DE1230431B - Process for the production of azodicarbonamides - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C07c

German KL: I2q-12

Number: 1230 431

File number: W 30929IV b / 12 q

Filing date: October 24, 1961

Display day: 1.5. December 1966

It is known that hydrazodicarbonamides oxidize with alkali metal dichromates to azodicarbonamides can be. However, this method is accompanied by disadvantages, such as. B. the formation of chromium By-products that were difficult to remove.

Chlorine is a common oxidizing agent, but has been used to oxidize hydrazodicarbonamides proved unsuitable. The reasons for this are not clear, among other things, the chlorine decomposes it obtained azodicarbonamide.

The process according to the invention for the preparation of azodicarbonamides of the general formula

Process for the production of
Azodicarbonamides

R ¹

R ³

N - CO - N = N - CO - N

R ²

in which R ¹ , R ² , R ³ and R ⁴ stand for a hydrogen atom or an alkyl, cycloalkyl, aryl or aralkyl group, by oxidation of corresponding hydrazodicarbonamides with an inorganic oxidizing agent is now characterized in that the oxidation in aqueous solution or in a mixture of water and an organic solvent at a pH of -2 to +7 in the presence of bromine or bromide ions, with chlorine as the inorganic oxidizing agent.

The success of the oxidation in this way is surprising, since it causes decomposition of the azodicarbonamide is avoided and other common chlorine activators the oxidation of hydrazodicarbonamides Do not favor or catalyze with chlorine.

In particular, R ¹ , R ² , R ³ and R ^{4 denote} a hydrogen atom, an alkyl group (e.g. an alkyl group having 1 to 12 carbon atoms, ζ. B. the n-propyl, isobutyl, octyl and dodecyl group, preferably however the methyl and ethyl group), a cycloalkyl group (e.g. the cyclopentyl and cyclohexyl group), an aryl group (e.g. the ethylphenyl and naphthyl group, but preferably the phenyl group) or an aralkyl group with 1 to 5 carbon atoms in the Alkyl group (e.g. the naphthylethyl group, but preferably the benzyl group).

The chlorine can be used in a liquid, gaseous or dissolved state. Most convenient has been found to pass gaseous chlorine through the reaction mixture. Possibly Applicant:

Whiffen & Sons Limited,

Loughborough, Leicestershire (UK)

Representative:

Dr. W. Schalk, Dipl.-Ing. P. Wirth,

Dipl.-Ing. G. E. M. Dannenberg

and Dr. V. Schmied-Kowarzik, patent attorneys,

Frankfurt / M., Große Eschenheimer Str. 39

Named as inventor:

Neil William Woodrow Porter, Loughborough,

Leicestershire (UK)

Claimed priority:

Great Britain of October 25, 1960 (36 513),
of November 29, 1960 (40 884)

can also use chlorine-releasing substances such. B. hypochlorite or a mixture of hydrogen chloride and Hydrogen peroxide, can be used. However, it is preferred to use chlorine per se. The amount of chlorine should not be used in excess of the stoichiometric amount, since the introduction further amounts of chlorine lead to a decomposition of the azoamide according to the following equation:

R ¹

R ³

N-CO-N = N-CO-N + Cl ₂ HH ₂ O

R ^a R ⁴

_> NR ¹ R ² H ₂ Cl + NR ³ R ⁴ H ₂ Cl + 2 CO ₂ + N ₂

It can be seen that this decomposition of the product results in the formation of a large volume of gas leads, from which the end point of the reaction - can easily be determined.

The temperature for carrying out the oxidative chlorination is not critical as long as side reactions,

609 747/329

which are noticeable at elevated temperatures (e.g. hydrolysis of the carbamoyl groups), are kept to a minimum. The oxidation is advantageously carried out at a temperature between -10 and 45 ° C, preferably between 0 and 30 ⁰ C.

The oxidation with chlorine can be carried out batchwise or continuously. In any case, however, it is necessary that the amount of chlorine does not exceed the stoichiometric amount. The amount of chlorine introduced however, there can be used in a substantial excess over the stoichiometric amount where some of the chlorine escapes unreacted.

