CS259388B1 - Process for producing 2-alkoxypropene - Google Patents

Abstract

Production of 2-Alkoxypropene of the general formula I, in which R is an alkyl having 1 to 3 carbon atoms, by catalyzed addition of an alcohol Cx to C3 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 crude product by extraction, extractive distillation, especially extractive rectification with using either water or a dilute aqueous alkali metal hydroxide solution (aqueous solution of sodium hydroxide or potassium hydroxide). The alcohol or alcohols Ct to C3 are then separated from the extraction agent and other impurities are added. The method is suitable in the chemical industry for the use of residues of pyrolysis C3-fraction and the production of 2- -Alkoxypropenes.

Description

259388

The present invention provides a process for the preparation of 2-alkoxypropene, in particular 2-methoxypropene and 2-ethoxypropene, by the selective addition of methanol and the like. ethanol for alene and / or methylacetylene with other hydrocarbons, wherein the unconverted methanol and / or ethanol is effectively removed by extraction using a readily available extractant.

It is known that the reaction of alene and methylation-ethylene with alcohols results in the catalytic action of basic catalysts. iso-propenylalkyl ethers, respectively. 2-alkoxypropene: (-)

OH

CH 2, C = CH + CH 2 CH = CH 3 + ROH ------> CH 3 COR ch 2

Thus, the addition of methanol in the gaseous or liquid phase at about 200 ° C results in 2-methoxypropene and the addition of ethanol 2- (1,2-propadiene), respectively. its mixture with methyl ethoxypropene. For production it is used by ethylene ethylene which is isolated mainly from the desilator residue from propene production by pyrolysis. In particular, extraction rectification using toxic acetonitrile and other organic extraction agents is used for such isolation.

On the basis of such a mixture of alene (1,2-propadiene) with methylacetylene (propyne) catalyzed by the addition of methanol and / or ethanol, essentially 2-alkoxypropene is formed, in addition to the main product there are still unconverted however, it is not possible to utilize this in the use of the acodone alene with methylacetylene residual pyrolysis Ca-fraction, containing in the form of azeotropic mixtures, which are generally recirculated. in the majority of cases, in addition to alene and methylacetylene, mainly propene, other hydrocarbons are present, in which case all of the hydrocarbons form azeo-trether a mixture of unconverted methanol, ethanol, 1-propanol and 2-propanol, optionally 2- alkoxypropene.

However, the present invention provides for the production of a 2-alkoxypropene of the general formula

CH3COR1111 in which R is an alkyl of 1 to 3, catalysed by the addition of alcohol C | to C3 and / or mixtures thereof for the alene and / or methylacetylene in the liquid and / or gaseous phase at 80 DEG-280 DEG C., wherein the unconverted hydrocarbons are separated and optionally recirculated; alcohol

C 1 to C 3 selectively add to the alene and / or methyl acetylene contained at a concentration of 5 to 90% by weight. in admixture with other hydrocarbons and from the crude product, the alcohol or alcohols C 1 to C 3 are separated by extraction and / or extraction by distillation, preferably by extraction rectification, by treating water and / or an aqueous solution of alkali hydroxide as the extracting agent, wherein the extracting agent is generally subsequently separated from the alcohol -hol or alcohols Ct to Ca and additional organic impurities are possible. An advantage of the process of the present invention, even without any pretreatment, is to use the residual pyrolysis C3 fraction as the alene donor and methyl acetylene. Then, achieving high efficiency by using water or an aqueous solution of alkaline or recirculated water as the extraction agent . Last but not least, increased work safety and very good re-producibility, with residual alkene and methylacetylene, depending on the needs, can also be converted to acetone.

The feedstock for the production of 2-alkoxypropene by the alcohols to C3 (methanol, ethanol, 1-propanol, 2-propanol), pure amethylacetylene allene or mixtures thereof is, in particular, the residual C3-fraction of medium-temperature and high-temperature pyrolysis, typically containing 14%. % to 48 wt. mixtures of alkene with methylacetylene, the remainder to 100% being propene, propane, ethylene, ethane, and optionally admixtures of C4 and sulfur compounds.

Catalysts for the addition of alcohols C1 to C3 and alkene and methylacetylene are, in fact, selective catalysts, such as oxides, alkoxides and hydroxides of alkali metals and soils, or on the carrier. Further, the oxides, hydroxides and salts of zinc, cadmium, mercury, titanium alone or on a carrier, in particular on activated carbon, coke, alumina, oxide oxide, aluminosilicates of natural or synthetic, especially modified zeolites. Then anionites, silicon dioxide and palladium or silver admixture, semi-burnt dolomite granulated or abraded concrete.

The extractant is water or an aqueous alkali metal hydroxide solution, most often at a concentration of 0.1 to 5% by weight, especially an aqueous solution of sodium hydroxide, potassium hydroxide. As the dilute aqueous alkali metal hydroxide solution of the present invention is meant: a) an aqueous solution of an alkali metal hydroxide mixture, such as an alkali metal alkoxide with an alcohol C 1 to C 18 alkyl.

The aqueous alcohols obtained from the extraction or extraction distillation can be easily recovered by distillation or distillation in the case of methanol. rectification. In the C2 to C3 alcohols, azeotrope-picking is suitable, using known ternaryazeotropic mixtures, selective adsorbent water by hydrophilic, water-insoluble, but water-only swelling polymers and copolymers (cellulose derivatives such as hydroxyethyl cellulose) ap.

