Furfural treating

Furfural undergoes the Cannizzaro reaction (compare Benzaldehyde Section IV,123) when treated with sodium hydroxide solution ... 

Therapeutics. Compounds containing the furan or tetrahydrofuran ring are biologically active and are present in a number of pharmaceutical products. Eurfurjdamine [617-89-0] is an intermediate in the diuretic, furosemide. Tetrahydrofurfurylamine [4795-29-3] may also have pharmaceutical applications. 5-(E)imethyiaininomethyi)furfuryi alcohol [15433-79-17 is an intermediate in the preparation of ranitidine, which is used for treating ulcers. 2-Acet5dfuran [1192-62-7] prepared from acetic anhydride and furan is an intermediate in the synthesis of cefuroxime, a penicillin derivative. 2-Euroic acid is prepared by the oxidation of furfural. Both furoic acid [88-14-2] and furoyl chloride [527-69-5] are used as pharmaceutical intermediates. 

In the acid hydrolysis process (79—81), wood is treated with concentrated or dilute acid solution to produce a lignin-rich residue and a Hquor containing sugars, organic acids, furfural, and other chemicals. The process is adaptable to all species and all forms of wood waste. The Hquor can be concentrated to a molasses for animal feed (82), used as a substrate for fermentation to ethanol or yeast (82), or dehydrated to furfural and levulinic acid (83—86). Attempts have been made to obtain marketable products from the lignin residue (87) rather than using it as a fuel, but currently only carbohydrate-derived products appear practical. 

In order to gain some information about the fundamentals of the hydrothermal carbonization process, the hydrothermal carbonization of different carbohydrates and carbohydrate products was examined [12, 13]. For instance, hydrothermal carbons synthesized from diverse biomass (glucose, xylose, maltose, sucrose, amylopectin, starch) and biomass derivatives (HMF and furfural) were treated under hydrothermal conditions at 180 °C and were analyzed with respect to their chemical and morphological structures by SEM,13 C solid-state NMR and elemental analysis. This was combined with GC-MS experiments on residual liquor solutions to analyze side products... 

ThermoWood is not resistant to exterior weathering and the colour will gradually change to the grey that is characteristic of outdoor exposed wood. In addition, exposure in exterior conditions results in the formation of small cracks on the surface of uncoated wood. Unpigmented or low-build stain coatings do not protect the surface of the wood, but solvent-borne alkyds and water-borne acrylic paints have been found to exhibit better performance than on unmodified wood. VOC emissions from the heat-treated wood are lower compared to unmodified wood and the compositions of the emissions differ. The level of emissions is lower when the wood is treated at a higher temperature. Emissions of terpenes are reduced to very low levels, and the VOC content is dominated by furfural, hexanal and acetic acid (treated at 180 °C), and by acetic acid (treated at 230 °C). ThermoWood passes ecotoxicity tests. 

Feron VJ, Kruysse A Effects of exposure to furfural vapor in hamster simultaneously treated with benzo( ) pyrene or diethylni-trosamine. Toxicology 11 127-144, 1978... 

This compound is one of the more important furan derivatives, and is commercially available from pentosans (polysaccharides) which are present in rice husks, oats and corn residues (furfur is the Latin name for bran ). When treated with sulfuric acid, pentosans decompose into pentoses, which then undergo dehydration to the aldehyde (Scheme 6.31). 

In order to detect furfural degradation products of possible carbohydrates in the rock specimens (4), a 25-gram sample of crushed rock was treated with excess 6N hydrochloric acid, and 25 ml. of the resulting solution was collected by boiling into the empty cup of a Soxhlet extractor. Scanning the distillates... 

In an attempt to learn to what extent the substances may have been produced in laboratory preparation of the rock samples, specimens of recent marine algae from Oregon and California, freshwater pondweeds from Minnesota, and freshwater lake sediments from several localities were treated with acid and base and distilled in the same manner as the rock samples. The plant distillates yielded large quantities of furfurals only. The absorption spectra of the sediment samples showed several other peaks (mostly small) in addition to furfurals. A few sediment samples had large peaks. If the substances sepa-... 

This distillate is now treated with enough sodium hydroxide so that the mixture is left just faintly acid and the furfural separated. It amounts to 180 to 220 g. The wet furfural is distilled under diminished pressure from a Claisen flask which is heated in an oil-bath. The temperature of the bath is never permitted to rise above 130°. At first, water together with some furfural distils, and this fraction is separated to be worked up with a later portion. Finally, pure furfural (b. p. 90° at 65 mm.) distils and this fraction, collected separately, is found to be practically colorless. Its boiling point at 745 mm. is IS9°< The distillation of the crude material must not be carried out under ordinary pressure, or else the product turns dark rapidly... 

The cuticular fraction (10-12%) of the cell walls has not received much attention, nor has the part (55-70%) which is usually called hemicellulose. Carlier and Buffel34 found nearly 50% more pentosan (measured as furfural) in potato tuber treated with 1-naphthaleneacetic acid at 10 mg. per liter in agar pectin increased in almost the same proportion, and in proportion to the increased intake of water starch decreased by 36%, apparently to provide the substrate for increased respiration. 

