SU589908A3 - Method of preparing acetic anhydride - Google Patents

Description

This invention relates to a mapping technique. carboxylic anhydrides, in particular acetic acid.

Acetic anhydride is known as a chemical product already used

long and 6 large quantities to produce cellulose acetate. It is usually produced on an industrial scale by the interaction of ketene with acetic acid LIJ. This method has the disadvantages of L2J associated with the use of explosive ketene, and therefore improvements to the methods of producing acetic achydride are currently ongoing.

There is also known a method of producing acetic anhydride, which is carried out by the interaction of methyl acetate, carbon monoxide and hydrogen in L-methyl pyrrolidone in the presence of cobalt iodide at this temperature and a pressure of 70 O atm for 17 sc. Yield, 60% h.

The main disadvantage of this method lies in the use of very high pressures and relatively low yield of the product.

The invention chain consists in increasing the yield of the target product.

This is achieved by the fact that methyl iodide in the presence of a rhodium or iridium or osmium catalyst and CO or iodoacetyl acetyl is reacted with methyl acetate or dimethyl ether in a divider medium at a temperature of 45-225 C.

In a preferred variant of this method. Acetyl iodide is obtained by reacting carbon monoxide with methyl iodide in the presence of a Group W111 Metal as a catalyst. The resulting acetyl iodide is reacted with methyl acetate or dimethyl ether. Acetic anhydride is obtained and methyl iodide is regenerated. The latter is separated from the desired product and recirculated to the step of obtaining sheztil iodide a.

Another preferred embodiment of the present invention is that methyl iodide and methyl acetate or dimethyl ether are heated in the presence of carbon monoxide and a catalyst in a carbon metal group, followed by separation of the reaction mixture, for example, fractional ne. by distillation ..

The use of this method will result in obtaining acetic anhydride with a yield close to the calculated value, taking into account the methyl acetate or dimethyl ether that has entered into the reaction, and also makes it possible to exclude the use of high pressure,

Example 1. 3.7 parts by weight, methyl acetate and 8.5 parts by weight acetyl iodide. Kip t t under reflux for 4 hours. Maintain the temperature in the reverse refrigerator at the level of 45-50 G, and the uncondensed steam from this refrigerator. The condensation is in the second refrigerator, in which the temperature is kept at 10 ° C. 2.8 parts by weight of the second refrigerator are collected. methyl iodide. together with 1-5.% methyl acetate and get in the cube residue containing 20 wt.% acetic anhydride (2.2 weight.h.). The remaining part of the cube residue is a mixture of unpressed methyl acetate and and monomer methyl.

Example 2, In a stainless steel autoclave with a stirrer lined with Hastellry B alloy, in an atmosphere of oxide

carbon (Р61,3-41,5 kg / cm, Р

Partz

2 o

7.0 kg / cm) is heated at 175-2OO C

a mixture of 71 weight.h. methyl iodide and 0.83. weight.h. rhodium trichloride hydrate with zoo weight.h, methyl acetate. After 3 hours, 0.7 mol of carbon monoxide is absorbed per 1, O M of methyl iodide.

Analysis of the mixture according to gas chromatographic analysis gives 7.79 & acetyl iodide and 8.7% acetic anhydride. The remainder of the reaction mixture consists of unreacted reactants and a catalyst. The autoclave is cooled, purged with air, and the reaction mixture is discharged. It is diluted with HU weight.h. nonane to facilitate separation and distilled at atmospheric pressure on an Oldershaw column; Methyl iodide and methyl acetate are distilled off at 45-37 ° C, then 18.7 parts by weight are taken. Acetyl iodide fraction with m. bale. 10-8-111 C and the fraction of acetic anhydride-nonane with m. Kip. 113127, 5 C. Separate the phase with a low, boiling point of 21.6 parts by weight. pure acetic anhydride (according to gas chromatography and IR spectroscopy). The resulting ethyl iodide is used for the synthesis according to the method of Example 1.

Example 3. In an autoclave, made of stainless steel with a stir bar, lined with spasm Hastella B, in an atmosphere of carbon oxide 41, 5 kg / cm} of the genus (Р 7О, 3 kg / cm Р

parts

heated at 20 ° C. mixture ZOR weight.h. methylacetate, 35 weight.h. methyl iodide and

1.6 weight.h. rhodium chloride hydrate. After 2 hours, 0.46 mole of carbon monoxide is absorbed onto 0.246 mole of methyl iodide.

