SE187604C1 - - Google Patents

Description

CLASS IN NTERNATIONAL SWEDISH C 07 d12q: 24 PATE NT- 0 C H REGISTRATION RING SVERKET Ans. 1424/1960, 12/2 1960 THE NORWICH PHARMA.CAL Co., NORWICH, NY, USA Procedure for Nitrating Furan Derivatives Inventors: KJ Hayes and JG Michels Priority Required from February 20, 1959 (USA) of furan derivatives, in particular for the preparation of methyl 1-5-nitro-2-furyl-ketone. The compound Sr in highly diluted concentrations useful in preventing the growth of molds (Japanese Patent Application 7799/57; September 17, 1957).

The best method to date for nitrating furan compounds has been described in U.S. Pat. No. 2,490,006. According to this, an intermediate is prepared by treating the furan compound with acetic anhydride and concentrated nitric acid. The intermediate is then transferred to nitrofuran by adding an aqueous solution of a base to the nitrating mixture, which has formed a buffer system in the presence of acetic acid. In the preparation of methyl 5-nitro-2-furyl ketone according to this process, the yield of the desired end product is close to 18%.

It has been found that it is possible to produce 5-nitro-2-furyl ketone in 45-60 percent yields by treating one. intermediate, which can be prepared by adding methyl furyl ketone to a mixture of attic anhydride and nitric acid, with a salt of a strong base under anhydrous conditions. tiver lining Sr Mit to perform, since it is only necessary to add the anhydrous base to the mixture obtained during the nitration, containing the intermediate.

In the practical practice of the present process, concentrated nitric acid is preferably used. It is also advisable to add a small amount of sulfuric acid to the nitrating agent.

According to the invention, there is first prepared a nitrating agent, consisting of concentrated nitric acid and acetic anhydride and corn containing a very small amount of strong acid, e.g. sulfuric acid, as a catalyst and the methyl furyl ketone, typically dissolved in the attic acid hydride, was then added to the edge of this mixture. The resulting mixture is treated with a salt of a strong base, e.g. potassium acetate, under anhydrous conditions. The reaction mixture is then cooled, e.g. by holding on ice, the solution is stirred and the precipitated crystals of methyl 5-nitro-2-furyl ketone are filtered off. The filtrate is extracted with an organic solvent, e.g. chloroform, whereby an additional amount of the product can be recovered or alternatively a carbonyl-containing precipitant, e.g. semicarbazide hydrochloride, is added, so that the product is obtained in the form of a derivative, which Sr is easy to isolate.

Example 1 A nitrating agent is prepared by adding 0.66 mol (41.8 cm nitric acid (70%) and 10 drops conc. sulfuric acid with stirring and cooling was added to 1.8 mol (185 cm 3) of attic anhydride under 12 mm at 20-25 ° C.

To this nitrating agent was added 0.3 mol (33 g) of methyl 2-furyl ketone, dissolved in 25 cm 3 of acetic anhydride, with stirring and cooling for 13 minutes at 15-18 ° C and this temperature was maintained for 10 minutes.

To this mixture was added with stirring and cooling 0.9 moles of anhydrous potassium acetate (87 g). The potassium acetate was added in such portions that the temperature rose below 35 ° C (addition below 10 mm). After stirring at 30 ° C for 20 minutes, the mixture is heated to 65 ° C in a hot water bath. After the mixture has been stored for 12 minutes at 60-65 ° C, it is cooled to 30 ° C and poured into 500 cm 3 of ice and water with stirring. Crystals are formed. After stirring for 1 hour, the solid is filtered off, washed with cold water (40 ° C) and air dried to constant weight - 9.9 g; melting point 70-78 ° C. 2— - The filtrate and washings are treated with semicarbazide hydrochloride. A volume decrease is obtained. This is filtered and the filtrate is treated with more semicarbazide hydrochloride.

Additional semicarbazone is precipitated. This is collected and washed.

The had fractions of semicarbazone tor-has at 110 ° C: The first fraction 9.3 g has the melting point 245-255 ° C (probe division) The second fraction 18.0 g has the melting point 248 ° C (probe division).

The melting point of the methyl 5-nitro-2-furyl-ketone semicarbazone is 248 ° C (probing). The first fraction of semicarbazone is dissolved in 200 cm 3 of hot dimethylformamide, treated with activated carbon, hot filtered and diluted with 3 volumes of water. A yellow fanning crystallizes out. This is collected and dried at 110 ° C. After recrystallization, the first fraction of semicarbazone (6.3 g) reaches a melting point of 248 ° C (with probing).

The yield of methyl 5-nitro-2-furyl-ketone-semicarbazone is 24.3 g, which corresponds to 17.75 g of methyl 5-nitro-2-furyl-ketone.

The yield of ketone is 27.65 g (59.5%).

Example 2 To 135 cm 3 of attic anhydride was added for 15 minutes 45 cm 3 of 70% nitric acid and 10 drops of sulfuric acid at 15-25 ° C.

To the nitrating agent was added for 10 minutes 33 g of methyl furyl ketone in 50 cm 3 of attic anhydride at 15 ° C.

The mixture is stirred at 15-20 ° C for 12 hours. Then anhydrous potassium acetate (87 g) is added while cooling, the temperature being measured at 35 ° C. The temperature is kept at 35 ° C for 1 hour and then at 40-45 ° C for 2114 hours.

The solution is mixed in 500 cm 3 of ice and 250 g of water and stirred for 1 hour. Formed crystals are then collected and whales are washed with water. These are recrystallized from 100 units of isopropyl alcohol and air dried for 36 hours (10.2 g; m.p. 78-79 ° C).

The filtrate is extracted 3 times with 125 cm 3 of chloroform each time. The combined extracts are evaporated using a rotary vacuum evaporator, connected to a water pump, a steam bath and the residue is recrystallized using the mother liquor (isopropanol) Iran the first fraction. Crystals (9.3 g; mp 77-78 ° C) are obtained.

The reaction filtrate is extracted with 300 cm 3 of chloroform, which is flared with the filtrate from the recrystallization and evaporated in vacuo (water suction) on a steam bath. To the residue is added 50 cm 3 of fresh isopropyl alcohol and the whole solidifies, then filtered and the solid to give a third fraction (1.4 g; mp 70-74 ° C).

The yield of methyl 5-nitro-2-furyl-octane is 20.0 g (45%).

Example 3 In this case the procedure is the same as in the above example, except that the potassium acetate is replaced by sodium acetate, and similar results are obtained.

Claims (3)

Patent claim: A process for the preparation of methyl 5-nitro-2-furyl ketone by nitration of methyl 2-furyl ketone with a nitrating mixture containing attic anhydride and nitric acid, characterized in that the resulting reaction mixture is treated with a salt of a strong resin under anhydrous conditions. 2. A process according to claim 1, characterized in that the salt is potassium acetate. 3. A process according to claim 1, characterized in (Bray, that the salt is sodium acetate. Cited publications;