United States Patent (19) | 11 3,960,955 Kuntschik et al. (45) June 1, 1976

10/1970 Williams ...... 260/96.5 54) PURIFICATION PROCESS 3,534,097 2/1973 Ruyle...... 260/96.5 75) Inventors: Lawrence F. Kuntschik, Nederland; 3,717,623 Orville W. Rigdon, Groves, both of Primary Examiner-Delbert E. Gantz Tex. Assistant Examiner-C. E. Spresser 73) Assignee: Texaco Inc., New York, N.Y. Attorney, Agent, or Firm-T. H. Whaley; C. G. Ries; Bernard Marlowe 22 Filed: Nov. 15, 1974 21 Appl. No.: 524,109 57 ABSTRACT This invention concerns a process for purifying crude oximes, particularly crude n-paraffinone oximes con 52 U.S. Cl...... 260/566 A; 260/96.5 R taining carbonyl and/or chlorine contaminants, con (51 Int. C.’...... C07C 131100 sisting essentially of treating said crude oximes with 58 Field of Search...... 260/96.5 R, 96.5 U, urea or thiourea, in the presence of water and lower 260/96.5 T, 566. A alkanol, heating to decompose thermally unstable con taminants, filtering off the insoluble urea (or thiourea) 56) References Cited carbonyl complexes formed, leaving a purified oxime UNITED STATES PATENTS which can be further purified by conventional purifi 2,569,985 10/1951 Fetterly...... 260/96.5 cation methods such as vacuum distillation. 2,681,334 6/1954 Gorin...... 260/96.5 3,316,236 4/1967 Starks et al...... 260/96.5 8 Claims, No Drawings 3,960,955 2 1 chlorine impurities. Desirably, the purification proce PURIFICATION PROCESS dure would utilize the 95 percent and lower oxime This process concerns a method for purifying crude content product of the above application and convert it oximes containing substantial quantities of carbonyl to a product of 98 percent and higher oxime content. type and/or chlorine contaminants by treatment of a 5 Ideally, the novel process would be relatively inexpen urea-type reagent in the presence of a water-inert sol sive, would require no particular expertise and would vent mixture to form a carbonyl-urea complex rela utilize commercially available equipment. tively insoluble in the reaction media and using the insolubility of said complex to separate the carbonyl BRIEF DESCRIPTION OF THE INVENTION type complex from the soluble oxime and recovering 10 In practice, an oxime product, however derived, con the oxime in a purified and/or concentrated form by taminated with substantial quantities of carbonyl-type extraction using an appropriate solvent system or by and/or organic chlorine impurities is treated at elevated any other conventional purification technique. temperatures, in an aqueous-inert, solvent medium More particularly, this invention relates to a process with urea-type reagent. Sufficient urea-type reagent is wherein a crude oxime product containing carbonyl- 15 used to convert all of the carbonyl-type impurities pre type and chlorine impurities derived from a photolytic sent to a urea-type complex insoluble in the reaction catalyzed nitrosation of Co-Cs mixture of n-paraffins, medium. The heating with stirring is continued until the preferably using nitrosyl chloride and hydrogen chlor organic chloride impurities are decomposed. Then the ide, is freed of carbonyl-type and chlorine impurities by reaction medium is cooled and the urea-type carbonyl heating the crude oxime reaction medium consisting 20 complex precipitates out. At this time the insoluble essentially of oxime, ketones and organic chlorides urea-type carbonyl complex is usually removed from with urea, water and/or lower alkanol at elevated tem the oxime for further use. peratures until the chloride impurities are converted to In the favored practice, a paraffinone oxime product ketones and urea-ketone complexes are formed, cool containing from 5 to 30 or more carbon atoms, having ing and filtering off the insoluble urea-ketone complex 25 an oxime content of 95% by weight or less, and con from the residual oxime-rich filtrate, concentrating the taining a substantial quantity of carbonyl-type and or purified oxime by solvent extraction or equivalent ganic chloride impurities, is treated at about 25 to methods, optionally followed by further purification 200°C, in the presence of a water-lower alkanol mix techniques such as extraction and/or distillation under ture with 10 to 100% by weight of urea (based upon the low pressures. 