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Dec. 17, ,1946. a. J. MAYLAND FURFURAL RECOVERY Filed Feb. 8, 1945 o 2,412,823 Patented Dec. 17, 1946 ' 2,412,823 UNITED STATES PATENT OFFICE 2,412,823 FURFURAL RECOVERY Bertrand Jesse Mayland, Bartlesville, Okla., as signor to Phillips Petroleum Company, a cor poration of Delaware Application February 8, 1945, Serial No. 576,849 9 Claims. This invention relates to the recovery of fur fural from admixture with hydrocarbons boil _ing above the hydrocarbon for which the fur fural has been used as an extraction agent, espe cially from furfural-hydrocarbon mixtures from which the furfural is not readily removable by (Cl. 260-347) ' 2 of the column.4 Through foaming and entrain ment furfural may be carried overhead in the hy drocarbon products from the extractive distilla tion and stripper columns resulting in a loss of furi'ural and contamination of the hydrocarbon products. ' ‘ ordinary fractional distillation either because of the formation of azeotropes or because of the closeness of the boiling points of the furfural and Various methods for removing these hydrocar bon contaminants from furfural have been here tofore disclosed. For example, the copending ap hydrocarbons. 10 plication of Thodos and Weinaug, Ser. No. 546, In the extractive distillation of unsaturated ali 371, filed July 24, 1944, discloses the use oi light phatic hydrocarbons using furfural as the sol hydrocarbons such as isopentane, normal pen vent, especially in the recovery of oleñns and tane, hexane, etc., in excess of their solubility in dioleflns particularly normal butylenes and/or furfural at some predetermined temperature. butadiene, the furfural gradually becomes con 15 The light hydrocarbon and furfural are intimate taminated with close-boiling hydrocarbons which ly mixed and phase separation allowed to occur are objectionable for a number of reasons. One wherein a light hydrocarbon-rich and a furiural diiîlculty caused by the presence of a substantial rich phase are obtained. Most of the contami amount of these oils in the furfural solvent is nating hydrocarbons by reason of their greater that they cause the furfural to foam in the eX-‘ 20 solubility in the light hydrocarbon remain in the tractive distillation columns and in the strippers light hydrocarbon phase. Thus a furfural-rich thereby interfering seriously with their operation and causing loss of valuable furfural overhead. These hydrocarbon contaminants having boiling phase relatively free of contaminating hydrocar bons is obtained. y The copending application of Thodos, Ser. No. points above that of the hydrocarbon for which 25 572,532, ñled January 12, 1945, shows a method of the furfural is used as an extraction agent tend removing both polymer and foaming oils from to accumulate in the furfural, since they are not furfural by extraction with light hydrocarbon removed in conventional furfural re-running op which leaves the polymer undissolved followed by erations which are commonly conducted in ac cooling of the extract phase of hydrocarbon and cordance with U. S. Patents to Buell et al. 2,350, 30 furfural to effect separation into two layers, 584, and Hachmuth 2,350,699, and in Hachmuth namely, a furfural layer relatively free of foam copending application Ser. No. 460,874, filed Oct. ing oils and a hydrocarbon layer containing most 5, 1942, such re-runnlng effecting only the re of the foaming oils. moval of polymer from the furfural in the sys The copending application of Weinaug and tem. These hydrocarbons may enter the system from valve, compressor, pump, etc., lubricating devices and from traces of heavy hydrocarbons retained Buell, Ser. No. 576,852, ñled February 3, 1.945, shows a method of recovering furfural from ad mixture with close-boiling oils by water extrac tion with such an amount of water that all of the in the feed to the extractive distillation step. furfural can readily dissolve in the water at the The hydrocarbon contaminants may comprise bu 40 temperature of extraction which preferably lies tadiene cyclic dimer (4 - vinylcyclohexene-l') between 90 and 150 degrees F. followed by azeo formed in the extraction of >butadiene-containing tropic fractional distillation of the water ex streams. In time these hydrocarbons may ac tract to give an overhead of the azeotrope of fur cumulate to objectionably high concentrations fural and water which upon condensation sepa resulting in a decrease in the selectivity and ca 45 rates into two layers. By the use of an excess of pacity of the furfural to function as a selective water in the extraction step over that required to solvent in the solvent extraction process for which dissolve all of the furfural the loss of furfural it is being used. Also, such hydrocarbon con by its remaining dissolved in the hydrocarbon taminants have a tendency to cause foaming in phase is minimized and 'the necessity for the use the extractive distillation and stripping steps. 