DE1015791B - Process for cleaning acrylic acid ester mixtures - Google Patents

Description

GERMAN

The subject of patent 965 237 is a method for purifying acrylic acid ester mixtures which by reacting acetylene with carbon dioxide and alcohols in the presence of carbonyl-forming ones Metals, especially of cobalt or nickel or their compounds, were obtained by this is characterized in that the metal carbonyl compounds still present in the crude ester mixtures before distillation by treatment with halogens, in particular with bromine or iodine, decomposed.

It has now been found that one can produce catalytically from acetylene, carbon oxide and alcohols Acrylic acid esters can be cleaned particularly advantageously if the crude esters with about 1 to 15 mol percent Halogen, based on the ester, treated and then with aqueous inorganic, alkaline washes off reacting compounds.

The crude esters to be purified by the process of the invention can be in the form as they incurred during production in the presence of carbonyl-forming metals and their compounds, directly use, but any lower-boiling constituents that may be present can be used before the halogen treatment or remove solvent. The treatment temperature is generally chosen to be low, e.g. B. between about -10 and + 10 °, since this is the undesirable addition of the halogen to the Acrylic acid ester hardly takes place. If you work quickly enough and avoid an excess of halogen can also be moderately elevated temperatures such. B. 20 and 40 ° apply.

Suitable halogens are primarily chlorine and bromine, optionally with inert gases or Liquids can be diluted. The highest amount of halogen required can be due to the Easily determine the proportion of interfering by-products, primarily divinylacetylene, by means of preliminary tests; it is generally between 1 and 15 mol percent, based on the ester. The procedure can be used in batches in stirred vessels or other effective mixing vessels or continuously, z. B. while flowing through a pipe.

After the halogen treatment, the ester, expediently after the addition of a polymerization retarder, once or several times with aqueous alkalis, in particular aqueous 5 to 40% solutions of alkali hydroxides, carbonates or bicarbonates, usually at normal or moderately elevated levels Temperature washed. Here, too, you can work continuously. Appropriately, one connects to the Alkali wash still a water wash.

If ammonia or ammonium carbonate is chosen as the alkali, it is advantageous to use the treatment as a method for cleaning
of acrylic acid ester mixtures

Addendum to patent 965 237

Applicant:

Aniline & Soda Factory in Baden
Aktiengesellschaft, Ludwigshafen / Rhein

Dr. Herbert Friederich, Worms,

and Dr. Hans Lautenschlager, Ludwigshafen / Rhine,

have been named as inventors

Avoid converting the ester into the amide at temperatures of 0 ° or below. Under certain circumstances it is also sufficient to treat the crude ester treated with halogen by adding aqueous or alcoholic alkalis, e.g. B. dilute sodium hydroxide solution or milk of lime to neutralize and then after washing with water or directly in a water washing column by distillation to work up.

It is known that colored acrylic acid esters can be obtained by treatment with alkali or alkaline earth metal hydroxides can discolor. However, by removing the colored impurities, complete cleaning is not achieved. In particular divinylacetylene present as an impurity cannot be removed by alkali treatment will.

It is also known that crude acrylonitrile can be purified by treatment with chlorine can without attacking the acrylonitrile. The treated acrylonitrile is before Distillation appropriately treated with alkaline substances to remove any traces that are still present To bind hydrogen chloride. But it was surprising that you can acrylic acid esters by reaction of acetylene with carbon dioxide and alcohols were obtained by a halogen and subsequent Alkali treatment can clean without the acrylic acid esters being attacked. the Purified crude esters can be distilled without difficulty, and it is expedient to add of polymerization retarders and under

709 697/418

reduced pressure works. The distilled esters can be polymerized very easily and stand out mainly because the polymers produced therefrom can be easily dissolved in cold benzene or ethyl acetate and are completely soluble and have a high if value own. The / f value is a measure of the inherent viscosity of the polymers (cf. H. Fikentscher, Cellulosechemie, Vol. 13, 1932, p. 58).

example 1

IO

The starting material is 98% ethyl acrylate, which has been prepared from acetylene, carbon oxide and ethanol in the presence of bis (triethylbutylammonium) nickel tetrabromide [(C ₂ H ₅ ) ₃ N (C ₄ H ₉ )] ₂ Ni Br ₄ . A slow stream of chlorine is passed through a frit at 0 ° into 500 parts of the ester, with vigorous stirring, until the increase in weight is 17 parts. This takes about 10 minutes. 0.5 part of methylene blue and 0.5 part of phenthiazine are then added to the mixture and this is vigorously stirred with 200 parts of 10% strength aqueous sodium bicarbonate solution at room temperature and then with 200 parts of water. After the aqueous layer has been separated off, 2 parts of phenoxypropene oxide are added and the mixture is distilled in a column filled with Raschig rings at 400 torr. 478 parts of a 99.5% strength ethyl acrylate, _{boiling point 409} = 76 °, are obtained, along with 41 parts of residue. When polymerized with potassium persulfate, the ester gives a polymer which is soluble in cold ethyl acetate and has an if value of 124. The distillate of the untreated ester, on the other hand, gives a polymer with an if value of 42, which is not clearly soluble in cold ethyl acetate.