30 amount of the crude oximes to be purified) to form a reaction mixture. The heating of said mixture is contin BACKGROUND OF THE INVENTION ued until the organic chloride impurities are decom Oximes are useful as organic intermediates and for posed, the mixture is then cooled to facilitate precipita various other applications. For example, they undergo tion of the urea-carbonyl complex which is separated the Beckmann rearrangement, can be alkoxylated and 35 from the purified oxime for further use and/or purifica hydrogenated, and are useful as lubrication additives tion. and anti-icing additives. Some oximes can be converted In the preferred practice, a crude oxime product to synthetic fibers (i.e. cyclohexanone oxime can be derived from the photolytic nitrosation of n-paraffins converted into caprolactam, an intermediate for the with nitrosyl chloride and hydrogen chloride contain commercial preparation of Nylon 6). ; : 40 ing from 10 to 15 carbon atoms, said product having an Paraffinone oximes have been prepared by the base oxime content of 95 percent or less, and containing up catalyzed reaction of ketones with hydroxylamine salts to 10% by weight or more of ketones and organic chlor and more recently by the photolytic nitrosation of nor ide impurities, is mal paraffins. Both of these synthetic methods can a mixed with from about 10 to 100% by weight urea produce a crude product which contains substantial 45 in the presence of 1 to 20% by weight water and 2 to quantities of contaminants boiling close to or overlap 50% by weight methanol, then heated between about ping the boiling points with the oxime product. Most of 25 to 125°C until the thermally unstable chlorides are these impurities encountered in both processes are decomposed and converted to ketones; aldehydes or ketones (which are referred to generically b. cooled below 25°C to facilitate precipitation of all as carbonyl-type impurities), while in the photolytic 50 the ketones to the insoluble urea-ketone complex; process gem-nitrosochlorides and gem-nitrosochloride c. filtered to remove the urea-ketone complex, leav condensation products can also cause separation prob ing the purified oxime soluble in the filtrate, and lems. In any event, conventional distillation under high d. extracted or distilled to separate the purified vacuum of the crude oxime obtained through photo oxime contained therein. lytic nitrosation fails to produce high purity (i.e., 9555 . percent or higher) products free from ketone impuri DETAILED DESCRIPTION OF THE INVENTION ties. Examples 1 and 2 provide evidence of this anom In order to aid in the understanding of the inventive aly. process, the following additional disclosure is submit In view of the separation difficulties presented by ted. these impurities, there is a need for a purification pro- 60 A. Paraffinone Oxime Product - Any oxime, partic cedure directed to the purification of paraffinone ox ularly, paraffinone oxime products containing at least 5 imes containing substantial quantities of carbonyl-type carbon atoms up to 30 or more carbon atoms, can be and organic chlorine impurities. Particularly useful utilized as charge stock as long as it contains substantial would be a simple treatment whichh would utilize as quantities of carbonyl-type and/or organic chlorine starting material a crude oxime product derived from 65 impurities. The favored oximes are the linear and cyclic the photolytic nitrosation of n-paraffins such as dis crude oximes such as the hexanone oximes, the cyclo closed in U.S. Pat. No. 3,578,575, and which contains hexanone oximes, the heptanone oximes, the octanone substantial quantities of carbonyl-type and/or organic oximes, the nonanone oximes, the decanone oximes, 3,960,955 3 4 the undecanone oximes, the dodecanone oximes, their 25 to 125°C, these temperatures represent the pre higher homologues and/or mixtures thereof. The pre ferred range. ferred oximes are crude cyclohexanone oximes and the 2. Pressure - Ordinarily atmospheric or near atmo paraffinone oximes containing 10 to 15 carbon atoms spheric pressures are employed. Since no apparent and having 95% or less oxime content. They can be in 5 advantage results from the use of super or sub-atmos the form of the relatively dry, crude single oxime prod pheric pressures and these extremes of pressures are uct, free from inert solvent, or