50 of high temperatures which are objectionable is Foaming decreases the eifectiveness of the fur eliminated. The furfural being much more solu fural for making the desired separation because ble than the hydrocarbon in Water is selectively foam from the lower part of the extractive distil dissolved to give two phases, a hydrocarbon con lation column will be entrained by the upwardlyl phase and a water furfural-rich rising vapors and carried into the upper parts 65 taminant-rich phase. The present invention relates to an im 2,412,828 tion. 4 sitate excessively high pressures at the extrac tion temperature in order to hold it in the liquid phase, although the hydrocarbon contaminants in the furfural exhibit considerable solubility for provement over this method of water extrac , The hydrocarbon contaminant-rich phase in all the foregoing cases will contain appreciable amounts of furfural and the present invention is particularly applicable for recovering the small amounts of furfural remaining in the hydrocar bon-rich phases from the above described proc esses for purifying furfural in admixture with close-boiling hydrocarbons. However, the process of the present invention may be equally well applied to the recovery of furfural by the water extraction method before any such hydrocar bon contaminant concentrate is prepared and in the latter aspect it is an improved way of car rying out the water extraction method. The principal object of the present invention is to provide an improved method of recovering furfural from admixture with hydrocarbon' and the propane so ‘that the pressure required to keep the propane in solution in the liquid higher-boil ing hydrocarbons is not as high as it would be to maintain pure propane in liquid phase at the same temperature. One advantage of a normally gase ous material such as propane or butane is that it can be very easily separated from the heavy hydrocarbon-containing phase, In general, nor mal pentane is most highly preferred as the light hydrocarbon since it meets the foregoing require ments or desiderata better than any other hydro carbon. . Instead of a single light hydrocarbon, mixtures of two or more of the foregoing hydrocarbons may be employed. For example, light straight-run Ordinarily particularly close - boiling hydrocarbons from 20 naphtha may be used in some cases. it is preferred that a parailln be used and that it be substantially free from oleñns, diolefins, naph „ which it is diiiicult or impossible to separate the furfural by distillation such as fractional distil lation or steam distillation. Another object is to provide an improved method of carrying out the water extraction of furfural from such mixtures. Another object is to provide an improved method comprising water extraction followed by azeo thenes and aromatics because these increase the loss of furfural by reason of the greater solubility f. ‘ tropic distillation of the water extract for recover of furfural therein during the extraction, because the unsaturates are not desirably inert, and be cause .these hydrocarbons are too costly for the - purpose at hand. The amount of the light hydrocarbon employed ing furfural from such mixtures. Another object is to accomplish the foregoing objects in a simple 30 may vary within quite wide limits. In general, .the weight ratio of light hydrocarbon to oils in and economical> manner employing equipment the oil-furfural mixture being extracted may which is simple and not excessively expensive and range from 10 to 1 to 100 to 1, a ratio of from 50 adapted to operation for long periods of time. to 1 to 100 to 1 often being preferred. Numerous other objects will hereinafter appear. The amount of water employed may likewise The accompanying drawing portrays diagram 35 vary widely depending upon a number of circum matically one arrangement of equipment which stances, as explained in the copending applica may be used for carrying out the present inven .tion of Weinaug and Buell'above-identifled. Fac tion. I have found that furfural containing hydro-1v ‘ tors affecting the weight ratio of Water to fur fural in the oil-furfural mixture being extracted carbon contaminants having higher boiling tem include temperature of extraction, concentration peratures than the hydrocarbon for which the ‘of furfural, degree of saturation of the water furfural has been used as an extraction agent, phase with furfural desired, etc. It is usually especially hydrocarbons difficult or impossible to preferred to use a considerable excess of water separate from furfural by fractional distillation over that required to dissolve all of the furfural either because of their close-boiling nature or by contained in the oil-furfural mixture; for exam reason of the formationof azeotropes between ple, enough water to give a solution of furfural them and furfural, may be more easily freed of in water which isi not over 50% saturated rang these hydrocarbon contaminants by Water ex ing down to 10% saturated at the extraction tem traction provided a light hydrocarbon is present 50 perature. Use of .too much Water is undesirable in the extraction zone. because it requires an excessive amount of heat As the light hydrocarbon employed in accord Áto carry tbut; thedistillation applied to the Water ance withthe present invention, it is' preferred furfural mixture to obtain the furfural-water to use a hydrocarbon having not more than eight azeotrope as the overhead product. carbon atoms per molecule and >which is vcapable The extraction may be conducted at tempera of existing as a liquid under the conditions of tures ranging in the extreme from 50 to 300 de the extraction. 