DE1244742B - Process for the production of difluoroamine - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

COIb

C 0 1 B -21/0

German class: 12 i- 21/18

Number: 1 244 742

File number: A 48206 IV a / 12 i

Filing date: January 22, 1965

Opened on: July 20, 1967

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

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 now been found that sulfamic acid, water and elemental fluorine, under certain circumstances, are easy to controlling conditions can be reacted with one another so that difluoroamine in good yields is formed. The gross formula of the implementation is:

NH ₂ SO ₃ H + H ₂ O + 2F ₂ ~> H ₂ SO ₄ + 2HF + HNF ₂

It is from the German Auslegeschrift 1180 721 known by reacting urea, diurea, biuret and similar compounds with gaseous Fluorine at a temperature of -30 to + 40 ° C, subsequent heating of the liquid Pure reaction mixture and fractional condensation of the gaseous products obtained To produce difluoroamine. However, this method has certain disadvantages. At one point it requires work under anhydrous conditions and thus careful drying of the reactants, and for others must use an absorber to collect hydrogen fluoride formed as a by-product will. Finally, the distillation required to isolate the difluoramine is carried out under vacuum carried out, which because of the highly corrosive gases, a great deal of effort for pumping systems and requires other facilities.

In contrast, the reaction according to the present invention takes place in a liquid medium, see above 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 Absorbers as a special part of the system are superfluous, and c) the Difluoramin by simple Heating the aqueous reaction product; d. H. by a measure which is contained in vessels from the ordinary Glass can pass through, can be isolated.

The process of the invention for the preparation of difluoroamine is that one gaseous elemental fluorine in an aqueous sulfamic acid solution in an amount of not more than 2.5 moles Introduces fluorine per mole of sulfamic acid, while one processes for the preparation of difluoroamine

Applicant:

Allied Chemical Corporation,

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

Representative:

Dr. I. Ruch, patent attorney,

Munich 5, Reichenbachstr. 51

Donald Hoyt Kelly, Gladstone, N. J .;

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

maintains the temperature of the solution in the range of 0 to 30 ° C, and then the reaction mass at a Maintains temperature in the range of 10 to 85 ° C to avoid the evolution of gaseous difluoroamine to effect the reaction mass.

The minimum desired amount of water is that which is required to keep up with the used Amount of sulfamic acid to form an easy-to-stir liquid. The ratio of Sulfamic acid and water can be such that the aqueous solution is not saturated with sulfamic acid. However, the use of a larger amount of water than leads to the formation of a practically saturated one Dissolution of the sulfamic acid in water is required, entailing no particular advantages. Practically saturated Solutions are preferred.

The introduction of fluorine can, for example, consist of a nickel-copper alloy, polytetrafluoroethylene or heat-resistant glass reactor with an inlet for gaseous fluorine, a gas outlet and conventional means for maintaining the desired temperatures. The apparatus for obtaining the difluoramine formed as a product can be used from a drying tower Removal of moisture from the reactor exhaust gas and a cold trap which is cooled so that the Difluoroamine condensed in it exist.

Fluorine can be present in any amount with which substantial amounts of difluoroamine are formed Reactor to be initiated. However, in order to prevent the formation of considerable amounts of nitrogen trifluoride than To avoid by-product, no more than about 2.5 moles of fluorine per mole of sulfamic acid are used. Quantities as low as 1.0 to 1.5 moles of fluorine per mole of sulfamic acid can also be used. To however on the one hand the formation of nitrogen trifluoride is possible

709 617/509

3 4

can be prevented and, on the other hand, the highest possible temperatures practically momentary and imperceptible.

Achieving yields of difluoroamine will have to proceed in stages beforehand,

preferably not more than 2 moles of fluorine per mole of sulphate. The product can

amic acid initiated. can be obtained by conventional methods. The Ab-

Usually sulphamic acid and fluorine in 5 gas can for example through a dry urine a ratio of slightly less than about 2 moles to be passed to water and any sulfur-fluorine used per mole of sulfamic acid. Separate acid mist, and the dried gas

To avoid the possibility of the formation of Stickstofftri- can then be limited by means of dry ice to a fluoride still further, the einge- -80 ⁰ C cooled trap can be directed to the color-fluoro initiated with at least 4 volumes of inert io loose liquid Difluoroamine condense out. The gas, like nitrogen or helium, can be diluted. Exhaust gas from the cold trap can be nitrogen or something else. In general, 5 to 15 volumes of diluent are preferably inert gas and quantities per volume of fluorine are used. The implementation of trace amounts of nitrogen oxide, silicon tetrafluoride, stickers takes place quickly. The fluorine is preferably introduced with about substance trifluoride and carbon tetrafluoride, at the same rate as that at which it can be consumed after the batch has ended. The corresponding rate obtained by conventional distillation from the cold trap can easily be determined from the absence of fluorine in the be, and the difluoroamine thus obtained is practically exhaust gas. table clean.