as mixtures of the ox more costly to maintain, atmospheric pressures are imes having 10 to 15 carbon atoms, either relatively preferred. free from solvent or containing up to 25% by weight of 3. Reaction Time - The reaction time varies accord inert solvent. The C to C group of oximes, whether O ing to the reaction temperature and concentration of solvent-free or not, are preferred because they are charge used, as well as the size of the batch being available in large quantities from the nitrosation of the treated, and for these reasons cannot be defined pre corresponding paraffins as described in U.S. Pat. No. cisely. However, under most conditions the reaction 3,578,575. will be completed within 0.1 to 12 hours of treatment B. Urea-Type Complexing Reagent. The "urea-type' 5 with longer times not being harmful. Under the more usual reaction conditions the reaction will be complete reagent is selected from the group consisting of urea, within about 1 to 2 hours. thiourea and mixtures thereof. These reagents are em 4. Separation of Solid Materials - The separation of ployed in sufficient quantities to complex at least all of the precipitate of carbonyl-urea complex and the ex the ketones contained in the crude oxime including the 20 clusion of entrained oxime is assured by washing the ketones obtained through decomposing the chloride complex with solvents having limited urea solubility. impurities originally present in the oxime. These com These include among others, alkanes from pentane to plexing reagents are ordinarily employed in stoichio decane and their mixtures, cycloalkanes, cyclohexanes metric excess (based upon ketone present and ketone etc., cold alkanols containing from 1 to 5 carbon atoms to be formed from chloride impurities in the crude 25 and their mixtures as well as ketones containing 3 to 10 oxime). In practice where from about 5 to 10% ketone carbon atoms and mixtures. w is present in the oxime from 10 to 100% by weight of 5. Mole Ratio of Urea Type Material to Crude Oxime urea based on the oxime charge is employed. If thio - Fairly good results have been obtained with ureafox urea is employed a proportionately higher range is ime mole ratios of 0.3 to 3.0 of urea for each mole of required. 30 crude oxime to be purified. However, consistently good C. Water - The presence of water during the forma results have been obtained with urea to oxime mole tion of the urea-carbonyl-type complex is critical for ratios ranging from 0.5 to 2.0 and these represent the the satisfactory removal of ketones (or aldehydes) preferred ratios. from the crude oximes. Satisfactory results have been 6. Mole Ratio of Urea to Ketone in Oxime - While obtained when from about 1 to 20% by weight of water 35 a mole ratio of 5 to 50 moles of urea type complexing (based upon the quantity of oximes) is present with the agent per mole of the ketone impurities known to be preferred results consistently being noted when about 4 present in the crude oxime to be purified is satisfactory, to 15% by weight of water is present during complex the preferred weight ratio is from about 10 to 25 moles formation. Further, the presence of water leads to the of urea per gram of ketone present in the oxime. The conversion (during the heating) of nitrosochlorides and 40 narrower mole ratio is preferred because it produces a related compounds present to ketones which subse consistently good yield of purified oxime free essen quently complex with the urea-type reagent. Finally, tially from carbonyl impurities particularly of ketones. based upon the results shown in Examples 6 through G. Process Conditions: 12, the satisfactory removal of ketones (or aldehydes) As described supra, the gist of this invention is the from the crude oxime can only be accomplished in the 45 discovery that the oxime content of crude oximes can presence of a water-alkanol solvent system, particularly be substantially increased with a corresponding de when the mole ratio of water varies from 0.1 to 2.0 crease in the proportion of contaminants of the car moles of water per mole of alkanol present. bonyl type (essentially ketones) as well as those re D. Cosolvent with Water - As indicated supra water ferred to as organic chloride impurities by urea or thio and at least one inert, water-miscible solvent must be 50 urea complex