The rate of oxidation depends on the effectiveness of the contact between gas and Liquid from, d. that is, in order to achieve a high reaction rate, the reaction mixture must be stirred vigorously.

The oxidation can be carried out in water or a mixture of water and an organic solvent. If a mixture of water and organic solvent is used, one uses z. B. dioxane, ethyl glycol, dimethyl sulfoxide or sulfolane. The oxidation takes place at a pH range from -2 to +7 and preferably at a pH range from -1 to +2. The pH is adjusted by adding a strong acid, preferably a non-oxidizing acid, most preferably hydrochloric acid. Other acids, e.g. B. hydrobromic acid, sulfuric acid, phosphoric acid and trichloroacetic acid are also suitable. The oxidation can take place at atmospheric, subatmospheric or Tiber atmospheric pressure. However, while it is usually more convenient to operate at atmospheric pressure, the rate of the reaction is increased by superatmospheric pressures. Elevated pressures for carrying out the method are in the range from atmospheric pressure up to about 9.5 kg / cm ² , in particular overpressures from 0.35 to 2.8, e.g. B. 1.5 kg / cm ^{2 is} suitable.

The bromine or bromide ion can be used in widely varying amounts, but need only be present in catalytic amounts. The amount of bromine or bromide ion is expediently about 1 to 20 percent by weight, based on the hydrazodicarbonamide used as starting material, preferably about 2 to 10 percent by weight. Compounds which can be used to provide bromide ions are, for. B. alkali bromides, such as sodium bromide and potassium bromide, alkaline earth bromides, such as calcium bromide and barium bromide and also other metal bromides, such as iron (III) bromide, chromium (III) bromide, copper bromide, strontium bromide, cobalt bromide and tin bromide, such as hydrobromic acid and also Bromine monochloride. The compound supplying bromide ions can also be an organic bromide, e.g. B. a quaternary ammonium bromide, e.g. B. Tetramethylammoniumbromid or Tetraäthylammoniumbromid be. The rate of the reaction depends on the concentration of the bromide ion or bromine in the whole of the reaction liquid. She cherishes expedient than about 0.1 ° / ₀ volume weight such. B. at 0.1 to 0.5% by weight volume, and expediently at about 1% by weight volume. The weight volume ratio is calculated as g / cc.

The following examples illustrate the invention. All parts and percentages are parts and percentages by weight.

example 1

100 parts of hydrazoformamide were suspended in 700 parts of concentrated hydrochloric acid (36 ° / ₀ ) and 300 parts of water in which 12 parts of ferribromide were dissolved. The pH was below 0. 74 parts of chlorine were then passed into the suspension, which had been cooled ^{to 10 ° C.} After filtration and washing with 200 parts of water, 91 parts Azoformamid xo were obtained corresponding to a yield of 93 ° / _0th

Example 2

100 parts of hydrazoformamid were in 300 parts

concentrated hydrochloric acid (36%) and 700 parts of water, in which 10 parts of sodium bromide were dissolved, suspended. The pH was below 0. Now were

65 parts of chlorine is introduced into the cooled to 30 ⁰ C suspension. After filtration and washing with 100 parts of water, 93 parts Azoformamid were obtained corresponding to a yield of 95 ° / _0th

Example 3

100 parts of hydrazoformamid were suspended in 600 parts of concentrated hydrochloric acid (36%) and 400 parts of water in which 7 parts of bromine were dissolved. The pH was below 0. 78 parts of chlorine were then introduced into the suspension, which was kept ^{below 20 ° C.} After filtering and washing with 80 parts of water, 95 parts of azoformamide were obtained, which corresponded to a yield of 97%.

