WO2018036848A1

WO2018036848A1 - Vinylation with acetylene in the presence of water

Info

Publication number: WO2018036848A1
Application number: PCT/EP2017/070530
Authority: WO
Inventors: Veit WASCHOLOWSKI; Franz Niklaus Windlin; Pavel TUZINA; Pierre Fournier
Original assignee: Basf Se
Priority date: 2016-08-23
Filing date: 2017-08-14
Publication date: 2018-03-01

Abstract

The invention relates to a method for producing a vinyl compound by vinylating a starting compound having at least one primary or secondary amino group, at least one hydroxyl group, or at least one thiol group with acetylene, characterized in that the vinylation is performed in the presence of 0.2 to 5 parts by weight of water, in relation to 100 parts by weight of the starting compound.

Description

The invention relates to a process for preparing a vinyl compound by vinylating a starting compound having at least one primary or secondary amino group, at least one hydroxyl group or at least one thiol group with acetylene, which is characterized in that the vinylation in the presence of 0.2 to 5 parts by weight of water, based on 100 parts by weight of the starting compound is performed.

Technically of particular importance are vinyl ethers which are prepared by vinylation of hydroxy compounds with acetylene or else, for example N-vinylpyrrolidone, which is prepared by vinylation of pyrrolidone with acetylene.

US 2003/0105354 describes such vinylations of starting compounds having at least one secondary amino group, at least one hydroxyl group or at least one thiol group. The described implementation has two stages. In a first step, the starting compound is reacted with an alkali metal. The obtained salt of the starting compound acts as a catalyst. The resulting in the reaction of water and optionally used as a solvent for the alkali metal hydroxide are distilled off. Then the vinylation takes place.

Accordingly, WO 2009/074534 or DE-A 19509362 describes the vinylation of pyrrolidone with acetylene. Water is separated in the described method from the reaction with the alkali metal.

What is desired is a method in which the space-time yield is as good as possible. The proportion of by-products should be as low as possible.

Accordingly, the method defined above has been found.

To the vinyl compounds and their starting compounds

The starting compound contains at least one primary or secondary amino group, at least one hydroxyl group or at least one thiol group.

Preferred starting compounds having at least one primary or secondary amino group are cyclic or non-cyclic amides. Preferably, these starting compounds contain only one amino group.

Non-cyclic amides are in particular those of the formula I. R ² -C (= O) -NHR wherein R ^{1 is} an H atom or a C ¹ to C 4 alkyl group and R ^{2 is} a C ¹ to C 10 alkyl group.

The amino group is preferably a secondary amino group; R ¹ then represents a C ¹ - to C ⁴ -alkyl group. R ² is preferably a C ¹ - to C ⁴ -alkyl group.

The starting compounds of the formula I are vinyl compounds of the formula II

wherein R ¹ and R ^{2 have} the above meaning or preferred meaning.

A particularly preferred starting compound having a primary or secondary amino group is N-metylacetamide, the vinyl compound obtained therefrom is N-vinyl-N-methylacetamide (VIMA) of the formula III:

Preferred cyclic amides (lactams) are caprolactam, piperidone or pyrrolidone. The vinyl compounds obtained therefrom are N-vinylcaprolactam, N-vinylpiperidone and N-vinylpyrrolidone.

Preferred starting compounds having at least one hydroxyl group are aliphatic or cycloaliphatic compounds having one or two hydroxyl groups. Preference is given to aliphatic or cycloaliphatic compounds having 1 to 20 C atoms, in particular having 2 to 14 C atoms. The aliphatic or cycloaliphatic compounds may contain further heteroatoms, in particular they may contain ether groups. In a particularly preferred embodiment, the starting compounds having at least one hydroxyl group are aliphatic or cycloaliphatic see compounds having one or two hydroxyl groups, which consist of a total of 2 to 14 carbon atoms, which may contain ether groups and except oxygen contain no further heteroatoms, ie consist exclusively of H, C and O. Mention may be made of alkanols, in particular C 2 - to C 8 -alkanols, alkanediols, in particular C 2 - to C 8 -alkanediols, polyalkyleneglycols, in particular di-, tri- or tetraalkyleneglycols, preferably di-, tri- or tetraethylene glycols, and also cyclohexanol, cyclohexanediol, hydroxyalkylcyclohexanes, in particular hydroxymethylcyclohexane, and bis-hydroxyalkylcyclohexanes, in particular bis-hydroxymethylcyclohexanes.

