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‘2,411,832 Patented N09. 26, ‘1946 ‘UNITED STATES PATENT. OFFICE WATER-INSOLUBLE SOAPS Hooper Linford, Manhattan Beach, and William J. Baral, Long Beach, Calif., assignors to Union ' Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application July 2'7, 1942 Serial No. 452,418 7 Claims. (01160-438) 1 metals and organic acids. The term “salts” is sometimes used to describe process for preparation of soaps which are rela tively water-insoluble from soaps which are rela some of the metal-organic compounds which we refer to as “soaps,” but we prefer to use the term tively water-soluble, by metathesis; a preferred embodiment being improvements in the process “soaps” in this application to avoid ‘confusion with the inorganic “salts” suchas copper sulfate of metathesizing sodium naphthenate and copper sulfate to form the water-insoluble copper naph thenate. The uses of such soaps are many and varied. Copper naphthenate is at present in great de mand for treatment of burlap sacks to retard rotting. Other water-insoluble 'soaps to which our invention is applicable have been employed as components of inks, paints, driers, fungicides, adhesives, dyes, pigments, lubricants, fuels, oint '10 and sodium chloride, etc., which are also in volved in the reactions. As a second item of nomenclature, the terms “soluble” and “insol uble” as used in this speci?cation, except when quali?ed, shall be construed to mean “water-sol uble” or “water-insoluble,” respectively. Similar- ‘ 1y, by “naphthenic acids” is meant the usual mix 15 ture which may contain some acids of other types such as the acyclic arachidie acids for example. In the past, the commonly used method of ments, etc. Metathesis, or double decomposition, is a com mon type of chemical reaction which may be illus trated by the following equation: 2 tion is applicable to the soaps of many other This invention relates to improvements in the preparing a water-insoluble soap such as copper naphthenate by metathesis, has involved mixing 20 equivalent proportions of water solutions of so dium naphthenate and copper sulfate, with added naphtha as a gathering agent for the water-in» In applying this general equation to the speci?c soluble soap, agitating until the reaction is com example of the preceding paragraph, AX would plete, settling, drawing off the water layer, wash represent the' sodium naphthenate, BY the cop per sulfate, AY the sodium sulfate, and BX the 25 ing the oil-copper naphthenate layer with wa ter, ?ltering, and if desired, removing the added copper naphthenate. The driving force of the naphtha by distillation. reaction may be considered to be the insolubility The above process has several features which of one of the reaction products (in this example are decidedly, objectionable froma commercial the copper naphthenate), and the completeness of the reaction will depend on the relative degree 30 standpoint. One of the worst of these is the tendency of the reaction mixture and the water of insolubility of one of the products (or its .ef washing mixtures to form emulsions which are fective removal from the system) as compared extremelyslow in breaking. This makes the en with that of the reactants. The invention is ap tire process a very slow one, increases costs, and plicable, therefore, to the preparation of any soap which may be formed bythe above type of re- : so Ll tends to cause high material losses. There is also a distinct ?re hazard involved where, naph action, i. e., to the formation of a water-insoluble tha is present in the open kettlesnormally em soap from the corresponding water-soluble soap and a relatively water-soluble salt of the desired ployed in the metathesis step; , It is theprincipal object of this invention to metal. The organic acid constituent of the soaps involved is preferably a relatively strong organic ll) provide improvements. in the above process of preparing insoluble soaps which eliminate many acid having a dissociation constant greater than of its‘ defects." These improvements canbe more about 10-”, as for example a fatty acid, naph thenic acids extracted from petroleum, a prod uct of oxidation’ of petroleum fractions, a sul fonic acid derived by sulfuric acid treatment of _ petroleum fractions, or any other similar organic ‘ ‘clearly understood after considering‘the follow ing description of the complete improved proc ess, which for convenience is outlined as a series of steps and is exempli?ed by a description of copper napthenate, this being a preferred form ‘acid; however, it may be a relatively weak acid of the invention. > such as the "phenols” extracted from petroleum, an alcohol, mercaptan, imide, etc., in some in Step 1.