The production method of the present invention can be broken, broken or continuous. Further details of the implementation of the present 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 continuous rectification column, the richer portion of which has 22 and 15 poor theoretical degrees, wherein the column is provided with 2 injection sites, a reboiler and a rectification head, 100 gh-1 of the "degassed" reaction mixture was injected at a temperature of 22 to 30 ° C to a 16-thet degree. This reaction mixture has a composition (in% by weight): 36.1% 2-methoxypropene, 62.8% methanol and 1.1% blend with methylacetylene, propene and propane. water at 100 gh-1 is injected at a temperature of 38 ° C at a temperature of 22 to 25 ° C, with a control possibility in the range of 20-70 ° C. After equilibration, at a boiling temperature of 78 ° C and temperature about 30.5 cm @ 2 / h of distillate and 169.5 cm @ 3 of distillation at the top of the column at 30 DEG -34 DEG C. are used.

The distillate contains 98.5 + 5, 5% by weight. 2 - methoxypropene, 0.05 to 0.2 wt. of methanol, 0.6 to 1.0% by weight; acetone; the hydrocarbons are C3 and 2,2'-dimethoxypropane. The methanol and acetone are then separately distilled off from the distillation residue, returning the methanol to the synthesis stage and adding water to the continuous extraction rectification stage. Example 1

The procedure is similar to that of Example 1, but instead of water as the extraction agent, 100 g of 1% aqueous potassium hydroxide solution at a concentration of 1% by weight is sprayed. 2-methoxypropene, 0.002 to 0.05% by weight of methanol and 0.5 to 0.7% by weight; acetone, another admixture of hydrocarbons and 2,2'-dimethoxypropane. Example 3

A nitrogen pressure of 490 cm < 3 > of methanolic potassium hydroxide solution at a concentration of 30% by weight is pumped into the continuous nitrogen pressurized reactor. The pressure in the apparatus by passing nitrogen through to 4 MPa. Thereafter, pre-warmed methanol is pumped to a temperature of 100 to 130 ° C in an amount of 93 cm -1 and a residual pyrolysis C3-fraction of 123.5 g. h_1 with a content of 31 wt. mixtures of methylacetylene with salen (propadiene of this composition (in% by weight): propane = 47.8; propene - 19.2; a-cetylene = 0.31; isobutylene = 0.53; alene = 13.4; methylacetylene - 17 , 6 and butadiene = 0.90.

Reactor temperature is 185 ± 3 ° C. 216 g of h isurated product of this composition (in% by weight): 2-methoxypropene = 19.3; alene == 1.48; methylacetylene = 4.67; methane-1 = -38.6; propane - 25.7; propene = 10.22 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 rectification similar to that described in Example 1, with an extractant in the amount of 80%. wt. the weight of the residue is water. 2-Methoxypropene of 98.1% by weight is obtained, with a methanol content of 0.11-0.20% by weight. The yield of 2-methoxypropene sprayed with propadiene and methylacetylene is 61.5% by weight. at their conversion of 62.9 ° / o. Example 4

A procedure similar to that of Example 3 is followed, with 0.5% by weight being added to the methanolic potassium hydroxide solution only. powder powder. This will increase the conversion of the mixture of alene with methylacetylene to 68.3% and the yield of 2-methoxypropene to 66.1%. Example 5

In a similar manner to that described in Example 4, an isopropyl alcohol solution containing 25 wt. sodium isopropyl alcoholate and instead of methanol at a reactor temperature of 193 + 3 ° C is a dilute solution (0.3% w / w) of hydroxy-

Claims (1)

259388 du sodium with 0.1 wt. powdered sodium in isopropyl alcohol. With the addition of 123 cm < -1 > of isopropanol / 95 g < -1 > of residual C3-fraction specified in Example 3, an alene / methylacetylene conjugate of 63.2% and 2- (2-propoxy) yield is obtained. ) of 61.9%. EXAMPLE 6 A degassed crude reaction mixture specified in Example 1 was fed to a continuous reactor at 100 g. with an extraction agent of 100 gh-1, consisting of an aqueous solution of sodium hydroxide at a concentration of 0.9% by weight, so that the residence time is at least 15 minutes. The reaction mixture is further discharged into the separator. -Methoxypropene (2-methoxypropene content 96.5 wt%, water 1.1%, hydrocarbons 0.23% and the rest are methanol) is led to rectification. The aqueous layer from the separator is passed through a methanol column, where the recovered methanol is collected as the main product and the boiling residue (aqueous-methanolic sodium hydroxide solution) is returned to the extraction. SUBJECT A process for producing a 2-alkoxypropene of the general formula CH 2 COOR 11 CH 2 in which R is an alkyl of from 1 to 3, catalyzed by the addition of C 1 to C 3 alcohol or mixtures thereof to the alene and / or methylacetylene in liquid and / or gas phase at wherein the nonconverted hydrocarbons are separated and optionally recirculated, characterized in that the alcohol C (up to C 3 is selectively added to the alene and / or methyl acetylene at a concentration of 5 to 90% by weight). the mixture with other hydrocarbons and from the crude product separates the alcohol or C-C až C3 alcohol by extraction and / or extraction by distillation, preferably by extraction rectification, by treating water and / or aqueous solution of alkali hydroxide as the extraction agent, usually from the extraction agent subsequent separation of the alcohol or alcohols C 1 to C 3 and additional organics admixtures Severografla, op race 7, Moat Price 2.40 KCa