'I‘he hydrocarbon should be lower grees F. but preferably 90. to 150 degrees F. The boiling or lighter than furfural and hydrocarbons advantages of moderate temperatures are set having not over eight carbon atoms per molecule forth in detail in the copending application of meet these requirements. Aliphatic hydrocar bons are preferred. In general, any aliphatic 60 Weinaug'and Buell referred to above. While it is possible to carry out the extraction at tempera hydrocarbon having from three to eight carbon atoms may be employed. The hydrocarbon may .tures equal to or above the critical solution Item isobutane, n-pentane, isopentane, normal hexane, of the use of an excess of water, so that a dilute etc., up to octanes and octylenes. The lighter the hydrocarbon the more satisfactory it is. Thus pentane is preferred to octane. While propane aqueous phase with respect to furfural results', is that the solubility of oil in such a dilute aqueous phase is very low whereas as the aqueous phase ,may be used in the extraction its use may neces- - ^ becomes saturated with furfural the solubility of perature for proportions of Water and furfural, it be a paraffin or an olefin, the paraflìns being would not normally be completely desirable. It is preferred because of their inertness and lower solubility for furfural. While in extreme cases 65 preferred to use such a proportion of water that all of the furfural can dissolve .therein at moder a dioleiin such as butadiene might be used, in ate temperatures of not over 150° F., since much general, the dioleñns are not preferred because of expense, excessive solubility for furfural, and better recovery of furfural from oil' is thereby ob other considerations. Examples of suitable hy tained, the loss of furfural in solution in the oil drocarbons are:A propane, propylene, n-butane, phase being at a minimum. Another advantage 2,412,823 5 . oil therein increases.` Another advantage of the use o1' moderate temperatures, i. e. not over 150° F., is that the amount of oil dissolved in the aque ous phase is minimized since the solubility of oil in aqueous furfural rises with increasing tem perature. The pressure at >which the extraction is con ducted may depend somewhat on the tempera 6 , tion of oil contaminated furfural with a light hydrocarbon solvent as disclosed in the copend ing application of Thodos and Weinaug, Ser. No. 546,371, iìled July 24, 1944. In such case most of the contaminating oils present in the furfural by , reason of their ‘greater solubility in the light hydrocarbon extractant‘appear in the light hy drocarbon phase. Some furfural is also dissolved in the light hydrocarbon phase. The present in erately superatmospheric. The extraction is gen 10 vention is readily applicable to such a light hy erally conducted in closed pressure-resisting drocarbon phase to recover the furfural content equipment in order .to minimize losses by vola thereof. ‘ tiiization. The pressure is generally suilicient to The invention may also be applied to the‘light maintain all ofÁ the light hydrocarbon employed extract obtained from extraction of in the liquid state, that is, either dissolved in the 15 ahydrocarbon furfural-oil-polymer mixture to free it from oil phase or as a separate liquid phase. ~ polymer in accordance with the copending appli The water extraction may be carried out in cation of George Thodos. Ser. No. 572,532, filed l any suitable way, for example, by intimately mix January 12, 1945. The polymer-free extract re ing the water, furfural-oii mixture and light hydrocarbon in a mixing pump or other adequate 20 sulting from such a process 4may be treated in such manner as to effect separation into a pre mixing means and then allowing the resulting dominately light hydrocarbon phase containing mixture to separate into two phases or layers most of the oil and some furfural and a purified in a settling zone or chamber or by continuously >i'urfural phase relatively free from oil. The light countercurrently contacting the water extractant hydrocarbon phase so obtained may be employed and the furfural-oii mixture in the presence of .ture but usually ranges from atmospheric to mod the light hydrocarbon which in such case is usual ly dissolved in the furfural-oil mixture, in a column equipped with the usual contacting means such as bubble caps, packing, etc. The operation may be either single stage orl multistage and may be carried out either batchwise or continuously. The two phases. namely, extract and rañinate, are separately withdrawn in the usual manner.