The most import uni cyclic ethers arc (he furan compounds Furfural is manufactured by treating pentosan with sulfuric acid and steam stripping mil the furfural a n is formed The sources of pentosan arc such agricultural products uv comet tbs. oat hulls, and hagavtc Furfural is used to produce furan and tetrahydro furan fTHF) These products are used as organic intermediates, extraction solvent, polymer solvents, and in polyurethane applications... 

With products from wheat-milling, it is sometimes necessary to distil more than 400 c.c. to obtain all the furfural in such case, the distillate collected after 400 c.c. have passed over is treated separately with a small quantity of phloroglucinol and the precipitate formed weighed separately. 

For this purpose a standard solution containing 0-005 gram of furfural per litre of pure 50% alcohol is prepared, the spint to be tested being also brought to 50% concentration. 10 c c of each of the two liquids are treated at the same time with 10 drops of aniline and 1 c c of concentrated acetic acid. If, after 20 minutes, the colorations are approximately similar, they are compared in the Duboscq colorimeter, if, however, the two colorations differ greatly, the test is repeated m the manner described for the determination of the aldehydes (tee above). The proportion of furfuraldehyde present is readily calculated from the colorimeter readmgs... 

At that time, however, these reactions were not brought to the level of preparative synthesis of nitriles. The main obstacle seemed to be further transformation of the nitriles to acids. In some cases, upon treating al-doximes with alkalies, it was not at all possible to fix nitriles since they immediately converted to acids. The anti(E)-isomers exhibit an enhanced reactivity in these cases. Thus, when boiled in 2 N NaOH, -aldoximes are slowly converted to a mixture of the corresponding carboxylic acids and sy/i(Z)-aldoximes to evolve ammonia (36JA1227). Under these conditions for 4 hr the - and Z-benzaldoximes undergo 13 and 48% conversion to form benzoic acid in 10 and 38% yield, respectively. Analogously, the -and Z-oximes of furfural, under the same conditions for 1.5 hr, are converted to furan-2-carboxylic acid in 33 and 62% conversion and 18 and 49% yield, respectively. 

Unfortunately there seems to be no supplementary evidence on copolymerization initiated by phosphines. In a typical experiment, a solution of acrylonitrile in petroleum ether is treated with a little triethyl phosphine. A greenish-brown product settles on the walls of the flask. It is soluble in acetone, furfural, methyl ethyl ketone and DMF. Polymer precipitated from acetone by toluene is of low molecular weight and contains perhaps 0.5% combined phosphorus. In similar experiments it is possible to obtain pale yellow polymers with number average molecular weights of around 30,000 and with about one atom of P per polymer chain. On the basis of these results Horner and coworkers proposed the scheme (72) ... 

CA 31,2126(1937)(Rapid detn of acetone in w conducted by mixing 1 ml of soln to test with 1 ml of 0.2% furfural and 1 ml KOH soln. Treat in a similar manner 1 ml w contg 0.05% and 1 ml w contg 0.025% serving as standards. Compare the rates of pptn of sample with those of standards and calc concn of acet from the formula given in paper. The accuracy of the method is 5%) 12)Kirk Othmer, 1(1947),92(Analytical procedures and specs for acet) 13)T.G.Bonner, Anaiysr 72,434-39 (1947) 14) W.B.Huckabay et al, AnalChem 19,... 

The Purdue concepts have been applied to several different agricultural products, such as corn stalks, alfalfa, orchard grass, tall fescue, and sugarcane bagasse. No experiments have been reported on either hardwoods or softwoods. The processes have been explored in two major modes. In the first, the entire agricultural residue is treated with solvent in the second, a dilute acid pretreatment to remove hemicellulose precedes solvent treatment. The first process is especially desirable for making furfural or fermentation products from hemicellulose as a separate activity. Then, the hemicellulose-free raw material can be converted to substantially pure glucose. 

To optimize the operating conditions for the detoxification of the hydrolysates with resins, experiments were carried out with synthetic solutions. Table 3 shows how the detoxifying efficiency of the anionic resin Dowex 1 diminished with increasing treated volume. Aliquots of the solution eluted through the column were sampled after 120,230, and 250 mL. As a whole, after the early 600 mL, the column still had a fair cleaning efficiency for acids but a reduced removal efficiency toward the furan compounds the data show that the cleaning efficiency of the column was 99% for formic acid, 87% for acetic acid, 40% for HMF, and 46% for furfural. An optimized resin/solution ratio of 0.14 g/g was thus extrapolated. The addition of a subsequent detoxification step with the cationic resin Dowex-50W left the concentrations of the acids almost unchanged whereas it further reduced those of HMF and furfural by 14 and 26%, respectively. The detoxification of the hydrolysate was performed on the basis of this optimized detoxification setup. 

Considering the volatiles that evolve from hot pressing and heat-treating operations, it is concluded that the major chemical changes occurring in this stage are pyrolytic. Methanol, acetic acid, furfural, and ligneous tars are the common volatiles produced by the slow pyrolysis of wood practiced in destructive-distillation processes. The temperatures used in the board conversion operations approach pyrolysis temperatures of wood and the evidence indicates that pyrolysis is indeed active in board conversion. 

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