formation in a water-based solvent sys employed for effective removal of carbonyl-type impu tem. In these systems oximes do not appear to form rities from the crude oxime through separation of the urea (or thiourea) complexes whereas insoluble urea urea-type complex which is insoluble in the reaction type carbonyl complexes are readily formed. This is media. While alkanols containing 1 to 5 carbon atoms particularly useful in crude oximes containing 90 to are useful, and methanol is preferred, other inert sol- 55 95% of oximes and 5 to 10% by weight of said carbo vents can be employed. These are illustrated by the nyl-type (largely ketones) impurities and the aforemen following solvents, among others: acetone, methyl ethyl tioned chlorine containing compounds constituting the ketone, methyl acetate and the like. remainder of the impurities. Crude oximes of this type E. Solvents employed to wash Urea-type Carbonyl are derived from photolytic nitrosation sources, partic Complexes - In order to minimize the loss of oxime 60 ularly from processes derived from the photolytic nitro entrained in the insoluble Urea complexes, wash sol sation of the corresponding n-paraffins. Peculiarly vents having limited urea or thiourea solubility, i.e. less enough, unless the photolytically derived oximes are than 0.1% by weight of urea in the solvent can be used. initially treated with a strong base prior to distillation, F. Reaction Conditions: even molecular distillation fails to maintain the initial 1. Temperature - The reaction temperatures re- 65 reduction in carbonyl-type plus organic chlorine impu quired for the inventive process are relatively flexible, rities. (See U.S. Pat. No. 3,764,622.) Further, the pa ranging from about 25 to 200°C. In view of the fact tented process has the disadvantage of converting the that the best results have been obtained between about ketone impurities to heavy residuum condensates 3,960,955 S 6 which can only be discarded whereas the instant pro- -. Having described the inventive process in general cess permits the ketones to readily be recovered and be terms, the following examples and embodiments are sold as chemical intermediates. Moreover, the urea submitted to supply more detailed illustrations of its ketone complexes form selectively even when in the workings. presence of large excesses of mixtures of Co to C, 5 Embodiment A - Preparation of a Crude Mixed paraffinone oximes. C-C Paraffinone Oxime Product Containing Sub The closest known prior art is Industrial and Engineering Chemistry, Vol.47, pages 216-222 which discloses urea-ketone among many other stantial Quantities of Carbonyl-Type Impurities: complexes but fails to teach the use of these complexes as an oxime A 22.981 kg. portion of mixed Co-Can-paraffins is purification technique. charged to a photoreactor equipped with heating and In the most preferred process, the steps for purifying O cooling means and a means of directing a light source the crude oxime consist essentially of: which excludes wave lengths below 200 millimicrons. l. Admixing a crude oxime mixture of n-paraffinone The paraffin mixture is reacted with an excess of gase oximes having 10 to 15 carbon atoms containing 90 to ous nitrosyl chloride at 60°F in the presence of gaseous 95% oxime and 5 to 10% by weight ketones and from hydrogen chloride at flow rates of 1.64 grams per min about 0% to 5% of organic chlorides (based upon initial 15 ute and 0.95 grams per minute, respectively. After oxime content) with from 15 to 70% by weight of urea separation of the crude oxime-acid salt, the acid is in the presence of 4% to 15% water and from 5 to 30% neutralized with aqueous ammonia and the crude by weight of lower alkanols, for 0.5 to 5 hours at tem Co-C3 oxime mixture is separated. The molar selectiv peratures ranging from about 85° to 125°C to decom ity to crude oximes is 87.4% with an overall recovery of pose the aforementioned organic chloride impurities to 20 90.7% by weight oxime. The crude oxime product con ketones forming a mixture of the soluble oxime and tains about 4% by weight of Co-C3 ketones. insoluble urea-ketone complex, 2. Cooling the mixture of said soluble and insoluble EXAMPLE urea complexes to about -10 to +10°C, separating the Attempted Purification of Neutralized Crude Co-Ca insoluble urea-ketone complex