` The hydrocarbon phase is fractionally distilled to sep arate as an overhead the light hydrocarbon from a bottoms product of the oil contaminants orig inally present in the furfural. The water-fur fural phase is also subjected to fractional distil lation to separate the azeotrope of furfural and 25 as the feed to the present invention. ' It has been found that vthe presence of a light hydrocarbon in the water extraction of furfural from oil greatly Vfacilitates such an extraction. It brings about sharper separation into a water furfural-rich phase and a hydrocarbon-rich phase. The amount of furfural dissolved in the hydrocarbon phase is considerably reduced and the amount of hydrocarbon dissolved in the wa ter-furfural-rich phase is likewise greatly lowered by reason of the presence of the lighthydrocar bon in .accordance with `the present invention. 'I'he light hydrocarbon prevents emulsification between the hydrocarbon phase and the water water overhead from a bottoms product composed 40 furfural phase, permits shorter settling time and effective separation between furfural and essentially of the remainder of the water which i more oily contaminants. is recycled to the water extraction unit in order The invention will be more readily understood to save water and the small amount of furfural by referring to the accompanying drawing which which may be dissolved therein. The overhead vapors are cooled and totally condensed and the 45 .shows one possible modification. In `the draw ing, the feed maybe Iderived from a furfural condensate caused to form two separate liquid puriñcation process wherein light hydrocarbon is layers. The upper layer is composed of water used for separating the hydrocarbon contami nants from the furfural. The hydrocarbon-rich phase, containing a small amount of furfural be 50 fore removal of the light hydrocarbon treating furfural productsl or jme,lirwlention..y ` " “` agent, enters via line i and is intimately mixed The light hydrocarbon obtained by distillation with water entering via line 2 and fed into ex of the hydrocarbon phase is recycled to the ex traction settler 3 where two-phase separation traction unit either directly or by recycling to occurs. If desired, a mixing pump 4 may be the unit wherein the furfural‘is extracted with - interposed for‘the purpose of effecting intimate light hydrocarbon; in the latter case the light admixture of the water and the feed. In set hydrocarbon ultimately appears in the feed to tler 3 a hydrocarbon-rich phase, greatly reduced the process of the present invention. The process in furfural content, is obtained >as the top layer of the present invention is preferably carried out and a water-furfural-rich phase as the bottom under such conditions that the hydrocarbon phase 60 layer. The hydrocarbon-rich phase is fed via (rafllnate) does not contain more than 3 weight line 5 to fractionator 6 `where the light hydro per cent of furfural and that the extract phase saturated with furfural at the existing temper ature and is totally reiluxed to the azeotrope co1 umn while the lower layer constitutes the oil-free ` carbon treating agent is recovered as the over does not contain more than 0.1 weight per cent of oil. 'I‘he former limitation insures against \ . head product. 4The overhead product is con excessive loss of furfural and the latter speciñca 65 densed, a portion is refiuxed to column 6 and the remainder is recycled via lines 'i and 8 to tion insures that the purified furfural product the furfural purification process (not "shownl, contained not over 0.1 weight per cent of hydro The bottom productfrom fractionator 6 is with y drawn via line 9 and consists primarily of the 'I'he process of the present invention is applica hydrocarbon contaminant greatly reduced in fur ble to any oil-furi'ural mixture. The light hydro 70 fural content. , carbon may be already present in the oil-,furfural Thev water-furfural phase from settler 3 is mixture or it may be added in any suitable way `withdrawn via line i0 and fed to azeotrope col. in the zone in which the water extraction is con umn I i wherein there is taken overhead the azeo ducted. The invention is especially applicable to carbon. trope of water and furfural. The overhead is the oil-furfural mixture obtained by the extrac 75 completely condensed and allowed to separate 2,419,898 8 ’ and is totally reiluxed via line I3. The lower layer consists of furfural saturated with water and is withdrawn via line Il as the product of the process, The bottoms product from column I I is composed essentially of water and is recycled via lines I5 and 2 to the extraction unit. If de sired, makeup water may be introduced to the system vla line I6. In situations where the in 10 of the same amount of furfural from 100 pounds oi’ feed as in the above example was about 11_0 pounds. . . , present invention- presents numerous advantages over simple water extraction in the absence of a ght hydrocarbon as disclosed in the copending gpplication of Weinaug and Buell referred to bon or does not contain a sufficient concentration above. \ The process of the present invention of a light hydrocarbon, light hydrocarbon is in troduced'to the water extraction system vial line l1. If