If 250 parts of the crude acrylic acid ester are reacted with chlorine until the increase in weight is 9 parts, in this way, after the distillation, 212 parts of the 99% strength acrylic acid ethyl ester are obtained, which still contains 0.8% chlorine contains 47 parts of residue.

The if value of the polymer produced from this ester is 68. When stored at 0 ° the ester polymerizes after 38 hours without any further action, while the ester, which has been cleaned by chlorine and a subsequent alkaline wash, still polymerizes is unchanged after 2 months.

On the other hand, 250 parts of the crude ethyl acrylate with 100 parts of a 20% strength sodium bicarbonate solution are used and then washed with 100 parts of water, this is obtained after separating off the water and after adding 1 part of phenoxypropene oxide in the distillation 236 parts of a 99.6% strength acrylic acid ethyl ester in addition to 3 parts Residue. The polymer made from this ester is insoluble in cold ethyl acetate and cold benzene. The if value of the filtered hot benzene solution is 41.

Example 2

250 parts of the ethyl acrylate prepared in Example 1 are treated with chlorine in a washing vessel while cooling with water for 5 minutes, the internal temperature rising to 30 ° and the weight increasing by 17 parts. After adding the stabilizers given in Example 1 and washing with 100 parts of 10% sodium bicarbonate solution and 100 parts of water and separating off the water, 1 part of phenoxypropene oxide is added to the ester and it is distilled. 191 parts of 99.5% strength ethyl acrylate are obtained, b.p. ₄₀₀ = 76 °, in addition to 69 parts of residue. The polymer produced from the ester is soluble in cold ethyl acetate and has a .K "value of 104.5.

Example 3

400 parts of the ethyl acrylate prepared in Example 1 are stirred and cooled 40 parts of bromine are slowly added with water, an internal temperature of 28 ° being established. To The mixture becomes discolored for 30 minutes. After their alkali and water washing according to the procedure of Example 1, after adding 1.5 parts of phenoxypropene oxide, 328 parts are obtained by distillation 99% ester in addition to 68 parts of residue. The polymer is clearly soluble in cold ethyl acetate and has the if value 115.2.

Example 4

The starting material used is a crude ester prepared by reacting acetylene with carbon oxide and alcohol in the presence of bis (triethylbutylammonium) nickel tetrabromide [(C ₂ Hg) ₃ (C ₄ H ₉ ) N] ₂ NiBr ₄ , the 70% ethyl acrylate and next to it Contains free ethanol. 400 parts of this crude ester are treated with chlorine at 0 ° in the manner described in Example 1 until the increase in weight

9 parts. The ester is then washed with aqueous sodium bicarbonate solution and water, separates the organic layer and distills it after adding 1.5 parts of phenoxypropene oxide. In addition to 48 parts of an azeotropically boiling first runnings, 178 parts of a 98% strength ester are obtained 44 parts residue. The polymer of the ester is soluble in cold ethyl acetate, its if value is 121.5.

Example 5

In 400 parts of the crude ethyl acrylate prepared in Example 4, 13 parts of chlorine are added at 0 ° initiated within 30 minutes with vigorous stirring. Eventually the highly acidic solution becomes after the addition of the stabilizers mentioned in Example 1 while cooling with ice and vigorous stirring with 125 parts of 2N sodium hydroxide solution, the neutral aqueous layer after

Stirring is removed for 10 minutes and the organic layer is washed three times with 100 parts of water. Their distillation gives, after adding 2 parts of phenoxypropene oxide, in addition to 45 parts of an azeotropically boiling first runnings, 168 parts of a 99.5% strength ester and 56 parts of residue. That with Polymers of the ester made from potassium persulfate are soluble in cold ethyl acetate; it has the if value 123.

Example 6

In 250 parts of an acrylic acid methyl ester prepared from acetylene, carbon oxide and methanol in the presence of bis (triethylbutylammonium) nickel tetrabromide [(C ₂ H ₅ ) ₃ NC ₄ H ₉ ] ₂ Ni Br ₄ , 9 parts of chlorine are added with vigorous stirring at 0 ° slow current initiated. After the addition of 0.2 part of methylene blue and 0.2 part of phenthiazine, the mixture is vigorously stirred with 150 parts of 10% sodium carbonate solution and then twice with 100 parts of water at room temperature. After the aqueous layer has been separated off and 2 parts of phenoxypropene oxide have been added, the ester is distilled in a column filled with ring-like packing. 186 parts of a 100% strength acrylic acid methyl ester are obtained in addition to 52 parts of residue. During the polymerization with potassium persulfate, the ester yields a polymer with the which is soluble in cold ethyl acetate

'Value 108. The ester which has not been treated with chlorine, on the other hand, produces a polymer with an if value of 18, which is not soluble in cold ethyl acetate.

Claims (1)

PATENT CLAIM: "Process for cleaning acrylic acid ester mixtures, by reacting acetylene with carbon dioxide and alcohols in the presence of carbonyl-forming metals, especially cobalt or nickel or their compounds were, by treatment with halogens according to patent 965 237, characterized in that the crude acrylic ester mixture with about 1 to 15 mole percent halogen, based on the Ester, treated and then with aqueous inorganic, alkaline compounds washes. Considered publications:
German Patent Nos. 512 223, 851 341;
U.S. Patent Nos. 2,463,608, 2,465,991. © 7ΟΪ6ϊι / 418 9.57