—-Preparation of the water soluble ‘soap stances. The metals most commonly forming 50 ' < solution water-insoluble soaps are the polyvalent metals Kerosene and gas oil fractions from a Califor such as copper, lead, tin, aluminum, iron, zinc, barium, chromium, etc., although monovalent _ nia crude oil were each extracted with aqueous caustic soda solution originally containingabout metals such as silver may also be included. These mentioned are merely examples, and the inven 55 6 lbs. NaOH per bbl.,, until the bulk of the caustic 2,411,832 1 ' ' 4 3 in each case was converted to sodium naphthenate (3) No water washing is used. It has been by the naphthenic acids present in the oil frac tions and the resulting solution had a basicity to phenolphthalein equivalent to an NaOH content of about 0.5 lb. per bbl. These “crude soaps” cluding the water soluble salts by dehydrating found that removal of inorganic impurities in and settling is fully as effective and much more rapid than the usual water washing, and also results in a product soap completely free from were then blended, and the blend Was acidi?ed with sulfuric acid to obtain a supernatant layer of "crude acids” having an acid number of about 150 mg. KOH per gram. water, and‘therefore having improved oil solu bility characteristics. The “crude acids” were then" ' ' ' separated and distilled, taking a “heart out” com prising about a 5% to 80% overhead fraction, this material being designated “distilled crude acids” and. having an acid number of about 1'75 mg. KOH per gram. A charge of about 30 tons (175 bbls.) of these “distilled crude acids” was then introduced into an “agitator” equipped for heating, cooling, and agitation, and the calculated equivalent amount of caustic, namely about 92 tons (500 ' ' The invention therefore resides in the produc tion and separation of the Water-insoluble soap phase by‘ the addition of solid salt to the reaction ' mixture in the absence of any added oil or naph tha as a gathering agent; in the puri?cation of the Water-insoluble soap phase by heating to drive off volatile impurities and adding a solvent to facilitate settling or ?ltration to remove solid ' impurities; in the combination of these steps; and in an improvement designed to facilitate the bbls.) of an aqueous caustic soda solution con separation of the water-insoluble soap phase taining 15 lbs. of NaOH per bbl. was added. The 20 from the aqueous phase described below. mixture was heated to a temperature between The invention has been illustrated by the met 150° F. and 175° F. and agitated for about 21/2 hours to complete the saponi?cation, and‘ the pH of the resulting solution was adjusted to 8.0 by addition of a small quantity of caustic (naph- -‘ thenic acids may be required in some instances). Step 2.-—Formation of the insoluble soap- by met athesz's ‘ ' To the above prepared aqueous sodium naph- ; thenate solution was added slowly with agitation the metathetical equivalent weight, 11.7 tons, of solid copper sulfate (CuSO4.5I-I2O) in the form of small granules. The mixture was again agitated hot for about 2 hours, and allowed to settle. The aqueous phase was then withdrawn from the su pernatant liquid copper naphthenate soap layer. Step 3.--Puri?cation of the insoluble soap The above copper naphthenate soap phase, which carried with it small amounts of water and other impurities such as water-soluble salts, was charged to a shell still, in which it was heat vedjust suf?ciently to boil off all of the water. This also effectively precipitated the water-solu ble salts. About 200 bbls. of mineral spirits, was then added and the charge was mixed, and set tled until clear. The clear solution of copper naphthenate in mineral spirits, which was the desired. product in this example, was decanted, leaving in the still a small residue of copper naphthenate solution plus the settled solid impur ities. The still was then flushed with mineral spirits (which was drawn off into an auxiliary tank, allowed to settle, and used as the diluent for the next batch of copper naphthenate), and ?nally ?ushed ‘with water and steam. ' It may be observed that the above'process dif 'fers_ from the conventional _ ing particulars: process in the follow ‘ v (l) The precipitating salt employed in the metathesis‘is used in the form of a solid instead ‘of an aqueous solution. This eliminates the step athesis‘ of sodium naphthenate and copper sulfate to produce copper naphthenate. However, the inventionis applicable to the preparation of a very large variety of soaps as indicated above. The following description is intended to show the reasons for some of the operating conditions used in the above preparation of copper naphthenate, and to clarify the operating conditions which may be used in other preparations. In the extraction of petroleum fractions with caustic soda to form the “crude soaps” as in Step 1 above, it is desirable to employ a solution