DE1911032C - Process for the distillation of a mixture of acetic acid and vinyl or allyl acetate - Google Patents

Description

3. Method according to one of the preceding This method runs in a rudimentary manner and can be Claims, characterized in that this is not carried out continuously.

Mixture of acetic acid and vinyl or allyl 35 Finally, it is known to use ethyl acetate

acetate in the column in about half the height from glacial acetic acid and alcohol or benzoic acid ethyl

introduces. esters of benzoic acid and alcohol or nitrous oxide

4. The method according to any one of the preceding isoamyl esters of sodium nitrite and amyl alcohol Claims, characterized in that the preparation in the presence of acid and the respective Distillation at a temperature of 125 to 30 esters to deacidify with soda solution.

160 ⁰ C carries out at the lower end of the column. Even then, these known methods do not offer any

5. The method according to one of the preceding solutions to the problem of the distillation of a claim, characterized in that a mixture of acetic acid and vinyl or allyl acetate, The residue is withdrawn from the lower end of the column if it is used using the methods known per se and after heating the column recirculates 35 modified column distillation. If you namely and that from this continuous cycle, for example, a sodium acetate at the upper end of the run a partial stream, preferably continuously, column or together with the Säi'ienbeschussung withdraws and evaporates. would introduce a sodium chloride in

6. Separate the method according to one of the preceding the column. The resulting Claims, characterized in that the column filling is coated with sodium chloride Lithium salt or lithium hydroxide or that would complete the entire further distillation Make the sodium or potassium salt or hydroxide ineffective. If, on the other hand, you have the sodium one Amount up to 5 times the molar amount of salt would introduce at the bottom of the column of the hydrogen chloride present. the clogging of the column with a solid chloride

7. To avoid the method according to one of the preceding 45, then the hydrogen chloride would not claims, characterized in that one is neutralized from, since it withdraws a liquid portion upwards and not downwards from the distillate, after flowing, so that the corrosion effect of the chlorine water Cooling nitrated, the filtrate extracted with hot water substance in the next distillation column of a Abvon preferably 80 to 100 ⁰ C and the separation system would be transferred, unless the lithium salt or lithium hydroxide obtained would be the aqueous hydroxide containing hydrogen chloride at the top Solution is fed back to the column through additional devices, for example the distillation column at the top. wise a cold trap to intercept.

8. The method according to claim 7, characterized in that there would now be a method for distilling a indicates that before extraction with a mixture of acetic acid and vinyl or AHyI water an inert, water-immiscible acetate with hydrogen chloride or chlorine-containing solvents admits. bonds that convert to hydrogen chloride

can, found in the presence of alkalis, which is characterized in that the mixture

distilled in a distillation column, in the am

60 upper end a lithium salt or lithium hydroxide is introduced that one is at the lower end

In British Patent 964 001, a residue accumulating in the column is removed and used for the production of unsaturated esters, such as those described in the presence of a sodium or potassium vinyl acetate or allyl acetate, which salt or hydroxide therein at 120 to 200 ⁰ C and pre-existing that an "-olefin, such as ethylene or propylene, 65 distilled, preferably under atmospheric pressure and recovered with a palladium salt either under substantially, optionally the lithium salt or lithium hydroxide borrowed anhydrous conditions or in the presence,
of a specified smaller amount of water and preferably in the distillation of the

3 4

Residue obtained distillate in the column residue consists essentially of sodium

returned. _or potassium chloride. The vaporizer can be used with a

At least part of the hydrogen chloride is at a temperature in the range from 120 to 200 ⁰ C, in particular

an evaporator, in which the evaporation instead of 135 to 150 ⁰ C, preferably below atmospheric

finds, are operated as low pressure sodium or potassium chloride,

hit. _That fed to the top of the column

The mixture of acetic acid and vinyl or allyl lithium salt is a salt that reacts with hydrogen chloride

Acetate can also contain other components that can react with the formation of lithium chloride,

if these do not interfere with the procedure. So you can use lithium carbonate or a lithium carboxy

can this distillation process subjected xo lat, z. B. an alkanoate with up to 6 carbon atoms, such as

Product of the process according to British patent lithium acetate. Most useful, however

writing 964 001 from water, acetaldehyde, methyl- one uses lithium hydroxide, since this is easy

acetate, ethylene glycol acetate and ethylidene diacetate is available The lithium salt or lithium hydroxide

as well as other substances. The chlorine content can be added in a molar amount that

of the mixture is up to 0.5 weight percent 15 to 5 times the molar amount of that present

or more and can be made from organic chlorine compounds

fertilize, especially by water with the formation of molar amounts of the lithium salt or lithium hy-

vcη hydrogen chloride hydrolyzed ^ are exist. droxyds, however, about twice the molar amount

