US3256303A - Sulfonation of fatty acids and their esters - Google Patents

Description

June 14, 1966 w. STEIN ETAL 3,256,303

BYEULM DLL-Kufe 5 AOR YS United States Patent 3,256,303 SULFNATEON 0F FATTY ACIDS AND THEIR ESTERS Werner Stein, Dusseldorf-Holthausen, Herbert Weiss, Cologne-Deutz, and Otto Koch, Hilden, Rhineland, Germany, assignors to Henkel & Cie. G.m.b.H., Dusseldorf-Holthausen, Germany Filed May 15, 1962, Ser. No. 194,840 Claims priority, application Germany, Aug. 8, 1961,

H 4 58 Claims. (Cl. 2450-400) This invention relates to new and useful improvements in the sulfonation of fatty acids and their derivatives. The invention more particularly relates to an improved process for sulfonating fatty acids or ltheir derivatives, such as their esters or nitriles, using an excess of sulfur trioxides gas as the sulfonation agent.

sulfonates of fatty acids and of fatty -acid derivatives, su-ch as esters or nitriles, constitute commercially valuable materials due to Vtheir surface-active characteristics and resistance to hard water which render the same suitable as detergents and wetting agents. These sulfonates are conventionally produced by the sulfonation of the corresponding fatty acids or fatty acid derivatives. When sulfonating these materials using an excess of gaseous sulfur trioxide, the reaction products produced were dark colored, brown-black products which, due to this discoloration, were unsuitable for commercial use. While it was possible to obtain somewhat lighter colored products by operating under milder conditions of temperature, as for example 60-65 C., the use of these temperatures could not produce the satisfactory degree of sulfon-ation, and when the temperature was increased, in order to obtain more completely sulfonated products, then the darker colored reaction pro-ducts were produced. While it was possible to recover utilizable sulfonates from these dark colored reaction products by recrystallization thereof in the form of their alkali metal salts, this increased the pro- 'duction costs and presented technical diiculties.

One object of this invention is the obtaining of lighten colored reaction products, after the extensive sulfona-tion of fatty acids or their derivatives, using gaseous sulfur trioxide, as the sulfonation agent.

rl`hese and still further objects will become apparent from the following description read in conjunction with the drawings in which:l

FIG. 1 diagrammatically shows an embodiment of an apparatus for effecting the sulfonation in accordance with sulfonated to lighter colored reaction products using -anv excess of gaesous S03 as the sulfonation agent if the sulfonation is initially effected at a temperature not exceeding 70 C. and using not more than about 65-90% of the total S03 quantity and, if, thereafter the sulfonation is continued preferably in a further sulfonation step or steps at a temperature above 70 C. using the remainder of the sulfur trioxide. Preferably the sulfonation is initially effected in a first sulfonation step at a temperature between 30 and 70 and preferably 40-65 C., using not more than 65*90% of a l.l to 1.8 and preferably 1.2 to 1,6 molar quantity of S03 based on the fatty acid radicals to be sulfonated .and thereafter the sulfonation is concluded in one or more additional separate sulfonation steps at a ICC temperature between about and 95 C. and preferably -90" C., using the balance of said molar quantity. If more than two sulfonation steps are used, the temperature is preferably progressively increased within the range indicated from step to step.

The starting materials processed, in accordance with the invention, are fatty acids or their derivatives, such as esters or nitriles which may be of any origin `and contain fatty acid radicals with y6-28, and preferably 8-18 carbon atoms. These fatty acid radicals may come from the natural fats of plants, landor water-animals. Through selection of the starting fats it is possible to extensively influence the properties of lthe sulfonates to be produced. Thus, from the fats which predominantly contain fatty acids with l014 carbon atoms per fatty acid radical, such as from the fats of the lauric acid group which are particularly rich in fatty acids with l2 carbon atoms, products which are soluble at lower temperatures of, for example, 20-45 C., are obtained, while from other fats which predominantly contain fatty acids with l6-18 and more carbon atoms per fatty acidradical, for example from other plant fats than the above named, or from tallow or from whale and fish oils, products are obtained which are particularly well suited for use at temperatures within the range of 50100 C.

