Funnels Furfural

C. Fumaric acid from furfural. Place in a 1-litre three-necked flask, fitted with a reflux condenser, a mechanical stirrer and a thermometer, 112 5 g. of sodium chlorate, 250 ml. of water and 0 -5 g. of vanadium pentoxide catalyst (1), Set the stirrer in motion, heat the flask on an asbestos-centred wire gauze to 70-75°, and add 4 ml. of 50 g. (43 ml.) of technical furfural. As soon as the vigorous reaction commences (2) bvi not before, add the remainder of the furfural through a dropping funnel, inserted into the top of the condenser by means of a grooved cork, at such a rate that the vigorous reaction is maintained (25-30 minutes). Then heat the reaction mixture at 70-75° for 5-6 hours (3) and allow to stand overnight at the laboratory temperature. Filter the crystalline fumaric acid with suction, and wash it with a little cold water (4). Recrystallise the crude fumaric acid from about 300 ml. of iif-hydrochloric acid, and dry the crystals (26 g.) at 100°. The m.p. in a sealed capillary tube is 282-284°. A further recrystaUisation raises the m.p. to 286-287°. 

Place 200 g. (172 -5 ml.) of redistilled furfural (1) in a 1 litre beaker, provided with a mechanical stirrer and surrounded by an ice bath. Start the stirrer and, when the temperature has fallen to 5-8°, add a solution of 50 g. of sodium hydroxide in 100 ml. of water from a separatory funnel at such a rate that the temperature of the reaction mixture does not rise above 20° (20-25 minutes) continue the stirring for a further 1 hour. Much sodium furoate separates during the reaction. Allow to cool to room temperature, and add just enough water to dissolve the precipitate (about 65 ml.). Extract the solution at least five times with 60 ml. portions of ether in order to remove the furfuryl alcohol the best results are obtained by the use of the continuous extraction apparatus (charged with 350 ml. of ether) depicted in Fig. //, 44, 2. Keep the aqueous layer. Dry the ethereal extract with a httle anhydrous... 

A. 2(SH)-Furanone. A 6-L, three-necked, round-bottomed flask equipped with two condensers, a dropping funnel and a 12 x 55 mm magnetic stirring bar is charged with 480 g (5 mol) of furfural (Note 1) and 2.0 L of methylene... 

In a 5-I. flat-bottom flask, equipped with a condenser (Note 1), a separatory funnel and a mechanical stirrer (Note 2), are placed 450 g. (2.24 moles) of sodium chlorate, 2 g. of vanadium pentoxide (Note 3) and 1 1. of water. The mixture is heated (Note 4) to 70-750 by supporting the flask to cm. above an electric hot plate. To the well-stirred solution is then added 200 g. (2.06 moles) of furfural (Note 5) over a period of seventy to eighty minutes. After the addition of furfural is complete, the mixture is heated at 70-75°, with stirring, for ten to eleven hours, and then allowed to stand at room temperature overnight. The mixture is filtered by suction, and the crude fumaric acid is dried in the air. The yield is 155-170 g. (65-72 per cent of the theoretical amount) (Note 6). 

In a typical reaction, a mixture of 16 g of chipped laminated particle board, 150 mL of ethanol, and 3 g of concentrated sulfuric acid was heated at 200 C for 30 minutes in a 300-mL Parr pressure reactor. The mixture was allowed to cool to room temperature. The product mixture was filtered with a Biichner funnel, and the charcoal residue was washed with ethanol and dried to give 5.4 g of charcoal. The filtrate was neutralized with sodium bicarbonate and distilled to recover the excess ethanol and the water, ethyl formate, and trace amounts of diethyl ether produced in the reaction. To extract the levulinate ester, diethyl ether was added to the residue from the distillation, which contained a small amount of ethanol. The insoluble portion of the distillation bottoms gave the resin product (3.3 g). The ether-soluble portion contained ethyl levulinate and a small amount of furfural. After the ether was stripped on a rotary evaporator, the residue (4.5 g) was vacuum-distilled to give ethyl levulinate (3.8 g) and impure furfural (0.4 g). 

In a round-bottomed flask equipped with a mechanical stirrer, dropping funnel, and reflux condenser are placed 100 gm of furfural, 100 gm of potassium dichromate, and 10 gm of water. On a steam bath the flask is heated to 100°C while a mixture of 200 gm of sulfuric acid and 100 gm of water is added during 30-45 min. The heat of reaction is such that the steam bath is removed after a short time. When reaction is complete, the reaction mixture is cooled and nearly neutralized with sodium hydroxide. Then it is completely neutralized with sodium carbonate. The chromium hydroxide that is filtered off weighs 56 gm after drying. The filtrate is made acid with sulfuric acid and the dark brown precipitate of furoic acid is filtered. More furoic acid is obtained by concentrating the filtrate. One hundred and five grams of crude material is collected. The product is recrystallized from water to yield 87 gm of white crystals of furoic acid (75%), mp 131.5°C. 

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