System furfural

Type C requires the most complex data analysis. To illustrate, we have reduced the data of Henty (1964) for the system furfural-benzene-cyclohexane-2,2,4-trimethylpentane. VLB data were used in conjunction with one ternary tie line for each ternary to determine optimum binary parameters for each of the two type-I ternaries cyclohexane-furfural-benzene and 2,2,4-... 

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 is very thermally stable in the absence of oxygen. At temperatures as high as 230°C, exposure for many hours is required to produce detectable changes in the physical properties of furfural, with the exception of color (17). However, accelerating rate calorimetric data shows that a temperature above 250°C, in a closed system, furfural will spontaneously and exothermically decompose to furan and carbon monoxide with a substantial increase in pressure. The pressure may increase to 5000 psi or more, sufficient to shatter the container (18). 

Holdren, R.F. and Hixon, R.M. Vapor pressure and vapor-liquid equilibria in the system furfural—2-methylfuran, Ind. Eng. Chem., 38(10) 1061-1062, 1946. 

Solubilities and Phase Equilibria for the System Furfural -CH3COOH - H2O and Supercritical CO2... 

The recovery and purification of furfural from aqueous effluents by high-pressure extraction is of technical interest. Alternative extraction tests with supercritical carbon dioxide were carried out [1,2]. Further research [3-5] led to the conclusion that carbon dioxide is a good alternative to organic solvents with comparable and even better extraction results. For all these experiments the system furfural - water without acetic acid was used. 

In the present research program the high-pressure extraction of furfural from aqueous effluents, considering the multi component system furfural - acetic acid and water, has been studied. Solubilities of furfural in supercritical CO2 were measured at different temperatures and pressures. Furtheron phase equi-... 

Phase Equilibrium of the Quaternary System Furfural-Acetic Acid-Water-CC>2... 

The ternary system furfural-water-C02 has been studied before in different research works [1,2,9]. In this project the influence of acetic arid on the distribution of furfural was determined. According to the results of the solubility measurements temperatures were adjusted at 298 and 313 K and the equilibria were investigated at pressure levels of 90, 130 and 160 bar. Furtheron the con-... 

Staroske, J. Figurski, G. Das Dampf-Fluessigkeits-Gleichgewicht des temaeren Systems Furfural -Ethylacetat - Methanol und dessen binaeren Randsysteme bei 298,15 K. Chem. Tech. (Leipzig) 1992,44,... 

To illustrate, predictions were first made for a ternary system of type II, using binary data only. Figure 14 compares calculated and experimental phase behavior for the system 2,2,4-trimethylpentane-furfural-cyclohexane. UNIQUAC parameters are given in Table 4. As expected for a type II system, agreement is good. 

The optimum parameters for furfural-benzene are chosen in the region of the overlapping 39% confidence ellipses. The ternary tie-line data were then refit with the optimum furfural-benzene parameters final values of binary parameters were thus obtained for benzene-cyclohexane and for benzene-2,2,4-trimethyl-pentane. Table 4 gives all optimum binary parameters for this quarternary system. 

Figure 4-21. Parameters obtained for the furfural-benzene binary are different for the two ternary systems. An optimum set of these parameters is chosen from the overlapping confidence regions, capable of representing both ternaries equally well.

Figure 4-23. Calculated and experimental selectivities and distribution coefficients for the type-I ternaries in the 2,2,4-trimethyl pentane-cyclohexane-furfural-benzene system.

Calculated and Experimental Liquid-Liquid Equilibria for a Quarternary System at 25 C 2,2,4-trimethylpentane(1)-furfural(2)-cyclohexane(3)-benzene(4)... 

High Carbon Yield. Furfuryl alcohol and furfural are reactive solvents (monomers) and are effective in producing high carbon yield (heat induced carbonization in a reducing atmosphere). They function as binders for refractory materials or carbon bodies. Furfuryl alcohol usually requires acidic catalysis and furfural basic catalysis. Mixtures of furfuryl alcohol and furfural are generally catalyzed with acid although some systems may be catalyzed with base. 

Other Uses. Anisotropic and isotropic carbon are produced from furfural-modified systems glassy carbon is produced primarily from furfuryl alcohol or BHMF resins (78,79). 

Liquid—hquid extraction can be used to obtain high purity linoleic acid from safflower fatty acids or linoleic acid from linseed fatty acids using furfural and hexane as solvents (18). High purity linoleic acid has been obtained from sunflower fatty acids using a dimethylformamide and hexane solvent system (19). 

Sodium cyanide is soluble in Hquid ammonia. At temperatures below —31°C, sodium cyanide pentaammoniate [69331-34-6] NaCN-5NH3, separates in large flat crystals. At 15°C, 100 g anhydrous methanol dissolves 6.44 g anhydrous sodium cyanide at 67.4°C, it dissolves 4.10 g. Sodium cyanide hemihydrate [69331 -35-7] NaCNO.5 H2O, has been obtained by recrystaUization from cold 85% alcohol. The system NaCN—NaOH—H20 has been studied (48,49). Sodium cyanide is slightly soluble in formamide, ethanol, methanol, SO2, furfural, and dimethylformamide. 

A delaminated zeolite with an Si/Al ratio of 29, derived from the layered zeolite Nu-6(1), was employed as catalyst for dehydration of xylose at 170 °C, using a water-toluene biphasic reactor-system.140 This material, designated del-Nu-6(l), proved to be efficient for this transformation, giving 47% selectivity to furfural at 90% xylose conversion. 

Fig. 146 Other deviant behavior (but no azeotropes) in the furfural -cyclohexane system.

In fact a 1,4-dissonant system may be also reconnected to a dissonant 5-membered heterocycle. This solution is also valid when the heterocycle is an easily available starting material such as furan or furfural. For instance, syntheses of cis-jasmone (3) have been reported which follow retrosynthetic schemes shown in Scheme 5.24 [27] ... 

Recent work on the synthesis, structure and some properties of macromolecules bearing furan rings is discussed. Two basic sources of monomers are considered, viz. furfural for monomers apt to undergo chain polymerization and hydroxymethylfurfural for monomers suitable for step polymerization.Within the first context, free radical, catiomc and anionic systems are reviewed and the peculiarities arising from the presence of furan moieties in the monomer and/or the polymer examined in detail. As for the second context, the polymers considered are polyesters, polyethers, polyamides and polyurethanes. Finally, the chemical modification of aU these oligomers, polymers and copolymers is envisaged on the basis of the unique reactivity of the furan heterocycle. 

Toxicology. Furfural is an irritant of the eyes, mucous membranes, and skin and is a central nervous system depressant. 

Toxicology. Furfural alcohol is an eye, nose, and throat irritant exposure to high concentrations causes central nervous system depression. 

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