desired, a portion or all of the light hy drocarbon flowing in line 'I may be recycled di rectly to the water extraction system by means » ' Emmiple A hydrocarbon-furfural mixture derived by i From the foregoing it will be seen that the coming feed does not contain a light hydrocar of lines I 8 and I1. . each case. The remaining equipment was the same as inthe above described modification. In the three-stage countercurrent arrangement the amount of water required to effect the removal into two layers in accumulator I2. The upper layer consists of water saturated with furfurai brings about a sharper separation between fur fural and oil and substantially reduces the loss of iurfural, correspondingly increasing the re covery of valuable furfural. Thev phase separa tion is accomplished more easily andwith less emulsification and >in a shorter time. Other 20 advantages of the process of the present inven tion will be apparent to those skilled in the art. I claim: _ . treating contaminated furfural with a light hy 1. The process for recovering furfural from drocarbon, n-pentane, in the manner described admixture with hydrocarbons having boiling above to remove the hydrocarbon contaminants was intimately mixed with water and introduced 25 points so close to that of furfural as to be diillcult to separate from furfural by distillation which into extraction settler 3. The composition ofthe comprises subjecting such furfural-hydrocarbon hydrocarbon-furfural mixture was: mixture to water extraction in the presence of a Furfurai- ____________________ __pounds-6.1 liquid hydrocarbon having a boiling point sub Water ' ` do Heavy oils ‘ Trace stantially lower than the `boiling point of fur 1.2 30 fural. ` dn Normal pentane ______________________ __ 92.7 2. The process for recovering furfural from ad mixtu're with hydrocarbons having boiling points I I 100.0 so close to that of' furfural as to be difdcult to separate from furfural by distillation which com prises subjecting such furfural-hydrocarbon mix ture to water extraction yin the presence of a liq uid hydrocarbon having not more than 8 carbon Four hundred sixty pounds of water were used . per 100 pounds ofv feed of the above composition. In extraction-settler 3 two liquid phases sepa rated, a hydrocarbon-rich and a water-furfural rich phase. The hydrocarbon-rich phase con sisted of about 0.95 pound furfural, trace of wa ter, 1.2 pounds heavy oils, and 92.7 pounds nor mal pentane per 100 pounds feed. The water furfural-rich phase consisted of about 460 pounds atoms per molecule- i 3. 'I'he process for recovering furfural from ad mixture with hydrocarbons having boiling points so close to that of furfural as to be dii'iicult to separate from furf'ural by distillation which com prises subjecting such furfural-hydrocarbon mix water, a trace of’ heavy hydrocarbon.' and 5.15 pounds furfural. The hydrocarbon-rich phase ture to water extraction in the presence of a liq was fed to fractionator 6 to recover substan uid aliphatic hydrocarbon having from 3 to 8_ tially pure normal pentane as the overhead prod carbon atoms per molecule. mixture with hydrocarbons having boiling points ulator I9. A portion of the overhead product was returned to fractionator 6 as reflux. ' 4. The process for recovering furfural from ad uct which was condensed and collected in accum so close to that of furfural as to be diñicult to The l separate from furfural by distillation which com prises subjecting such furfural-hydrocarbon mix remaining portion was recycled via lines 'l and 8 to steps (not shown) for removing relatively heavy hydrocarbon contaminants from furfural. The bottom phase from extraction-settler I3 was . ture to water extraction in the presence of a liq uid paraffin hydrocarbon having from 3 to 8 car fed to water-furfu'ral fractionator II. In this bon atoms per molecule. ` '_ 5. The process for recovering furfural from ad fractionator a furfural-water azeotrope was mixture with hydrocarbons having boiling points taken overhead, condensed,'coo1ed. and collected in accumulator I2. Two liquid phases'separated so close to that of furfural as to be difficult to separate from furf‘ural by distillation which com rich and the lower phase was furfural-rich. The 60 prises subjecting such turfural-hydrocarbon mix in accumulator I2; the upper phase was water- ‘ ture to water extraction in the presence of liquid normal pentane. 