from the soluble oxime 25 N-paraffinone Oxime Mixture Using Conventional by filtration, centrifugation and the like. Distillation Under Moderate Vacuum 3. Washing the insoluble urea-ketone complex with solvent in which urea has a limited solubility and com An 800-gram crude mixture of Co-Can-paraffinone bining the wash liquid with the soluble oxime-rich fil oxime prepared as in Embodiment A and containing trate, and 30 4.3% by weight of ketones and 0.41% by weight chlo 4. Subjecting the solution of oxime-containing filtrate rine is batch vacuum fractionated at 0.4 to 0.6 mm of plus washings, to dilution with about 10 to 100% by mercury on an 18 inch Hempel column packed with 4 volume with water, and extracting said water-diluted inch protruded stainless steel packing in the presence oxime-rich solution with a solvent such as dialkyl ethers of 100.0 grams of 700°F hydrocarbon chaser. The fol and stripping off the solvent from the purified oxime to 35 lowing summarizes the results: recover the purified oxime. H. Distillation at High Vacuum - Optionally, the % by weight purified oxime recovered by stripping off solvents can Fraction Boiling Pressure of Ketones be further purified especially in regard to color removal No. Point, C mm Hg Wt.grams in Fraction 40 10() ().5 6. () 50 by distillation under high vacuum. By High Vacuum 2 () (3.6 74.() 9 Distillation is meant distillations carried on at less than 3 108 ().4 64. 3 10 mm of mercury, preferably under 1 mm of mercury. 4 108 0.4 204.3 9 5 2 0.4 0.2 13 While no particular mode of vacuum distillation is 6 120 0.5 37.0 19.5 required, especially good results have been obtained 7 13() 0.6 58.2 3() using molecular distillation techniques and for this 45 reason these techniques are favored. Molecular distilla tions as used herein refer to those distillation means As the increases in ketones (>175 by weight in where the vapor path of the molecules being distilled is crease) indicates, conventional vacuum distillation unobstructed and the condenser in the apparatus is without prior treatment with urea-type reagents to separated from the evaporation by a distance less than 50 remove ketone contaminants actually worsens the pu the mean free path of the evaporating, emerging mole rity of oxime product. This distillate product exhibits cules. While molecular distillation techniques are fa an undesirable hazy appearance. vored, as is frequently the case where a species selected from a broad class is employed, a more specific tech EXAMPLE 2 nique or process within the broad class is preferred for 55 Attempted Purification of Crude Co-C one reason or another. In the instant case, distillation N-paraffinone Oxime Mixture Using Continuous Thin within a molecular pot still is preferred since it pre Film Distillation (Distillation Under High Vacuum) serves the low contaminant level of the treated oxime Without a Preceding Purification with Urea substantially unchanged. These types of distillations can be carried out in a variety of apparatus at vacuums 60 A 90-gram portion of crude Co-Ca paraffinone ranging from 0.001 to 0.0001 mm of mercury. Two oxime prepared as in Embodiment A and containing types of commercially available molecular stills which 3.6% by weight of ketones and 1.15% by weight of are widely used employ either centrifugal or continu chlorine, is charged to a 2 inch Rodney Hunt Vacu ous (or falling) film techniques. Illustrative stills are Film Processor, sold by Rodney Hunt Machine Com described in Chapter 17, pages 29-32, of the Chemical 65 pany (currently sold by Arthur F. Smith Co.) and Engineering Handbook by Perry, Chilton and Kirkpa heated to 100 to 105°C at 0.3 mm Hg pressure. A light trick, 4th Edition, published by McGraw Hill Inc., New colored oxime distillate (67.0 grams) containing 2.6% York, N.Y., among other publications. by weight of ketones and 0.93% by weight of chlorine 3,960,955 7 8 is obtained. The product exhibits an undesirable hazy that essentially no ketones are separated from the appearance. oxime by this procedure. This example demonstrates that without the novel The substitution of ethanol for methanol on a mole preceding treatment with urea (or thiourea) to remove for mole basis gives the same poor results. ketones, continuous thin film distillation is not a singly 5 effective means of