DE1244131B - Process for the production of difluoroamine - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Int. Cl .:

COIb

GERMAN

PATENT OFFICE

EDITORIAL

German class: 12 i- 21/18

C 01 B -21 /

Number: 1 244 131

File number: A 48205IV a / 12 i

Filing date: January 22, 1965

Opened on: July 13, 1967

The invention relates to a process for the production of difluoroamine, HNF ₂ , which is a colorless gas with a boiling point of about −23 ° C. under normal conditions.

Difluoroamine is a valuable compound that can be reacted with boron trichloride or carbonyl chloride, for example, to give chlorodifluoroamine, F ₂ NCl, which in turn can be used as an intermediate _{compound for the production of tetrafluorohydrazine, N 2} F _4.

It has been found that sulfamide, water and elemental fluorine, under certain conditions, are easy to control Conditions can be reacted with one another in such a way that difluoroamine is formed in good yields will. The gross formula of the implementation is:

NH ₂ SO ₂ NH ₂ + H ₂ O + 2F ₂ - * HNF ₂ + NH ₂ SO ₃ H

From the German Auslegeschrift 1180 721 it is known, by converting urea, diurea, Biuret and similar compounds with gaseous fluorine at a temperature of -30 to + 40 ° C, subsequent heating of the liquid reaction mixture and fractional condensation of the thereby obtained gaseous products to produce pure difluoroamine. However, this method has certain disadvantages. On the one hand, it requires working under anhydrous conditions and therefore careful work Drying of the reactants, and on the other hand, an absorber must be used to collect By-product formed hydrogen fluoride can be used. Finally, the isolation of the Difluoramine required distillation carried out under vacuum, which is because of the highly corrosive Gases requires a great deal of effort for pumping equipment and other facilities.

In contrast, the reaction according to the present invention takes place in a liquid medium, so that a) the reactants do not need to be predried, b) the hydrogen fluoride formed is immediately absorbed by the reaction mixture, so that the use of a Corrosion-resistant absorber as a special part of the system is unnecessary, and c) the difluoroamine by simply heating the aqueous reaction product, d. H. by a measure that is can be carried out in vessels made of ordinary glass, can be isolated.

The process of the invention for the preparation of difluoroamine is that one gaseous elemental fluorine in an aqueous sulfamide solution in an amount not substantially more than 4 moles Introducing fluorine per mole of sulfamide, while the temperature of the solution in the range from 0 to Process for the production of difluoroamine

Applicant:

Allied Chemical Corporation,

New York, N.Y. (V. St. A.)

Representative:

Dr. I. Ruch, patent attorney,

Munich 5, Reichenbachstr. 51

Named as inventor:

Donald Hoyt Kelly, Gladstone, N. J .;

Bernard Sukornick, Elizabeth, N. J. (V. St. A.)

Holds 5 ⁰ C, and then the reaction mass is heated to a temperature not exceeding 85 ° C in order to cause the evolution of gaseous difluoroamine from the reaction mass.

Preferably, 2 to 4 moles of fluorine are introduced per mole of sulfamide. The minimum amount desired of water is that which is required to easily use the amount of sulfamide used to form stirring liquid. The proportion of sulfamide and water can be such that the aqueous solution is not saturated with sulfamide.

However, the use of a larger amount of water than leads to the formation of a practically saturated one Dissolution of the sulfamide in water is required, entailing no particular advantages. Practically saturated Solutions are preferred.

The introduction of fluorine and the development of difluoroamine can be carried out as separate process steps in the same reactor, for example can consist of a nickel-copper alloy, polytetrafluoroethylene or heat-resistant glass, and a gaseous fluorine inlet, gas outlet and conventional means for maintaining desired ones Has temperatures, are carried out. During the introduction of the fluorine, the Temperature of the reactor and its contents can be controlled by immersion in an ice bath. the Apparatus for obtaining the difluoramine formed as a product can be removed from a drying tower moisture from the reactor exhaust gas and a cold trap which is cooled so that the difluoroamine condensed therein.

Fluorine can in any amount with which considerable amounts of difluoroamine are formed,

709 610/499

are introduced into the reactor. However, to the formation of considerable amounts of nitrogen trifluoride Avoid as a by-product, preferably no more than 4 moles of fluorine per mole of sulfamide used. Quantities as low as 1.0 to 1.5 moles of fluorine can also be used. However, on the one hand to prevent the formation of nitrogen trifluoride as far as possible and, on the other hand, the highest possible yields to achieve difluoroamine, 2 to 4 moles of fluorine per mole of sulfamide are introduced.