Typically, the starting mixture consists of the hydrogen chloride present. The lithium salt

the process according to the invention from 15 to 30Ge-20 is preferably fed continuously,

weight percent vinyl acetate, 40 to 65 weight percent The sodium or

Acetic acid, remainder water, acetaldehyde and hydrolyte- Potassium salt is a salt that is taking with lithium chloride

soluble chlorine-containing impurities. Formation of sodium or potassium chloride react

The mixture of acetic acid and vinyl or kr in. It can be sodium or potassium carbonate

Allyl acetate is expediently 35 or sodium or potassium carboxylates, e.g. B. Alkano

about half the height of the column, while ate with up to 6 carbon atoms such as sodium acetate,

however, the vinyl and allyl acetate at the top and the turns will be most convenient

Acetic acid at the lower end of the column - the hydroxides, especially sodium hydroxide,

be taken. Also other possibly existing set. The sodium or potassium salt or hydroxide,

high-boiling esters, such as ethylene glycol acetate and which is preferably fed in continuously, can

Ethylidene diacetate, flow down the column in a molar amount that can be used up

and can be removed with acetic acid. Is 5 times the molar amount of what is present

Vinyl acetate is the ester to be separated off, so the amount of hydrogen chloride is. It is preferably

Temperature at the upper end of the column is usually about twice the molar amount of what is present

73 ° C, d. H. the boiling point of vinyl acetate is below 35 hydrogen chloride.

the preferred operating pressure, ie atmospheric pressure. The removal of the solid residue from the pressure. The temperature at the upper end of the column can be dampened with the continuous ·! However, operation of the vaporizer may be less than 73 ° C depending on how easily the vaporizer does not perform. In one other low-boiling component, preferred embodiment of the claimed vennent, such as acetaldehyde, is present in the starting mixture. In the 40 driving, two evaporators are therefore provided, present in front. Water forms vinyl acetate one of which any arbitrary from the distillation column azeotropic boiling point of 66 ⁰ C, so this can then be isolated. In this way, mari can use one damper, which is close to the temperature at the top of the column, while the other is being cleaned. Likewise, the temperature of the upper can will, and the exchange of the one against the other end of the column at 103 ⁰ C allyl acetate, that is the boiling point 45 can take place without interruption of the process, the temperature of allyl acetate, and 83 ° C, that is in the evaporator the concentration of the acetic acid boiling temperature " ⁴ λ azeotropic allyl acetate-water - chosen so that the lithium as lithium acetate before mixture. The temperature is at the lower hand that is soluble in the acetic acid medium. The end of the column is expediently approximately. In addition to the inorganic salts, there are also organic salts at 118 ^° C. (the boiling point of acetic acid). As there are 50 connections in the evaporator. V »'enn ζ Β. but it is preferred to remove the acetic acid at one point * the mixture of acetic acid and vinyl or AHyI- the column wall as a side stream, acetate from the process according to the British patent, which is slightly higher than the lowest point of the column writing 964 COl, so become organic Proliegt, the temperature at the lower end of the products such as polyvinyl acetate, Diawtoxyäthan, ethylidene column can be a little more than 118 ° C, z. B. 125 to 160 ⁰ C, 55 diacetate and 2-chloroethyl acetate carried forward in the evaporator, be available. Since these connections have a higher

Preferably the distillation column has a boiling point than acetic acid, which increases Provided reboiler, which the residue from the lower concentration, these compounds together with Is fed to the end of the column. This residue is the continuously formed lithium acetate. It is is heated in the reboiler and is therefore necessary in the column in the 60, returned to the continuous cycle when the sodium is withdrawn. Measure or potassium chloride from the evaporator from the Men can then be taken to make up a portion of lithium acetate? .t in solution in acetic acid and one or of the residue periodically or preferably in several of the above-mentioned organic products to be taken continuously from the reboiler and removed from it.