substantially removing carbonyl EXAMPLE 5 type and organic chlorine impurities from the crude Failure of Urea to Remove Ketone Impurities OX16. Contained in Crude Oxime in the Presence of Water but in the Absence of Lower Alkanol During Complex EXAMPLE 3 () Formation Failure of Urea to Remove Impurities Contained in A 50 gram portion of a crude n-Cio-Cia oxime mix Crude Mixtures of Co-Ca Paraffinone Oximes ture (containing 4.3% by weight of ketones and 1.12% (Obtained Through Photolytic Nitrosation of by weight of chlorine) and 100 grams of distilled water N-paraffins) Unless Water is Present During are refluxed for 3 hours. After cooling, the mixture is Complexation extracted twice with 100 ml of cyclohexane and the A 50-gram mixture of Co-Cia paraffinone oximes pooled cyclohexane extract is stripped in vacuum to prepared as in Embodiment A, containing approxi remove the cyclohexane. A 31-gram portion of oxime mately 5% by weight of ketones and 1.5% by weight of obtained from the cyclohexane extraction (containing chlorine is mixed with 500 ml of mixed heptanes, 20 ml 7.2% by weight of ketone) is mixed with 25 grams of of methanol and 80 grams of urea in a reaction vessel 20 urea and 25 ml of absolute methanol and the mixture is and heated to 22°C for 1 hour. After vacuum filtration kept for 30 minutes at 22°C. After cooling to about 5°C of the precipitated crystal complexes the crystals are in an ice bath the crystals of urea complex are vacuum washed with mixed heptanes (50 ml) and dissolved in filtered. The crystals are then dissolved in 50 ml of 200 ml of deionized water. The aqueous solution yields water and the aqueous solution is extracted twice with only a trace of ketone impurity after extracting twice 25 20 ml portions of diethyl ether. From the pooled ether with 100 ml of diethyl ether, pooling the ether extracts extracts, a one-gram portion of liquid containing 40% and evaporating off the ether solvent. The filtrate and by weight of ketones is recovered by evaporation of the washes, presumably oxime free from ketones, are ether. The oxime-rich filtrate from the crystal filtration pooled and washed with 200 ml of deionized water, is diluted with 50 ml of water and extracted twice with dried and stripped under vacuum to yield 41 grams of 30 100 ml portions of diethyl ether. The pooled ether recovered oxime. Upon analysis, however, the ketone extracts are stripped off yielding 28 grams of oxime content is not appreciably less than the initial 5% by containing 4.9% by weight ketone. Not only are poor weight concentration. This, when taken together with yields of oxime obtained but the diminution of oxime the following examples, is indicative of the fact that actually increases ketone content (from 4.3% by water should be present for effective formation of a 35 weight to 4.9% by weight) over the proportion of ke urea-ketone complex that will remove ketones from the tone present prior to treatment. crude oxime. The substitution of thiourea for urea upon a mole by mole basis is also ineffectual for the EXAMPLES 6 THROUGH 12 removal of ketones from the crude oxime. In the following examples 187 gram portions of crude 40 oximes produced as described in Embodiment A con EXAMPLE 4 taining 4.3% by weight of ketones are contacted with Failure of Urea to Remove Ketone Impurities quantities of urea ranging from 30 grams to 120 grams Contained in Crude Oximes in the Presence of Lower in the presence of both methanol (ranging from 0 (Ex Alkanols but in the Absence of Water During Complex 45 ample l l to 50 grams), and water (varying) from 9 to Formation 20 grams. The process consists essentially of: A 120 gram portion of urea and 500 ml of absolute a. Heating the reaction mixture of crude oxime(s), methanol are heated to reflux and 20 grams of crude methanol (except in Example 1 l) and water to reflux n-Cio-Cia oxime mixture (containing 5% by weight of while stirring for an hour to decompose any organic ketone and 1.5% by weight of chlorine) and 100 ml of 50 chlorine compounds present and to form the urea mixed heptanes are charged to the agitated refluxing ketone complexes, charge. After 2 hours the reaction is stopped, and reac b. Cooling the reaction mixture to between about tion mixture is cooled to about 5°C and the crystal -10° to +10°C until the insolubility of the