In order to limit the possibility of the formation of nitrogen trifluoride even further, this can be initiated Fluorine diluted with at least four volumes of an inert gas such as nitrogen or helium will. Preferably 5 to 15 volumes per volume of fluorine are used. The implementation takes place practically instantaneously at 0 to 5 ° C, and the fluorine is preferably released at the same rate, with which it is consumed. The corresponding speed can easily be found in the Determine the absence of fluorine in the exhaust gas.

During the reaction at temperatures from 0 to 5 ° C, the reaction exhaust gases contain only the inert gas used for dilution, if used, plus relatively small or trace amounts of nitrogen oxide, silicon tetrafluoride, nitrogen trifluoride and carbon tetrafluoride. If the fluorination is carried out at a higher temperature, for example 10 ^° C., the exhaust gases from the reaction contain only nitrogen trifluoride and nitrogen oxide. The implementation probably takes place in two stages, namely:

NH ₂ SO ₂ NH ₂ + 2F ₂

NF ₂ SO ₂ NH ₂ + H ₂ O |

NF ₂ SO ₂ NH ₂ + HF

HNF ₂ + NH ₂ SO ₃ H
(2)

from which it can be seen that the immediate fluorination product is Ν, Ν-difluorosulfamide. That is, the Overall implementation consists of two relatively clearly defined implementations, the first of which in a reaction of fluorine and sulfamide in the presence of water to form a fluorine-containing one Intermediate compound without formation of difluoroamine is, while the second is a reaction of the fluorine-containing Is intermediate compound with water to form difluoroamine and sulfamic acid. at At the end of the first reaction, the reaction mass in the reactor is a water-white solution.

In order to cause the evolution of the gaseous difluoroamine, the reaction mass is preferred warmed to above 15 ° C and usually to room temperature or 20 to 30 ° C. To the development to accelerate difluoramine in the reactor, this can with its contents also on temperatures by being warmed up abundantly above room temperature. At temperatures of considerable However, above 80 to 85 ° C, increasingly larger amounts of water and sulfuric acid are combined carried out of the reactor with the gaseous difluoroamine.

Preferably, the temperature of the reaction mass is during the separation of the difluoramine at Maintained 15 to 85 ° C.

The product can be obtained from the exhaust gases of the reactor by customary methods. That Exhaust gas can for example be passed through a drying tower to remove water and any sulfuric acid mist separated, and then passed through a cold trap cooled to - 80 ° C or below to condense out the colorless liquid difluoroamine. The exhaust gas from the cold trap can Nitrogen or other inert gas used as a diluent and trace amounts of nitrogen oxide, Contain silicon tetrafluoride, nitrogen trifluoride or carbon tetrafluoride. After completing the approach the difluoroamine can be obtained from the cold trap by conventional distillation, and so The difluoroamine obtained is practically pure.

The invention is illustrated in more detail below by means of examples.

example 1

10 g (0.1 mol) of sulfamide were dissolved in 100 ml of room temperature water in a three-necked flask Glass with gas inlet, stirrer and gas outlet, on which one after the other an anhydrous calcium sulphate Drying tower, a dry ice cooler equipped with a calibrated glass trap and an infrared cell were connected, solved. The reactor and contents were brought to 0 to 5 ° C. by means of an ice bath chilled. The reactor was filled with nitrogen blowing at a rate of about 30 minutes about 200 cc / min. was supplied, rinsed. This was followed by a mixture of nitrogen for about 4 hours and elemental fluorine at a rate of about 200 cc / min. Nitrogen and about 40 cc / min. Fluorine initiated. During this time the solution was stirred, and so did the reactor and contents were held at a temperature of about 0-5 ° C. At this feed rate the fluorine is supplied and consumed at practically the same rate.

The reactor exhaust gases were sequentially through the drying tower, the dry ice trap and the infrared cell directed. About 0.4 moles of fluorine were fed over the 4 hours, and the mole ratio the total number of reactants used was about 4 moles of fluorine per mole of sulfamide. While After fluorination, no difluoroamine or no material at all collected in the dry ice trap, and the exhaust gases from the dry ice trap contained only trace amounts, apart from nitrogen, according to infrared analysis Nitrogen oxide, silicon tetrafluoride, nitrogen trifluoride and carbon tetrafluoride, but no difluoramine. After the supply of fluorine has ended and the reactor and contents are still maintained at 0 to 5 ° C the solution and the system were purged with nitrogen for about 30 minutes. Then became removed the ice bath and the reactor and contents were allowed to warm to room temperature for approximately 2 hours left while a slow stream of nitrogen through drying tower, dry ice trap and infrared cell was directed. During this warm-up, the exhaust gases from the dry ice trap contained only trace amounts Nitrogen oxide, silicon tetrafluoride, nitrogen trifluoride and carbon tetrafluoride, but no difluoramine. Especially after the temperature of the reactor and contents has risen to above about 10 ° C was and approached room temperature, difluoramine began to collect in the trap and

