SU948288A3 - Process for producing alkylisocyanates - Google Patents

Description

This invention relates to an improved viy process for the preparation of alkyl isocyanates of the general formula

RNCO, (I)

where R is an unbranched or branched alkyl C —C.

A known method for producing alkyl isocyanates has a boiling point below the decomposition point of the corresponding carbamic acid chlorides, by thermal decomposition of cooTBe-associated carbamic acid chlorides in the presence of an organic solvent P.

The disadvantages of this method include the fact that the isocyanate formed and hydrogen chloride in the double cooling system must be removed separately. Separating the hydrogen chloride requires an expensive dimerising reflux condenser, which must be cooled strongly in order for the isocyanate and carbamic acid chloride to be quantitatively retained, and for separation of the isocyanate from the solvent and the carboxylic acid chloride by distillate and distillation, a high fraction fractioned fraction is required. from the solvent and carbamic acid chloride, the isocyanate is completely unsuitable. In the preparation of methyl-, ethyl-isopropyl isocyanate, the yield of pure isocyanate, which corresponds to each first fraction, is significantly shorter than the final yield: in the examples,%, methyl isocyanate 39, 33 and 65.4 are obtained; ethyl isocyanate 78.8; isoprobylsoocyanat 79.

The purpose of the invention is to simplify the process.

The goal is achieved by the fact that in the method of producing alkyl isocyanates of the general formula (1), an acid halide of the general formula

(il)