Control of the reaction temperature is essential. It has been found that difluoroamine can also be used after

lent for the success of the procedure. You can choose between 20 a process that can be viewed as a two-step process

0 and 30 ° C vary. It is called »reaction- can, can be produced when the temperature

temperature «the temperature during the time in which the aqueous solution during the introduction of

elemental * fluorine is introduced into the reactor. Fluorine between 0 and 10 ⁰ C is kept. Under

designated. under these conditions, a non-volatile ^{at 10 0 C.}

When an aqueous solution of sulfamic acid is formed at 25 intermediate. It was found that

a temperature of, for example, about 20 ° C, the exhaust gas at these fluorination temperatures

Exposed to the action of elemental fluorine, the cold trap used as a diluent

will react, as has been found, sulfamic acid, the inert gas and trace amounts of nitrogen oxide, SiIi-

Water and fluorine almost instantaneously with the formation of cium tetrafluoride, nitrogen trifluoride and tetrafluoro-

Difluoramine, which at the same time contains carbon as waste gas from the reac- 30, but no condensate in the dei

tion mass is released. Cold trap collects, from which it can be seen that no

"Simultaneously" means that difluoroamine is developed during the process. Preferably the Introduction of gaseous fluorine difluoroamine from the temperature of the reactor and contents approximately in that the reaction mass is developed. The implementation range is kept from 0 to 5 ° C. At this tempera can so carried out at around room temperature 35 doors that can be easily adhered to by which is of course a particular advantage of immersing the reactor in an ice bath Represents method of the invention. the fluorination rapidly, and the formation of the impurities

At reaction temperatures in the lower part of the cleaning it is largely prevented
specified range, for example at about 10 sam and economically undesirable. So if the room temperature or 20 to 30 ° C warms up. In order to accelerate the process in such a way that the development of difluoroamine in the reactor is initiated simultaneously fluorine and difluoroamine from the, the reactor can be discharged with its contents reaction mass, is preferably also at temperatures of well above room a reaction temperature of at least heated to a temperature of around 15 ° C. Applied at temperatures of. Reaction temperatures above 30 ° C offer considerably above 80 to 85 ° C, however, there are no particular advantages and should be avoided in order to prevent the formation of nitrogen trifluoride with water and sulfuric acid mist with the gaseous form. Difluoroamine carried out of the reactor.

The completion of the reaction can easily be recognized by the fact that no further liquid di-running reactions accumulate in the cold trap as a result of the above fluorine amine or that fluorine compounds a) and b) are shown in each stage of this process. That is, that is present in the exhaust gas. If desired, the non-volatile intermediate compound formed in the fluorination at low temperature after the end of the supply of fluorine can be increased presumably to 80 to 85 ° C, to 55 Ν, Ν-difluorosulfamic acid, which during the following of the reaction mass Difluoroamine located in full process stage at higher temperature to remove rapidly with constantly. The residue in the reactor reacts water, so that it comes to the development of the gas consisting of an aqueous solution of sulfuric acid-shaped difluoramine,
and hydrogen fluoride. The invention is illustrated by the following examples

In the method described above, there are 60 illustrated.

probably the following conversions: "·. , "

For example

NH ₂ SO ₃ H + 2F ₂ -> NF ₂ SO ₃ H + 2HF (a) _{5 g (005} mol) * sulfamic acid were in 45 ml

and room temperature water in a three-necked

NF ₂ SO ₃ H + H ₂ O -> H ₂ SO ₄ + HNF ₂ (b) ⁶⁵ glass flasks with gas inlet, stirrer and gas outlet

one after the other an ice trap, one with a potash

When these conversions take place, the Broken Glass Trap shows an equipped dry ice cooler and

found that they were connected to an infrared cell at the temperature described above. That

System was running for about 1 hour with nitrogen blowing at a rate of about 200 cc / min. was supplied, rinsed. Thereafter, a mixture of nitrogen and elemental fluorine was applied for 2V for ₂ hours at a rate of about 200 cc / min. Nitrogen and about 15 cc / min. Fluorine fed into the reactor. During this time the solution was stirred and kept at about room temperature. At this feed rate, the fluorine was consumed and supplied at practically the same rate.

The reactor exhaust gases were passed successively through the ice trap to condense out water, through the dry ice trap to condense out difluoroamine, and then through the infrared cell. During the 2 ¹ I ₂ hours, supplied about 0.1 moles of fluorine, and the ratio of reactants used was a total of about 2 moles of fluorine per mole of sulfamic acid. During the fluorination, the exhaust gases from the dry ice trap contained nitrogen and, as indicated by infrared analysis, traces of nitrogen oxide, silicon tetrafluoride, nitrogen trifluoride and carbon tetrafluoride, but no difluoroamine. At the end of the batch, during which difluoroamine had developed continuously, about 1.4 ml of a water-white liquid had collected in the cold trap. The cold trap was removed from the dry ice bath and allowed to warm up. The liquid in the trap was evaporated into a nitrogen stream and carried by this into the infrared cell. Infrared analysis showed that the exhaust gas from the heated trap contained only difluoroamine and nitrogen. The mass spectrogram of the contents of the trap also showed that it consisted of practically pure difluoroamine. From the amount of liquid that had collected in the cold trap and the amount of sulfamic acid used, the yield of difluoroamine is 77% of theory.

