DE1268610B - Process for the preparation of carboxylic acid nitriles - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

German class:

Number:
File number:
Registration date:
Display day:

C07c

BOIj
C07b

12-11

120-14; 12Ο-21;

12 g-11/00; 120-27

July 23, 1964

May 22, 1968

From US Pat. No. 2,590,986 it is known to produce nitriles of aliphatic monocarboxylic acids by that one evaporates the carboxylic acid, this vapor ammonia gas in a ratio of 1 to 2 mol Ammonia is added to 1 mol of acid and the mixture is carried out at a temperature of 300 to 400 ° C conducts a catalyst brought into the flow state ("fluidized bed") by the steam flow.

The present invention relates to an improved process for the preparation of carboxylic acid nitriles by reacting carboxylic acid with ammonia on fluidized bed catalysts. This procedure is characterized in that one is brought into the flow state by ammonia gas and on a temperature above 200 ° C heated catalyst applies liquid carboxylic acid and the resulting Carboxylic acid nitrile withdraws from the fluidized bed.

Surprisingly, good conversions and yields are obtained even when using liquid carboxylic acids of nitriles, so that there is no evaporation of the acids. Due to the associated protection of the Acids is the process according to the invention in contrast to the aforementioned known process not limited to the implementation of saturated aliphatic monocarboxylic acids, but can also on aromatic and especially heat-sensitive aliphatic dicarboxylic acids, ζ. B. adipic acids, can be applied.

The amount of ammonia is expediently about three to thirty times that theoretically required Lot.

Any suitable catalyst for nitrile synthesis that can be brought into a flowable state can be used as a catalyst Substance to be used. Suitable catalysts are, for example, silica gel, boron phosphate and impregnated with acids or esters such as phosphoric acid or phosphoric acid esters or boron phosphate Silica gels and aluminum oxides. Silica gels that contain Molybdenum, tungsten, vanadium and titanium salts are impregnated. Silica gels are particularly effective, which have a phosphoric acid content of 0.1 to 30%.

The carboxylic acid can be fed to the fluidized catalyst bed at any point, e.g. B. on the surface of the fluidized bed or at a point below.

If the carboxylic acid is dropped onto the swirling catalyst surface, it can only partially occur Conversion of the carboxylic acid and the remainder of this acid in a downstream second catalyst bed implemented.

Method of manufacture
of carbonitriles

Applicant:

Paint factories Bayer Aktiengesellschaft,

5090 Leverkusen

Named as inventor:

Dr. Hermann Schnell, 4150 Krefeld-Uerdingen;

Dr. Hans-Helmut Schwarz,

4150 Krefeld-Bockum

The process can be carried out under normal, positive or negative pressure.

example 1

In a heatable fluidized bed reactor with a diameter of 6 cm and a height of 18 cm, which is made of stainless steel, 100 g = 173 ml of a silica gel loaded with 5.9% phosphoric acid with 390Nl ammonia gas per hour, which is heated to 360 ° C is heated, made to whirl. 75.5 g of adipic acid are added dropwise to the swirling catalyst in one hour. The heating of the fluidized bed is controlled so that the temperature of the catalyst is 360 ⁰ C. The steam mixture leaving the fluidized bed reactor is cooled ^{to 20 ° C.} An aqueous and an organic layer are separated out, in which, by analysis, 49.6 g of adipic acid dinitrile and 3.02 g of adipic acid are found. This corresponds to a yield of 90%, based on the converted adipic acid, and a conversion of 96% of this acid. The adipic acid dinitrile is isolated from the aqueous phase by extracting the aqueous phase four times with 20 ml of methylene chloride each time. The combined methylene chloride extracts are mixed with the organic phase of the reaction mixture and largely freed from the solvent by distillation. Adipic acid dinitrile, which boils at 159 to 160 ° C. at a pressure of 11 torr, is obtained from the residue by fractional vacuum distillation after a forerun which contains low-boiling substances. The ammonia, which has been cooled and freed from the reaction products, is returned to the fluidized bed after heating.

Example2

In the apparatus as used in Example 1, 130 ml of one with 10% phosphoric acid

809 550/505

loaded silica gel with 390Nl ammonia gas per hour, which is heated to 360 ° C, made to vortex. 66.6 g of adipic acid are added dropwise to the fluidized bed every hour. The heating is regulated so that the temperature of the catalyst is 360 ⁰ C. ^{After cooling to 20 °} C., the vapors leaving the fluidized bed reactor give two layers in which 43.4 g of adipic acid dinitrile and 5.8 g of adipic acid are detected by analysis. This corresponds to a conversion of 91.3% ^and a yield of 96.5%> calculated on the converted adipic acid. Adipic acid dinitrile, whose boiling point is 168 ° C. at 20 torr, is obtained from the reaction mixture according to the procedure of Example 1.