R NH-CO-X

where R - has the indicated value, X - halogen, is subjected to interaction with an isocyanate selected from the group of N-alkyl-isocyanates with alkyl -Cjp, N-cycloalkyl isocyanates with cycloalkyl C, N-arylisocyanates, N-alkoxy-apylisocyanates with alkoxy Cj, N-aryl diisocyanates , alkyl diisocyanates with 414 carbon atoms, then carry out dehydrohalogenation at 20-60 ° C and a pressure of 0.01-200 mmHg. Art. Carbamic acid chlorides used as starting materials are obtained by gas-phase phosgenation of the corresponding amines. Isocyanates are suitable for absorbing carbamic acid chlorides of structural formula (11) hydrogen chloride, which have a boiling point above the decomposition point of corresponding carbamic acid chlorides, which means that aliphatic isocyanates, aliphatic components, aromatics, aromatics, and aromathematic components that form aliphatic components. their mixtures. C-to-c -methyl-2-propoxyethyl isocyanate, propoxypropyl isocyanate, isobutoxypropyl isocyanate, N-cycloalkoxyl cilisocyanates, for example cyclohexyloxypropylisocyanate, N-dicloalkyl isocyanates with cycloalkyl Gg, for example cyclohexylisocyanate, N-dicloalkyl isocyanates with cycloalkyl Gg, for example cyclohexylisocyanate, N-dicloalkyl isocyanates with cycloalkyl Gg; cyanate, N-arylisocyanates, for example, phenyl isocyanate, 1-naftalizotsianat, W-tolyl isocyanate, benzyl isocyanate. Diisocyanates are used for dehydrohalogenation, for example, alkyl diisocyanates with alkyl C, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, cycloaliphatic diisocyanates, for example, 4,4-dihydrohexylmethane diisocyanate, L-aryl diisocyanates, and a couple of a few methods. For the preparation of N-alkyl isocyanate with 5 C atoms using N-pentyl isocyan as a dehydrohalogenation agent, both pentyl residues should differ from each other in the structure. Moreover, residues containing isocyanate groups can also be used, for example, from the initial mixtures of phosgenirovanium. The preparation of these isocyanates suitable for dehydrohalogenation is known. They can be used after preparation without further purification. The process is carried out as follows: the high-boiling isocyanate is added with stirring an equimolar amount of carbamic acid halide of structural formula (II), the resulting alkyl isocyanag of the structural formula (1) is then withdrawn at a temperature below the decomposition point of the resulting carbamic acid anhydride under reduced pressure. Depending on the volatility of the alkyl isocyanate of the structural formula (1), a temperature range of 20 to 60 ° C and a pressure of 0.01 to 200 mm Hg are preferred. Art. The formed alkyl isocyanate can also be removed by injecting an inert gas into the reaction solution at atmospheric pressure. The interaction can be carried out in the presence of an inert organic solvent. Suitable aliphatic hydrocarbon series, such as octane, ligroin, petroleum ether, chlorinated hydrocarbons, aliphatic series, for example, 1,2-dichloropropane, 1,2-gthgyuretan, tsiklogeksnlhlorid, AMYL CHLORIDES, cyclic hydrocarbon series such diklogeksan, metilsch1klogeksan, decalin, tetrahydronaphthalene , aromatic hydrocarbons, for example benzene, toluene, xylene, cumene, dizgilbeizol, ethylbenzene, ethylnaphthalene, chlorinated aromatic hydrocarbons, for example monochlorobenzene, dichlorobenzene, chlorotoluenes, chloronaphthalene as well as mixtures of these aliphatic and aromatic hydrocarbons, ketones, for example, methyl ethyl ketone, acetophenone, esters, for example, ethyl acetate, butyl ester of acetic acid, alkyl ester of propionic acid with alkyl, dimethyl ester of phthalic acid, phthalic acid diethyl ester; phthalic acid methyl ethyl ester. In particular, hydrogen hydrocarbons of the aromatic series and chlorinated hydrocarbons of the aromatic series are considered suitable. The proposed method can be carried out intermittently or continuously. The resulting carbamic acid halide of high boiling isocyanate can be thermally dehydrohalogenated at 80-250 ° C, preferably 80-180 ° C. AlKylcarbamyl chloride residues of structural formulg (II) remaining in the reaction solution are then distilled off and regenerated. Losses on the product in the case of continuous operation in the way are extremely insignificant. Thermal dehydrohalogenation of carbamic acid halide, and. thus, the regeneration of high boiling isocyanate can be facilitated by working under reduced pressure or by introducing inert gas as well as phosgene. In cases where the carbamic acid halide formed by the reaction of the reaction is in solid form, it can be kept in dissolved state by means of an excess of isocyanate or with the addition of a solvent. 95%, and with a discontinuous - above 85% of the theoretical amount. The latter, not yet converted to an alkyl isocyanate, is a residue of a carbamic acid halide of the formula (G1 is regenerated upon thermolysis of the residue from the reaction and used again. The overall yield of the reaction in terms of carbamic acid chloride of the structural formula (I) is quantitative. The degree of purity of alkyl isocyanates is not less than 97% The isocyanates obtained according to the proposed method are valuable starting products for the production of Dili agents for the protection of plants, pest control agents, dyes, and synthetic materials. l, synthetic materials, means of hydrophobing textiles, detergents, bleaches and adhesives. In particular, their interaction with the formation of urethanes plays an important role, for example, for use as foams or high molecular weight coatings of high elasticity, or urea. K125 parts by weight of cyclohexyl isocyanate, 46.7 parts by weight of methylcarbamic acid chloride