The polyalkylene glycols preferably correspond to the formula HO- (Y-O-) _n -Y-OH, where n is an integer of at least 1 and Y is an alkylene group having 1 to 10 C atoms, preferably having 2 to 4 C atoms , particularly preferably with 2 or 3 C atoms. Preferably n = 1 (dialkylene glycol), n = 2 (trialkylene glycol) or n = 3 (tetraalkylene glycol).

The vinyl compounds obtained from starting compounds having at least one hydroxyl group are vinyl ethers. For starting compounds having a hydroxyl group, monovinyl ethers are obtained. Starting compounds having two hydroxyl groups result in monovinyl ethers, or divinyl ethers or mixtures thereof. This depends on the molar ratios of the starting materials used and / or their conversion.

Preferred starting compounds having at least one thiol group are aliphatic compounds having a thiol group, in particular alkanethiols having 2 to 8 C atoms or alkanethiols having 2 to 8 C atoms substituted by a hydroxyl group. The vinyl compounds obtained therefrom are vinyl thioethers. Specifically, mention may be made of S-vinylmercaptoethanol. Thiol groups generally react faster with acetylene than hydroxyl groups. Therefore, in reactions of compounds having a thiol group and a hydroxyl group, S-vinyl compounds containing a hydroxyl group can be selectively obtained. In particular, the starting compounds of the vinylation are cyclic amides or compounds having one or two hydroxyl groups or compounds having a mercapto group; the corresponding vinyl compounds are cyclic N-vinylamides, monovinyl ethers, divinyl ethers or monovinylthioethers, e.g. S-vinylmercaptoethanol.

With particular preference the starting compounds of the vinylation are a compound having one or two hydroxyl groups. The corresponding vinyl In the case of the starting compound having a hydroxyl group, compounds are monovinyl ether. In the case of the starting compound having two hydroxyl groups, the corresponding vinyl compounds are monovinyl ethers, divinyl ethers or mixtures thereof. With very particular preference the starting compounds of the vinylation are a compound having two hydroxyl groups; the vinyl compounds obtained therefrom are monovinyl ethers, divinyl ethers or mixtures thereof; in particular, the products of vinylation are the corresponding divinyl ethers. Pyrrolidone, caprolactam, di- or triethylene glycol and bis-hydroxyalkylcyclohexanes, in particular bishydroxy- methylcyclohexanes, may be mentioned in particular as starting compounds. The vinyl compounds obtained therefrom are N-vinylpyrrolidone, N-vinylcaprolactam, diethylene glycol monovinyl ether, diethylene glycol divinyl ether, triethylene glycol monovinyl ether, triethylene glycol divinyl ether, bis-hydroxymethylcyclohexane monovinyl ether or bis-hydroxymethylcyclohexane divinyl ether.

Very particularly preferred vinyl compounds are diethylene glycol divinyl ether, triethylene glycol divinyl ether and bis-hydroxymethylcyclohexane divinyl ether, in particular 1,4-bis-hydroxymethylcyclohexane divinyl ether.

To the procedure

The vinylation of the starting compound is carried out with acetylene in the presence of 0.2 to 5 parts by weight of water, based on 100 parts by weight of the starting compound.

The content of water is preferably at least 0.3 and more preferably at least 0.5 parts by weight, in particular at least 0.7 parts by weight, based on 100 parts by weight of the starting compound.

The content of water is preferably not more than 3, in particular not more than 2 and particularly preferably not more than 1.5 parts by weight of water, based on 100 parts by weight of the starting compound. In particularly preferred embodiments, the reaction with acetylene in the presence of 0.2 to 3 parts by weight of water, in particular from 0.3 to 2 parts by weight of water and most preferably from 0.5 to 1, 5 parts by weight of water per 100 parts by weight of starting compound.