6. The process for recovering furfural from ad water-rich phase was totally refluxed to frac tionator I I. The furfural-rich phase constituted the purified furfural product which was returned via line I4 to butadiene recovery steps (not shown). - ‘ mixture with hydrocarbons having boiling points so close to that of furfural as to be diflicult to n separate' from furfural by distillation which com prises-subjecting such furfural-hydrocarbon mix ture to water extraction ln the presence of a liq uid hydrocarbon having a boiling point substan The bottom product from fractionator II con sisted of substantially pure water. ThisA Water was recycled to be mixed with the hydrocarbon furfural mixture before introduction into extrac tion settler 3. > » 70 tially lower than that of furfural, separately In another modification of my invention a three stage countercurrent extraction arrange ment was substituted for extraction settler 3. Water was introduced at the top and the hydro-l carbon-furfural-rich mixture at‘the bottom in w s withdrawing the resulting aqueous phase and the resulting hydrocarbon phase, subjecting said aqueous phase to fractional distillation in a frac tionation column and thereby separating it into an overhead fraction of furi'ural and water in 2,412,823 azeotropic proportions and a bottoms fraction of water, condensing said overhead and causing the liquid condensate to separate into a water phase and a furfural phase essentially free of hydrocar bons, withdrawing said water phase and reflux ing said column therewith, and separately with drawing said furfural phase as the product of the process. ` ’ 10 ing hydrocarbon phase, subjecting said aqueous phase to fractional distillation in a fractionation column and thereby separating it'into an over head fraction of furfural and water in azeotropic proportions and a bottoms fraction of water, con densing said overhead and causing the liquid con densate to separate into a water phase and a iur ' fural phase essentially free of hydrocarbon, with~ drawing said water phase and refluxing said col mixture with hydrocarbons having boiling points 10 umn therewith, separately withdrawing said fur 7. The process for recovering furfural from ad so close to that of furfural as to be difficult to separate from furfural by distillation which com prises subjecting such furfural-hydrocarbon mix ture to water extraction in the presence of a liq uid parañln hydrocarbon having from 3 to 8 car bon atoms per molecule, separately withdrawing the resulting aqueous phase and the resulting hy- » drocarbon phase, subjecting said aqueous phase fural phase as the product of the process, and subjecting said hydrocarbon phase to fractional distillation to separate as an overhead said par aflin hydrocarbon having from 3 to 8 carbon 15 atoms per molecule from a bottoms fraction of said hydrocarbons having boiling points close to that of furfural. 9. The process for recovering `furfural from to fractional distillation in a fractionation co1 admixture with hydrocarbons having boiling umn and thereby separating it into an overhead 20 points so close to that of furfural as to be dif fraction of furfural and water` in azeotropic pro ilicult to separate from furfural by distillation portions and a bottoms fraction of water, con which comprises subjecting such furfuralèhydro densing said overhead and causing the liquid con~ carbon mixture to water extraction in the pres densate to separate into a water phase and a fur ence or liquid normall pentane, the amount of fural phase essentially free of hydrocarbon, with said-normal pentane being such as to give a drawing said water phase and refiuxing said col umn therewith, separately withdrawing said fur fural phase as the product of the process, and subjecting said hydrocarbon phase to vfractional distillation to separate as an overhead said hy drocarbon having from 3 to 8 carbon atoms per molecule from a. bottoms product of said hydro -carbons having boiling points close to that oi' furfural. 8. 'I'he process for recovering furfural from ad mixture with hydrocarbons having boiling points so close to that of furfural as to be diftlcult to separate from furfural by distillation which com prises subjecting such furfural-hydrocarbon mix ture to water extraction in the presence of a liq uid paraiiln hydrocarbon having from 3 to 8 car bon atoms per molecule, the amount of said par aiììn hydrocarbon being such as to give a weight ~' weight ratio of normal pentane to said hydro carbons having boiling ponts close to .that of furfural of from 10 to 1 to 100 to 1, conducting said water extraction at a temperature o1' from 90 to 150° F.,«separate1y withdrawing the re sulting aqueous phase and the resulting hydro carbon phase, subjecting said aqueous phase to fractional distillation in a fractionation column and thereby separating it into an overhead frac ' tion of furfural and water in azeotropic propor tions and a bottoms fraction of water, condens ing said overhead and causing the liquid con densate to separate into a water phase and a furfural phase essentially free of hydrocarbon, withdrawing said water >phase and refluxing said column therewith, recycling a bottoms> fraction of water to said extraction step, subjecting said hydrocarbon phase to fractional distillation to ratio of said paramn hydrocarbon to said hydro separate an overhead of normal pentane from a. carbons having boiling points close to that of 45 bottoms product of said hydrocarbons having furfural of from 10 to 1 to 100 to 1, said water boiling points close to that of furfural; and re-v extraction beingV conducted at a temperature ` cycling said normal pentane to said water ex ranging from 90 to 150° F., separately withdraw traction. ing the resulting aqueous phase and the result BERTRAND JESSE MAYLAND.