are added at room temperature The reaction mixture is heated to 40 ° C, at a pressure of 100 mm Hg. Art. methyl methyl is diverted, entering it into the cooling trap. Output 87% of theory; m.p. 38 ° C. Example 2. K 163 weight. including hexamethyl diisocyanate at room temperature with a mixture of added 46.7 weight. including the acid chloride methylcarbamic acid. The reaction mixture is heated to 40 ° C at a pressure of 100 mm Hg. Art. methyl isocyanate is withdrawn and introduced into the cooling trap. Yield 89% of theory; m.p. 38 ° C. Example 3. B168 weight. including hexamethylenediisodianate at room temperature add 54 weight. including acid chloride ethylcarbamide acid. The reaction mixture is heated d 30-35 ° C, at a pressure of 75 mm RT. Art. Distilled ethyl isocyanate, putting it into the cooling trap. Yield 90% of theory; m.p. 60 ° C. Example 4. To 84 wt. including hexamethylenediamine isocyanate, 121.5 wt. including acid chloride isopropyl carmine bamic acid. The reaction mixture is heated to, at a pressure of 50 mm Hg. Art. isopropyl isocyanate is withdrawn and introduced into a cooling trap. Output 92% of theory; m.p. 74-75 ° C. Example 5. B168 weight. including hexameti lendiisocyanate at room temperature dissolve 60.8 weight. including isopropylcarbamic acid chloride. At an internal temperature of 50 ° C and a pressure of 50 mm Hg. Art. the resulting isopropyl isocyanate is collected in a cooling trap. Yield 90% of theory; m.p. 73-74 C. Example 6. K126 weight. including hexamethylene diisocyanate, dissolved in 714 weight. including chlorobenzene, 121.5 wt. including isopropylcarbamic acid chloride. The reaction mixture is heated to, at a pressure of 100 mm Hg. Art. The distillate is discharged through the column and an 8 refrigeration trap is collected. Output 85% of theory; kip 73-75C. Example 7. To 232 wt. including bms- (3-methyl-4-isocyanatcyclohexyl) methane was added at room temperature to 108 weight. including the acid chloride n-butylcarbamic acid. At 20 ° C and a pressure of 0.01-0.1 mm Hg. Art. c-butyl isocyanate is cleaved from the reaction mixture and collected in a cooling trap. Output 78 wt. qt kip . Example 8. K 101 wt. including hexamelate lediisocyanate added at room temperature to 90 weight. including acid chloride 1,1-dimethyl-n-propylcarbamic acid. At 60 ° C and a pressure of 50 mm Hg. Art. 1,1-Dimethyl-to-propyl isocyanate is cleaved from the reaction mixture. Output 40 weight.h. m.p. . Example 9. K 348 weight. including technical toluene diisocyanate at room temperature, add 93 weight. including the acid chloride methylcarbamic acid. The reaction mixture is heated to 50 ° C, at a pressure of 50 mm Hg. Art. methyl isocyanate is withdrawn and introduced into the cooling trap. Yield 51.5%, kp. 38 ° C. Example 10. K 476 wt. including phenyl isocyanate at room temperature, add 187 weight. including the acid chloride methylcarbamic acid. The reaction mixture is heated to 40 ° C. and methyl isocyanate is obtained at a pressure of 50 mm Hg. Art. retracted, putting it into the cooling trap. Yield 66.7%, t. kip 38 C. Example I. K 200 wt. including 3-chlorophenyl isocyanate added at room temperature 50 wt. including the acid chloride methylcarbamic acid. The reaction mixture is heated to 50 ° C, at a pressure of 100 mm Hg. Methyl isocyanate is withdrawn and introduced into the cooling trap. Yield 68.3%, kp. 38 ° C. Example 12. K 143 wt. including 1-propoxy-2-propnyl isocyanate, 32.1 wt.% was added at room temperature. including ethylcarbamic acid chloraetidride. The reaction mixture is heated to 50 ° C and the resulting ethyl isocyanate at a pressure of 70 mm Hg. Art. Remove it from the cooling trap. The input of 83%, t. Kip. 60 C. Example 13. To 106 wt. Part 3,5,7,7-tetramethyloctacrylate at room temperature 18.7 wt. including acid chloride megilcarbamic acid. The reaction mixture is heated to 50 ° C and the resulting methyl isocyanate at a pressure of 100 mm Hg. Art. divert it into the cooling trap. Yield 81.6%, kp. 38-39 C. Example 14. K 196 weight. Part of 2,2,4-trime tyl hexamethylene diisocyanate is added at room temperature to 37.4 wt. including acid chloride metncarbamic acid. The reaction mixture is heated to 50 ° C and the resulting methyl isocyanate at a pressure of 100 mm Hg. Art. otvodlt entering it into the cooling trap. Yield 82.7%, - t. kip 38-40 ° C. Likewise, KN-c1o-s EHs about - RNcio + B-iTH-d Compounds are obtained in the table. Thus, the advantage of the proposed method is a high yield and the view rate of the purity of the target product, the short duration of the reaction and the technically not laborious implementation of the method. Due to the absence of auxiliary bases, the method is much more environmentally friendly than the known one. As a by-product only pure hydrogen halide is formed, which can be further processed, for example, to produce SALTIC acid.

CH, .c, and,

60

80

100

60

Claims (1)

Invention Formula The method of obtaining 1-p1 alkyl isocapate total forshchta (IV where R is unbranched or expanded CL-Su alkyl based on a halocarbene of carbamic acid of the general formula. 994828810. . where R - has the specified value, X - halogen, C3, N-arnldnizotsnanatov, alknldnnzotsyanatov This is because, with a target with 4-14 carbon atoms, then simplified oyurob, galogenangadrnd karbam-dehydrohalogenated prn 20-60 C and davlek and The new acid is reacted with c0, mm Hg. Art. isocyanatm. selected from the group of N-alkshgazo-j Istogaki information, cyanates with alcpl C -Cjjo Nc) alkylklycoryprinated in vnmanna prn expert | anatov with cycloalkyl Cd, N-arylisocyan 1. German Patent N 1193034, cl. 12 about 22, comrade, Nalki-kaiiapkilizozaloi Ianatov with alkoxypoly. 1966 (prototype).