The starting materials, .e. the fatty acids and their derivatives, such as their esters or nitriles, should not contain apart from the alpha-position hydrogen atom, other sulfatizable or sulfonatable groups, such as forexample double-bonds or alcoholic hydroxyl-groups. The fatty acid esters to be processed in accordance with the invention may be derived from monoor polyvalent alcohols, particularly from monoto trivalent-alcohols, and, as mentioned above, must not contain lany alcoholic hydroxyl groups or other sulfatizable or sulfonatable groups. As far as the fatty acid esters of monovalent primary aliphatic alcohols are concerned, the radical may con-tain- 1-20 carbon atoms in the molecule. Thus, for example, the esters of fatty acids with methyl to nonyl-alcohols may be used. It is also possible to use fatty acid esters which contain radicals of such still higher alcohols'in the molecule as for example are produced by reduction of the initially mentioned fatty acids or fatty acid mixtures, or synthetically in some other manner. Examples of readily available esters of fatty acids with higher fat alcohols include the hydrogenation products of the oleyloleate occurring in the sperm oil or the naturally occurring or synthetically produced wax esters.

Many fats, particularly those of natural origin, and the fatty acids and their derivatives produced therefrom often contain accompanying substances, which, upon sulfonation produce strongly colored decomposition products. Although it is also possible to bleach these decomposition products according to a process mentioned hereinafter, it is advisable not to burden the sulfonation and the bleaching process through the decomposition products of such accompanying substances, which may be forthwith removed from .the fats and/ or the therefrom produced fatty `acids or their derivatives before the sulfonation. Examples ofV products which give with the sulfonation agent strongly colored impurities include unsaturated fatty acids or fatty acid derivatives. Therefore, the fats to be processed are to be, as far as possible, extensively saturated, i.e., they are to have iodine numbers below 5, preferably below 2.

The starting fatty acids to be sulfonated are preferably in the form of distillates as are the fatty acid derivatives, insofar as these are distillable under the technical prerequisites in each case. If distillation is not practical on account of a high boiling point or for other reasons, such as for example in the case of triglycerides, then it is advisable to initially remove the impurities present in the starting material to be sulfonated in another manner. Thus, for example, in the case of the natural fats, and particularly the natural triglycerides, albuminous substances and slimy substances (mucins) should be separated in the deacidification and refining of the oils in a manner known per se.

These starting materials are preferably pr-ocessed in the absence of inert solvents.

The total quantity of sulfur-trioxide to be used, is inter alia, dependent on the starting material to be sulfonated, and in general ranges from 1.1-1.8, preferably 1.2-1.6 m-ol sulfur-trioxide per mol fatty acid radical. The quantity of the sulfur-trioxide applicable for as extensive as possible a sulfonation increases somewhat with the size of the fatty acid radical and in connection with monovalent alcohol esters, greatly increases with the size of the alcohol radical.

The sulfonation in accordance with the invention is effected in at least two reaction steps with the first reaction step conducted at temperatures between 30 and 70 and preferably between 40 and 65 C. and the second reaction 4step conducted at temperatures within the range of 75-95 and preferably 80-90 C. It is advisable to let the temperatures rise gradually so that the sulfur trioxide is constantly consumed and the temperature-limit of 70 C. is only exceeded after at least 50% preferably at least 65% of the total sulfur trioxide quantities have been used. In the sulfonation of Cm-Cls-fatty acids, their triglycerides and esters with monovalent C1-C5 alcohols, 1.2-1.6 mol sulfur-trioxide per mol fatty acidl radical are required for an extensive sulfonation and preferably 70- 85% -of this total are added before the 70 C. temperature is exceeded.

