DE1192642B - Process for the production of isonitriles - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C07c

C07d
German class: 12 ο - 22

Number: 1192642

File number: F 40677IV b / 12 ο

Filing date: September 5, 1963

Open date: May 13, 1965

It is known that isonitriles from formamides with dehydrating agents, especially with acylating agents, in the presence of tertiary amines (cf. Ber., 94, p. 2802 [1961]; 93, p. 239 [1960]).

In this process, substituted formamides in a solvent with acylating agents, such as phosphorus trichloride, phosphorus oxychloride, benzenesulfonyl chloride, phosgene, and tertiary amines, such as triethylamine or dimethylalkyl and -arylamines, or pyridine implemented. The work-up of the reaction mixtures which, in addition to the isonitrile, also contain salts of the tertiary amine and by-products contain, takes place in that the reaction mixture is mixed with water and the isonitrile with extracted a low-boiling organic solvent, the amine salts in the aqueous Phase remain. The separated solution of the isonitrile is dried with desiccants and the solvent was removed by filtration by distillation. The crude isonitrile obtained as a residue is purified by fractional distillation or crystallization.

It has now been found that isonitriles of the general formula

R- (N ^ C) _n

in which R is a mono- or polyvalent aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical and η is an integer from 1 to 6, from formamides of the general formula

R - (NH - CUO) _n

in which R and η have the meaning given above, obtained in the presence of a tertiary amine and an acylating agent in an organic solvent with elimination of water, if, after the elimination of water, the reaction mixture is treated with gaseous or liquid ammonia, optionally at elevated pressure. As a result, the strong acids which are bound to tertiary amines and released from the aylating agent are converted into their ammonium salts, which are insoluble in the usual organic solvents and can be separated off by filtration. From the nitrated solution obtained, in addition to the isonitrile, both the solvent and the tertiary amine are recovered in such purity that they can be used directly for further isonitrile batches.

Process for the production of isonitriles

Applicant:

Paint factories Bayer Aktiengesellschaft,
Leverkusen

Named as inventor:
Ivar Ugi, Leverkusen

■ 5 2

The process according to the invention is illustrated in more detail by the following reaction scheme:

R - NH - CHO + COCl ₂ + 2 NR ₃ '
-> R - N ^ C + 2 NR ₃ '• HCl + CO ₂ T

NR ₃ '· HCl + NH ₃ -► NR ₃ ' + NH ₄ Cl J

It constitutes formamides according to the invention at temperatures from -40 to 100 ^0C, preferably at -20 to +50 ⁰ C, with 0.5 to 2 moles, preferably 0.7 to 1.1 moles, per mole of an acylating agent in the presence of 2 formylamino to 10 moles of a tertiary amine per mole of acylating agent used. It is also advantageous to work under increased pressure.

The ammonia is added in gaseous or liquid form at temperatures of -60 to +100 ⁰ C, optionally under elevated pressure, at up to about 20 microns. When using liquid ammonia one works expediently at temperatures from -60 to -20 ⁰ C. As acylating agent z. B. can be used: phosgene, phosphorus oxychloride, phosphorus tribromide, benzenesulfochloride and toluenesulfonyl chloride. Examples of suitable tertiary amines are: trimethylamine, triethylamine, tripropylamine, dimethylisopropylamine, triisopropylamine. Dimethyl - cyclohexylamine, ethylpiperidine, tetramethyl - ethylenedianiine, dimethylaniline and pyridine.

The following combinations have proven particularly useful: phosgene, trialkylamine and phosphorus oxychloride or benzenesulfonyl chloride, pyridine. Suitable solvents are all solvents which are sufficiently inert to acyl halides and bases. The following may be mentioned as solvents: gasoline fractions with b.p. 30 to 200 ⁰ C, cyclohexane, benzene, toluene, xylenes, methylene.

509 569/37 +

lene chloride, chloroform, carbon tetrachloride, chloroethylene, Tetrachlorethylene, chlorobenzene, tetrafluorochloroethane, diethyl ether, tetrahydrofuran, dioxane. Ethyl acetate, glycol monomethyl ether acetate.

