacted during 72 Hours was introduced to stood. This corresponds to a yield of 73% of the

15 16

Theory. The product possessed after recrystallization that nitrogen in an amount of

from hexane a melting point of 47 to 48 ^° C. 112 kg / ha (100 pounds per acre) is supplied. the

. -iz- soil is filled with 50 to 100 mm (2 to 4 inches) of water

Examples during the growing season to achieve high levels of

5,6-dichloro-2- (trichloromethyl) -pyridine ₅ hives irrigated on commercially available corn.

In a corresponding manner, 60 g of 5-chlorine-2- (trichloromethyl) -pyridine prepared by the process according to the invention in a temperature range, enriched in heptachloropicoline mixtures from 120 to 130 ° C by passing chlorine through in can be used unchanged or in their Mainly an amount of 0.4 mol per hour for 2.5 hour components chlorinated for the final use together, with crude 5,6-dichloro-2- (trichloro-io compositions or as starting materials for the methyl) -pyridine in one yield of 65 g obtained production of other desired products was separated. The desired product was made to be 64.5 moles. Thus, the 3,4,5,6-tetrachloro-2- (trichloro percent of the product mixture from, as by analysis methyl) -pyridine enriched with inert product was determined by vapor phase chromatography, adjuvants for the production of pest and was from the mixture can be diluted by fractionated 15 herbicides. Obtained by distillation. The 5,6-dichloro-2- (trichloro-such a use is the product with methyl) -pyridine formed a white crystalline solid-dispersant and mixed in water to a spray of m.p. = 38 ° C. agents dispersed when applied to the leaves. · Ι ₇ ^of beans, pigweed and fox-B e 1 s ρ 1 e 1 7 _ao tail plants cause a complete destruction of these 3,5,6-trichloro-2- (trichloromethyl) -pyridine plants. The 3,4,5,6-tetrachloro-2- (tri-

In a similar way, 43 g (0.16 mol) of 3,5-dichloromethyl) pyridine were enriched but chlorine-2- (trichloromethyl) pyridine can also be used at a temperature to obtain 3,4,5,6- Tetrachloro-2- (tri in the range from 135 to 145 ° C chlorinated, giving chloromethyl) pyridine or 3,4,5-trichloro-2- (trichloro-3,5,6-trichloro-2- (trichloromethyl) pyridine 25 methyl) pyridine, which was separated in. The conversion of converted 3,5-di-pest control or weed-killing chlorine-2- (trichloromethyl) -pyridine to 3,5,6-trichloro-agents can be used.
2- (trichloromethyl) pyridine was 50%. The Product The products prepared according to the examples shown in Examples 3 to 8 by fractional distillation and light methods have numerous uses which have a boiling point at a pressure of 1 mm Hg. They are, for example, than 12O ⁰ C. effective components in the! production of

At room temperature, 3,5,6-trichloro-2- (trichloro-agents which are suitable for agricultural methyl) -pyridine, a white crystalline substance, are suitable for use. They are also called Un-F. = 58 to 59 ° C. herbicides or pesticides _. . . "35 medium, without further modification in such appli ^exs P ^{J e} dung as nematocides, fungicides, disinfectants, 3,4,5,6-tetrachloro-2- (trichloromethyl) pyridine germicides, herbicides and insecticides have value in a similar manner 40 g (0.13 moles) 3,4,5-tri-full. The usefulness of 6-chloro-2- (trichlorochlor-2- (trichloromethyl) -pyridine under irradiation and methyl) -pyridine compounds as nematocides can be seen from the following remarks by heating with a sunlamp at about 150 ° C. Various passes of gaseous chlorine in an amount of aqueous compositions were prepared which chlorinated 0.5 moles per hour for 5 hours, one of the following 6-chloro-2- (trichloromethyl) pyridine being the desired 3,4,5,6-tetrachlor -2- (trichloro- compounds contained: 6-chloro-2- (trichloromethyl) methyl) pyridine with a conversion of about 27% pyridine, 5,6-dichloro-2- (trichloromethyl) pyridine, 3,4, 5, of the reacted 3,4,5-trichloro-2- (trichloromethyl) -pyri- 45 6-tetrachloro-2- (trichloromethyl) -pyridine and 3,5,6-tridine was obtained. chloro-2- (trichloromethyl) pyridine. This co-