The sulfur trioxide is used in mixture with inert gases, such as for example air, nitrogen, carbonio acid, etc. and these mixtures may contain 2-40 volume percent, preferably 3-20 volume percent, sulfur trioxide.

. The sulfur-trioxide addition and the course of the temperature are adjusted in dependence on one another and the time so that the sulfur trioxide added reacts as extensively as possible. The rst reaction step is to be conducted over a longer reaction period than the second step with the latter requiring not more than l/s-t of the total reaction time but not less than about 5 and preferably not less thanA-15 minutes. If during the entire reaction time, the velocity of the sulfur trioxide addition is kept constant, then the second reaction step needs at most 1/3 of the entire reaction time. However, it is possible to still further shorten the reaction time in the second step through increased velocityof the sulfur trioxide addition. The first step may also be effected with a non-uniform addition of the sulfur trioxide. Thus, for example, it is possible to charge approximately 30-60% of the theoretically necessary sulfur trioxide quantity within a short time at the start of the reaction. This addition may if desired, take place at below the reaction temperature in the cooled starting material and then after the start of lthe reaction and its becoming faster with the temperature rise an amount of sulfur trioxide is added which will replace the amount being consumed in the reaction.

The velocity of the sulfur trioxide may be varied through the ow velocity of the sulfur trioxide and/ or in the case of sulfur trioxide inert gas mixtures through their concentration.

The reaction time depends on the starting material, on the sulfur trioxide quantity used, and on the temperature of the reaction. In general, times between and 150 minutes, preferably between 40 and 120 minutes, are to be used.

The products obtained in accordance with the invention' are sometimes still colored brown. However, they contain, assuming comparable conditions, such as for example equal degrees of sulfonation and equal sulfonation agent excesses, much less colored impurities than the products produced according to known processes. Theyl may thus be converted with much smaller bleaching agent quantities into light-colored unobjectionable products.

The bleaching of the acid sulfonation products may be carried out according to copending application Serial No. 194,998 tiled the same day herewith by treatment with hydrogen peroxide in amounts of 0.2-6 weight percent and preferably 1-4 weight percent hydrogen petroxide, calculated as 100% product. With the sulfonation products in accordance with the invention, it is possibleto manage in general with less than 4% and frequently less than 3% so far as the processed starting materials Vdid not contain any impurities of accompanying substance, forming in the sulfonation colored decomposition products. The hydrogen peroxide is preferably charged as 20-75 weight percent product and particularly as 30-50 weight percent product. Furthermore, it is advisable to so choose the concentration of the hydrogen peroxide to be used in dependence on its quantity that the sulfuric acid, formed at the start of the bleaching process from free sulfur trioxide and the Water quantity introduced with the hydrogen peroxide, is n-ot more diluted than a 20% su-lfuric acid. Preferably this sulfuric acid, mathematically considered, should represent a mixture of sulfur trioxide and water with a sulfur trioxide content up to 95 weight percent and preferably up to -50 weight percent. The bleaching is effected at temperatures within the range of 20-100 and preferably of 40-80 C. i

insofar as fatty acids are sulfonated in accordance with the invention, the products produced may be converted into esters in a manner known per se. As esterication components the monoor polyvalent alcohols present as alcohol components in the initially mentioned fatty acid esters may be used. This esteriiication is desirable above all for the production of the esters from sulfo-carboxylic acids and monovalent alcohols containing at least 6 carbon atoms because the esters per se when used as startin-g materials fo-r the sulfonation react slower within increasing magnitude of the alcohol radical and good degrees of sulfonation are obtainable only with greater quantities of sulfur trioxide.

The esteriiication of the acid sulfonation products may take place before or after the bleaching. If the bleached su-lfo-fatty acids are used, then the mono-salts neutralized at the sulfo-'acid group may also be processed.

The sulfonation is preferably carried out continuously i in such a manner that the starting material is passed through reaction zones, in which the temperature is raised from zone to zone, and in which, according to the proportion of the consumption, sulfur trioxide is dissolved in the starting material.