B e i s ρ i e 1 3

In the apparatus as used in Examples 1 and 2, 130 ml of a silica gel loaded with 5.3% phosphoric acid are swirled with 150 Nl ammonia gas per hour, which is heated to 360.degree. 112 g of adipic acid are added dropwise to the fluidized bed every hour. The heating is regulated so that the temperature of the catalyst is 360 ° C. ^{After cooling to 20 °} C., the vapors leaving the fluidized bed reactor give two layers in which 65.8 g of adipic acid dinitrile and 5.05 g of adipic acid are detected by analysis. This corresponds to a conversion of 95.5% and a yield of 79.3%> based on the converted adipic acid. Working up the reaction mixture according to the instructions in Example 1 gives adipic acid dinitrile with a boiling point of 159 to 160 ° C. at 11 torr.

35

Example 4

130 ml of a silica gel loaded with 5.5% phosphoric acid are swirled with 390 l (STP) of ammonia gas per hour, which is heated to 360.degree. 108.3 g of sebacic acid are added dropwise to the fluidized bed every hour. The heating is regulated so that the temperature of the catalyst is 360 ° C. After cooling to 20 ° C., the vapors leaving the fluidized bed reactor give two layers in which 1.6 g of sebacic acid and 69.8 g of sebacic acid dinitrile are detected by analysis. This corresponds to a conversion of 98.5% and a yield of 80.6% based on converted sebacic acid. The aqueous phase of the reaction mixture is extracted with 30 ml of methylene chloride. The organic phase and the extract are combined and freed from methylene chloride by distillation. The residue is heated in a vacuum at 16 Torr, wherein Sebacinsäuredinitril distilled at 203-206 ⁰ C.

Example 5

There are 180 ml of a loaded with 7.5% phosphoric acid and 7.5% dipotassium phosphate silica

55 gels with 150 Nl ammonia gas per hour, which is heated to 360 ° C, made to swirl. 321 g of oleic acid are added dropwise to the fluidized bed over the course of 7 hours. The heating is regulated so that the temperature of the catalyst is 360 ° C. After cooling to 20 ° C., the vapors leaving the fluidized bed reactor give two layers in which 225 g of oleic acid nitrile are detected by analysis. This corresponds to a yield of 85%, based on the oleic acid used. Work-up is carried out as described in Example 4. The oleic acid nitrile obtained by this method boils at 12 Torr from 203 to 204 ° C.

Examples

180 ml of a silica gel loaded with 7.5% phosphoric acid and 7.5% dipotassium phosphate are vortexed with 150 Nl ammonia gas per hour, which is heated to 360 ° C. 250 g of 2-methylbenzoic acid are added dropwise to the fluidized bed in the course of 4 hours. The heating is regulated so that the temperature of the catalyst is 360 ⁰ C. After cooling to 20 ° C., the vapors leaving the fluidized bed reactor give two layers in which 130 g of 2-methylbenzoic acid nitrile are detected by analysis. This corresponds to a yield of 60.5%. based on the 2-methylbenzoic acid used. After mixing with 50 ml of water, the aqueous phase is separated off from the reaction mixture. It is extracted with 30 ml of methylene chloride. The distillation of the combined with the organic phase extract o-tolunitrile provides with a boiling point of 206-206 ⁰ C under atmospheric pressure.

Claims (4)

Patent claims: 1. Process for the preparation of carboxylic acid nitriles by reacting carboxylic acids with Ammonia on fluidized bed catalysts, thereby characterized in that one is brought into the flow state by ammonia gas and at a temperature above 200 ° C heated catalyst applies liquid carboxylic acid and that resulting carbonitrile is withdrawn from the fluidized bed. 2. The method according to claim 1, characterized in that the ammonia gas in one Amount three to thirty times the theoretically necessary amount is used. 3. The method according to claim 1, characterized in that one adipic acid at a temperature of about + 360 ° C in the fluidized catalyst bed. 4. The method according to claim 1 and 3, characterized in that there is a catalyst with Phosphoric acid loaded silica gel used. 809 550/505 5.68 © Bundesdruckerei Berlin