CS259388B1 - Method of 2-alkoxyprene production - Google Patents

Abstract

Production of 2-alkoxypropene of general formula I, wherein R is an alkyl of 1 carbons to 3, catalyzed by the addition of Cx to C3 to the alene and / or methylacetylene to the mixture with other hydrocarbons in liquid or gaseous phase at a temperature of 8 to 280 ° C the crude product separates the alcohol or alcohols by extraction, extraction distillation, especially by extraction rectification using either water or diluted aqueous alkali metal hydroxide pitch (aqueous) sodium hydroxide solution or hydroxide potassium). Extraction agent is subsequent separation of alcohol or Ct alcohols to C3, and additional impurities will occur. Make them suitable for use in the chemical industry pyrolysis C3-fraction residues and 2- -alkoxypropenes.

Description

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

It is known that the reaction of alene and methylacetylene with alcohols under the catalytic action of basic catalysts results in the formation of alkali catalysts. isopropenylalkylethers, respectively. 2-alkoxypropén:

(-)

OH

CH ₃ C = CH + CH _{2 s} C = CH ₃ + ROH ------ CH ₃ COR ch ₂

Thus, the addition of methanol in the gas or liquid phase at a temperature of about 200 ° C results in 2-methoxypropene and the addition of ethanol 2 (1,2-propadiene), respectively. its mixture with methylethoxypropene. For the production, allene is used by cetylene, which are isolated mainly from the distillation residue from propene production by pyrolysis. Extraction rectification using toxic acetonitrile and other organic extracting agents is mainly used for such isolation.

On the basis of such a mixture of the 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, the raw product also contains unconverted starting materials, from which these can also be separated in the form of azeotropic mixtures, which are generally recirculated. However, this method cannot be used when using an allene-methylene-ethylene donor pyrolysis residual C ₃ -fraction, containing essentially, mostly, in addition to the alene and methylacetylene, mainly propene, propane, and possibly other hydrocarbons. In this case, with all the hydrocarbons, the azeotropic mixture forms unconverted methanol, ethanol, 1-propanol and 2-propanol, and optionally 2-alkoxypropene.

However, according to the present invention there is provided a process for the preparation of 2-alkoxypropene of the general formula

CH ₃ COR '11 CH ₂ wherein R is an alkyl having a carbon number of 1 to 3, catalyzed by the addition of a C 1 -C 3 alcohol; to C ₃ or> mixtures thereof to allene and / or methylacetylene in the liquid and / or gas phase at a temperature of 80 to 280 ° C, wherein the unconverted hydrocarbons are separated and optionally recirculated by carrying out the alcohol

C 1 to C 3 selectively adds to the allene and / or methylacetylene present at a concentration of 5 to 90% by weight. when mixed with other hydrocarbons and the crude product is separated by alcohol or. alcohols, C, to C ₃ extraction and / or extractive distillation, preferably extractive rectification, by the action of water and / or aqueous solution of an alkali such exxtrakčného agent, wherein the extraction medium is typically subsequently separating the alcohol or alcohols, C _t to _C, and optionally other organic impurities.

An advantage of the process according to the invention is the possibility, even without any pretreatment, of using the residual pyrolysis C ₃ fraction as the donor of allene and methylacetylene. Then, achieving high efficiency using water or an aqueous solution of alkaline or recirculated water hydroxide as the extracting agent. Last but not least, increased occupational safety and very good reproducibility of production, while residual allene and methylacetylene, depending on needs, can also be converted to acetone.

The raw material for the production of 2-alkoxypropene in addition to alcohols up to C ₃ (methanol, ethanol, 1-propanol, 2-propanol), pure alene and methylacetylene or mixtures thereof is primarily residual C ₃ fraction from medium and high temperature pyrolysis, usually 14-48 % wt. naphthalene mixtures of methylacetylene, the balance for 100% consisting of propene, propane, ethylene, ethane, and optionally ingredient C ₄ hydrocarbons and sulfur compounds.

The catalysts of addition of alcohols C _t to C ₃ to naphthalene and methyl acetylene are effectively selective catalyst, such as oxides, alkoxides, hydroxides of alkali metals and earth metals, alone or on carriers ·. Furthermore, oxides, hydroxides and salts of zinc, cadmium, mercury, titanium alone or on supports, in particular on activated carbon, coke, alumina, cre259388

6 microbes, aluminosilicates, natural or synthetic, in particular modified zeolites. Then anions, silica and alumina with the addition of palladium or silver, semi-burnt dolomite granulated or crushed concrete.

The extracting agent is water or an aqueous solution of an alkali metal hydroxide, most often in a concentration of 0.1 to 5% by weight, in particular an aqueous solution of sodium hydroxide, potassium hydroxide. A dilute aqueous solution of an alkali metal hydroxide according to the invention is understood to include an aqueous solution of a mixture of alkali metal hydroxides as well as an alkali metal alcoholate with a C1-C12 alcohol _. .

Aqueous solutions of alcohols obtained from the extraction or extraction distillation of methanol can easily be recovered by distillation or distillation. rectification. In the case of alcohols, C ₂ and C ₃ is a suitable azeotropic distillation, using known ternary azeotropic mixture, by selective adsorption of water hydrophilic, water-insoluble, but water-swellable polymers, and as copolymers (cellulose derivatives such as hydroxyethyl cellulose), etc..

The production method of the invention can be carried out continuously, semi-continuously or continuously.

Further data on carrying out the method of the invention as well as other advantages are evident from the examples.

