Patented Mar. 6, 1951 2544,562 UNITED STATES PATENT OFFICE 34,568 PROCESS FOR RECOVERNG ALDREY DES AND ENONES Westa F. Michael, Tulsa, Oka, assignor to Stano ind Oil and Gas Company, Tulsa, Okla, a co poration of Delaware No Drawing. Application July 18, 19, Serial No. 62,001 5 Cams. (C. 260-588) This invention relates to the recovery of alde hydes and ketones from solutions thereof. More Cetones may be regenerated from the resulting particularly, it relates to an improved process for extract by heating to a temperature above about separating aldehydes and ketones from aqueous 40 C. and aldehydes may be regenerated by solutions of bisulfite-aldehyde and bisulfite heating to temperatures above about 80 C. The ketone adducts. regeneration is preferably carried out by steam distillation at or above the temperatures desig It is well known that alkali-metal bisulfites nated above. The separation of aldehydes form addition compounds with aldehydes and and/or ketones may also be carried out by ex with ketones, and this reaction has been used as traction with a suitable solvent, such as a light a means for separating aldehydes and ketones O from other organic materials and for isolating hydrocarbon fraction, an alkyl ether, or an ester, the aldehydes or ketones in substantially pure at ordinary or elevated temperatures. form. In carrying out such a purification pro In addition to a striking improvement in the cedure, the aldehyde or ketone is first extracted eficiency of regenerating aldehydes and ketones, with a bisulfate solution, suitably sodium bisulfite, 5 my process has other notable advantages: In the which ordinarily has a pH between about 3 and pH range that I prefer to use, the problem of 5 when prepared by dissolving sodium bisulfite apparatus corrosion is virtually eliminated. in water. The aqueous extract is then made Moreover, the losses of active material from the strongly acid or strongly alkaline, the bisulfilte system are small. Sulfur dioxide is not liberated salt being thereby destroyed, and the aldehyde or during heat treatment or distillation; there is ketone is released, ordinarily as a separate liquid substantially no loss in bisulfite concentration of phase. Alternatively, the aldehyde and/or ke the extracting solution through reduction by tone may be released from the extract by heating ferric ions or through other mechanisms; and to an elevated temperature, without adjustment there is substantially no tendency to precipitate of the pH. As a further alternative, the aldehyde bisulfite adducts in the cold section of the appsa and/or ketone may be separated from the extract, ratus after repeated cycles. My process is there without adjustment of the pH, by extraction with fore ideally adapted to operation on a continuous a suitable solvent, the adducts being thereby pro or semicontinuous basis, with recycling of re gressively displaced toward the free aldehyde generated bisulfite solution. and/or ketone, owing to the equilibria that are Water-soluble bisulfites in general are suitable known to exist. 30 for carrying out my process, including bisulfites I have now discovered that the separation of of alkali metals, specifically lithium, sodium, po aldehydes and/or ketones from aqueous solu tassium, rubidium, and cesium; alkaline-earth tions of bisulfite adducts is greatly facilitated by metals, such as calcium, barium, and strontium; carrying out the heat treatment and/or extrac and annonium and substituted ammonlum, such tion of the aqueous adduct solution at a pH within as methylammonium, diethylammonium, tris the range of about 6 to 7; and I have obtained (2 - hydroxyethyl) ammonium, benzyltrimethyl improved results, compared with the results ob ammonium, and the like. I prefer, however, to tained in the prior art, by carrying out the sepan use sodium and/or potassium bisulfites, owing to ration within the range of about pH 5 to 8. their cheapness and availability. Solutions hav My process may embody a preliminary extrac 40 ing a concentration between about 1 and 10% by tion step, wherein aldehydes and/or ketones are weight, calculated as the anhydrous bisulfite salt, removed from other organic liquids by extraction are most satisfactory. For most effective extrac with an aqueous solution of a water-soluble bi tion of aldehydes or ketones from any given solu sulfite. The preliminary extraction is prefer tion, the solution should be contacted with sub 45 stantially more than the equimolar ratio of bi ably carried out at ordinary temperatures, but sulfite, based on the number of carbonyl groups may be carried out at temperatures as low as present, and the extraction is preferably carried around 0° C. The extraction of ketones may be out in countercurrent flow. carried out as high as around 40 C., and the ex My process is suitable for recovering or isolat traction of aldehydes proceeds satisfactorily at ing aldehydes and ketones from solution in virtu temperatures as high as 80 C. ally any organic liquid which is not miscible with 8,544,063 3 4. aqueous bisulfite solutions and which does not Eacample react with or destroy