The analysis of the mixture according to the gas chromatographic analysis shows the content of 15, U of acetic anhydride (4O parts by weight) and 4.5% of acetyl iodide (11.9 parts by weight). The remainder of the reaction mixture consists of unreacted reagents and catalysts.

Example 4. In a rotating vessel lined with glass for 16 hours in an atmosphere of carbon monoxide (P21.1 kg- /

 TI aOIX

. / CM-) heated at 175. With a mixture of 6 parts by weight methyl acetate, 0.7 weight.h. methyl iodide and O, 1 weight.h. rhodi chloride. .

. The analysis of the mixture according to gas chromatographic analysis shows the content of 10% of acetic anhydride (0.6 parts by weight) and 2.8% of acetyl iodide (0.17 parts by weight). Remaining part of the reaction mixture is the same as shown in examples 2 and 3.

Example 5. Ek rotating glass-lined vessel for 16 hours in an atmosphere of carbon monoxide (P24.6

2 ° P kg / cm) are heated at 175 ° C with 6 parts by weight. me-

tilatacet, 0.7 weight.h. methyl iodide and O, 1 weight.h. iridine iridium.

Analysis of the mixture according to gas chromatographic analysis shows the content of 15% acetic anhydride (0.9 parts by weight) and 2.8% acetyl iodide (0.17 parts by weight) and the mixture with unreacted reagents and catalyst.

Example 6. In a stirred stainless steel autoclave in an atmosphere of carbon monoxide (P 56.2 kg / cm, P

2o

8.8 kg / cm) is heated at 15 ° C mixture

ZOO weight.h. methyl acetate, 182 weight.h. dimethyl ether, 8.8 weight.h. lithium iodide, 65 weight.h. methyl iodide, 3 weight.h. hydrate of 3 r.pium chloride and 3 parts by weight powdered metallic chromium. After 1 hour an analysis of the mixture according to gas-chromatographic analysis shows the content of 54% acetic anhydride (4O7 parts by weight) and 31% methyl acetate (233 parts by weight). The remainder of the mixture consists of unreacted reactants, intermediates, and catalytic components.

