CA1051455A

CA1051455A - Process for producing metal salts of organosulfonic acids

Info

Publication number: CA1051455A
Application number: CA243,019A
Authority: CA
Inventors: Lawrence V. Gallacher; Robert G. King
Original assignee: King Industries Inc
Current assignee: King Industries Inc
Priority date: 1975-01-08
Filing date: 1976-01-06
Publication date: 1979-03-27
Also published as: FR2297210A1; GB1472735A; DE2600179C2; FR2297210B1; DE2600179A1

Abstract

Abstract of the Disclosure.- An improved process for producing metal salts of organosulfonic acids comprises reacting the sulfonic acid with a slight excess of the corresponding metal carbonate until the carbonate/acid equilibrium point is reached, and then adding a very small amount of stronger base to effect complete neutralization of the remainder of the sulfonic acid.

Description

This invention relaies to an improved method for . producing neutral metal salts of organosulfonic acids.

Background of the Invention - Salts of high molecular weight sulfonic acids of organic compounds have found use as rust inhibitors in motor fuels and lubricating ' oils, and as rubber plasticizers. See, for example, R. G.
:" :~ King and G. W. Thielcke, U.S. 2,764,548. Other uses for , such salts are found in textile treating solutions, and as wetting agents ., ,,: .

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2 no-, di- and trisulfonic acids of aliphatic and aromatic hydrocarbons, containing from about 6 to about 60 carbon atoms, , 4 including branched and strai~ht chain alkanes, mono- and poly-S cyclic aromatics and alkyl substituted such compounds. The 6 molecular we~ghts will range from about 150 to about 1500.
7 M~nosulfonic acids with molecular weights greater than about 350 8 tend to be oil soluble while those with lower molecular weights 9 tend to be water soluble. In the case of di- and tri-sulfonic acids, the minimum molecular weights for oil solubility tand to ll be higher. Particularly valuable salts are alkali metal, alka-1~ l~e earth metal, lead ant zinc salts of such organosulfonic 13 acids as dinonylnaphthalene mono- and disulfonic acid. Special ~4 m~ntion is made of such salts, and especially the sodium, potass-ium, ~alcium, magnesium, barium and zinc salts of dinonylnaph-16 thalene disulfonic acid. The latter family of salts are dis-17 closed in the sait patent, U.S. 2,~64,548. The barium and 18 calcium salts, particularly, form products having exceptional 19 rust inhibiting properties.
~0 Commercially, such salts are often prepared by using 21 oxites or hydroxides of the corresponting metal to neutralize 22 the sulfonic acit. ~owever, this is disadvantageous because 23 the oxides and hydroxides are highly caustic and, in some cases, 24 toxic. Noreover, end-point control is difficult and requlres accurately stopping the flow of neutralizing agent. -26 Exact neutrality can be very important because, for example, 27 overneutralized metal salt sulfonates tend to be difficult to 28 filter. Also, the salts of sulfonic acids are frequently used in 2g combination with ester iubricants or other additives including amines and weak acids which cannot tolerate free acidity or 31 ~asicity, .' ` ' . ~ I
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In the said patent, U.S. 2,764,548, it is suggested 1 that the metal be reacted in the form of a carbonate with the 2 - organosul~onic acid, and this indeed is more economical, much

3 ~afer, and more controllable. However, even with the carbonate,

4 as is specifically taught in the patent, end-point control is

-5 very important from a processing standpoint, because if an exces~ of carbonate was added, filtration is necessary to free ? the finished product from turbidity. Thus, it is taught that the 8 batch should be transferred to solvent recovery when the 9 neutrality point has been reached.
Surpsisingly, however, it has now been discovered that 11 carbonate neutralization appears to be limited by a carbonate/
12 acid equilibrium, which prevents complete neutralization of the 13 sulfonic aci~. Measurements have determined that the equilibrium 14 po~nt is just shy of a`true end point, regardless of the excess of carbonate present. As a result of this unexpected observation, 16 the subsequent finding that the addition of a very tiny amount 17 of strong metal base pushes the neutralization to completion and 18 gives a substantial improvement in process economics and in 19 the quality of the product is most surprising. These process advantages have wide applicability to the formation of numerous 21 metal salts of organicsulfonic acids. Surprisingly, it is 22 critical to add the strong base after the carbonate. If the order 23 is reversed, all advantages are lost. Moreover, if water is 24 excluded from the process, no neutralization occurs with metal carbonates. The key requirement in selection of the strong base 26 is to use one which has a base strength greater than that of the 27 bicarbonate ion. The pKa of the conjugate acid (H2C03) of the 28 bicarbonate ion (HC03-) is 6.35. Accordingly, suitable strong 29 bases will be those whose conjugate acid have pKa's of greater than 6.35, and especially those of greater than 7.