The desired amount of water can be added, for example, to the starting materials or directly to the reaction mixture of the vinylation. The water content is determined according to Karl Fischer by volumetric titration.

However, water is generally already contained in the starting material by a preliminary reaction of the starting material with an alkali metal hydroxide. The alkali salt of the starting material serves as a catalyst in the vinylation. It is described in the prior art that the by-product salt formation or the water used as the solvent for the alkali hydroxide is removed by distillation prior to the vinylation. In a preferred embodiment, therefore, no water must be added. Rather, the water content must be adjusted during or after the reaction of the starting material with the alkali metal hydroxide. Generally, excess water must be removed, preferably by distillation. In a preferred embodiment of the method is therefore

the starting compound is reacted with an alkali hydroxide before the vinylation,

adjusted by removal of water from the reaction mixture, a water content of 0.2 to 5 parts by weight of water, based on 100 parts by weight of the starting compound and

the resulting mixture of starting compound, alkali salt of the starting compound and water (called short starting mixture) is then fed to the reactor for vinylation with acetylene.

With the alkali hydroxide, e.g. to act a lithium, sodium or potassium hydroxide; particularly preferred is potassium hydroxide.

The alkali hydroxide may be used as a solid or in the form of an aqueous solution. The content of alkali hydroxide in the aqueous solution may be e.g. 5 to 90 wt.%, Based on the solution amount; In particular, it is 30 to 60 wt.%, Particularly preferably 45 to 55 wt.%.

The amount of alkali hydroxide is preferably selected so that 0.25 to 25 wt.%, Preferably 1 to 10 wt.% Of the starting compound is present as an alkali metal salt. In the alkali salt, at least one hydrogen of the primary or secondary amino group or the hydrogen of the hydroxyl group or the thio group is replaced by the alkali cation (for example, alkanol as potassium alkoxide, pyrrolidone as potassium pyrrolidate, etc.).

The reaction of the compound with the alkali hydroxide is preferably carried out at temperatures of 50 to 250 ° C and 1 mbar to 1 bar, in particular at 20 to 250 ° C. Preferably, the reaction takes place in a column, particularly preferably in a packed column or packed column, which is operated at the above temperatures and pressures. The temperature at the top of the column is preferably 20 to 100, in particular 25 to 60 ° C; the temperature in the bottom of the column is preferably 100 to 250 ° C, in particular 120 to 200 ° C.

The reaction can be carried out batchwise, semi-continuously or continuously. In a preferred embodiment, it is operated continuously.

Also suitable are columns which contain both random packings and packings, e.g. in the lower part contain random packings and in the upper part with packing elements (for example built-in steel sheets).

The column preferably has at least two, more preferably at least 3 theoretical plates. It can e.g. 2 to 100, especially 3 to 20 theoretical plates have. The alkali metal hydroxide and the compound are preferably added in the upper third, more preferably in the upper fourth of the column.

In the reaction, the corresponding alkali metal salt of the starting compound is formed. The mixture obtained from the reaction can be withdrawn continuously in the lower part of the column or at the bottom of the column.

The resulting mixture contains the starting compound, the alkali salt of the starting compound and water. The resulting mixture is referred to below as the starting mixture

Subsequently, the vinylation of the starting compound or the starting mixture with acetylene is then preferably carried out in a separate reaction vessel. The vinylation with acetylene can be carried out batchwise, semicontinuously or continuously.

The reaction can be carried out in any reactors, which may be mentioned, for example, stirred tanks, stirred tank cascades, tubular reactors or loop reactors. Preferably, the reaction takes place in a loop reactor. In particular, the reaction takes place while avoiding a contiguous gas phase of the acetylene, as described in EP-A 733,401. For this purpose, the reaction vessel is preferably completely filled with the starting mixture and acetylene introduced into the liquid phase to the desired degree of saturation. A portion of the output stream is preferably expanded into a surge tank and returned to the reactor so as to determine the composition and acetylene concentration in the reaction mixture.

