Alcohol, furfuryl

Furfuryl alcohol is the most important derivative of fiirfural. At present, approximately 65 percent of all furfural produced is converted to furfuryl alcohol as there is a good demand for this product in the manufacture of foundry resins. 

The manufacture of furfuryl alcohol is a simple hydrogenation, with copper chromite used as catalyst  

Survival was reduced in groups of rats receiving 90 mg/l /day for 13 weeks by gavage, and qU oplasmic vacuolization of hepatoqU es was increased in exposed males. In mice cen-trilobular coagulative necrosis and/or multifocal subchronic inflammation of the liver occurred at doses up to 1200mg/kg.  

In 2-year gavage studies there was some evidence of carcinogenic activity in male rats based on increased incidences of cholangiocar-cinomas and bile duct dysplasia and fibrosis. There was also some evidence of carcinogenicity in female mice based on increased incidences of hepatocellular adenomas. Male mice showed clear evidence of carcinogenicity based on increased incidences of hepatocellular adenomas and carcinomas. The development of liver tumors may be related to the chronic inflammatory effects noted at this site. In another experiment with hamsters, exposure to furfural vapor 7 hours/day, 5 days/week for 1 year caused irritation of the nasal mucosa and growth retardation but no evidence of carcinogenic effects.  

The lARC has determined that there is limited evidence in animals and inadequate evidence in humans for the carcinogenicity of furfural. Overall, furfural is not classifiable as to its carcinogenicity to humans. 

Furfural was genotoxic in vitro in mammalian cells, causing chromosomal aberrations, gene mutations, and sister chromatid exchanges it was not mutagenic in a number of bacterial assays.  

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for furfural is 2 ppm (7.9mg/m ) with a notation for skin absorption. 

---

Furfuryl acetate. Reflux a mixture of 39 2 g. (34-8 ml.) of redistilled furfuryl alcohol, 48 g. of glacial acetic acid, 150 ml. of benzene and 20 g. of Zeo-Karb 225/H in a 500 ml. bolt-head flask, using the apparatus described under iaoPropyl Lactate. After 3 hours, when the rate of collection of water in the water separator is extremely slow, allow to cool, separate the resin by suction filtration, and wash it with three 15 ml. portions of benzene. Remove the benzene, etc., from the combined filtrate and washings under reduced pressure (water pump) and then collect the crude ester at 74-90°/10 mm. a small sohd residue remains in the flask. Redistil the crude ester from a Claisen flask with fractionating side arm pure furfuryl acetate passes over at 79-80°/17 mm. The yield is 14 -5 g. 

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... 

Supplement (combined with Volumes XVIII and XIX) XVII, 2nd 1934 2359-3031 Hydroxy compounds Furfuryl alcohol, 112. Carbonyl compounds Butyrolactone, 234. Furfural, 272. 2-Aoetyl-thio-phene, 287. Xanfhone, 366. Succinic anhydride, 404. Phthalio anhydride, 469. 

Oxalic acid Furfuryl alcohol, silver, mercury, sodium chlorate, sodium chlorite, sodium hypochlorite... 

The most important physical properties of furfural, as well as similar properties for furfuryl alcohol, tetrahydrofurfuryl alcohol and furan are given in Table 1. The tabulated properties of furfural are supplemented by a plot (Fig. 1) of the vapor—Hquid compositions for the system, furfural—water (15,16). 

Furfural Furfuryl alcohol Furan Tetrahydrofurfuryl alcohol... 

Depending on catalysts and conditions, products of hydrogenation can include furfuryl alcohol [98-00-0] tetrahdrofurfuryl alcohol [97-99-4] 2-meth5ifuran [534-22-5] and even 2-methyltetrahydrofuran [96-47-9]. Under strongly reducing conditions, the ring is opened. 

Furfural can be oxidized to 2-furoic acid [88-14-2] reduced to 2-furanmethanol [98-00-0] referred to herein as furfuryl alcohol, or converted to furan by decarbonylation over selected catalysts. With concentrated sodium hydroxide, furfural undergoes the Cannizzaro reaction yielding both 2-furfuryl alcohol and sodium 2-furoate [57273-36-6]. 

Furfural is a resin former under the influence of strong acid. It will self-resinify as well as form copolymer resins with furfuryl alcohol, phenoHc compounds, or convertible resins of these. Conditions of polymerization, whether aqueous or anhydrous, inert or oxygen atmosphere, all affect the composition of the polymer. Numerous patents have issued relating to polymerization and to appHcations. Although the resins exhibit a degree of britdeness, they have many outstanding properties a number of appHcations are discussed under "Uses."... 

Uses. Furfural is primarily a chemical feedstock for a number of monomeric compounds and resins. One route produces furan by decarbonylation. Tetrahydrofuran is derived from furan by hydrogenation. Polytetramethylene ether glycol [25190-06-1] is manufactured from tetrahydrofuran by a ring opening polymeri2ation reaction. Another route (hydrogenation) produces furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran, and 2-methyltetrahydrofuran. A variety of proprietary synthetic resins are manufactured from furfural and/or furfuryl alcohol. Other... 