The process according to Examples 1 to 3 was repeated, but in one case no bromine or Bromide, but in other cases the bromine is replaced by the same amount of ferric chloride, sodium iodide, Antimony trichloride, stannous chloride, arsenic (III) oxide, sulfur, sodium dichromate, chromium sulfate and Nitric acid or replaced by bromine and an equivalent amount of sodium chlorate. The results of all Comparative tests were as follows:

r \ λ f · ++ ι% yield

Oxidizing agent azoformamide

Chlorine alone less than 1

Chlorine plus ferric chloride less than 1

Chlorine plus sodium iodide less than 1

Chlorine plus antimony trichloride .. less than 1
Chlorine plus stannous chloride .... less than 1
Chlorine plus arsenic (III) oxide ... less than 1

Chlorine plus sulfur less than 1

Chlorine plus sodium dichromate less than 1

Chlorine plus chromium sulfate less than 1

Chlorine plus nitric acid less than 1

Sodium chlorate plus bromine ... less than 1

From these experiments it can be seen that by the method according to the invention in comparison with analogous Oxidation process exceptionally high yields can be achieved.

Example 4

100 parts of hydrazoformamid were suspended in 250 parts of concentrated hydrochloric acid (30 ° / ₀ ) and 750 parts of water, in which 10 parts of cobalt bromide were dissolved. The pH was below 0. Now were

66 parts of chlorine were passed into the suspension kept at 10 to 15 ° C. After filtration and washing with 200 parts of water 94.5 parts Azoformamid were obtained, which corresponded to a yield of 96.5 ° / _0th

5 6

Example 5 under 0. 68 parts of cold liquid chlorine were now

with vigorous stirring to the temperature of 20 to 25 ° C

118 parts of hydrazoformamide were added in a maintained mixture, the resulting azo

Mixture of 300 parts of concentrated hydrochloric acid (36 ° / ₀ ) filtered off formamide, washed and so 93 parts of the

and 700 parts of water in which 10 parts of sodium 5 obtained compound to a yield of 95 ° / ₀

bromide were dissolved, suspended. The pH was the same.

below 0. The mixture was, while 72 parts of chlorine Example 12
were introduced at a pressure of 1.4 kg / cm ² ,

stirred in a closed vessel. After the 100 parts of hydrazoformamide were in one

Filtration and washing were 113 parts of azo ίο mixture of 300 parts of concentrated hydrochloric acid

formamide obtained, which gives a yield of 97 ° / ₀ (36 ° / ₀ ), 700 parts of water and 8 parts of bromine sus-

corresponded. pending. The pH value was below 0. For this

Example 6 were mixed 440 parts of a solution containing 15 weight

percent sodium hypochlorite at 15 to 20 ° C

100 parts of hydrazoformamide were added in a 15. After filtering and washing were

Mixture of 800 parts of water, 200 parts of concentrated 88 parts of azoformamide is obtained, which is a yield

trated hydrochloric acid (36 ° / ₀ ) and 1 part calcium bromide of 90 ° / ₀ ,

suspended. The pH was below 0. Now were. -I ₁ ,

67 TeUe of chlorine in the suspension cooled to 25 ° C J3 e 1 s ρ 1 e I 13

introduced. After filtering and washing with 20 100 parts of hydrazoformamide were in a

200 parts of water were 94 parts of azoformamide mixture of 700 parts of water and 300 parts of hydrochloric acid

obtained, which corresponded to a yield of 96%. (30%) and 12 parts of tetramethylammonium bromide

. suspended. The pH was below 0. In the 20

ö e 1 s ρ 1 e 1 7 to 25 ° C held suspension, 67 parts of chlorine

100 parts of hydrazoformamide were introduced into a 25. After filtering and washing were

Mixture of 900 parts of water, 100 parts of concentrated 92 parts of azoformamide is obtained, which is a yield

trated hydrochloric acid (36%) and 20 parts bromine water of 94% corresponded,
chemical acid (48%) suspended. The pH was at

6about 0. 66 parts of chlorine were then added to Example 14, which was heated to 20 ° C

cooled suspension passed. After filtering 30 100 parts of hydrazoformamide were in a

and washing with 300 parts of water, 93 parts of a mixture of 700 parts of water, 300 parts of concentrated

Obtain azoformamide, which gives a yield of 95% trated hydrochloric acid (36%) and 15 parts of bromine mono-

corresponded. chloride suspended. The pH was below 0. In

Example 8 this suspension kept at 20-25 ° C

Initiated 35 64 parts of chlorine. After filtering and

100 parts of hydrazoformamide were obtained in 1000 parts of washing, 93 parts of azoformamide