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S~ IARY OF THE INVENTION iO S 1 4 5 5 In one particular aspect the present invention provides a process for producing a metal salt of an organosulfonic acid and a metal selected from alkali metals, alkaline earth metals, lead and zinc, said process comprising the steps of: (i) providing a mixture comprising the organosulfonic acid and a small, effective amount of water; (ii) adding to the mixture a compound of at least one of said metals in the form of a carbonate, in an amount sufficient to provide a molar excess of said compound of at least about 1%; (iii) reacting the mixture until the carbonate/acid equilibrium point is reached;
and (iv) adding a small amount of a metal compound which has a base strength greater than that of bicarbonate ion, sufficient to effect complete neutralization of the remainder of said organosulfonic acid.
In another particular aspect the present invention provides a process for producing a metal salt of dinonylnaphthalene . sulfonic acid and a metal selected from sodium, potassium, calcium, magnesium, barium, and zlnc, said process comprising the steps of:
(i) forming a solution of dinonylnaphthalene sulfonic acid in an inert volatile organic solvent and a small, effective amount of water; (ii) adding to the solution a compound of at least one of said metals in the form of a carbonate, in an amount sufficient to provide a molar excess of said compound in the range of from 1 to 10%; (iii) reacting the mixture until the carbonate/acid equilibrium point is reached; and (iv) adding a small amount of a metal compound which has a base strength greater than that of the bicarbonate ion, sufficient to effect complete neutralization of the remainder of said dinonylnaphthalene sulfonic acid.
BRIEF DESCRIPTION OF T~E DRAWING
The drawing illustrates in flow diagram form, an ~ 4-, . . . . . . . .
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lnsl~ss an arrangement of processing components in which the present process may be practiced.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawing, metal carbonate is introduced through conduit 2 into slurry tank 4 and mixed with an inert suspend-ing medium, e.g., a hydrocarbon oil, which is introduced through conduit 6. The slurry thus produced is transferred through conduit 8 and is slowly introduced into neutralizer 10, which contains sulfonic acid solution, e.g., in an inert solvent, such as naphtha or heptane and water, e.g., 5-20% by weight, and optionally, a hydrocarbon oil added through respective conduits 12 and 14. In neutralizer 10, the metal sulfonate is produced and carbon dioxide gas is liberated. If desired, the mixture can be 1 ,.
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~ng-3 1 agitated and heated, e.g., to 60-90C. to speed attainment 2 of the carbonate/acid equilibrium point. Then a relatively 3 ~mall amount, e.g., less than 1% by weight of the carbonate 4 previously added, of strong metal base is introduced through S port 16 into the reaction mixture in neutralizer 10. Weutraliza-

6 tion, as measured by conventional titrations is substantially ? complete in only a very short time. At this point, a precisely 8 neutral salt has been formed ~nd the solution can be used as g such, or worked up by a conventional technique.
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11 In one work up procedure, the water and volatile 12 solvent are stripped by distillation and the oil soluble salt 13 remains dissolved in the hydrocarbon oil still bottoms; this 14 can be filtered and, if the hydrocarbon oil content is ad3usted to provide from 30 to 70% of metal sulfonate, a valuable 16 commercial concentrate is provided directly.

18 If, for example, the mixture in neutralizer 10 is.
19 sllowed to settle after the strong base addition is complete, water can be separated and trawn off, e.g., through conduit 18.
21 Then the neutral organic layer is transferred through conduit 22 20 to still 22, wherein the volatile inert organic solvent and 23 water are removed overhead and finally the solution of product ~4 in hydrocarbon oil is transferred through conduit 24 to filter 26, from which it is taken for packaging and storage.

27 Obviously, suitable modifications will be used if the 28 starting organosulfonic acid is water soluble. These are conven-29 tional and well within the capabilities of those skilled in this art. The most important distinction will be in the work up _ 5 _ , .
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~la~-3 1 O S 5 5 `'' 1 procedure, in which any water layer, which may contain the 2 product, is not drawn off and discarded, but rather is treated by distillation, thin film evaporation, liquid-liquid extrac-4 tion or other techniques if the solvent (water)-free product i8 desired.