of such strength as to minimize emulsi?cation of the two phases‘ which may otherwise result in loss of sodium naphthenate to the oil and in excessive entrainment of oil in the “crude soaps.” Some entrainment always occurs, however, as evidenced by the fact that the “crude acids” cracked out from the “crude soaps” as described above, may contain about 25% or 30% of “unsaponi?ables” such as entrained oil and unstable asphaltic or resinous materials. . The “crude acids” or “crudesoaps” may be used in place of the “distilled crude acids” or the soaps made therefrom in our process, particularly when the petroleum fractions being extracted are “clean” distillates of relatively lowv molecular weight, such as kerosene, stove oil, etc., and the percent of unsaponi?ables is relatively low, self below about 20%. It is preferable, however, es pecially where cracked, residual, ‘or. high molecu lar weight stocks are extracted, to use the “dis tilled crude acids” as described above, since these are free from, high molecular weight materials, unstable materials, etc., which might cause exces sive emulsi?cation in the succeeding metathesis. The “distilled crude acids” described usually vcontain about 15% to 20% of dissolved entrained ,oil of‘ moderate molecular weight (kerosene to gas oil). This is not a necessary part of the in vention however, since as described below, our process is also applicable to highly re?nednaph of dissolving the salt, and reduces the volume of thenic acids, which contain 3% or less of .un the reaction mixture. 65 'saponi?ables, as well as to organic acids other (2) No naphtha is added to the reaction mix than naphthenic acids, which may containno ture. This practically eliminates ?re hazards in oil. It has been found, moreover, that the pres this step. Furthermore, the absence of added ence of such normally entrained oil of moderate naphtha and the reduced volume of aqueous solu molecular weight (a portion of thefstock being tion as noted above result in the formation of an 70 extracted) is, ‘not analogous to the presence. ofa aqueous phase consisting of a moderately concen similar or larger amount of naphtha used as a trated salt solution and a supernatant phase con gathering agent in conventional processes, in that sisting of nearly pure insoluble soap. These two it does not result in objectionable emulsifying concentrated phases occupy a relatively small vol tendencies. For example, a highly re?ned sam ume, and have very little tendency to emulsify. 75 vple of naphthenic acids of the above type con‘ 2,4115% 5 The most common bases employed for forma taining only about 3% of unsaponi?ables was tion of the soluble soaps are those of the alkali metals, especially sodium and potassium, and ' ammonia. Ammonia, of course, can not be used for the preparation of copper soaps, or the soaps of any other metal which forms a stable am used in two series of similar experiments in which copper naphthenate was formed and separated as in Steps 1 and 2 above, except that the experi ments were conducted on a smaller scale. In each series of experiments, oil was added to the monium complex which prevents the added salt acids in amounts of 15%, 30%, 100% and 200% from entering into the metathesis reaction. by weight‘, respectively. In ‘one series the »oil In the metathesis, Step 2 above, the water-in was" a portion of the parent gas oil-kerosenefrac soluble soap phase may be either the upper or 10' tion from which the acids were originally ex the lower layer after stratification. In the above tracted; while in the other series the oil was copper naphthenate example, it was the upper a naphtha (mineral spirits). The degree of layer, while in a similar preparation of lead naph emulsi?cation experienced in the metathesis step thenate, it was the lower layer. Obviously, there in each experiment was measured by the vol ume of emulsion “cuff” remaining after 2 hours 15 will be other preparations or variations in oper ating conditions which will result in approxi of settling, expressed as a percent of the volume mately equal speci?c gravities for both the in of the clear supernatant copper naphthenatc soap soluble soap phase and the aqueous phase, thus phase. The results follow: > making the rate of Strati?cation extremely slow. 20. In this event the speci?c gravity of one of the Resulting per cent emulsion phases must be modi?ed. based on clear soap phase The speci?c gravity of the aqueous phase may be modi?ed by a change in the concentration of Weight per cent oil added based on acid content In presence Infprgsfrace the base used to saponify the organic acid in the of added gnzilnereal ' preparation of the soluble soap. For example, the parent oil 2 5 i2 ____________ ._ Spirits 100 50 75 50 re?ned naphthenic acids containing about 3% 0f unsaponi?ables described above