DE881193C - Process for the production of oxidation products from furan and its offshoots - Google Patents

Description

Process for the production of oxidation products from furan and its Descendants In patent 875 8io is a process for the production of oxidation products from furan or its derivatives substituted by alkyl or aryl radicals simple treatment with oxygen or oxygen-containing gases at temperatures has been described below 25o °.

It has now been found that the oxygen uptake of furan or its descendants can be considerably accelerated if one takes the same exposure in the presence of photosensitizers such as eosin, chlorophyll, pinacyanol, pseudoisocyanin, suspends. In this reaction, the furans concerned or their derivatives alone or in solutions in ethyl, n-propyl or isopropyl alcohol or in benzene or toluene or other suitable solvents can be used. Under these the use of ethyl alcohol has proven particularly effective.

The primary products of this oxidation with photosensitizers are formed as oxidation products in particular the corresponding peroxides, which as such or can be obtained in the form of their stable rearrangement products.

For photooxidation in accordance with the present invention, use is made expediently the following equipment: A lamp known as the Osram Nitra lamp by Zoo Watt is in a filled with water and provided with inflow and outflow Beaker; this is from a second slightly wider beaker, which is the one to be irradiated solution contains and is provided with an agitator, surrounded. To make the best possible use of it To achieve the light energy, the apparatus is in one with mirror glass panes lined box set.

The separation of the oxidation products or their stable rearrangement products from the reaction solutions takes place in a manner customary per se. So you can use the solvent expediently distilled off in vacuo and the reaction mixture remaining as residue continue to use.

If stable rearrangement products are obtained, these can be passed through If necessary, fractionate the distillation in vacuo or with steam.

The oxidation products according to the invention or their rearrangement products or the raw products thereof can be converted into valuable substances by hydrogenation convict. So z. B. from furan photoperoxide of the formula (C @ H403) x by careful obtained catalytic hydrogenation succinaldehydic acid.

The oxidation products according to the invention from furan and its derivatives are valuable intermediates for the preparation of technically important compounds. As well as the oxidation products have a peroxidic character, they can also be used as Find polymerization pathogen use.

The substances obtained from them by hydrogenation, such as succinaldehydic acid, belong to the bifunctional, simple aliphatic that have become very important today Links. There are also products such as maleic aldehydic acid or succinaldehydic acid particularly suitable for hardening gelatine emulsions for photographic purposes.

It is known, however, that certain derivatives of furan, e.g. B. furfural, furan, pyrogenic acid, furfural alcohol, in the gaseous state at higher temperatures (25o to 410 °) in the presence of vanadium oxide as catalysts by oxidation with air or oxygen can be converted into maleic anhydride (German patent 478 726; British patent 297 667, 295 270, French patent specification 689 61o; J. Amer. Chem. Soc., Volume 57, 1935, p. 1389; Chemisches Zentralblatt = 935, 1I, p.3911).

This method leads to the claimed method in which the action of air or oxygen on furans in liquid or dissolved form made at a much lower temperature in the presence of photosensitizers becomes, to completely different kind, valuable oxidation products, the photoperoxides, which are created by adding one mole of oxygen to the furan core. These peroxides can then through further conversions, e.g. B. by hydrogenation in valuable, otherwise connections that are difficult to access and that extend from the to the previously known processes available products, e.g. B. maleic anhydride by fundamentally differentiate the oxo group.

Example i 80 g of 2-methylfuran are present in 3,000 cc of ethanol of 80 mg of eosin shaken with oxygen at atmospheric pressure with exposure to light. After the uptake of oxygen has ceased, the @ 2-methylfuran photoperoxide present in solution becomes expediently hydrogenated catalytically with ice cooling or with zinc dust and glacial acetic acid. Customary work-up gives 35 to 45 g at 70 to 75 ° and a pressure of 12 mm Levulinic acid and at 14o to 1q4 ° and 12 mm pressure 1o to 12 g of levulinic acid.

The 2, 5-Dimethylfuranphotoperoxide is represented in the same way, after completion of the oxidation and after removal of the solvent in vacuo the remaining reaction material as a solid colorless compound of the composition (C, 118 03) x is obtained. The decomposition point of the compound is around 125 °. In the catalytic hydrogenation of this product, acetonylacetone is formed.

Under the same test conditions, furan in alcoholic solution absorbs oxygen when exposed to eosin in the presence of eosin and forms the peroxide of the formula C4 HI 03. This oxidation product disproportionates extremely easily to malealdehyde acid, which results in succinaldehydic acid on subsequent hydrogenation. Example 2 30 g of 2-methylfuran are shaken in 2,000 cc of ethanol (absolute, also denatured with 2 % toluene) in the presence of 0.5 g of rosin with oxygen at atmospheric pressure with exposure to light. When the uptake of oxygen has ceased, the solvent is distilled off at ordinary pressure. In the connected vacuum distillation, 10.5 g of pseudoethyl acetylacrylate are obtained as a pale yellow liquid as the main fraction at 85 to 88 ° at 10 mm. 1 g, 9 g of resinification products remain in the distillation flask, some of which are converted into oxalic acid when standing with concentrated nitric acid. If the pseudo-ester is boiled with equal parts of dilute hydrochloric acid, then solution occurs immediately and alcohol begins to distill off. After cooling, ß-acetylacrylic acid crystallizes out (mp 124 to 125 °).