7 Although the process conditions can vary over rather

8 broad ranges, best results w~th oil-soluble organosulfonic

9 acits appear to result from use of a general procedure outlined as follows:
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12~ ~uality of organo-culfonic acid, e.g., 20-50Z of 13 dinonylnaphthalene sulfonic acid, dissolved in 35-55% of a 14 volatile solvent, such as naphtha or heptane, and 1-25 ant preferably, 10-20%, water (all parts by weight) is introduced 16 into the reactor and heated to 50-65C. Then a slurry in oil, 17 e.g., mineral oil of the respective alkali metal, alkaline earth 18 metal, lead or zinc carbonate in an amount sufficient to p~ovide 19 from 1 to 10 and preferably, from 2 to 4 mole Z excess of the latter per le of sulfonic acid groups is added over a long 21 enough period to accommodate any foaming d~ring reaction to pro-22 tuce the metal sulfonate and carbon dioxide gas. To assist 23 reaching equilibrium, the mixture can be refluxed, e.g., at 24 75-80C. and stirred and samples are taken and titrated, or checked with Congo red indicator paper or the lihe until reaction 26 is as complete as possible. This may take 3 to 4 hours. At 27 this point, there is added a small amount of a strong metal base, 28 which can be the same metal as used in the carbonate or different 2g but preferably the former, and illustratively is a hydroxide, oxide or quaternary ammonium base, and the like, but preferably, ~' ,, ., . I
, ~ , ~Lng-3 1 1 O 14S5 1 ¦ the oxide or Sydroxid . Generally, only from abou~ 0.1 to 1%
2 ¦ by weight (based on the original weight of carbonate) is used 3 ¦ and again the end point is determined by tiration tests for 4 I acid or base numbers, respectively, in accordance with well S ¦ known techniques. A clear haze-free neutral solution is 6 ¦ produced which can be used as such. However, it is also 7 ¦ convenient to cool the mixture, e.g., to 65^70C. and allow 8 ¦ it to settle. After the excess carbonate settles, a clear, 9 ¦ neutral sulfonate-in-oil solution is produced which can be used ¦ as such. A lower water layer may also be present, depending on -li ¦ the amount of water in the original mixture. Neutralization `
L2 ¦ pro~uces wa~er and simultaneously reduces the solubility of 13 ¦ water in the system.

¦ Description of the Preferred Embodiments.- The 16 ¦ following examples illustrate the method of the present inven-17 ¦ tion. They are not intended to limit the scope of the claims 18 I in any manner whatsoever. All percentages are by weight, 19 e~cept where otherwise indicated.

22 Nine thousand seventy one pounds of a solution of `
23 approximately 35.5% dinonylnaphthalene sulfonic acid, 45%
24 heptane, 15% water and 5% unsulfonated nonylnaphthalenes, produced by the process described in U.S. 2,765,548, is added 26 to a steam-jacketed 1600 gallon reactor at 50C. A slurry 27 of 7S9 lbs. of barium carbonate (7.5% molar excess based on the 28 sulfonic acid) in about 200 gallons of mineral oil diluent 29 ¦ is prepared in a separate vessel. The slurry is added to the ¦ acid mixture wieh strong agitation over a period of l.S hours.

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C~rbon dioxide is evolved with foa~ing and heptane vapor is 2 condensed and returned ~o the reactor-neutralizer. Then 100 3 gallons more of mineral oil is added. The mixture is heated 4 to refluxing at 78C. and refluxed for 3 hours with agitation S to produce an equilibrium with the carbonate. After settling, 6 the pH of a sample (1:10 wt.lwt. in 50-50 mixture of`heptane 7 (88% isopropanol-12% water)) is 6.17. The acid number is 8 0-03 Then 1/2 pound of calcium hytroxide i~ added as the strong 9 base to the mixture at about 71C. and the mixture is agitated without supplying more heat for about 1 hour. A 1~ g. sample, 11 diluted as above, has a pH of 7.5. The base number is 0.03 12 (ml. of O.lN HCl per 1 g. of sa~ple). T~e mix~ure i3 cooled 13 to 65-70~C., allowed to settle and the lower water layer is i4 trawn off. The remaining water and heptane are removed by dis-tillation unter vacuum to 138C. ant the product is filtered 16 to remove unreacted carbonate. There is produc~d a clear, 17 neutral solution of the barium salt of dinonylnaphthalene 18 sulfonic acid in m~neral oil.
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The procedure is repeated on a smalier scale with a 21 2 and a 4% molar excess of barium carbonate, respectively, and 22 using barium octahydrate as the strong base. Substantially, 23 the same results are obtained.

