CS262799B1 - Process for producing 2-alkoxypropene - Google Patents

Abstract

Production of 2-Alkoxypropene of the general formula OR / CH5C=CH2, in which R is alkyl with 1 to 3 carbons, by catalyzed addition of Cl to C3 alcohol to allene and/or methylacetylene in a mixture with other hydrocarbons in the liquid or gas phase at a temperature of 8 to 280 °C, so that the alcohol or alcohols are removed from the raw product by extraction, extraction distillation, especially extractive rectification using an aqueous solution of at least one Cl to C3 alcohol or an aqueous solution of alkali metal hydroxide with at least one Cl to C3 aliphatic alcohol. The alcohol or alcohols Cl to C3 are subsequently separated from the extraction agent and other impurities are added. The method is suitable in the chemical industry for the use of residues of the pyrolysis C3-fraction and the production of 2-alkoxypropenes.

Description

262799 3 4

The present invention provides a process for the preparation of 2-alkoxypropene by selective addition, in particular of 2-methoxypropene, 2-ethoxypropene, 2-propoxypropene and isopropyloxypropene, methanol or ethanol or propanols to the alene and / or methyl acetylene in admixture with other hydrocarbons, the unconverted starting alcohol is effectively removed by extraction using a readily available extraction agent.

It is known that the reaction of the alene and methylacetylene with alcohols under the catalytic action of basic catalysts results in the formation of isopropynyl alkyl ethers, respectively. 2-alkoxypropene:

CH 2 Cl 2 CH 3

Thus, the addition of methanol in the gaseous or liquid phase at about 200 ° C results in 2-ethoxy-propene and 2-ethoxy-propene by addition of ethanol. For production is used alene (1,2-pro-pandiene), respectively. its mixture with methylacetylene (propyne), which is isolated mainly from the desilator residue from propene production by pyrolysis. In particular, extraction rectification using toxic acetonitrile and other organic extraction reagents is used for such isolation. Based on such a mixture with methylacetylene catalyzed by the addition of methanol and / or ethanol, essentially 2-alkoxypropenes are formed. In the crude product, in addition to the main product, there are still unconverted starting materials, which can also be separated in the form of azeotropic mixtures which are generally recirculated. However, this method cannot be utilized for use as an alene donor with a methylacetylene residual pyrolysis C3-fraction, containing mainly propene, propane, and, in particular, other hydrocarbons, mainly in the majority of the alene and methylacetylene. In this case, with all the hydrocarbons, the non-converted ethanol, ethanol, 1-propanol and 2-propanol form an azeotropic mixture, optionally also 2-alkoxypropene.

However, according to the present invention, there is provided a process for the preparation of 2-alkoxypropene of the general formula CH3COR in which the carbon number of CH2 is 1-3 catalysed by the addition of alcohol C1 to C3 or a mixture thereof to alkene and / or methyl acetylene in liquid and / or gaseous phase. 80 DEG-180 DEG C., whereby the unconverted hydrocarbons and alcohols are separated, optionally recirculated, by the alcohol C1 to C3 being selectively added to the alkali and / or methylacetylene contained in a concentration of 5 to 90% by weight. in admixture with other hydrocarbons and from the crude product, the alcohol or alcohols C1 to C3 are separated by extraction and / or extraction distillation, preferably by extraction rectification, by treatment of an aqueous solution of at least one alcohol C 1 to C 3 with subazeotropic water concentration or a mixture of an aqueous alkali metal hydroxide solution with at least one aliphatic alcohol C1 to C3. Subsequently, the alcohol or alcohols C1 to C3 are separated from the extractant, followed by additional organic mixtures. The advantage of the method of the present invention, even without any pretreatment, is to use the residual pyrolysis C3 fraction as an alene donor and methyl acetylene donor and thus to evaluate it more economically and economically than it is usually evaluated by palladium selective hydrogenation. Thereafter, it achieves high efficiency by using an aqueous solution of the alcohol or alcohols C1 to C3, or a mixture of an aqueous solution of alkali metal hydroxide and an alcohol C1 to C3 as the extraction agent. Utilization of the possibility of ternaryazeotropic. Last but not least, increased work safety and very good reproducibility of production, with residual alene amethylacetylene, depending on the needs, can also be converted to acetone.