If the photooxidation of 30 g of methylfuran is carried out as described above, but with the addition of 0.5 g of eosin and 0.1 g of vanadium pentoxide, 30.4 g of a yellow, between 8o to 95 ° at 10 mm are obtained after the reaction mixture has been worked up obtained distillate which consists essentially of ß-acetylacrylic acid pseudoethyl ester.

Example 3 309 furan are photooxidized as described in Example 2. When the reaction has ended, the solvent is distilled off under normal pressure and the residue is then fractionated in vacuo. In this case, 20 to 30 g of pseudoethyl malealdehyde ester are transferred at 99 to 101 ° / 13 mm. This ester is a pleasant, slightly pungent smelling liquid that distills undecomposed under normal pressure at 214 to 215 ° and crystallizes between 1.5 and 2.5 °.

In aqueous hydroxylamine chlorohydrate or. p-nitrophenyl hydrazine chlorohydrate solution The oxime or that forms in just a few hours when standing in the cold p-Nitrophenylhydrazone of maleic aldehyde acid. The action of dilute alkali lye or dilute hydrochloric acid causes very rapid saponification of the pseudo-ester.

Example 4 100 g of furfural were dissolved in 100 cc of absolute ethanol which = g eosin dissolved in a large Erlenmeyer flask (base about 600 cm2) exposed to direct sunlight in the presence of oxygen. To After the usual work-up, 66.7 g of pseudoethyl malealdehyde ester were obtained within 1/2 days obtain.

Example 5 100 g of furfural (freshly distilled) are shaken in 31 absolute alcohol (with 2 l) /, toluene denatured) in the presence of ig eosin with oxygen at atmospheric pressure with exposure to an Osram lamp of 300 watts. After 3o 1 of oxygen has been consumed in about 14 days, the solvent is removed by distillation over a so-called Vigreux column at normal pressure (wheel temperature up to 245 °). The dark-colored reaction material remaining in the flask is fractionally distilled over a Widmer column at 15 mm Hg. After a first run of 1.4 g, 89.6 g of pseudoethyl malealdehyde ester passed over at 97 to 10 °, almost colorless, which, based on furfural, corresponds to a theoretical yield of 67.2%. 43 g of a dark resin that contained some pyric acid remained in the still. To identify the pseudoester, the p-nitrophenylhydrazone of maleic aldehyde acid with a temperature of 228 to 23o °, the phenylhydrazone with a temperature of 156 ° and the oxime with a temperature of 130 to 132 °. EXAMPLE 6 50 g of furfural (freshly distilled) were shaken in 21 absolute alcohol (denatured with 2% toluene) in the presence of 0.5 g of vanadium pentoxide with oxygen at atmospheric pressure with exposure to a 300 watt lamp. After only about 300 cc of oxygen had been absorbed in 6 days, 100 mg of eosin were added to the solution and photooxidation was continued. The initially quite lively uptake of oxygen came to a standstill after about 6 days due to the evolution of carbonic acid and was restarted by thorough evacuation to remove the carbonic acid formed. This process was repeated several times. After 18 days and a measured oxygen uptake of 13.51 (the actual oxygen uptake is much greater), the work-up was carried out in the usual way. After a first run of 3 g of furfural, 54 g of pseudoethyl malealdehyde ester passed over, which, if one takes into account the recovered furfural, corresponds to a theoretical yield of 86.2%. 10.3 g of a black resin which still contained small amounts of pyric acid remained in the still.

