DE1116209B - Process for the preparation of chlorobenzonitriles - Google Patents

Description

British Patent 807485 states that aromatic nitriles and derivatives thereof which are substituted by alkyl groups and in which a halogen atom is bonded to the aromatic nucleus can be prepared by preparing a gas mixture at elevated temperature which consists of an aromatic substituted by at least one alkyl group Hydrocarbon or a derivative thereof substituted by a halogen atom in the nucleus, ammonia, 4 to 10 percent by volume oxygen and nitrogen, passes over a catalyst consisting of vanadium oxide deposited on activated aluminum oxide. For the known process, toluene, monoethylbenzene, o-, m- and p-xylene, mesitylene, o-, m- and p-di-isopropylbenzene, o-, m- and p-cymene and α- or / 3- Methylnaphthalene may be suitable. However, exemplary embodiments have only been described for m- and p-xylene. As monohalogen derivatives, 0-, m- and p-chlorotoluene are mentioned; however, the production of a chlorobenzonitrile therefrom is not described.

US Pat. No. 2,499,055 describes a process in which a gas mixture consisting of toluene or p-chlorotoluene, ammonia and air is brought into contact at elevated temperature with a catalyst containing vanadium, molybdenum and phosphorus on aluminum oxide as a carrier and is obtained in the strength R of toluene, at 95% ^e transformation thereof, an 75% yield of benzonitrile and p-chlorotoluene, at 82% conversion thereof, a yield of 47% of p-chlorobenzonitrile.

When using a Toloulder derivative, the p-permanent .dig has a chlorine atom in the benzene nucleus with respect to the methyl group, is thus obtained by the process of the United States patent a considerably lower yield of nitrile than when using toluene even with essentially the same degree of conversion. To this end, it was found that during manufacture ammonium chloride is formed as a by-product of p-chlorobenzonitrile according to this process; this should Side reactions in which the chlorine atom participates can be ascribed.

It is known that when the number of halogen atoms bonded to the nucleus in benzene or toluene is increased, a halogen atom is more easily replaced in substitution reactions than when only a single halogen atom is bonded to the benzene nucleus. This is due on the one hand to the increase in the "halogen concentration" in the molecule, and on the other hand to the associated increase in the reactivity of the individual halogen atoms. It is also known that by the method of manufacture
of chlorobenzonitriles

Applicant:

N. V. Philips' Gloeilampenfabrieken,

Eindhoven (Netherlands)

Representative: Dipl.-Ing. H. Zoepke, patent attorney,

Munich 5, Erhardtstr. 11

Claimed priority:
Netherlands of April 28, 1959 (No. 238 685)

Harmannus Koopman, Weesp (Netherlands),
has been named as the inventor

Presence of different groups in the molecule of a halogenobenzene or halogenotoluene and in particular from negative groups, such as B. cyano groups, the reactivity of the halogen atoms is influenced and that in particular a strong influence on this reactivity of one with respect to the halogen atom o-constantly bound negative group emanates.

In view of this and of acquaintances from the aforementioned USA patent specification, it was therefore not to be expected that the aforementioned process for the preparation of polychlorobenzonitriles from the corresponding Polychlorotoluenes would be suitable. This was to be assumed in particular for those cases that one or two chlorine atoms are o-position with respect to the cyano group.

From 2,6-dichlorotoluene it is known that the Methyl group is difficult to oxidize and is therefore to be regarded as a group that is difficult to transform is.

It has now surprisingly been found that the aforementioned processes for the preparation of Polychlorobenzonitriles and especially for the production of di- and trichlorobenzonitriles from the corresponding polychlorotoluenes are suitable. This arises depending on the reaction conditions more or less ammonium chloride as secondary

109 737/406

3 4

product. By choosing suitable conditions are present. The oxygen concentration is with

the formation of ammonium chloride can be adjusted widely, optionally with the addition of air

restrict going. additional nitrogen.