at the end of the warm-up time, when the reactor contents had reached room temperature, had collected about 1.2 ml of a water-white liquid in the dry ice trap. This liquid became removed from the trap, allowed to warm and then evaporated into a stream of nitrogen through which the Vapors have been carried into the infrared cell. The infrared analysis revealed that the exhaust gas was the heated Trap contained only difluoroamine in addition to nitrogen. Based on the amount of liquid that is in the cold trap had collected, and the amount of sulfamide used was the yield of difluoroamine about 16 to 17%> of theory.

Example 2

10 g (0.1 mol) of sulfamide were dissolved in 150 ml of room temperature water in that described in Example 1 The reactor was dissolved, and the reactor and contents were cooled to 0-5 ° C using an ice bath. The reactor was filled with nitrogen blowing at a rate of about 200 cc / min for about 30 minutes. was supplied, rinsed. This was followed by a mixture of nitrogen and elemental for about 4 hours Fluorine at a rate of about 200 cc / min, nitrogen and about 40 cc / min. Fluorine initiated. During this time the solution was stirred and the reactor and contents were at one temperature held from 0 to 5 ° C. At the specified feed speed the fluorine was consumed at practically the same rate as it was supplied became. In the 4 hours a total of about 0.4 moles of fluorine was fed, and the mole ratio the total number of reactants used was about 4 moles of fluorine per mole of sulfamide. During the Fluorination showed the infrared analysis that the reactor exhaust gases only trace amounts in addition to nitrogen Nitrogen oxide, silicon tetrafluoride, nitrogen trifluoride and carbon tetrafluoride.

After completion of the fluorine supply and during the reactor and contents still held at 0 to 5 ° C the reactor was purged with nitrogen for about 30 minutes. Then the gas outlet of the Reactor connected to a drying tower filled with anhydrous calcium sulfate, to the successively a cooling device with a calibrated glass trap that uses trichlorofluoromethane and liquid Nitrogen was cooled to about -120 ° C and an infrared cell was connected. Then became the ice bath was removed and the system was primed with nitrogen at a rate of about 50 cc / min. was supplied, rinsed. The reactor was surrounded by a heating mantle, and at a time of The reactor and contents were gradually heated to a temperature of about 80 ° C. for about 2 hours. The reactor exhaust gases were passed through the drying tower in order to condense out water, and passed through the cold trap and then through the infrared cell. During the warm up, in particular after the temperature of the reactor and contents had risen to above about 10 ° C and Approaching room temperature, difluoroamine began

ίο to collect in the trap. The infrared analysis showed that the exhaust gases of the trap only trace amounts of nitrogen oxide, silicon tetrafluoride, nitrogen trifluoride and Carbon tetrafluoride but not containing difluoroamine. Had after the 2 hour warm up About 3.5 ml of water-white liquid condenses in the trap. The cold trap was removed from the cooling bath taken and allowed to warm and the liquid in the trap was evaporated into the nitrogen stream and carried by it into the infrared cell.

The infrared analysis showed that the exhaust gases from the heated trap, in addition to nitrogen, only contained difluoroamine contained. Based on the amount of liquid that had condensed in the cold trap and the amount used Amount of sulfamide, the yield of difluoroamine was about 48% of theory.

Claims (4)

Patent claims: 1. A process for the preparation of difluoroamine, characterized in that gaseous elemental fluorine in an aqueous solution of sulfamide in an amount of not essential more than 4 moles of fluorine per mole of sulfamide is introduced while the temperature of the solution is maintained in the range of 0 to 5 ° C, and the formed difluoroamine from the Separated reaction mass in the vapor phase at a temperature not exceeding 85 ° C will. 2. The method according to claim 1, characterized in that 2 to 4 moles of fluorine per mole of sulfamide be initiated. 3. The method according to claim 1, characterized in that the temperature of the reaction mass during the separation of the difluoramine is kept at 15 to 85 ° C. 4. The method according to any one of claims 1 to 3, characterized in that the fluorine im Mixture with an inert gas containing not less than 4 volumes of inert gas per volume of fluorine contains, is initiated. Considered publications:
German publication No. 1180 721. 709 610/499 7.67 Bundesdruckerei Berlin