the bisulfite. As examples The following example illustrates the extrac of such organic liquids may be cited alcohols such tion of a typical aldehyde from solution in a hy as n-butyl alcohol, capryl alcohol, benzyl alcohol, drocarbon and the subsequent regeneration of cyclohexanol, and furfuryl alcohol; aliphatic hy the aldehyde according to my process. drocarbons, such as hexanes, heptanes, octanes. A 780-ml, portion of sodium bisulfite solution, petroleum naphthas, and the like; allicyclic hy prepared as described in Example I, was agitated drocarbons, such as cyclohexane, methylcyclo with one liter of heptane containing 5 percent hexane, and the like; aromatic hydrocarbons, butyraldehyde by volume. Within three minutes, such as benzene, toluene, xylene, and the like: the temperature of the reacting mixture increased and ethers, such as ethyl ether, isopropyl ether, from 26 to 34 C., after which the temperature butyl ether, ethyl butyl ether, and the like. slowly decreased. The aqueous extract was sepa From such liquids, my process may be used to rated from the heptane and steam distilled. The separate aldehydes, such as acetaldehyde, pro plonaldehyde, butyraldehyde, isobutyraldehyde, results were as follows: valeraldehyde, octanal, benzaldehyde, furfural, Butyraldehyde in heptane, Vol. percent: and the like; and ketones, such as acetone, ethyl Before extraction ---------------------- 5 methyl ketone, methyl n-propyl ketone, methyl After extraction -------------------- 0.002 In-butyl ketone, cyclopentanone, cyclohexanone, pH of bisulfite solution: and the like. - 20 Before extraction -------------------- 6.82 My invention is particularly suited for the sepa After extraction --------------------- 7.93 ration of ketones from hydrocarbon Solutions After distillation -------------------- 8.68 thereof produced in the hydrogenation of carbon Butyraldehyde recovery, percent of original: monoxide by the Fischer-Tropsch process, and by First 100 ml. condensate -------------- 38.4 the numerous modifications thereof; for the re 25 covery of aldehydes and ketones from the al Second 100 ml ----------------------- 20.4 cohols produced by the so-called "Synol" process; Third 100m------------------------- 12.0 for the recovery of aldehydes and ketones from solution in organic liquids resulting from the Total ----------------------------- 68.8 oxidation of hydrocarbons; and for the recovery 30 1 Wolume adjusted to original by addition of distilled water. of aldehydes from the hydrocarbon solutions Eacample II thereof resulting from the contacting of olefins The effect of pH on the recovery of butyralde with carbon monoxide and hydrogen in the so hyde from sodium bisulfite solutions by steam dis called "Oxo" process. tillation was studied by preparing four solutions The following examples will more clearly illus of aqueous .5% sodium bisulfite having a range trate my invention and demonstrate its superior of pH levels from 4.21 to 6.53. A 780-ml. portion ity over the prior art processes: of each solution was then reacted with 25 m. of cample butyraldehyde, and the adduct solution was steam The following example shows that the extrac O distilled. The results were as follows: tion of carbonyl compounds in my process takes place very rapidly, effective equilibrium being at Initial pH of HISO solution--------------- 4.2. 6,028.33 6.53 tained in a contact time as short as one-half ura-ar-r-rearramm--ms----- Wolume butyraldehyde recovered, ml.: minute. First 100 ml. condensate...------------- 45 8econd 100 ml. condensate.------------ An aqueous sodium bisulfilte solution was pre pared by dissolving 260 grams of sodium meta bisulfite (Na2S2O3) and 74 grams of sodium hy droxide in water and diluting to one liter. The sodium hydroxide reacted with part of the sodiurn Eacample IW bisulfite to form sodium sulfite, and thereby 50 The following example demonstrates that the raised the pH of the solution to 6.6 from an initial bisulfite extractant solutions of my invention may value of 4.2. A sufficient quantity of sodium bi be effectively regenerated by steam distillation, sulfite was present over the amount required to and when so regenerated, are as effective as fresh react with the sodium hydroxide to form a solu bisulfite extractant solution. Both the bisulfite tion containing 6.8 percent by weight of free 5 5 solutions and the hydrocarbon solutions of car sodium bisulfite. bonyl compounds were substantially the same as A series of extractions were made at 25 C. at those employed in Example I. contact times between 0.5 and 15 minutes, using In the experiment with fresh bisulfite Solution, in each experiment one liter of bisulfite ex a single one-liter portion of the hydrocarbon tractant solution, prepared as described above, 60 solution of carbonyl compounds was extracted re to extract one liter of a hydrocarbon solution peatedly with fresh one-liter portions of bisulfite containing 0.328 gram-mole of mixed aldehydes solution, and the hydrocarbon solution was and ketones, comprising primarily C-C12 com analyzed for carbonyl compounds after each ex traction.