П Р and м.е Р 7. In a stirred tank lined with glass in the atmosphere

carbon dioxide (P 24.6 kg / cm, P

parts

4.64 kg / cm) is heated at 15 C a mixture of 15O weight.h. methyl acetate, 0.75 weight.h. Rhodi trichloride hydrate, 18.5 parts by weight methyl iodide, 1.0 weight.h. powdered metallic chromium and 3 full. titanium dioxide. Analysis of the mixture 4 hours after the start of the reaction, according to a gaochromatographic analysis, shows the content of 39% acetic anhydride (81 parts by weight). . . Example 8. In a stirred container lined with glass in the atmosphere. carbon monoxide (P 24.6 kg / cm, R. par. OO 4.64 kg / cm) heated at 175 C a mixture of 15O weight.h. methyl acetate, O, 75 wt ,, ,, trichloride hydrate {zod, 18.5 wt.h. yo disty methyl and 5.7 weight.h. carbonyl chromium. Analysis of the mixture 4 hours after the start of the reaction, according to gas chromatographic analysis, shows the content of 51% acetic anhydride (SW weight.h.). Example 9. In the mixed bone lined with glass, in a carbon monoxide atmosphere (P 24.6 kg / cm, P, 64 kg / cm), at 175 C, the mixture is heated to 150 parts by weight. methyl acetate, 0.75 weight.h. hydrate trichloric rhodi, 1.0 weight.h. powdered metallic chromium, 2.5 wt. alumina and 18.5 parts by weight iodide methyl Analysis of the mixture according to gas chromatographic analysis. 4 hours after the reaction time, the content of 59% acetic anhydride is shown (122 parts by weight). Example 10. In a measured container, lined with glass, in an atmosphere of carbon monoxide (P 4.64 kg / cm) a mixture of 150 parts by weight is heated. methyl acetate, O, 75 weight.h hydrate of rhodium trichloride, 37 weight.h. methyl iodide, 2.2 parts by weight carbonyl chromium and 1, O weight.h. Atiomini oxides. Analysis of the mixture according to gas chromatographic analysis after 3 hours after the start of the reaction shows the content of 56% acetic anhydride (127 parts by weight). Note: P 11. In a stirred stainless steel autoclave in an atmosphere of carbon monoxide (P 24.6 kg / cm, P par. -. 4.64 kg / cm) at 175 ° C heating) tmM 6OO 6 . methyl acetate, 3.5 weight.h. methyl iodide, 7 o weight.h. lithium iodide and 3, About weight.h. Rhodi chloride hydrate; After 8 hours analysis of the mixture according to gas chromatographic data, after the beginning of the reaction, the content of 78.4% acetic anhydride (707 parts by weight) is shown. Example 12 In a stirring stainless steel toklav in an atmosphere of carbon monoxide (Р 7О, 3 kg / cm Р 22.5 .- .. kg / cm) at 225 ° С nb Heat a mixture of 30% of weight. methyl acetate, 35 weight.h. methyl iodide and 2.2 wt.h, iridium trichloride, Analysis of the mixture according to gas chromatographic analysis 14 hours after the start of the reaction, shows the content of 22% acetic anhydride. The remaining part of the mixture consists of unreacted reagents, intermediate products and a catalyst. Example 13. In a stirred container lined with glass, in an atmosphere of carbon monoxide (P 24.6 kg / cm, P 4.92 kg / cm) at 175 ° C heat the mixture 15O weight, and methyl plastic, 18.5 parts by weight. methyl iodide, 0.75 weight.h. Rhodi trichloride hydrate, 1.0 weight.h. powdered metallic chromium and 7.0 weight.h. sodium methylate. Analysis of the mixture according to a gas chromatographic analysis 4 hours after the start of the reaction, shows the content of 22.5% acetic anhydride (41.5 parts by weight). P P and ivi e P 14. In a glass container lined in an atmosphere of carbon monoxide (P 24.6 kg / cm, P4.92 parts. Kg / cm when the mixture is heated 15 O.W. Of methyl acetate, O, 75 weight. including hydrate, three sulfuric rhodi, 1.5 parts by weight hexacarbony la molybde), 16.0 parts by weight iodide Metipa and .2.5 wt.h. lithium iodide.: Analysis of the mixture according to gas chromatographic analysis after 4 hours after the beginning of the reaction shows the content of 40.0% acetic anhydride (82.7 parts by weight). Example 15. In a stirred stainless steel autoclave in an atmosphere of carbon monoxide (P 56.2. Kg / cm, P.. Arc. 8.4 kg / cm) at 150 ° C heat the mixture 19O weight.h. dimethyl ether, 300 vbs. methyl acetate, 7 4 weight, h. methyl iodide. n 3, About weight, h. trichlorus parents Analysis of the mixture according to gas chromatographic analysis 2 hours after the start of the reaction, shows the content of 76% methyl acetate (489 parts by weight): and a small amount of acetic acidic acid, P – P e ≤ 16. In a stirred autoclave made of stainless steel in an atmosphere of carbon monoxide (P 56.2 kg / cm 2 O kg / cm) at 11 ° C heat the mixture 37 5, parts by weight dimethyl ether, 7 5 weight.h. Iodine methyl and 3 wt.h, hydrate of trichloro horny. The analysis of the samy by daznny gas chromatograph of the analysis at 2 h after the start of the reaction shows the content of 16.3%. m & tilatsetat (80 weight.h.) and 2.4% acetic anhydride (12 weight.h.).

78,

Claims (2)

1. The method of obtaining .Angus angizri-Sources: information taken in question about the fact that, in the examination: by increasing the yield of the target product, Weigand-Hipgetag1 Methods of experimental methyl in the presence of a rhodium or cop in organic chemistry, Chemistry, fA.t iridium, or osmium catalyst i1968, p. CO or acetyl iodide is subjected to mutual 2. Buhler, K., Pearson. Jlf Organic exposed to methyl acetate or dimethyl syntheses. Peace, M., 1973, Part 2, p. 369 589908 45-225 ° C.