The invention is thus a method It was found that the use of a

for the production of chlorobenzonitriles by catalyzing 5 significant excess of ammonia than theoretical

table conversion of mixtures of chlorotoluenes, required higher yields of di- or trichloro

Ammonia, oxygen and an inert gas in the benzonitrile, based on the di- or used

Gaseous phase at elevated temperature on a vana trichlorotoluene supplies. There, as I said above, the

dium oxide-containing catalyst, which is characterized by the formation of ammonium chloride which occurs

is drawn that the starting material is polychlorinated side reaction, this is particularly surprising,

toluenes, the two or three nucleus-bound chlorine atoms Good results are obtained when using the 5

included, used. up to 12 times and in particular 6 to 10 times the

The method is particularly important for the theoretically required amount of ammonia,

position of 2,6-dichlorobenzonitrile from 2,6-dichloro It has been found that particularly good

toluene and 2,3,6-trichlorobenzonitrile from 2,3,6-tri-15 results can be obtained if the above

chlorotoluene. The first-mentioned benzonitrile has hereably described conditions are met and

cidal effectiveness and is strong growth- the concentration of di- or trichlorotoluene in the

inhibitory for germs and seedlings of a single and gas mixture between 2 and 4 percent by volume,

bilobed. Plants. It is also found to be moderate at around 3 percent by volume,

it has been found that the 2,6-dichlorobenzonitrile is insecticidal 2 ° Further it has been found that the contact time,

Has efficacy in the sense that it is in relation to d. H. the time during which the gas mixture with the

Colorado potato beetle acts selectively. The 2,3,6-tri-catalyst is in contact, the result of the

In the literature, chlorobenzonitrile has not yet been influenced quite strongly by experience, namely in that

been written. It has been found that this means that with approximately the same yields of benzonitrile

the formation of by-products and the amount of

like. recoverable raw materials dependent on it

When chlorinating toluene or o-chlorotoluene in is. It was z. B. found that in two samples for the presence of a catalyst such. B. iodine, iron, production of 2,6-dichlorobenzonitrile from 2,6-di-ferric chloride, antimony chloride, or another chlorotoluene with a yield of 48% ^a * & 2,6-Dif for this reaction known catalyst, results 3 ° chlorobenzonitrile in both cases when using a mixture consisting essentially of the isomeric di- and trichloro contact time of 5 seconds 51% ammonium toluenes, in which the chlorine chloride is bonded to the nucleus as a by-product and for a contact time. The obtained isomers of 2.5 seconds, less than half of which compounds were formed practically indistinguishable from each other. The percentages of ammonium formed separate. When using such mixtures, 35 chlorides are obtained, based on the amount of chlorine in the 2,6-dichloro, according to the process according to the invention, a mixture of toluene, which was assumed.
from the corresponding di- and trichlorobenzonitriles. The suitable contact time is z. B. from the reaction by distillation or crystallization from tion temperature dependent; at 360 ° C it is about 2.5 seconds for solvents, preferably aliphatic aroma.

table hydrocarbons and aliphatic hydrocarbons 40 The results of a number of examples of the process

get it, let it be separated. In this way, according to the invention, are summarized in a table

an inexpensive raw material, toluene, which can be grasped. In the columns of this table are one after the other

2.6-Di- is coveted for its effect on plants: the number of the example, the concentration

chlorobenzonitrile and 2,3,6-trichlorobenzonitrile carry-out the di- and trichlorotoluene, the oxygen

to produce part. 45 and the ammonia in the gas mixture in percent by volume,

As a catalyst, vanadium oxide, the reaction temperature in degrees Celsius, comes into consideration, the con on a support material. You can also cycle time of the gas mixture with the catalyst mass a mixture of vanadium oxide and other metal in seconds, the yield of di- or trichlorooxides, eg. B. oxides of chromium, molybdenum, thorium benzonitrile, based on the di- or od. Like. Use. Trichlorotoluene and the amount of ground ammonium stone, pumice stone or aluminum oxide and chloride formed, based on the amount of chlorine in the di- or activated aluminum oxide, are suitable as carrier material. The latter can be trichlorotoluene, which has been assumed. z. B. obtained by the fact that the aluminum The inert gas in the gas mixture was nitrogen. In oxide prior to applying the Vanadiumoxyds about the examples 1 to 14 were 10 percent by weight for 20 hours had been heated to about 1000 ⁰ C. The 55 in Example 15 2 percent by weight vanadium oxide vanadium oxide can, for. B. be applied to the carrier on activated aluminum oxide, in Example 17 material that this material 5 percent by weight of vanadium oxide on not activated with a solution of z. B. vanadium oxalate poured over, tem aluminum oxide, in Example 16 10 weight percent of a mixture of vanadium oxide and the resulting catalyst in Example 16 evaporated the solvent and then heated to 350 to 400 ° C in a 60 chromium oxide (weight ratio 2: 3) on an activated air stream. Aluminum oxide, in Example 18, 11 percent by weight