Water, in which 8 parts of sodium bromide dissolved corresponded to a yield of 95%,
were suspended. The pH of the medium

was 7. 69 parts of chlorine were now added to Example 15 at 10.degree

cooled suspension passed. After filtering 40

and washing gave 91 parts of azoformamide, 13.2 parts of methylhydrazoformamide

which corresponded to a yield of 93%. _(GH> . _NH . _CONH . _NH . _{Co. ΝΗ>)}

^exs P * ^e were suspended in a mixture of 80 parts of water and 100 parts of hydrazoformamide in a mixture of 20 parts of concentrated hydrochloric acid (36%) containing 1 part of a mixture of 800 parts of water and 100 parts of sulfur-bromine. The pH was below 0. Acid (pure) and 12 parts of potassium bromide suspended. The pH was below 0. 7.7 parts of chlorine were slowly passed into the suspension, which was kept at 20 to 25 ° C., and the suspension was slowly cooled to 30 ° C., and 66 parts of chlorine were passed into the suspension. After nitrating, washing and filtering and washing to 12.1 parts of monomethyl, 89 parts of azoformamide 50 were dried azoformamide,
obtained, which corresponded to a yield of 91%.

Example 10 Example 16

100 parts of hydrazoformamide were converted into 20.8 parts of N-methyl-N-phenylhydrazoformamide

Mixture of 150 parts of concentrated hydrochloric acid 55 in 75 parts of water, which concentrated 25 parts

(36%), 750 parts of water and 10 parts of cupric phosphoric acid (85%) and 1.7 parts of concentrated

bromide suspended. The pH was below 0. Now hydrobromic acid (20%) contained, suspended,

86 parts of chlorine were in the at a pressure of The pH of the medium was below 0. In this on

1.75 kg / cm ² and a temperature of 20 to 25 ° C for 10 to 15 ⁰ C suspension were held 8.4 parts

held suspension introduced. After filtering, passed in 60 chlorine and so 17 parts of N-methyl-N-phenyl-

and washing, 92 parts of azoformamide were obtained, azoformamide was obtained,
which corresponded to a yield of 94%.

Example 17

100 parts of hydrazoformamide were in a 65 23.6 parts of N-ethyl-N-phenyl-N'-methylhydrazo

Mixture of 800 parts of water, 200 parts of concen formamide in 100 parts of hydrochloric acid solution, the

trated hydrochloric acid (36%) and 10 parts of strontium contained 15 parts of hydrogen chloride, suspended. Of the

bromide suspended. The pH of the medium was below 0. In the one kept at 25 to 30 ° C

1.1 parts of aluminum bromide were added to the suspension and 8.2 parts of chlorine initiated. After filtering, washing and drying the product were 22.7 parts of N-ethyl-N-phenyl-N'-methylazoformamide obtain.

Example 18

32.6 parts of N-methyl-N-benzyl-N'-ethyl-N'-phenylhydrazoformamide were suspended in 60 parts of water. There were 40 parts of concentrated hydrochloric acid (36%) and 0.8 parts of cadmium bromide were added and 8.3 parts of chlorine were introduced into the suspension kept at 10-15 ° C. So were 27.4 parts of N-methyl-N-benzyl-N'-ethyl-N'-phenylazoformamide obtain.

Examples

23.9 parts of Ν, Ν, Ν ', Ν'-tetrabenzylhydrazoformamide were suspended in 50 parts of water containing 50 parts of concentrated hydrochloric acid (36 ° / “) and 1.0 part of lithium bromide. After introducing 4.0 parts of chlorine at 20 to 25 ^° C., 22 parts of N, N, N ', N'-tetrabenzyl azoformamide were obtained.