The apparatus according to FIG. 1 may, for example, be used for the carrying out of the process. The reaction vessel consists of the pipe 1, which is divided through partitions 2 into reaction zones. These partitions are here shown as sieve bottoms but, of course, in their place other separations which permit a owing through of the material to be sulfonated from above downwardly and of the sulfur trioxide inert gas mixture from below upwardly may be used. The reaction zones may also be provided with contact improving installations, such as for example, filling bodies, bellor sieve-bottoms or other known installations, which improve the contact between gas and liquid wherein the liquid to be sulfonated lls the Zones more or less completely, or, for example, in trickling through vessels with bottom type installations only occupies a small part of the vessel space. Each reaction zone is surrounded by a temperature jacket 6 which hasl an inlet and an outlet 7 and 8 for the heat exchange agent. At the lower end of each reaction zone a line 9 leads into the reaction chamber, through which the sulfur trioxide inert gas mixture is introduced. The starting material to be processed is passed through the line 4 into the head of the reaction vessel by means of the distributor 5 in the form of a sprinkler, a sprayer nozzle or the like. The material then ilowsthrough the individual reaction zones,

in which it is brought in contact with the freshly introduced sulfur trioxide, passed through the lines 9, in proportion with the progressing sulfonation. The sulfonated material runs off through the line 11 and the valve 12.

FIG. 2 shows a variant of the reaction zones according to FIG. 1. Here each reaction zone is defined by an independent vessel connected 'behind the other in series. The advantage of the working with the devices according to FIG.- 2 consists therein that in each reaction zone the inert gas free fram the sulfur trioxide is drawn off through the line 10. In FIG. 2 substantially the same reference numbers are used as in FIG. 1.

FIG. 3 shows a device, as it has proved suitable for both production and laboratory scale carr/ing-out of the process. The reaction vessel 13 is surrounded by a temperature jacket 6 with the inlet and outlet 7 and 8. Into the reac-tion vessel lead the lines 14 and 15 with the valves 16 and 17, through which the material to be sulfonated and the sulfur trioxide inert gas mixture are introduced. The inert gas, free from sulfur trioxide, leaves the reaction vessel through the line 19, and the processed material passes out, through the overflow 1.8 at a rate corresponding to the rate of introduction of new material into the reaction vessel. The overliow 18 is connected to the inlet 4 of a further series connected reaction vessel of identical construction and several such vessels may be series connected.

The following examples are given by way of illustration and not limitation:

Example 1 For the carrying out of the process described here, 5 vessels according to FiG. 3 are connected one after another in series. The content of each vessel up to the over-iiow amounts to 40 ccm. As starting material, there is used a lauric acid methyl ester, which had been obtained from a coconut-oil hardened to an iodine number of 0.2 and esteried with methyl alcohol followed by fractionating'out of the lauric acid methyl ester.

The first four reaction vessels were filled with this ester and the heating adjusted so that the reaction mixture present in the vessels had during the entire test the following temperatures, increasing from vessel to vessel: 1st vessel: second vessel: 60, third vessel: 70; vfourth vessel 80, fifth vessel: 80 C. Sulfur trioxide, diluted with a 20-fold quantity of air was blown in the first four vessels in such quantities that in the individual Vessels the following sulfur trioxide quantities were taken up, in percent of the stoichiometrically necessary quantity for a quantitative sulfonation: 1st: 52, 2nd: 78, 3rd: 104, and 4th: 130%. No sulfur trioxide air mixture was blown 'into the 5th vessel. After these quantities had been taken up, 107 g. ester per hour was continuously introduced drop by drop into the first vessel and so much of the above-mentioned sulfurtrioxide air mixture was introduced into the first four vessels that the total quantity of the sulfur trioxide introduced amounted to 1.3 mol per mol of the continuously introduced fatty acid radical, and in vessel 1, 40%, in the vessels 2-4, 20% each of this sulfur trioxide quantity was taken up. No sulfur trioxide was blown into the last vessel, this vessel being used for the after-reacting. The product running off from the last vessel was cooled and, after addition of 2 weight percent H2O2 (used as 40% aqueous solution) was bleached for 2 hours at temperatures of 55-60 C. and subsequently neutralized with 10% soda lye. The degree of sulfonation of the product was 95%. A 5% solution of the sulfonate, in reference to crude acid sulfonation product, showed in the Lovibond Tintometer in a 4l cell, the following color values:

Yellow: 6.0, red: 1.0, blue 0.0.

In a repetition of the example only 1.2 mol sulfur trioxide was used per mol fatty acid radical, andthe temperature in the last reaction vessel was increased to 85 C. The crude acid reaction product was bleached with 2% of its weight H2O2 (used as 30% aqueous solution), and neutralized with 20% soda-lye. The product had a degree of sulfonation of A 5% solution of the crude acid sulfonation product showed, measured in the Lovibond-Tintometer in a 4" cell, the following color values:

Yellow: 3.0, red: 0.3, blue: 0.0.

Example 2 As starting material a fatty acid ethyl ester, which had been obtained from hardened coconut oil (iodine number=0.2) through reesterilication with ethyl alcohol and distilling off of the fatty acid ethyl ester was used. The sulfonation was carried out as in Example 1. The through-put of coconut oil acid ethyl ester amounted to g. per hour. The crude acid sulfonation product was bleached for 2 hours at 55-60 C. with 2% of its weight H2O2 (used as 40% aqueous solution), and then neutralized with 15% soda-lye. The degree of sulfonation amounted to 96%. A 5% solution of the crude -acid sulfonation product showed in the Lovibond-Tintometer in a 4 cell the following color values:

Yellow: 6.0, red: 0.5, blue: 0.0.

Example 3 As starting material, the ethyl ester (iodine number=1) of a hardened and distilled tallow-fatty acid was used. This product was processed in a similar manner Ias described in Example 1. 1.4 mol sulfur trioxide per mol of ester was used. At the start of the test the sulfur trioxide` was blown in, diluted with a 20-fold quantity of air, in such quantities that in the first four vessels the followingv sulfur trioxide quantities were taken up (indicated in percent of the quantities stoichiometrically necessary for a quantitative sulfonation): 56, 84, 112, and respectively. The reaction was then continued in continuous operation with 151 g. ester put-through per hour. So much sulfur trioxide wascontinuously introduced into the individual vessels that the above-indicated sulfur trioxide quantities were dissolved in the material leaving the individual vessels.

The product running off from the last vessel was cooled and bleached with the addition of 4 weight percent H2O2 (used as 40% aqueous solution), in the course of 2 hours at temperatures' of 55-60 C., and subsequently neutralized with 15 soda-lye. The degree of sulfonation of the product was 93%; A 5% solution of the crude acid sulfonation product, showed in the Lovibond-Tintometer in a 4 cell, the following color values:

Yellow: 10.0, red: 2.5. blue: V0.0.

Example 4 A distilled sec.butylester (iodine number=0.5), produced from hardened coconut oil acid was used as the starting material. This `material was sulfonated in the manner described in Example 1 with a through-put of 132 g. ester per hour with 1.57 mol S03 per mol fatty acid radical. The sulfur trioxide quantities taken up at the start of the test and during the same in the lirst four reaction vessels amounted to 63, 94, 133, and 157% respectively, of the stoichiometrically necessary quantity for a quantitative sulfonation. No sulfur trioxide was introduced into the last vessel and the temperature of this vessel was maintained at 90 C. The sulfonation product was bleachedfor 2 hours at 55-60" C. with 3% H2O2 and then neutralized with 5% soda-lye. The degree of sulfo-V nation of the product was 94%. A 5% solution of the crude acid sulfonation product showed in the Lovibond- Tintometer in a 4 cell, the following colorAvalues:

Yellow: 18,red: 2.5, blue: 0.0.