To feed the evaporator. The in the evaporator 65 If necessary, the lithium or a part Steamed vapors consist mainly of vinegar - extracted from the evaporation residue acid and can be returned to the distillation column by converting some of this residue into liquid are given. The solid form that accumulates in the evaporator is removed from the evaporator and then

is cooled and filtered, whereupon the Rltrat with hot Via line 12, an azeotropic vinyl water was extracted and an aqueous lithium acetate-water mixture was removed, and acetic acid was removed acetate solution is separated. withdrawn via line 11. The residue poured

The liquid removed from the stand under evaporation in the constant cycle through the reboiler 2 contains some solid 5 from which a partial flow is diverted and one of the two sodium or potassium chloride in suspension. This vaporizer was fed. Any vaporizer solids are filtered off. could be out of operation by means of valves 5 or 6

The liquid can be put into the Xa steamer continuously, while the other evaporator can be taken out on loan or intermittently. The tem- operation was up. The evaporators were heated to a temperature of 140 to 145 ° C, the liquid equals the temperature inside, and the vapors drawn off at 7 became half of the evaporator and is returned to the column by cooling. The evaporators have been reduced. The filtered liquid can be switched a little periodically, and the solid residue, amount of sodium or potassium chloride in solution, was taken out. This residue consisted of acetic acid, diacetoxyethane, and ethylidene diacetal, l-chlorine, mainly of sodium chloride. The use of beäthylacetat and polyvinyl acetate together with the 15 carried 1500 ml / h, and an aqueous 1-mol solution of lithium acetate in solution. The filtrate is lithium hydroxide was continuously introduced via line 13 at 30 to 50 ml / h with hot water, preferably at 80 to 100 ° C. The treated, whereby the lithium acetate is dissolved out, evaporates a 5 mole solution of sodium, and the organic residue remains. Since hydroxide is continuously metered through line 8 or 9, the organic residue may be an ao. Hydroquinone has a high content of polyvinyl acetate via line 15, it can be introduced beforehand in order to stabilize the vinyl acetate during the distillation, so that this residue is viscous and sticky lation. The chloride content of the abisi. To facilitate handling, drawn vinyl acetate and drawn off acetic acid can therefore be used in an inert, water-immiscible solvent. Acid was less than 0.002%. The chloride content can be added prior to the extraction with water, as can be recirculated via the reboiler if desired, more than one extraction with product was kept at less than 0.06 mole. Water to be carried out. The aqueous thus obtained.

Lithium acetate solution can go back to the top end of example 2

the distillation column are passed around the there The distillation apparatus according to FIG. 2 exists

introduced lithium salt or a part of it to 30 from a column!, a boiling point 2 and twin form. Vaporizers 3 and 4. The vaporizers were with

The unsaturated esters contained in the starting material for the inventive isolating valves 5 and 6, a common return process are both line 7 for the vapors and agents 8 and 9 for easily polymerizable. To ensure the occurrence of a poly- continuous addition of sodium salt, To prevent merisalion in the distillation column, 35 branch lines 16 lead over isolation valves 17 is preferably a polymerization inhibitor, e.g. B. and a filter 22 to an extraction apparatus 18 Hydroquinone, introduced into the distillation column. with a water inlet 19 and phase discharge line

F i g. 1 shows a flow diagram for an apparatus 20 and 21 respectively. The column is shown with an inlet without means for lithium production, and line 10 and outlet lines 11 and 12 for vinegar.

Fi g. 2 shows a foot diagram for the same apparatus 40 acid or vinyl acetate. The vinyl acetate

door with means for lithium production. was partly injected into the column as reflux.

'. . . , out, on line 14. At the top

ti e 1 s ρ 1 e 1 1 _{end of the} column are means 13 and 15 for the

The distillation apparatus according to FIG. 1 consisted of the supply of the lithium salt or hydroquinone from a column 1, a reboiler 2 and twin 45 provided. The starting mixture comes from the Evaporators 3 and 4. The evaporators were with palladium catalyzed oxidation of ethylene Isolation valves 5 and 6, a common steam in the presence of oxygen, acetic acid, Lithiumrückleituiig 7 and means for the continuous addition of acetate, lithium chloride and copper chloride according to the of sodium salt 8 and 9, respectively. The column was British patent specification 964 001 and typically consists of a feed line 10 and outlet lines, or see the trap of 25 percent by weight vinyl acetate, 12 for acetic acid and vinyl acetate. The vinyl x 15 weight percent acetaldehyde, 12 weight percent acetate was partly in the column as reflux water and about 21 percent by weight by-products, returned via line 14. The remainder is acetic acid.