26 Two hundred grams of dinonylnaphthalene sulfonic acid 27 solution of the composition used in Example 1 is placed in a 28 1000 ml. flask fitted with a stirrer, thermometer and condenser.
29 The flask is heated and 8.55 g. of powdered calcium carbonate (10% exFess based on the sulfonic acid) i8 added with agitatLon.

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1 After a few minutes, carbon dioxide evolution ceases. The 2 mixture is refluxed for 30 minutes, then the solids are allowed 3 to settle. A 10 ml. sample diluted with a mixture of heptane 4 and i50propanol as des~ribed in Example 1 and then filtered has a pH of about 6.0, indicating that the carbonate/acid 6 equilibrium has been reached. Then 2.0 g. of calcium hydroxide ? in 98 g. of mineral oil is prepared and 2 mls. of the mixture ~ i8 added (0.02 g. of strong base). Finally, 60 g. of mineral 9 oil is added, and the heptane and water are distilled off.
lQ The remaining fluid is filtered hot, at 130-140G., through a 11 pressure filter. There is produced a completely neutral solution 1~ of calcium dinonylnaphthalene sulfonate in mineral oil.

'4 Ihe following demonstrates the need for a small, effective amount of water in the reaction between metal carbonate 16 and sulfonic acids.

18 100 grams of a solution of dinonylnaphthalene s~ul-19 fonic acid in mineral oil, containing 34.47. acid and 1.2Z water by weight, are placed in a 5~0 ml. flask. Five grams of 21 powdered calcium carbonate, USP grade, is added and dispersed 22 by v~gorously swirling the contents of the flask. No foaming 23 occurs, indicating that the carbonate and acid are not reacting.
24 Then 3 milliliters of water are added individually and mixed after each addition. There is no evidence of reaction. Finally, 26 after a fourth milliliter of water is added to the contents of 27 the flask and mixed, vigorous foaming begins, accompanied by 29 ¦¦ gradual dlsappearance mo6t of the calciu~ carbo~ate.

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, , , IS~ng-3 ~05~ S5 1 This demonstrates that at least a small amount 2 ~of water is necesqary for the reaction of calcium carbona~e and 3 ~ulfonic acid, and further, that a definite minimum quantity 4 of water i9 required. In thi8 case, the minimum requirement corresponds to 3 or more moles of water per equivalent of sulfonic acid. This suggests that water present as water of 7 hydration is not effective? and that un-bound water is 8 required.
By "small, effective amount" of water, as used 11 herein and in the appended claims, there is meant at least 12 about 2 moles of water per equivalent of sulfonic acid.

14 Obviou~ly; other variations will suggest themselves to those skilled in this art in view of the above detailed 16 description. For example, instead of dinonylnaphthalene 17 sulfonic acid, other organosulfonic acids can be used such 18 as hexane sulfonic acid, hexadecane sulfonic acid, the sulfonic 19 acid derivative of white mineral oil, dinonylnaphthalene di-sulfonic acid, dodecyl benzene sulfonic acid, polydodecyl 21 benzene sulfonic acids, didodecylnaphthalene sulfonic acid, 22 petroleum sulfonic acids, and the like. Instead of barium 23 carbonate and calcium carbonate, sodium carbonate, potassium 24 carbonate, lithium carbonate, magnesium carbonate, lead carbonate and zinc carbonate can be used. Instead of barium 26 hydroxide and calcium hydroxide, sodium hyroxide, potassium 27 hydroxide, lithium hydroxide, magnesium oxide, lead oxide and 28 zinc oxide can be used. When neutralizing oil soluble sulfonic 29 acids, obviously instead of heptane as an inert volatile organic solvent, naphtha, toluene and chloroorm can be used. Furthermore .