Example 20

21.1 parts of Ν, Ν, Ν ', Ν'-tetraphenylhydrazoformamide were suspended in a mixture of 75 parts of water, 25 parts of concentrated hydrochloric acid (36 ° / ₀ ) and 1 part of sodium bromide. After introducing 4.1 parts of chlorine at 17 to 21 ° C, 18.2 parts of Ν, Ν, Ν ', Ν'-tetraphenylazoformamide were obtained.

Example 21

45.2 parts N-methyl-N-phenyl-N'-benzyl-N '- (7-ethylnaphthyl) hydrazoformamide were in a mixture of 20 parts of water, 60 parts of SuIfolan, Suspended 20 parts of hydrochloric acid (36%) and 1.1 parts of tetramethylammonium bromide. After initiating of 8.7 parts of chlorine in the suspension kept at 22 ° to 26 ° C., 40.0 parts of N-methyl-N-phenyl-N'-benzyl-N '- (7-ethylnaphthyl) -azoformamide were added obtain.

Example 22

19.8 parts of N-phenyl-N- (2-methyl-4-isopropylphenyl) -N'-n-pentylhydrazoformamide were in a mixture of 10 parts of water, 50 parts of dioxane, 40 parts of concentrated hydrochloric acid (36 ° / ₀ ) and 1, 1 part concentrated hydrobromic acid (25 ° / ₀ ) suspended. 3.9 parts of chlorine were passed into the suspension, which was kept at 15 to 17 ° C., and 14.9 parts of N-phenyl-N- (2-methyl-4-isopropylphenyl) -N'-n-pentylazoformamide were thus obtained.

Example 23

39.8 parts of Ν, Ν-dimethyl-N'-cyclohexyl-N'-n-dodecylhydrazofornamide were suspended in a mixture of 60 parts of water, 40 parts of concentrated hydrochloric acid (36 ° / ₀ ) and 0.8 part of bromine. 8.1 parts of chlorine were passed into the suspension, which had been cooled to 0 to 5 ° C., and 34.4 parts of Ν, Ν-dimethyl-N'-cyclohexyl-N'-n-dodecylazoformamide were obtained.

Example 24

22.4 parts of N-ethyl-N-sec-butyl-N '- (2-ethylphenyl) -N' - κ - naphthylmethylhyzoformamid were suspended in parts of water and 30 parts of concentrated hydrochloric acid (36%). Then 1 part of barium bromide and then 4.2 parts of chlorine were added, the suspension was kept at 28 to 30 ° C and so 21.0 parts of N-ethyl-N-sec-butyl-N '- (2-ethylphenyl) -Ν '-Λ-naphthylmethylazoformamid obtained.

Claims (7)

Patent claims: 1. Process for the preparation of azodicarbonamides of the general formula R ¹ R ³ N-CO-N = N-CO-N R * in which R ¹ , R ² , R ³ and R * stand for a hydrogen atom or an alkyl, cycloalkyl, aryl or aralkyl group, by oxidation of the corresponding hydrazodicarbonamides with an inorganic oxidizing agent, characterized in that the oxidation in aqueous solution or a mixture of water and an organic solvent at a pH of -2 to +7 in the presence of bromine or bromide ions, with chlorine as the inorganic oxidizing agent. 2. The method according to claim 1, characterized in that gaseous chlorine is used as the oxidizing agent used. 3. The method according to claim 1 and 2, characterized in that there is chlorine in a die stoichiometric amount not exceeding amount used. 4. The method according to claim 1 to 3, characterized in that the bromine or the Bromide ions in an amount of 1 to 20 percent by weight, preferably 2 to 10 percent by weight, based on the hydrazodicarbonamide used. 5. The method according to claim 1 to 4, characterized in that the reaction at a Temperature from -10 to + 45 ° C. 6. The method according to claim 1 to 5, characterized in that the volume bromine or bromide ion in a concentration more than 0.1 ° / ₀ by weight, preferably between 0.1 and 5 ° / ₀ by weight of volume used. 7. The method according to claim 1 to 6, characterized in that the oxidation at superatmospheric Printing. Considered publications:
U.S. Patent No. 2,605,260;
Organic Syntheses 32, 16 (1952). 609 74-7 / 32 »12.66 © Bundesdruckerei Berlin