were saponi ?ed as in Step 1 above by reaction with caustic of about 15 lbs. NaOH per bbl. strength (1 M) 30 in one experiment, and with caustic of about 3 lbs. Na'OI-I‘per bbl. strength (0.2 M) in a second These data show clearly one of ‘the advantages of operating without added naphtha, as well as , experiment. In the subsequent metathesis as in Step 2 above, the insoluble soap phase strati?ed above the aqueous phase in the ?rst experiment, the difference between the low boiling oilsadded in conventional processes, and the parent oil 35 and below the aqueous phase in the second ex normally present in extracted naphthenic acids, when each is present in relatively small quan tities. When naphtha is employed as a gather ing agent in the conventional processes, inciden tally, it is common practice to add 100% by weight or more on the above basis. periment. Similar. modi?cation of the speci?c gravity of the aqueous phase could be accom plished by adding either water or a water soluble salt or heavy brine to the reaction mixture during Step 2, 7 g The speci?c gravity of the insolublesoap phase may also be ‘modi?ed’ to avoid equal speci?c grav The strength of the caustic soda or other base ities of the two phases. The addition of naph used to form the aqueous solution of the water tha as in conventional processes tends to reduce soluble soap- is limited by the following‘ consider the speci?c gravity of this soap phase, but it may ations. It should be strong enough to keep the have the disadvantage of increasing emulsi?ca volume of the solution at a reasonably low value, tion tendencies as noted above. The addition of and to minimize emulsion tendencies; yet it small amounts of parent oil‘ would be preferable, should not be so strong as to interfere seriously in preparing naphthenate soaps. with the freedom of contact between the water soluble soap and the added salt, either by “salt 50' We have found a means of modifying the spe ci?c gravity of the insoluble soap phase. how ing on ” the water-soluble soap or by imparting ever. which is believed to be novel, and which has excessive viscosity or emulsi?ability to the solu an additional bene?cial effect in reducing emulsi tion. Bases having strengths of about 0.2 M to ?cation tendencies, which effect may be due to 2.0 M (mols per liter) have been found generally satisfactory. In the neutralization of naphthenic acids, using caustic soda as above, it is desirable to stop at an end point pH of about 8.0. This is modi?cation of the existing interfacial tension. The addition of carbon tetrachloride to the re action mixture in amounts as low as a few per cent or possibly as high as 100% of the volume of the aqueous phase will cause the insoluble soap done to insure minimum acid loss with maximum utilization of caustic, and to eliminate complica 60 phase to stratify below the aqueous phase in in stances where the two phases normally have ap tions resulting from precipitation of- insoluble proximately equal speci?c gravities, and will also . metal oxides or hydroxides. Similar considera markedly decrease tendencies toward emulsi? tions will dictate the pH to be used as an end cation. The carbon tetrachloride will then ac point in other preparations. For example, in neutralizing weaker acids such as the petroleum 65 company the insoluble soap to the subsequent puri?cation as in Step 3 above, where it may be phenols, it may be desirable to stop at a much distilled off with the entrained water and reused, higher pH, e. g, 10 or higher. If too high a pH etiher after separation'from the distillate water is employed, however, there may be a side reac layer, or in conjunction with that layer. Other tion involving considerable precipitation of an vinsoluble metal hydroxide during the metathesis 70 solvents which are suitable for this purpose are those organic liquids which are stable, non-reac step when certain metal salts are added, and tive, water-insoluble, and miscible with the wa this could cause contamination of the water-in ter-insoluble soap under the conditions of use, soluble soap phase with free organic acids, or even prevent appreciable metathesis of the water insoluble soap. and which have speci?c gravities above about 75 1.2, and boiling points between about 150° F. and 2,441,832‘ 300° F, These include allyl iodide, trichlorethane, butyl bromide, etc. . _, phase and an insoluble soap phase, separating said phases and then separating water and solid inorganic impurities from said insoluble soap It is obvious from the above disclosure that the occurrence of equal speci?c gravities of aqueous phase. . and insoluble soap phases may be avoided by 2. A process according to claim 1 in which the. any suitable combination of the methods de organic acid has a dissociation constant greater scribed. It should also be noted in this