3,4,5,6-Tetrachloro-2- (trichloromethyl) pyridine is a subsidence that was carried out in separate operations for 6 days

white crystalline solid substance from the F. = 58 to 60 ° C. long at about 27 ° C with larvae of tuberous

It is brought into contact in many organic solvents, such as bi- nematodes, and resulted in each

e.g. carbon tetrachloride, perchlorethylene, 50 cases a complete control of the nematode

Chloroform, diethyl ether and pentane, soluble and in larvae.

Practically insoluble in water. Certain of the 6-chloro-2- (trichloromethyl) pyridine

4-chlorine, 3,4-dichloro or 4,5-dichloro-2- (trichloro bonds also have antimicrobial properties.

methyl) pyridine can also be used in a manner that has been carried out in, for example, separate operations corresponds to that used in Example 7, chlorinated 55 5,6-pichloro-2- (trichloromethyl) pyridine and 3,6-dichloro

4,6-dichloro-, 3,4,6-trichloro- or 2- (trichloromethyl) -pyridine in a malt yeast agar

4,5,6-trichloro-2- (trichloromethyl) pyridine. Medium dispersed to produce culture media,

Compositions containing 6-chloro-2- (trichloromethyl) - which is one of the 6-chloro-2- (trichloromethyl) pyridine compounds

pyridine are valuable as nitrification inhibitor bonds in a concentration of 100% by weight. In a typical example of such a 60 parts per million contained. The media was

Use is 6-chloro-2- (trichloromethyl) -pyridine separated with Pullularia pullulans and Candida pelli-

dissolved in an aqueous ammonium fertilizer, inoculated to culosa and incubated for 3 days at 30 ° C,

to produce a soil treatment agent that contains 1000 Ge After this period of time, a complete in-

parts by weight of nitrogen and 1 part by weight of 6-chlorine inhibition of the growth of organisms

Contains 2- (trichloromethyl) pyridine. The mean can 65 respects.

as side dressing on rows of some of the 6-chloro-2- (trichloromethyl) pyridine compounds

Planted corn that binds in sandy loam soil are also valuable as insecticides. In both

a pH value of 7.9 grows, in such amounts, separate work steps became one

Achieved 100 ° / _o kill strength of houseflies and American cockroaches when these have been associated with compositions in contact, the parts by weight per million of 6-chloro-2- (trichloromethyl) -pyridine contained.

Claims (5)

Claims: ■: · f ...!; ■ · 1. Process for the preparation of 2- (trichloromethyl) -6-chloropyridine and its nuclear chlorinated derivatives by reaction of a-picoline hydrochloride, 2- (Trichloromethyl) pyridine or one of its chlorination products with gaseous Chlorine at an elevated temperature, characterized in that a) for the introduction of chlorine in the 6-position of the AE-picoline or 2- (trichloromethyl) pyridine-ring, the reaction is carried out under anhydrous conditions in a temperature range of 90 to 23O ⁰ C, applied the gaseous chlorine in excess and the hydrogen chloride which is evolved is removed from the reaction mixture; b) optionally for introducing chlorine into the 3-, 4- and / or 5-position and into the Methyl group of the oc-picoline initially chlorination of the liquefied starting material carried out in the presence of hydrogen chloride and then proceeding according to a) will. ■ 2. The method according to claim 1 for the preparation of 2 - (trichloromethyl) - 3,4,5,6 - tetrachloropyridine, characterized in that the reaction takes place in a temperature range from 95 to 105 ° C he follows. 3. The method according to claim 2, characterized in that the chlorine with the starting material is reacted in an amount of 11.5 to 21.5 parts by weight per part by weight of starting material. 4. The method according to any one of claims 2 and 3, characterized in that the reaction in the presence of a Lewis acid catalyst, such as AlCl ₃ , FeCl ₃ or PCl ₃ , takes place. 5. The method according to claim 4, characterized in that the catalyst in an amount of 0.5 to 1 percent by weight based on the weight of the starting material is used.