The vinylation with acetylene is preferably carried out at temperatures of 120 to 220, more preferably from 140 to 170 ° C and preferably at pressures of 1, 0 to 25, particularly preferably from 10 to 20 bar.

The product mixture obtained can be worked up and purified in a customary manner.

In a subsequent work-up of the product mixture, the basic salts of the alkali metals can first be separated off. This can be z. B carried in a thin-film evaporator through which the entire product mixture or only a partial stream of the product mixture are passed.

The further work-up of the product mixture can e.g. by distillation or extraction.

Unreacted starting compound can be recycled in a continuous procedure either in the reaction with the alkali metal hydroxide or in the vinylation.

By the method according to the invention vinyl compounds are available in high yield and purity. Compared with anhydrous procedure, a high yield is achieved faster. Therefore, the yield is higher for the same residence time, or the same yield is achieved after a shorter residence time in the vinylation. Also, the viscosity is reduced by the water content, which has an advantageous effect on the process control, in particular on the operation of pumps. Examples

The water content was determined by volumetric titration according to Karl Fischer with the 870 KF Titrino plus instrument from Metrohm (titrant Hydranal Composite 5).

Example: 1000 g of 1,4-cyclohexanedimethanol and 27 g of solid KOH were placed in a 2.5 liter autoclave. After dissolution of the potassium hydroxide, a water content of 1.1% by weight (according to Karl-Fischer) was measured.

The vinylation was carried out at 155 ° C and a pressure of 18 bar. Acetylene was continuously repressed to maintain the pressure of 18 bars. After 4.5 hours, no more acetylene was consumed, the reaction was stopped. A total of 309 liters of acetylene were added. The ratio 1, 4-cyclohexanedimethanol / monovinyl ether / divinyl ether was measured by GC (area%):

0.06 / 0.13 / 99.81

Comparative Example:

27 g of KOH was dissolved as above in 1000 g of 1,4-cyclohexanedimethanol.

Water was distilled off from a mixture until the water content (according to Karl Fischer) reached 0.10% by weight. The mixture was transferred to a 2.5L autoclave.

The vinylation was carried out at 155 ° C and a pressure of 18 bar. Acetylene was continuously repressed to maintain the pressure of 18 bars. After 6.5 hours, no more acetylene was consumed, the reaction was stopped. A total of 303 liters of acetylene were added. The ratio 1, 4-cyclohexanedimethanol / monovinyl ether / divinyl ether was measured by GC (area%):

0.00 / 0.07 / 99.93

The attached figure shows the uptake of acetylene as a function of the reaction time. The uptake of acetylene corresponds to the conversion of acetylene. In the case of the inventive example, the uptake of acetylene ends after 4.5 hours, i. the total sales of acetylene is essentially already after 4.5 hours.

Claims

claims

1 . A process for preparing a vinyl compound by vinylating a starting compound having at least one primary or secondary amino group, at least one hydroxyl group or at least one thiol group with acetylene, characterized in that the vinylation in the presence of 0.2 to 5 parts by weight of water, based on 100 parts by weight the starting compound is carried out.

2. The method according to claim 1, characterized in that it is the vinyl compound is a cyclic N-vinylamide, a monovinyl ether or a divinyl ether.

3. The method according to any one of claims 1 or 2, characterized in that it is a divinyl ether in the vinyl compound

4. The method according to any one of claims 1 to 3, characterized in that it is in the vinyl compound to Diethylenglycoldivinylether, triethylene glycol divinyl ether or 1, 4 Bishydroxymethylcyclohexandivinylether.

5. The method according to any one of claims 1 to 4, characterized in that the starting compound is reacted before the vinylation with an alkali metal hydroxide,

by removing water from the reaction mixture, a water content of 0.2 to 5 parts by weight of water, based on 100 parts by weight of the starting compound is set and

the resulting mixture of starting compound, alkali metal salt of the starting compound and water (abbreviated to the starting mixture) then the reactor for

Vinylation is supplied with acetylene.

6. The method according to any one of claims 5, characterized in that the reaction with the alkali metal hydroxide and the removal of the water by reactive distillation takes place in a column.