precipitate of complex which forms is vacuum filtered. The crystals urea-ketones is optimized, are washed twice with 50 ml of mixed heptanes and are 55 c. Filtering- off the crystals usingd from 10O to 50 ml of then dissolved in 200 ml of deionized water. The resul- methyl kept t" big to -- 0 aS a As tant solution is extracted twice with 100 ml portions of h 1 t o e E. trate and met WE diethyl ether. The ether is evaporated under vacuum to WaSneS Wit ml of water and extracting twice wit yield only 0.02 grams of ketone. The filtrate (and 50 to 100 m portions of diethyl ether to remove the washes) are washed with 200 ml of deionized water, 60 oximes present in the filtrate and wash solutions, and dried and stripped of solvent to yield 16 grams of re- Stripping off the ether to produce the purified coveredvered oxines.oximes. AnalysiAnalysis of the oxime productt shshows The following Table summarizes- the data obtained. TABLE EXAMPLES CHARGE COMPOSITION 6 7 8 9 1() l 12 C-C OXIMES ------PREPARED AS IN EXAMPLE 1 ------3,960,955 1-9 10 TABLE-continued

- . . EXAMPLES - CHARGE COMPOSITION 6 7 8 9 l() 2 wt., grams 187 187 . . 87 187 187 87 187 wt.% ketones 4.3 4.3 4.3 43 4.3 43 4.3 Urea wt. grams 120 60 6() 20 3() 30 60 Methanol Wt. grams 5() 32 32 :32 16 --- Water wt. grams 20 ... 8 9 18 9 9 18 Ureafoxime, mole ratio 2.0:1 (): .0:1 2.0:1 ().5:1 ().5:1 (): Urea/ketone, mole ratio 42.5:1 2.25: 2.25: 42.5: l().6:1 ().6: 21.25: Ureafoxime/water, mole ratio 1.8: 1.0: 20: 2.(): 1.0:1 1.0: (): moles water 1.() ().5 1.() ().5 0.5 1.() Treatment Temperature 90 90 90 190 19() 90 90 Time (on Temp.) Hrs. () () 1.() () 1.0 () 2.() Recovery Stripped Filtrate Wt. grams 132.4 33.6 (38.9 16.2 l61.4 748 (b) 627 (b) Wit. '% ketones ().75 8 .4 1.6 3. 4.8 2 () Product from Urea Crystals. . Wt. grams 6.5 38.8 44.6 19.3 150 3.2 4.3 Wt. %ketones 4() ().8 (3.5 4() 4() 9.3 4() "Oxiinc containca i. 12 wt.% of chlorinc 'Urea crystals were washed with petroleum ether prior to decomposition Embodiment B - Preparation of a Specific Oxime Containing Substantial Quantities of Carbonyl-Type said ketones contained in said crude oximes. It was also Impurities: quite unexpected to find that a useful oxime purifica Using the general procedure described in Sedgwick, 25 tion process not only required formation of the urea Organic Chemistry of Nitrogen, pages 169-175 (1937 ketone complexes but that few or none of the ketones Edition), 1.2 moles of 6-undecanone is reacted with an contained in the crude oximes can be removed as the alcohol solution of 1 mole of hydroxylamine at room urea-ketone complex unless from about 4 to 15% by temperature to produce 0.8 moles of 6-undecanone weight of water is present with the lower alkanol during oxime, 30 the formation of said urea-alkanol complex. See Exam ples 1 to 5 for documentation of this. In addition, the NOH claimed process offers the ancillary advantage of de composing organic chlorine compounds during the CH(CH) C(CH)CH, heating (usually refluxing) step that accompanies urea 35 ketone complexation. Further, inasmuch as the chlo contaminated with 3.5% 6-undecanone. rine-containing compounds are converted to ketones, the addition of urea complexes the converted ketones EXAMPLE 13 produced as well as the ketones originally present in Purification of a Specific Paraffinone Oxime the crude oxime. In contrast to conventional oxime Containing Substantial Quantities of Carbonyltype 40 purification, this process is advantageous in that it per Impurities mits the recovery of the ketones removed from the The 0.8 mole portion of 6-undecanone oxime pre oxime in a marketable form. Other advantages are the pared in Embodiment B is thoroughly mixed with 50 use of commonplace process techniques without the grams of absolute methanol, 20 ml of water and 120 need for elevated reaction temperatures and pressures, grams of urea to form a reaction mixture. The reaction 45 as well as the low costs of the urea or thiourea which mixture is heated to reflux for two hours then cooled to can be readily purified for further use. Finally, while about 0°C at which point the precipitate of urea-ketone water is essential during complex formation the lower complex is filtered off and washed with 20 ml of chilled alkanols, particularly methanol or ethanol can be used methanol to remove entrained