Example 2

In this approach, a mixture of nitrogen and elemental fluorine at a rate of about 200 ccm / min ^{was used for 1 1} J _{2 hours.} Nitrogen and about 30 cc / min. Fluorine introduced into the reactor. A total of about 0.12 mol of fluorine was introduced, and the quantitative ratio of the total reactants used was about 2.4 mol of fluorine per mole of sulfamic acid. The results were the same as in Example 1. However, at the end of the batch, about 1 ml of liquid had condensed in the cold trap. From the amount of liquid that had collected in the cold trap and the amount of sulfamic acid used, the yield of difluoroamine is about 55.5% of theory.

Example 3

5 g (0.05 mol) of sulfamic acid were dissolved in about 45 ml of water in the reactor of Example 1, and the reactor and contents were cooled to 0-5 ° C. The solution was ^{stirred for 1} J for ₂ hours and charged with nitrogen at a rate of about 200 cc / min. was supplied, rinsed. Thereafter, a mixture of nitrogen and elemental fluorine was applied at a rate of about 200 cc / min. For about 1 hour. Nitrogen and about 40 cc / min. Fluorine was introduced into the reactor while the solution was stirred and maintained at a temperature of 0-5 ° C. The rate of fluorine supply was such that the fluorine was consumed at substantially the same rate as it was supplied. About 0.1 mole of fluorine was fed in, and the proportion of the total reactants used was about 2 moles of fluorine per mole of sulfamic acid. During the introduction of the fluorine, the infrared analysis of the reactor exhaust gases showed that these gases contained only trace amounts of nitrogen oxide, silicon tetrafluoride, nitrogen trifluoride and carbon tetrafluoride, but no difluoroamine. After the introduction of fluorine had ended, the reactor was flushed with nitrogen for about 30 minutes, while the reactor and contents were kept at 0 to 5 ^° C. The gas outlet of the reactor was then connected to a drying tower filled with anhydrous calcium sulfate, to which a dry ice cooler equipped with a calibrated glass trap and an infrared cell were connected in succession. The ice bath was removed and the reactor and contents were allowed to _{warm up for approximately 1V 2} hours while the reactor exhaust gases were passed through the dry ice tower and dry ice trap. In particular, when the reactor and contents had reached a temperature above about 10 ° C and the temperature was approaching room temperature, difluoroamine began to collect in the cold trap. A slow stream of nitrogen was passed through the reactor for approximately 2 hours to purge difluoroamine out of the reactor and through the drying tower into the cold trap. During the warm-up and nitrogen purging, the exhaust gases from the dry ice trap contained only nitrogen and infrared analysis showed no difluoroamine. After purging with nitrogen had ended, about 1.4 ml of a water-white liquid had condensed in the cold trap. The cold trap was removed from the dry ice bath and allowed to warm up. The liquid in the trap was evaporated into a nitrogen stream and carried by this into the infrared cell. The infrared analysis showed that the exhaust gas from the heated trap contained only difluoroamine in addition to nitrogen. From the amount of liquid that had collected in the cold trap and the amount of sulfamic acid used, the yield of difluoroamine is about 77% of theory.

Claims (5)

Patent claims: 1. A process for the preparation of difluoroamine, characterized in that gaseous elemental fluorine is introduced into an aqueous solution of sulfamic acid in an amount of not more than 2.5 moles of fluorine per mole of sulfamic acid, while the temperature of the solution is in the range from 0 to 30 ° C is maintained, and the difluoroamine formed is removed at a temperature of 10 to 85 ⁰ C in the vapor phase of the reaction mass then. 2. The method according to claim 1, characterized in that fluorine in an amount of not significantly more than 2 moles per mole of sulfamic acid is introduced. 3. The method according to claim 1 and 2, characterized in that the temperature of the reaction mass during the separation of the difluoramine is kept at 15 to 30 ° C. 7 8 4. The method according to claim 1 to 3, characterized rend the introduction of the fluorine in the range of characterized in that the fluorine is kept in the mixture at 0 to 5 ° C. not less than 4 volumes of inert gas each Volume of fluorine is introduced. 5. The method according to claim 1 to 4, characterized in 5 publications considered: characterized in that the reaction temperature was German Auslegeschrift No. 1180 721. 709 617/509 7. 67 ® Bundesdruckerei Berlin