According to the invention, the reaction is carried out expediently vanadium oxide on a Ca-Mg silicate and at

moderately at a temperature between 300 and 450 ⁰ C Example 19 5 percent by weight of vanadium oxide

by. Used pumice stone. In Examples 1 to 19 was

The concentrations of di- or trichlorotoluene 65 of 2,6-dichlorotoluene, in example 20 of 2,3-di-

and the oxygen in the gas mixture are purposefully chlorotoluene, in Examples 21 and 22 of 2,3,6-tri-moderately chosen such that at least 3 grams of chlorotoluene, in Examples 23 and 24 of the Oxygen per gramol of di- or trichlorotoluene when chlorinating o-chlorotoluene or toluene in

Presence of a catalyst assumed mixture obtained. In Examples 20 to 24, a Mixture of 4 percent by weight of vanadium oxide and 5 percent by weight of chromium oxide on activated aluminum oxide used.

concentration Sour At the React Con the end Gebil in percent by volume material mo functional tact prey detes at 4.0 niak tempe- duration Poly- At the game Poly- 4.5 7.0 rature chlorine- mo No. chlorine- 5.5 7.0 in Se benzo- nium- lo toluene 5.5 14.0 in ⁰ C Customers nitrile chloride 0.85 10 14.0 360 2.5 in'Io in·/. 1 1.70 10 25th 360 2.5 45 34 2 0.80 7.0 30th 360 5 54 10 15 3 1.84 20th 7.0 360 5 44 23 4th 2.5 5.5 7.0 360 2.5 62 18th 5 3.0 5.5 1.8 360 2.5 62 15th 6th 1.35 4.5 3.5 360 2.5 60 18th 7th 1.42 5.5 7.0 360 2.5 55 8 20 8th 1.33 5.5 7.0 360 2.5 43 6th 9 1.45 5.5 3.5 360 2.5 40 43 10 1.35 5.5 3.5 360 2.5 54 25th 11 1.7 5.5 3.5 320 2.5 57 17th 12th 1.5 5.5 3.5 420 2.5 55 12 as 13th 1.5 5.5 3.5 360 5 51 35 14th 1.58 5.5 3.5 360 2.5 48 51 15th 1.52 4.0 3.5 360 2.5 48 23 16 1.57 4.0 7.0 360 2.5 56 20th 17th 1.59 5.5 7.0 360 1.9 27 17 30 18th 1.55 5.5 7.0 360 1.9 47 20th 19th 1.07 5.5 7.0 360 2.5 58 12th 20th 0.44 7.0 360 2.5 53 30th 21 1.55 360 2.5 48 40 22nd 1.47 360 2.5 68 16 35 23 1.54 360 2.5 63 20th 24 58 18th

Claims (6)

PATENT CLAIMS: 1. A process for the preparation of chlorobenzonitriles by reacting mixtures of chlorotoluenes, ammonia, oxygen and an inert gas at elevated temperature in the vapor phase over a vanadium oxide-containing catalyst, characterized in that the starting material is polychlorotoluenes, the two or three chlorine atoms bonded to the benzene nucleus included, used. 2. The method according to claim 1, characterized in that the ammonia in the 5- to 12 times and preferably 6 to 10 times the theoretical amount used. 3. The method according to claim 1, characterized in that the starting material is 2,6-dichlorotoluene or those trichlorotoluenes which are substituted in the 2,6-position, in particular 2,3,6-trichlorotoluene, used. 4. The method according to claim 1, characterized in that the starting material used in the Nuclear chlorination of toluene or chlorotoluene obtainable mixture of essentially di- and Trichlorotoluenes used. 5. The method according to claim 1 to 4, characterized in that the content of di- or Trichlorotoluene or the mixture obtainable in the nuclear chlorination of toluene or chlorotoluene holds in the gas mixture between 2 and 4 percent by volume, preferably at about 3 percent by volume. 6. The method according to claim 4, characterized in that that from the mixture of di- and trichlorobenzonitriles, the 2,6-dichlorobenzonitrile by distillation or by crystallization from a solvent, preferably an aliphatic one or aromatic hydrocarbon, isolated. 109 737/406 10.61