For the method according to the invention, for. B. used the following formylamines: methyl, ethyl, n- and iso-propyl, allyl, η- and tert-butyl, Cyclohexyl-, η- and tert-dodecyl- and n-octadecylformamide, 3-dimethylamino-1-propyl-formamide, 2-pyrrolidino-1-ethyl-formamide, 3-methoxy-1-propyl - formam id, formylamino - acetic acid tert. - butyl ester α - Formylamino - isovoleric acid - ethyl ester. α - cyano - cyclohexylformamide, benzyl - formamide, 3,4-dichlorobenzyl-formamide, α-indanyl-formamide, Formanilide, 2,4,5-trichloroformanilide, 2,4-dimethoxy-5-chloroformanilide, 3-nitroformanilide, 4-cyclohexylformanilide, 4-phenyl- and 4-phenoxy-formanilide, ^ perchlorbicycloheptenyl-formanilide, / 5-methoxyformylamino - naphthalene, α - formylamino - anthraquinone, 1 - furylmethyl - formamide, 3-formyl- ■ aminopyridine, 7-formylamino-quinoline, 2-formylamino - 3 - methoxy - diphenyloxyd, ethylenediformamide, trimethylene, tetramethylene, pentamethylene, Hexamethylene-, decamethylene-diformamide, di- (3 - formylamino - 1 - propyl) - methyl-, η - butyl-, 2-ethyl-1-hexyl-, -cyclohexyl and -benzylamine, 1,4-diformylamino - cyclohexane, 1,4 - di - [formylaminomethyl] cyclohexane, 1,4-di- [formylamino-methyl] -benzene and -tetrachlorobenzene, 1,3-di- [formylaminomethyl] -4,6-dimethylbenzene, 1,3- and 1,4-phenylenediformamide, 2-methoxy-1,4-phenylenediformamide, Diformylamino-1,3,5-triisopropylbenzene, 1,4-, 1,5- and 2,6-naphthylenediformamide, 3,3'-dimethyl- and 3,3'-dichloro-4,4'-diformylamino-diphenyl, 4,4'-diformylamino-diphenylmethane, 4,4'-Diformylaminodiphenylcarbonat, 3,3'-Dimethyl- or dimethoxy- or dichloro - 4,4 '- diformylamino - diphenylmethane, 3,3 '- dimethyl - 5,5' - diethyl - 4,4 - diformylamino - diphenylmethane, 4,4 '- diformylamino - diphenyl ether, 3.3 '- dimethyl - 5,5' - diethyl - 4,4 '- diformylaminothiodiphenyl ether, 4,4 ', 4 "-TriformyIamino-triphenylmethane, 4,4', 4" - Triformylamino - triphenyl - thione phosphate, 2,4,4'-triformylamino-diphenyl, 2,2 ', 4,4'-tetraformylamino-diphenyl, 1,4,7-triformylamino -1,1.4,7,7-pentamethyl-heptane, 1,6,11-triformylamino -undecane, tri- (3-formylamino-1-propyl) -amine.

The method according to the invention has the following technical advantages:

Working up with ammonia eliminates the cumbersome shaking and drying operations avoided. The solvent used and the tertiary amine fall without a special work-up process in high purity and can be used for the production of isonitriles directly to be reinstated. This makes it possible to use the method according to the invention continuously respectively.

Some isonitriles, ζ. B. benzyl isocyanide, store in aqueous organic solvents gradually-Jich water with discoloration or regression of the corresponding formamides. This isonitrile can only be obtained with difficulty in good yield by the previous processes. Since the inventive The process avoids the use of water, it is possible in this way, even against Water to produce unstable isonitriles.

example 1
nC ₄ H ₉ - NC

At -10 to 0 ^° C., 100 parts by weight of phosgene are introduced into the solution of 101 parts by weight of n-butylformamide in 150 parts by weight of trimethylamine and 700 parts by weight of methylene chloride with stirring in about one hour. The solution is left at 0 to 5 ⁰ C to react further and then passes under stirring until saturation dry ammonia. The solution is filtered and concentrated. The residue is distilled in vacuo. Boiling point: 80 to 85 ⁰ C / 150 Torr. Yield: 73 parts by weight of n-butyl isocyanide.

Example 2

127 parts by weight of cyclohexylformamide. 250 parts by weight of dry pyridine and 750 parts by weight of light petrol (boiling point 60 to 8O ⁰ C) are presented. 95 parts by weight of phosphorus oxychloride are added dropwise with ice-cooling and stirring. The mixture is stirred at 30 to 40 ^° C. for a further 30 minutes and ammonia is then passed in until it is saturated. It is filtered off, light gasoline and pyridine are distilled off under a slight vacuum and the residue is distilled in vacuo. Boiling point 55 to 58 ° C / 10 Torr. Yield: 97 parts by weight of cyclohexyl isocyanide.

Example 3
CN - CH ₂ - COO - C (CHs) ₃

159 parts by weight of tert-butyl formylglycine in 250 parts by weight of triethylamine and 750 parts by weight of chloroform are reacted phosgene at -10 to +10 ⁰ C with 100 parts by weight. It is saturated with ammonia, filtered off and distilled. Yield: 97 parts by weight of tert-butyl isocyanoacetate with a boiling point of 104 to 106 ° C./0.3 Torr.

Example 4

CH ₃

CH ₃

149 parts by weight of 2,6-dimethylformanilide are dissolved in 1000 parts by weight of pyridine, and 177 parts by weight of benzenesulfochloride are added. After 3tägigem standing at 10 to 20 ⁰ C is saturated with ammonia, filtered and distilled in vacuo. Yield: 102 parts by weight of 2,6-dimethylphenyl isocyanide with a boiling point of 50 to 53 ° C./0.01 Torr.