Example 1

From the reaction stage of the synthesis of 2-methoxypropene through a gas separator, a continuous rectification column, whose enrichment part has 22 and o-losing 15 theoretical stages, the column is equipped with 2 injection sites, a reboiler and a rectifying head, is fed to 16 theoretical stage at at a temperature of 22 to 30 ° C a "degassed" reaction mixture in an amount of 100 gh ^-1 . This reaction mixture has the composition (in wt.%): 36.1% 2-methoxypropene, 62.8% wt. % methanol and 1.1% alene / methylacetylene, propene and propane. At the top of the column at 38 theoretical, water is injected at a rate of 100 gh ^-1 at a temperature of 22 to 25 ° C, with control in the range of 20-70 ° C. After equilibration, the temperature of the reboiler 78 ° C and the head temperature 30 to 34 ° C for distillate to be removed at approximately 30.5 cm ⁹ .h ¹ and the distillation residue 169.5 cm ^3rd h ^_1 .

The distillate contains 98.5 ± 0.5 wt. % Of 2-methoxypropene, 0.05 to 0.2 wt. % methanol, 0.6 to 1.0% w / w; acetone; the rest are C ₃ hydrocarbons, and 2,2-dimethoxypropane Mr.

Methanol and acetone are then distilled off separately from the distillation residue, with methanol returning to the synthesis stage and alcohol-mixed water to the continuous extraction rectification stage.

Example 1 and d 2

The procedure is similar to that in Example 1 except that 100 g is injected instead of water as the extractant. h ¹ of 1% by weight aqueous potassium hydroxide solution. However, the distillate contains 98.9 ± 0.5 wt. % Of 2-methoxypropene, 0.002 to 0.05 wt. % methanol and 0.5 to 0.7 wt. acetone, followed by admixtures of hydrocarbons and 2,2'-dimethoxypropane.

Example 1 and d 3

490 cm @ ^{3 of} methanolic potassium hydroxide solution having a concentration of 30% by weight are pumped into a nitrogen-purged continuous pressure reactor. Thereafter, the pressure in the apparatus is adjusted to 4 MPa by passing nitrogen. The preheated methanol will draw at 100 to 130 ° C in an amount of 93 cm ³ .h ^J and pyrolysis residual C ₃ solvent system B, in an amount of 123.5 g. h ^_1 containing 31% by weight. mixtures of methylacetylene with alene (propadiene) of the following composition (in% by weight): propane = 47,8; propene - 19.2; acetylene = 0.31; isohutylene = 0.53; allen = 13.4; methylacetylene 17.6 and butadiene = 0.90.

The temperature of the reactor containing the reactants is 185 + 3 ° C. 216 g are obtained. h ^{-1 of the} crude product of the following composition (in% by weight): 2-methoxypropene = 19.3; allen = 1.48; methylacetylene = 4.67; methanol = - 38.6; propane - 25.7; propene = 10.22 and acetylene - 0.25.

The gaseous constituents are largely separated in a separator and the remainder, after addition of 0.1% hydroquinone as polymerization inhibitor, results in an extraction rectification similar to that described in Example 1, with an extraction agent of 80 pens. wt. the weight of the residue is water. 2-Methoxypropene of 98.1% by weight is obtained, the methanol content being 0.11 to 0.20% by weight. The yield of 2-methoxypropene on feed propadiene and methylacetylene was 61.5 wt. at their conversion of 62.9 ° / o. Example 4

The procedure is similar to that in Example 3, but only 0.5% by weight of methanolic potassium hydroxide solution is added. powdered sodium. This increases the conversion of the mixture of allene and methylacetylene to 68.3% and the yield of 2-methoxypropene to 66.1%.

Example 5

An isopropanol solution containing 25 wt. of sodium isopropyl alcohol, and instead of methanol, a dilute solution (0.3 wt.%) of sodium hydroxide is added to the reactor at 193 + 3 ° C. powdered sodium in isopropyl alcohol. At a feed rate of 123 cm @ ^-1 of isopropyl alcohol solution and 95 gh ^{@ -1 of the} residual C. fraction specified in Example 3, the conversion of the alene with methylacetylene was 63.2% and the yield of 2- (2-propoxy) propene was 61.9%.

Example 6

A " degassed " crude reaction mixture as specified in Example 1 in an amount of 100 g is fed to a continuous reactor. h ^-1 together with an extraction agent of 100

% gh ^-1 consisting of 0.9% by weight aqueous sodium hydroxide solution. so that the residence time is at least 15 min. The reaction mixture is then sent to a separatory funnel. The organic phase containing the "crude" 2-methoxypropene (2-methoxypropene content 96.5% by weight, water 1.1%, hydrocarbons 0.23% and the remainder being methanol) is led to rectification. a column where recovered methanol is removed as the main product and the digestion residue (aqueous methanolic sodium hydroxide solution) is returned to the extraction.

Claims (1)

Process for preparing 2-alkoxypropene of general formula CH ₂ CR ₂ in which R is alkyl of number of carbons 1 to 3, catalyzed by the addition of alcohol C _t to C ₃ or mixtures of the naphthalene and / or methyl acetylene in the liquid and / or gas phase at a temperature of 80 to 280 ° C and unconverted uVYNALEZU hfovodíky are separated and optionally recirculated, characterized in that the alcohol C _(and C ₃ selectively coupled with the naphthalene and / or methyl acetylene at 5 to 90% by wt. in admixture with other hydrocarbons, and the crude product is separated by alcohol or alcohols, C _t to C ₃ extraction and / or by extraction distillation, preferably by extraction rectification, by treatment with water and / or aqueous alkali hydroxide solution as the extraction agent, the alcohol or C 1 -C ₃ alcohols and possibly other organic impurities as a rule being subsequently separated from the extracting agent.