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Ua8-31 10514S5 the use of a hydrocarbon oil can be omitted, or it ca~ be added 2 at any stage of the process. The amount of oil can be varied, 3 but usually from 40 to 70% by weight of metal sulfonate in 4 the final composition is preferred. In preferred features, a relatively non-volatile ester lubricant, e.g., diisooctyl 6 sebacate or diisooctyl adipate, can be substituted for mineral ? oil, before removing the inert solvent and water to thereby 8 produce a soltuion of the metal salt in the ester lubricant.
Obviously, although batch processes have been described, the process can be practiced in a continuous fashion. Instead 11 of adding the metal carbonate as a slurry, it can be added 12 in other forms, such as a powder, if, for example, an appro-, 13 priate vapor lock is used. All such obvious modifications 17 I are uithin the ~11 ~ ded scope oi the appended clal=s 8 .

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Claims

Claims:

1. A process for producing a metal salt of an organosulfonic acid and a metal selected from alkali metals, alkaline earth metals, lead and zinc, said process comprising the steps of:
(i) providing a mixture comprising the organosulfonic acid and a small, effective amount of water;
(ii) adding to the mixture a compound of at least one of said metals in the form of a carbonate, in an amount sufficient to provide a molar excess of said compound of at least about 1%;
(iii) reacting the mixture until the carbonate/
acid equilibrium point is reached; and (iv) adding a small amount of a metal compound which has a base strength greater than that of bicarbonate ion, sufficient to effect complete neutralization of the remainder of said organosulfonic acid.

2. A process as defined in Claim 1 wherein the organo-sulfonic acid is an oil-soluble organosulfonic acid, and said mixture also includes an inert solvent.

3. A process as defined in Claim 1 wherein the metal compound added in step (iv) is an oxide or a hydroxide.

4. A process as defined in Claim 1 wherein the metal in the compound added in step (iv) is the same as the metal of the carbonate added in step (ii).

5. A process as defined is Claim 2 wherein the oil-soluble organosulfonic acid is selected from mono-, di- and trisulfonic acids of aliphatic or aromatic hydrocarbons, and has a molecular weight of greater than about 350.

6. A process as defined in Claim 5 wherein the oil-soluble organosulfonic acid is dinonylnaphthalene sulfonic acid.

7. A process as defined in Claim 1 wherein the organosulfonic acid is dinonylnaphthalene disulfonic acid.

8. A process as defined in Claim 1 wherein the metal in the carbonate used in step (ii? is selected from sodium, potassium, lithium, barium, calcium, magnesium, lead and zinc.

9. A process as defined in Claim 8 wherein the metal in the carbonate used in step (ii) is barium.

10. A process as defined in Claim 8 wherein the metal in the carbonate used in step (ii) is calcium.

11. A method as defined in Claim 3 wherein the metal compound added in step (iv) is barium hydroxide.

12. A method as defined in Claim 3 wherein the metal compound added in step (iv) is calcium hydroxide.

13. A process for producing a metal salt of dinonylnaphthalene sulfonic acid and a metal selected from sodium, potassium, calcium, magnesium, barium, and zinc, said process comprising the steps of:
(i) forming a solution of dinonylnaphthalene sulfonic acid in an inert volatile organic solvent and a small, effective amount of water;
(ii) adding to the solution a compound of at Least one of said metals in the form of a carbonate, in an amount sufficient to provide a molar excess of said compound in the range of from 1 to 10%;
(iii) reacting the mixture until the carbonate/
acid equilibrium point is reached; and (iv) adding a small amount of a metal compound which has a base strength greater than that of the bicarbonate ion, sufficient to effect complete neutralization of the remainder of said dinonylnaphthalene sulfonic acid.

14. A process as defined in Claim 13 including the steps of adding a relatively non-volatile hydrocarbon oil to the reaction mixture at any stage, and as a final step, selectively removing the inert volatile organic solvent and water, to produce a solution of the metal salt of said sulfonic acid in said hydrocarbon oil.

15. A process as defined in Claim 14 wherein the volatile solvent and water are removed by distillation and the amount of hydrocarbon oil used produces a solution comprising 40 to 70% by weight of the metal sulfonate.

16. A process as defined in Claim 13 wherein the metal in the carbonate compound used in step (ii) and in the metal compound of step (iv) is barium.

17. A process as defined in Claim 13 wherein the metal in the carbonate compound used in step (ii) and in the metal compound of step (iv) is calcium.

18. A process as defined in Claim 13 including the steps of adding a relatively non-volatile ester lubricant to the neutral mixture, selectively removing the inert volatile organic solvent and water and thereby producing a solution of the metal salt of said sulfonic acid in said ester lubricant.