oxime. At this time the as cosolvent, and the purified oxime may further be filtrate and methanol are diluted with 100 ml of water, 50 purified by well known techniques such as molecular extracted twice with diethyl ether and vacuum stripped distillation and/or chromatographic separation tech of solvent producing a purified 6-undecanone oxime niques without departing from the inventive concept. containing about 0.7% by weight ketones. The metes and bounds of this invention are best deter This example demonstrates: mined by the claims which follow, read in conjunction 1. That the claimed process is applicable to purify 55 with the specification. specific oximes rather than only to mixtures of oximes, What is claimed is: and 1. A process for purifying crude paraffinone oximes 2. That the process is useful to purify crude oxime containing from 5 to 30 carbon atoms, from impurities substrates derived from other than photolytic nitrosa consisting essentially of from about 0 to 20% by weight tion procedures. 60 of carbonyl compounds and from about 0 to 4% by As the several examples have indicated, the novel weight of organic chlorine impurities, said precentage oxime purification process is both surprising and ad of impurities based upon the weight of oxime, by: vantageous over the known prior art. For instance, a forming a reaction mixture by mixing each part by while it is well known that a large group of compounds weight of paraffinone oxime to be purified with from including ketones form urea or thiourea complexes it 65 about 0.01 to 0.2 parts by weight of water, from about was not known that crude oximes containing ketones 0.02 to 0.5 parts by weight of a lower alkanol contain and organic chlorine impurities could be purified by ing from 1 to 5 carbon atoms, and with from about 0.1 preparing urea (or thiourea) inclusion complexes of to 1 parts by weight of a complexing reagent selected 3,960,955 1. 12 from the group consisting of urea and thiourea, the about 0.02 to 0.20 parts of water and from about urea or thiourea being added in the presence of water, 0.02 to 0.5 parts by weight of alkanol containing b. heating said reaction mixture between about 25 to from 1 to 5 carbon atoms, 200°C until the organic chlorine impurities are b., heating said reaction mixture to reflux for about decomposed and an insoluble carbonyl complex is 5 0.5 to 5 hours to convert the nitrosochloride impu formed, rities to ketones and to form an insoluble ketone c. cooling said reaction mixture to between about complex, -10° and -10°C, and c. cooling said reaction mixture between about -10 d. removing the insoluble carbonyl complex from the and --10°C for at least 0.2 hours, purified oxime contained therein. 10 d. separating said insoluble complex from the cooled 2. The process of claim 1 wherein the crude paraffi reaction mixture, and none oximes are in the form of a mixture of 5 to 30 e. isolating the purified oxime contained therein. carbon atoms and the urea-type reagent is urea. 5. The process of claim 4 wherein the lower alkanol 3. The process of claim 1 wherein the crude paraffi is methanol, the carbonyl impurities are ketones and none oximes are in the form of a specific compound. the complexing reagent is urea. 4. A process for purifying crude paraffinone oximes 6. The process of claim 4 wherein the cooled insolu containing 10 to 15 carbon atoms, said oximes being ble complex is washed with methanol kept at least derived from the photolytic nitrosation of n-paraffins about -10°C, the washings are added to the cooled containing from 10 to 15 carbon atoms, said crude reaction mixture extracted at least twice with dialkyl oximes containing from about 0% to 20% of carbonyl 20 ether and the purified oxime isolated by removing the and nitrosochloride impurities, by: solvents under vacuum. a. forming a reaction mixture by mixing each part by 7. The process of claim 4 wherein the crude paraffi weight of crude paraffinone oxime to be purified none oxime is a specific paraffinone oxime. with from about 0.1 to 1 parts by weight of urea 25 8. The process of claim 4 wherein the crude paraffi complexing reagent selected from the group con none oximes are in the form of a mixture. sisting of urea and thiourea, in the presence of from ck ck ck ck ck

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