Example 5
CH ₃ N (CH ₂ CH ₂ CH ₂ - NC) ₂

203 parts by weight of di- (3-formylamino-1-propyl) -methylamine (accessible by reacting di- (3-amino-1-propyl) -methylamine and the calculated amount of formic acid in boiling xylene or chlorobenzene). 1300 parts by weight of methylene chloride and 500 parts by weight of triethylamine are presented. At 0 to 10 ⁰ C one passes with stirring 200 weight

divide phosgene. Then it is saturated with ammonia, filtered after about 5 hours and distilled the methylene chloride and triethylamine. 175 parts by weight of crude di- (3-isocyan-1-propyl) methylamine remain back, from which 93 parts by weight of pure product from the thin layer distillation Boiling point 128 to 131 ° C / 0.25 Torr can be obtained. After completion of the phosgenation can also the main part of the triethylamine hydrochloride is suctioned off and then the filtrate with ammonia be treated. The yield is the same as in the procedure described above.

CN

Example 6

CH ₂

NC

Example 7

CN

In the suspension of 214Gewichtsteilen 2,6-naphthylene diformamid into 1200 parts by weight of a recovered from an analog approach mixture of about 500 parts by weight of triethylamine and 700 parts by weight methylene chloride 200 parts by weight of phosgene at 0 to 20 ⁰ C. After one hour, the mixture is saturated with ammonia, filtered off with suction and concentrated. The residue is triturated with ether, filtered off with suction and dried in vacuo. Yield: 173 parts by weight of 2,6-naphthylene diisocyanide. that does not melt up to 280 ^{° C.}

Example 8

In the suspension of 218 parts by weight of finely powdered 4,4'-Diformylamino-diphenylmethane in 450 parts by weight of triethylamine and 600 parts by weight of trichlorethylene is added dropwise the solution of 200 g of phosgene in 300 parts by weight of trichlorethylene at 0 ⁰ C under stirring. The mixture is left for 30 minutes at 30 to 40 ⁰ C to react to completion, and then saturated with ammonia. It is filtered and concentrated, and the residue is recrystallized from ethyl acetate. Yield: 99 parts by weight of 4,4'-diisocyan-diphenylmethane with a melting point of 134 to 135 ^° C.

filtered and concentrated. The residue is recrystallized from toluene. Yield: 146 parts by weight of 2-isocyan-3-methoxy-diphenyloxide from melting point 172 to 173 ° C.

Example 9
CN -CH ₂ -CH ₂ -NC

116 parts by weight of ethylenediformamide (obtainable by reacting ethylenediamine with methyl formate), 450 parts by weight of triethylamine and 1200 parts by weight of methylene chloride are presented. At from 0 to 10 ^° C., 200 parts by weight of phosgene are introduced. It is saturated with ammonia, filtered and concentrated, 101 parts by weight of crude ethylene diisocyanide remaining. Short-path distillation in vacuo gives 48 parts by weight of pure product with a boiling point of 75 to 80 ° C / 0.003 Torr.

Example 10

CN

241 parts by weight of finely powdered 2-formylamino-3-methoxy-diphenyloxide, 800 parts by weight of dry diethyl ether and 230 parts by weight of triethylamine are presented. At −20 to 0 ^° C., 100 parts by weight of phosgene are introduced with stirring. C cooled and treated with 200 parts by weight of liquid ammonia 30 ⁰ - After one hour, is cooled to about. The temperature is allowed to rise to 0 to 20 ^° C., 240 parts by weight of finely powdered 4,4'-diformylaminodiphenyl, 500 parts by weight of triethylamine and 1500 parts by weight of methylene chloride are initially introduced. At 0 ° to 15 ° C., 200 parts by weight of phosgene are first introduced with stirring. then 68 parts by weight of ammonia. It is filtered, the filter residue is extracted three times with 1500 parts by weight of hot methylene chloride and / or benzene and the combined solutions are concentrated in vacuo. Yield: 183 parts by weight of 4,4′-diisocyan-diphenyl with a melting point of 133 to 136.degree.

Claims (1)

Claim: Process for the preparation of isonitriles of the general formula R-fN ^ C) _m in which R is a mono- or polyvalent aliphatic, cycloaliphatic ^ araliphatic, aromatic or heterocyclic radical and η is an integer from 1 to 6, from formamides of the general formula R — fNH —CHO) " in which R and η have the meaning given above, in the presence of a tertiary amine and an acylating agent in an organic solvent with elimination of water, characterized in that, after the elimination of water, the reaction mixture is treated with gaseous or liquid ammonia, if appropriate at elevated pressure, to treat the resulting The ammonium salts are separated off and the isonitrile formed, the amine and the solvents are isolated from the liquid phase in the customary manner. 509 569/374 5.65 © Bundesdruckerei Berlin