As can be seen, most of the furfural produced in this country is consumed as an intermediate for other chemicals. Hydrogenation to furfuryl alcohol is the largest use. Some of the furfuryl alcohol is further hydrogenated to produce tetrahydrofurfuryl alcohol. The next major product is furan, produced by decarbonylation. Furan is a chemical intermediate, most of it is hydrogenated to tetrahydrofuran, which in turn is polymerized to produce polytetramethylene ether glycol (PTMEG). 

Physical Properties. Furfuryl alcohol (2-furanmethanol) [98-00-0] is aHquid, colorless, primary alcohol with a mild odor. On exposure to air, it gradually darkens in color. Furfuryl alcohol is completely miscible with water, alcohol, ether, acetone, and ethyl acetate, and most other organic solvents with the exception of paraffinic hydrocarbons. It is an exceUent, highly polar solvent, and dissolves many resins. 

The physical constants of furfuryl alcohol are Hsted in Table 1. When exposed to heat, acid or air the density and refractive index of furfuryl alcohol changes owing to chemical reaction (51), and the rate of change in these properties is a function of temperature and time of exposure. 

Under acidic conditions, furfuryl alcohol polymerizes to black polymers, which eventually become crosslinked and insoluble in the reaction medium. The reaction can be very violent and extreme care must be taken when furfuryl alcohol is mixed with any strong Lewis acid or Brn nstad acid. Copolymer resins are formed with phenoHc compounds, formaldehyde and/or other aldehydes. In dilute aqueous acid, the predominant reaction is a ring opening hydrolysis to form levulinic acid [123-76-2] (52). In acidic alcohoHc media, levulinic esters are formed. The mechanism for this unusual reaction in which the hydroxymethyl group of furfuryl alcohol is converted to the terminal methyl group of levulinic acid has recendy been elucidated (53). 

Hydrogenation of furfuryl alcohol can yield 2-tetrahydrofurfuryl alcohol, 2-methylfuran, 2-methyltetrahydrofuran, or straight-chain compounds by hydrogenolysis of the ring. Ethoxylation and propoxylation of furfuryl alcohol provide usefiil ether alcohols. 

The chemistry of furfuryl alcohol polymerization has received much attention over the years. Several recent reviews have been written (5,6,54). Based on the accumulated data, furfuryl alcohol has to be considered a bifimctional monomer in the initial stage and its "normal" reactions give linear chains or oligomers containing essentially two repeating units (15,16) with (16) predominating. 

Manufacture. Furfuryl alcohol has been manufactured on an industrial scale by employing both Hquid-phase and vapor-phase hydrogenation of furfural (56,57). Copper-based catalysts are preferred because they are selective and do not promote hydrogenation of the ring. 

Furfuryl alcohol is shipped in bulk or dmms. Although not corrosive to metals, it is a powerful solvent and penetrant containers, tanks, lines, and valves need to be in good condition to avoid potential leakage. Furfuryl alcohol can be stored in containers lined with baked phenoHc resin coatings however, it should not be put in containers that are coated with lacquers, varnishes, or epoxy resins because it is an excellent solvent for many such coatings. 

Furfuryl alcohol, on long storage, becomes progressively darker and less water soluble, a change that is also caused by heat, acidity, and exposure to air. The reactions responsible for this change in water solubiUty may be retarded by the addition in small quantity of an organic or inorganic base. Commercial furfuryl alcohol, however, usually does not contain any additives. 

Furfuryl alcohol is comparable to kerosene or No. 1 fuel oil in flammabiUty, the Tag Closed Cup flash point is 170°F. In the presence of concentrated mineral acids or strong organic acids, furfuryl alcohol reacts with explosive violence. Therefore, precautions should be taken to avoid contact of such materials with the alcohol. Caution is also recommended to avoid over-catalysis in the manufacture of furfuryl alcohol resins. 

Worldwide furfuryl alcohol capacity in 1993 was estimated to be 110,000 metric tons (38). As with furfural, new capacity in developing countries is replacing older capacity in developed countries. China and South Africa have become significant producers of furfuryl alcohol. New plants have been built in Asia and Indonesia as well. Consumption of furfuryl alcohol is spread over the globe the largest use is in the foundry industry which is increasingly moving away from heavily industrialized countries. 

Uses. Furfuryl alcohol is widely used as a monomer in manufacturing furfuryl alcohol resins, and as a reactive solvent in a variety of synthetic resins and appHcations. Resins derived from furfuryl alcohol are the most important appHcation for furfuryl alcohol in both utihty and volume. The final cross-linked products display outstanding chemical, thermal, and mechanical properties. They are also heat-stable and remarkably resistant to acids, alkaUes, and solvents. Many commercial resins of various compositions and properties have been prepared by polymerization of furfuryl alcohol and other co-reactants such as furfural, formaldehyde, glyoxal, resorcinol, phenoHc compounds and urea. In 1992, domestic furfuryl alcohol consumption was estimated at 47 million pounds (38). 

The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

---