The upper end of the column were means 13 and 15 respectively

for the feed of the lithium salt and hydroquinone 55 to 80 ° C in the column, the temperature being provided. temperature at the upper end 63 ° C and at the lower end

The starting mixture came from the bedium-catalyzed oxidation of ethylene in counterpart with Palla column 135 ° C., under atmospheric pressure. An azeotropic vinyl content of oxygen, acetic acid, lithium acetate, a mixture of liquor and water is supplied via line 12 and via line 11 Thium chloride and copper chloride removed according to British acetic acid. Material flows continuously Patent specification 964 001 and consisted of a 25 weight cycle through the reboiler 2, from which a part percent vinyl acetate, 15 weight percent acetaldehyde, atrom and to one of the two evaporators 12 percent by weight of water, 21 percent by weight (in is supplied. Each vaporizer can mean the elwa) by-products, the remainder being acetic acid. Valves 5 and 6 are isolated, while the other

The mixture was operated at a temperature of 60 65. The vaporizers are set to 140 up Introduced into the column at up to 80 ° C., the temperature being heated to 145 ° C., and the withdrawn via line 7 temperature at the upper end 63 C and at the lower end vapors are returned to the column. the the column was 135 C under atmospheric pressure. Evaporators are periodically switched to

1

enable the solid residue to be removed. This residue consists essentially of sodium chloride.

A typical composition of the filtered partial flow from the evaporators is as follows: S

Lithium acetate 13.25 g

Sodium chloride 0.3 g

Polyvinyl acetate 15.01 g

Diacetoxyethane 10.63 g

2-chloroethyl acetate 1.17 g

Ethylidene diacetal 0.79 g

Acetic acid 32.43 g

This mixture is stirred in the extraction apparatus together with 50 g of water at 98 ° C. for 1 hour. An aqueous extract is then obtained with the composition:

Water 50.00g

Lithium acetate 11.2 g

Sodium chloride 0.28 g ^ao

Polyvinyl acetate 3.1 g

Diacetoxyethane 6.83 g

2-chloroethyl acetate 1.06 g

Ethylidene diacetate 0.56 g

Acetic acid 18.9 g * ^s

The organic layer consists of 3 g of material and a polymeric precipitate is also obtained.

032 *

The organic layer and the precipitate are washed with a further 50 g of water at 98 ^° C., the washings having the following composition:

Lithium acetate 2.3 g

Sodium chloride 0.05 g

Diacetoxyethane 1.89 g

2-chloroethyl acetate 0.10 g

Ethylidene diacetate 0.07 g

Acetic acid 5.7 g

The aqueous solution of lithium acetate obtained in this way can optionally after evaporation (dehydration) be returned to the distillation column.

The input is typically 1500 ml / h, and if no lithium acetate solution is recycled, an aqueous 1 molar solution of lithium hydroxide is continuously introduced via line 13 at 30 to 50 ml / h. A 5 mol solution of sodium hydroxide is continuously metered into the evaporators via lines 8 and 9, respectively. Hydroquinone can be introduced via the line at IS to stabilize the vinyl acetate during the distillation. The chloride content of the withdrawn vinyl acetate and the withdrawn acetic acid is less than 0.002 ^c / ₀ , and the chloride content of the material circulating through the reboiler is kept at less than 0.06 mol.

1 sheet of drawings

209682/303

Claims (2)

in the presence of a carboxylic acid, such as acetic acid, claims: Carboxylate ions, such as acetate ions, a redox system and molecular oxygen, is converted. 1. Process for the distillation of a mixture It should also be advantageous to use the process in counterpart Acetic acid and vinyl or allyl acetate with 5 wart of an alkali metal halide, e.g. B. Lithium hydrogen chloride or chlorine-containing compounds, chloride. which can convert to hydrogen chloride. The palladium (II) chloride can be the palladium (II) chloride and, in the presence of alkali salts, the redox system can be copper chloride. This "indicates that you increase the mixture in drive the chloride ions while the reaction of a distillation column is distilled in the io speed, but they lead to the formation of a lithium salt or lithium hydrogen chloride and / or chlorinated organic hydroxide that is introduced from the upper end the re-2-chloroethyl acetate accumulating on the by-products, e.g. ethylene chlorohydrin and the lower end of the column, is removed under hydrolytic conditions and cleaved in the presence of a dinguagenous, namely with the formation of sodium or potassium salt or hydroxide at 15 hydrogen chloride. Hydrogen chloride is especially after-120 to 200 ⁰ C and preferably below atmospheric because of its corrosive effect distilled to of 2. The method according to claim 1, characterized in that the unsaturated ester is increased. indicates that the distillation ao. It is also known to use a mixture of a of the residue obtained distillate in the Ko-acetic acid ester and a mineral acid in the presence lonne returns. to distill an alkali or alkaline earth acetate.