The raw material for the production of 2 alkoxypropene o-alcohols of C1 to C3 alcohols (methanol, ethanol, 1-propanol, 2-propanol), pure alene and methylacetylene or mixtures thereof is, in particular, the residual C3-fraction from medium to high temperature pyrolysis. Containing typically 14 to 48 wt. mixtures of alene with methyl acetylene, the remainder up to 100% being propene, propane, ethylene, ethane, and mixtures of C4 and S.

The catalysts for the addition of alcohols C1 to C3 with naphthalene and methylacetylene are in fact selective catalysts, such as oxides, alkoxides and hydroxides of alkali metals and soils or on carriers. Further, the oxides, hydroxides and salts of zinc, cadmium, mercury, titanium alone or on carriers, especially on activated carbon, coke, alumina, silica, nitro silicates, natural or synthetic, especially modified zeolites. , silica and palladium-added aluminum oxide. or silver, semi-burnt dolomite granulated or crushed concrete.

The extractant is an aqueous solution of at least one alcohol C 1 to C 3 with a sub-tropic concentration of water, mainly from the water-free removal of water from the crude reaction product or alkali metal hydroxide mixture in the aqueous solution with at least one aliphatic C1 to C3 alcohol. Most often, the concentration of acetic water and sodium hydroxide or 262799 potassium hydroxide in the aqueous alcoholic solution is 0.1 to 10% by weight. The dilute aqueous alcoholic alkali metal hydroxide solution of the present invention also comprises an aqueous alcoholic solution of a mixture of alkali metal hydroxides such as alkali metal alcohol alcohols with an alcohol C1 to C3.

The aqueous alcohols obtained from the extraction or extraction distillation can be easily recovered by distillation or distillation in the case of methanol. rektiflkáciou. In the C2 to C3 alcohols, azeotropic distillation, using known ternary azeotropic mixtures, is suitable for selectively adsorbing water with hydrophilic, water-insoluble but water-only swellable polymers and copolymers (cellulose derivatives such as hydroxyethyl cellulose and the like).

The production method of the present invention may be broken, semi-continuous or continuous. Further details of carrying out the method of the invention, as well as other advantages apparent from the examples. EXAMPLE 1 From the reaction step of the synthesis of 2-methoxypropane via a gaseous component separator to a batchwise rectification column having a richening portion of 22 and a depleting 15 theoretical degrees, wherein the column is provided with 2 injection sites, a reboiler and a rectification head at 16 theoretic the stage is sprayed at 22 to 30 degrees Celsius with a "degassed" reaction mixture of 100 g. li-1. This reaction mixture composition (in wt.%): 36.1% 2-methoxypropene, 62.8% wt. methanol and 1.1% of a mixture of alene with methylacetylene, propene and propane. A 10% w / w aqueous solution of methanol is injected into the top of the column at the theoretical stage. water in an amount of 100 g. h1- at a temperature of 22 to 25 ° C, with regulation in the range of 20 to 70 ° C. After equilibration, at a boiling temperature of 78 ° C and a column head temperature of 30 to 34 ° C, the distillate is collected in an amount of about 30.5 cm 3. h-1 and a residue of 169.5 cm 3. h "1.

The distillate contains 97.5 ± 0.5 wt. 2-methoxypropene, 0.65-0.8% wt. % methanol, 0.6 to 1.0 wt. acetone; residual hydrocarbons C3 and Ι, Γ-dimethoxypropane. The methanol and acetone are then separately distilled from the distillation residue, returning the methanol to the synthesis stage and methanols by adding water to the continuous extraction rectification step. Example 2

509 cm @ 3 of water-methanolic sodium hydroxide solution (9% by weight) are pumped into the nitrogen-purged continuous pressure reactor. % methanol and 3 wt. potassium hydroxide.

