Furylacrylic acid

Furfural condenses with acetic anhydride and potassium acetate to give furylacrylic acid (compare Perkin reaction, Cinnamic Acid, Section IV, 124)  

The acid may also be prepared by the condensation of furfural with malonic acid in the presence of pyridine fiuylmalonic acid is intermediately formed, which is decomposed upon heating in the presence of the base  

Method 2. Place 48 g. (41-5 ml.) of freshly-distilled furfural, 52 g. of dry malonic acid (1), and 24 ml. of dry pyridine (2) in a 500 ml. round-bottomed flask, fitted with a reflux condenser. Heat the flask on a boiling water bath for 2 hours, cool the reaction mixture and dilute with 50 ml. of water. Dissolve the acid by the addition of concentrated ammonia solution, filter the solution and wash the filter paper with a 

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Tsuda156 reported the preparation of poly(vinyl 2-furylacrylate) by the reaction of 2-furylacrylyl chloride with poly(vinylalcohol) in NaOH-water-methyl ethyl ketone. Up to 80% of the hydroxyl groups were esterified. The interest of this technique is obvious here, considering that the vinyl ester of 2-furylacrylic acid does not polymerize119 A similar procedure was employed by Gandini and Rieumont26,1 9 for the synthesis of poly(vinyl 2-furoate) another product unobtainable via a standard polymerization process (see Section 1II-B-3). 

Examples of the Knoevenagel reaction with aldehydes are given under crotonic acid (111,145), P-n-hexylacrylic acid (111,144), sorbic acid (111,145) and furylacrylic acid (V,10). 

Diethyl 7-oxopimelate has been prepared by saturating an ethanol solution of furylacrylic acid 3-7 or 7-oxopimelic acid dilactone 5 with hydrogen chloride. It was found as a by-product in the esterification of furylacrylic acid with ethanol in the presence of />-toluenesulfonic acid.8 This procedure is a modification of the original Marckwald process.3 4... 

A 3-1. three-necked flask equipped with a stirrer, reflux condenser, and gas inlet tube is charged with 476 g. (3.45 moles) of furylacrylic acid and 1580 g. (about 33 moles) of 95% ethanol (Note 1). The mixture is heated to boiling, and anhydrous hydrogen chloride is introduced at such a rate that the mixture... 

Furfuryl chloride, 35, 68 2-Furfuryl disulfide, 35, 68 S-2-Furfurylisothiourea, 35, 67 2-Furfuryl mercaptan, 35, 66 2-Furoic acid, 36, 36 Furylacrylic acid, 33, 25 Fusion, caustic, of vanillin, 30, 103... 

Furfuryl mercaptan, f48 Furylacrylic acid, d46 2-Fury 1 methyl ketone, a44 Galactitol, d824... 

Furylacrylic acid melting at 138-139° is sufficiently pure for most purposes. The acid is perfectly white when pure, but many recrystallizations are required to attain that state. It may be recrystallized from benzene or ligroin (90-100 °) with the addition of Norite. The loss is about 20-25 per cent, and the product melts at 139-140° (sometimes 140-141°). 

Furylacrylic acid has usually been prepared from furfural by the Perkin reaction.1 The use of potassium acetate is advantageous, since it allows the reaction to proceed rapidly at relatively lower temperatures. The acid has also been prepared from furfural and malonic acid in the presence of pyridine,2 and by oxidation of furfuralacetone with bleaching powder.3... 

After cooling slightly, the reaction mixture is transferred to a large flask and treated with 3.5 1. of water. Part of this is used to rinse out the reaction flask. The mixture is boiled with 30 g. of Norite for about ten minutes and is filtered while still hot with suction, using a preheated Buchner funnel. Furylacrylic acid tends to separate quickly and sometimes offers trouble in clogging the funnel. The filtrate is acidified to Congo red by the addition of a 1 1 solution of concentrated hydrochloric acid in water. 

Furocetic Acid. See Furylacrylic Acid, also known as Furfuralacetic Acid... 

Furylacrylic acid can be used for prepn of some expls (See below)... 

The synthesis of pyrrolizidine developed by LukeS and Sorm31 and by Micheel and Flitsch32 starts with furylacrylic acid (56) which is converted by the Markwald reaction into y-ketopimelic acid (57). The carbonyl group in 57 is replaced by an amino group via the oxime or by the Leuckart-Wallach reaction this substitution results immediately in the formation of the lactam 58, which can be converted by heat into 3,5-dioxopyrrolizidine (59). The latter compound yields pyrrolizidine... 

The preparation of furans by acid catalyzed dehydration of 1,4-diketones followed by cyclization of the monoenol has been comprehensively reviewed (69RCR389). This method of furan preparation is useful for all 1,4-diketones which are not sterically hindered with the highly hindered l,4-bis(2,4,6-triisopropylphenyl)-l,4-butanedione no cyclization occurs (50JA5754). Although sulfuric acid is normally used for cyclization, hydrochloric acid was employed in the conversion of a 1,2-diacylethylene to a furylacrylic acid derivative (59MIP31200). Other reagents used for this purpose include polyphosphoric acid, phosphorus trichloride, zinc chloride and DMSO. Both DMSO and phosphoric esters provide neutral... 

In a 1-1. round-bottomed flask fitted with a reflux condenser are placed 192 g. (166 ml., 2 moles) of freshly distilled furfural (Note 1), 208 g. (2 moles) of malonic acid (Note 2), and 96 ml. (1.2 moles) of pyridine (Note 3). The flask is heated on a boiling water bath for 2 hours, and the reaction mixture is cooled and diluted with 200 ml. of water. The acid is dissolved by the addition of concentrated aqueous ammonia, the solution is filtered through a fluted filter paper, and the paper is washed with three 80-ml. portions of water. The combined filtrates are acidified with an excess of diluted (1 1) hydrochloric acid with stirring. The mixture is cooled by running water and then allowed to stand in an ice bath for at least 1 hour. The furylacrylic acid is filtered, washed with four 100-ml. portions of water, and dried. The yield of practically colorless needles melting at 141° is 252-254 g. (91-92%). If a purer product is desired, recrystallization is best effected from dilute alcohol (Note 4). On slow cooling of the solution, needles melting at 141° separate. 

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