connec than about 10"’. tion that the temperature of the stratifying mix - ,3. A process for preparing a relatively water ture may play an important part in the relative insoluble metal soap of naphthenic acids which speci?c gravities of the two phases, since it has 10 will also form» a relatively water soluble soap of been observed that the co-e?icient of expansion a second metal, which consists in adding a solid of the insoluble soap phase is frequently much granular salt of said ?rst metal, with agitation, greater than that of theaqueous phase. In fact, to a water solution of a naphthenate of said secmixtures have‘ been prepared in which the in ond metal so as to form the naphthenate of said soluble soap phase will stratify above the aqueous 15 ?rst metal by metathesis, allowing the reaction phase while hot, yet will sink below the aqueous mixture to separate into an aqueous phase and phase when cold. an insoluble soap phase, separating said phases, It is not necessary in all cases to conduct the heating said insoluble soap phase to effect sub metathesis at elevated temperatures, but it gen stantial dehydration thereof and then separat erally shortens the reaction time, and may re ing solid inorganic impurities from the dehydrat duce emulsion troubles. It may be necessary, ed product. ' . moreover, in some cases, to operate above the 4. A process according to claim 3 in which a melting point ofv one of the constituents. For volatile hydrocarbon diluent is added to the in example, the ?nal step in purifying the water soluble soap phase after its separation from the insoluble soap, involving separation of solid im 25 aqueous phase to facilitate the separation of the impurities, purities by settling or ?ltration, obviously re quires liquid phase operation, and this may re 5. A process according to claim 3 in which the quire elevated temperatures when the desired separation of the reaction mixture into an aque soap is normally a'solid, and no diluent is pres ous phase and an insoluble soap phase is effected ent. 30 in the presence of a water insoluble, halogenated The addition of mineral spirits to the dehy organic liquid boiling between about 150° F. and drated. soap as shown in the example is not a vital about 300° F. and having a speci?c gravity great part of the invention, but in case the water-in er- than about 1.2 whereby said insoluble soap soluble soap is desired in the form of a solution phase is dissolved in said halogenated liquid and in mineral spirits or other diluent, it may be of 35 the solution separates as a lower layer. some advantage to add said diluent to the water 6. A process according to claim 3 in which the insoluble soap phase ‘ (after separation of the separation of the reaction mixture into an aque aqueous phase), so as toexpedite the settling or ous phase and an insoluble soap phase is effect ?ltering of the precipitated salts from the dehy ed in the presence of carbon tetrachloride where drated soap. It may be of some further advan 40 by said insoluble soap phase is dissolved in said tage to add the diluent before dehydrating, thus carbon tetrachloride and the solution separates providing mixing by convection. ' Also, if desired as a lower layer. in the latter operation. a portion of a suitable 7. A process for preparing copper naphthenate diluent may be taken overhead with the water in which consists in reacting an aqueous solution the dehydration, thus permitting a lower tem of- sodium naphthenate with a solid granular perature for the dehydration. copper salt at a temperature between about 100° It is obvious that many minor modi?cations in and the initial boiling point of the reaction speci?c procedures other than those mentioned mixture,‘ with agitation, so as to form copper may also be applied without exceedingr the scope naphthenate by metathesis, allowing the reac of the invention de?ned by the following claims. 50 tion mixture to separate into an aqueous phase We claim: > and a copper naphthenate soap phase, separat 1. A. process for preparing a relatively water ing said phases, heating said copper naphthenate insoluble metal soap of an organic acid which is phase to effect substantial dehydration thereof, also capable of forming a relatively water soluble adding a volatile hydrocarbon diluent to said de soap of a second metal, which consists in adding hydrated soap phase, separating solid inorganic a solid granular salt of said ?rst metal, with agi impurities from said diluted phase, and separat tation, to a water solution of a water soluble soap ing said volatile hydrocarbon diluent from the of said acid and said second metal so as to form said relatively water insoluble soap of said acid and said ?rst metal by metathesis, allowing the 60 reaction mixture to separate into an aqueous product. HOOPER LINFORD. WILLIAM J. BARAL.