The pressure in the apparatus is then adjusted to 4 MPa by passage of nitrogen. Thereafter, the preheated methanol is started to a temperature of 100 to 130 ° C in an amount of 93 cm 3. h-1 and the residual pyrolysis C3-fraction in 123.5 g / h < 3 > mixtures of methylacetylene with an alene (propane diene) of this composition (in% by weight): propane = 47.8; pro-pene = 19.2; acetylene = 0.31; isobutylene - = 0.53; alene = 13.4; methylacetylene-17,6a butadiene = 0.90. Reactor temperature is 189 + 3 ° C. 218 g are obtained. h-1 crude product of this composition (in% by weight): 2-methoxypropene = 19.3; alene - 1.48; methylacetylene = 4.3, methanol = 39.4; propane = 25.1; propene == 10.2 and acetylene = 0.25.

The gaseous components are largely separated in the separator and the residue, after the addition of 0.1% hydroquinone as polymerization inhibitor, results in an extraction recticell similar to that described in Example 1, with the extractant being 80% by weight. the weight of the residue is an aqueous solution of methanol at a concentration of 12% by weight. 2-methoxypropene is obtained with a purity of 98.1% by weight, with a methanol content of 0.45 to 0.65%. wt. The yield of 2-methoxypropene on propadiene and methylacetylene is 61.5% by weight. at their conversion of 62.9%

The procedure is similar to that of Example 1, with only 2-propanol containing 5% by weight of the extractant. water. The distillate contains 98 + 0.5 wt. 2-methoxypropene, 0.02-0.2per. wt. % methanol, 0.01 to 0.1% by weight of 2-propanol, 0.5 to 0.8% by weight. acetone, the remainder being hydrocarbons C3 and 2,2'-dimethoxypropane. The methanol and acetone are then separately distilled from the distillation residue, returning the methanol to the synthesis step and 2-propanol with methanol and water to a continuous extraction rectification step. Example 4

The degassed crude reaction mixture specified in Example 1 at 100 g is fed to a continuous reactor. h-1 with an extractant of 100 g, h-1 consisting of a water-propanol solution of sodium hydroxide at a concentration of 12% n-propanol and 1.2% w / w. sodium hydroxide such that the residence time is less than 15 minutes. The reaction mixture is further withdrawn into a separator. The organic phase containing the "crude" 2-methoxypropene (2-methoxypropene content of 96.5% by weight, water of 1.4%, hydrocarbons of 0.23% and the remainder being methanol and n-propanol) is rectified . The water layer from the separator is fed to a methanol column, where the recovered methanol is recovered as the main product and the boiling residue (soda-water hydroxide solution) is returned to the extraction.

Claims (1)

262799 SUBJECT A method for producing 2-alkoxypropene of the general formula CH3COR in which R is an alkyl of CH2 carbon atoms of 1 to 3, catalyzed by the addition of C1 to C3 alcohols or mixtures thereof to the alene and / or methylacetylene in the liquid and / or gas the non-converted hydrocarbons are separated and optionally recirculated, characterized in that the alcohols C1 to C3 are selectively added to the alene and / or methylacetylenes contained in the concentration 5 up to 90 wt. in a mixture with other angles and with the crude product, the alcohol or alcohols C 1 to C 3 are separated by extraction and / or extraction distillation, preferably by extraction rectification by treating an aqueous solution of at least one alcohol C 3 C 3 with a subazeotropic water concentration or a mixture of an aqueous solution of hydroxyalcal metal with at least one aliphatic alcohol C1 to C3, with the extracting agent generally separating the alcohol or alcohols C1 to C3 and additional organic impurities. Sevarograíla, n. P. Plant 7, Most Price 2.40 KCs