Example 7 50 g of furfural were present in 21 absolute methyl alcohol of 8 mg of eosin photooxidized in the usual way by exposure to a 300 watt lamp. After 16 days the measured oxygen consumption was 71/21. The methyl alcohol was distilled off at normal pressure and then the remaining one yellow liquid fractionated in vacuo using a Widmer column; after 21.2 g Furfural had passed over, 15.8 g of pseudomethyl malealdehyde were distilled at 92 to 93 ° at 12 mm almost colorless (yield 46.2% of theory). Maleic aldehyde pseudomethyl ester does not have a pleasant odor, but otherwise shows in its properties (Behavior against dilute caustic soda, Fehling's solution, bromine in glacial acetic acid, hydrogenation, Soda permanganate) is very similar to the maleic aldehyde pseudoethyl ester. This also applies to the precipitation of the oxime and the p-nitrophenylhydrazone, their identity with the corresponding maleic aldehyde acid derivatives by mixed melting point and analysis has been proven. When heated with dilute hydrochloric acid, the pseudomethyl ester goes immediately in solution with a faint yellow color, and begins with the onset of boiling Distill off methyl alcohol (flammable). A solution prepared in this way is very effective rapidly intense reddening of fuchsin sulphurous acid, while the pseudo-ester at Standing in the cold with fuchsin sulphurous acid only after many hours weak Red color generated. Example 8 50 g of furfural were present in 21 n-propyl alcohol photooxidized by 80 mg of eosin, a 300 watt lamp being used as exposure. After 12 days the oxygen uptake had reached its highest level of 686o ccm, In the next 6 days, no more oxygen consumption could be determined, because during this time, as a result of the release of carbonic acid, an increase in the gas volume entered at 11. The propyl alcohol was then distilled off in vacuo and the distillation residue fractionated via a Widmer column. Here, after 4.9 g of first run, 31.8 g of pseudo-n-propyl malealdehyde were obtained at 107 to 109 ° / 13 mm almost colorless over; Yield 47.6% of theory.

Maleic aldehyde pseudo-n-propyl ester, which smells pleasantly fruity, goes short when boiling with dilute hydrochloric acid (pseudoester upper layer) Time under a faint yellow color in solution. This solution reduces Fehling's solution when heated, as does the pseudo-n-propyl ester. With dilute sodium hydroxide solution occurs a deep red color, especially when heated. While bromine in glacial acetic acid only was absorbed very slowly and in greater quantity to form a solid resinous Body, soda permanganate is instantly reduced by the ester. The oxime with a temperature of 132 ° and p-nitrophenylhydrazone were also represented from the pseudo-ester from 228 to 236 °.

EXAMPLE 9 50 g of furfural were photooxidized in 2 liters of isopropyl alcohol in the presence of 80 mg of eosin by exposure to a 300 watt lamp and took up 6.61 of oxygen in ig days. The solvent was then first removed in vacuo without a distillation column and the only slightly discolored residue was then fractionated using a Widmer column. The following parts were obtained: I. 52 to 54 ° / 10 mm 5.19 furfural, yellowish; II. 70 to 73 ° / z1 mm 1.4 mixture of I and 11I; 11I. 98 to 100 mm 2.2 g of pseudoisopropyl malealdehyde ester, colorless.

2.5 g of a dark colored liquid remained in the still. The pseudoisopropyl ester dissolves when heated with dilute hydrochloric acid, reduction occurs when cooking with Fehling's solution. The pseudoester became the oxime of maleic aldehyde acid with a temperature of 128 ° and p-nitrophenylhydrazone are also shown from 222 to 224 °.

Example 10 509 furfural were photooxidized in 21 (freshly distilled) n-butyl alcohol in the presence of 80 mg eosin by exposure to a 300 watt lamp. After 22 days, the measured oxygen uptake was 7.551, whereupon the solution was first distilled off in vacuo until nothing passed over at a bath temperature of 0 ° and then the residue was fractionated using a Widmer column. After a forerun of 2.5 g (furfural) passed at 113.5 to 14 ° / 11 mm 10.6 g of pseudo-n-butyl malealdehyde ester became colorless. By further increasing the wheel temperature to 230 °, a dark-colored tail of 2.5 g was obtained.

Maleinaldehydsäurepseudobutylester reduces Fehling's solution in Heat; Soda permanganate changes instantly, bromine in glacial acetic acid changes very slowly discolored. The p-nitrophenylhydrazone was also produced from the pseudoester of maleic aldehydic acid of 23o °.

Example ii zoo g furfural, z.61 ethanol, i g eosin, 250 watt incandescent lamp. After 154 hours, 2o2 g of pseudoethyl malealdehyde and 13 g of furfural were obtained obtain. Yield of pseudoester: 82% of theory. 50 g residue.

Example 12 50 g furfural, 1.71 ethanol, 0.5 g methylene blue, 100 watt incandescent lamp. After 120 hours, 42 g of pseudoethyl malealdehyde ester were obtained. 14.5 g residue.

Example 13 100 g furfural, 400 cc alcohol, 1 g eosin, mercury vapor lamp "HgH iooo" (28o watts). Yield: 92 g of pseudoethyl malealdehyde ester, after 24 Hours exposure.

Claims (2)

PATENT CLAIMS: i. Process for the preparation of oxidation products from furan and its derivatives, characterized in that furans in liquid or dissolved form are exposed to oxygen or oxygen-containing gases in the presence of photosensitizing dyes and, if appropriate, the oxidation products obtained during or after the oxidation, a decomposition or rearrangement, if appropriate with hydrogenation, and the reaction products obtained are separated off in a customary manner. 2. The method according to claim i, characterized in that eosin is used as photosensitizing dye used.