In a repetition of the example in which the temperature of the last vessel was decreased to 85%, the degree of sulfonation of the product was 90%, and the following color values were measured:

Yellow: 18, red: 2.0, blue: 0.0.

Example A mixture of 2500 g. ethylester of a hardened palmkernel fatty acid and 2200 g. hardened palm-kernel fatty acid was sulfonated in the manner described in Example 1. For this purpose, 117 g. of this mixture (iodine number=0.3) per hour were brought together with gaseous sulfur trioxide, diluted with a -fold air quantity, wherein the 1.3-fold of the S03 quantity stoichiometrically necessary for a quantitative sulfonation, was used. The reaction vessels were kept during the sulfonation at the following temperautres: 50, 50, 65, 80, 80 C. respectively. The reaction product running olf was bleached for 2 hours at 50 C. with 3% H2O2 (as aqueous solution), and then neutralized. The degree of sulfonation of the product amounted to 95 The color Lovibond values were:

Yellow: 6.0, red: 1.0, blue: 0.0.

Example 6 in the latter was used diluted with a 20-fold air quantity.

The temperatures in the vessels were, as also in Example 5, 50, 50, 65, 80 and 80 C. respectively. The resulting reaction product was bleached for 2 hours at 55- 60 C. with 2% H2O2 (as 40% aqueous solution) and then neutralized with 5% aqueous-soda-lye. The degree of sulfonation of the product amounted to 95.5%, the Lovibond color values were:

Yellow: 18, red: 3.0, blue: 0.0.

Example 7 As starting material, there was used a palm-kernel-fattyacid-ethylester (iodine number=0.l), which was processed in an apparatus of stainless steel, similar in'all essential parts to the apparatus described in Example 1 except the content of the individual vessels to the over-flow amounted to 600 cm.

The first four reaction vessels were filled with the esterand the heating was so adjusted that the material in the vessels had during the entire test the following respective temperatures rising from vessel to vessel: 50, 50, 65, 80, 85 C.

Sulfur trioxide, diluted with a 20-fold quantity of air, was blown in the rst four vessels in such quantities that the ester present therein had taken up the following sulfur trioxide quantities, measured at the stoichiometrically necessary quantity for a quantitative sulfonation: 52, 78, 104 and 130% respectively. No sulfur trioxide air mixture was blown into vessel 5. After these quantities had been taken up, 1.71 kg. ester per hour was continuously pumped into the first, and into the first four, reaction vessels so much of the above-mentioned sulfur trioxide air mixture was introduced that the ester passing out of the fourth vessel had taken up in all 1.3 mol per mol of fatty acid ester and in the 1st vessel 40% and in the 2nd to the 4th vessels 20% each of this sulfur trioxide quantity had been taken up. No sulfur trioxide was blown into the fifth vessel; this vessel serving for the after-reacting.

The product thus obtained was continuously bleached and for this purpose was rst of all cooled to 20-22 C. Then, 2420 g. per hour of the cooled product were mixed with 181 g. per hour of 20% aqueous hydrogen peroxide. The initially occurring reaction heat was removed in a cooler which the product left at a temperature of 40 -with the invention.

C. Thereupon the temperature was kept for 2 hours at 40 C. and then still a further hour at 60 C. The bleached product was neutralized with 6% aqueous soda lye. The process was run continuously for 72 hours and delivered a completely uniform product which had a degree of sulfonation of 95% and showed the following Lovibond color values:

Yellow: 2.0, red: 0.1,` blue: 0.0.

Example 8 The part-s a and b of this example demonstrate a continuous mode of operation falling outside of the scope of the invention for comparison with part c in accordance As starting material, an ethyl ester (iodine number=0.2) produced from hardened fatty acids of the palm-kernel fat was used. The tests described.

under a, b, and c were carried out in the same apparatus; however, in the -tests a and b all parts -of the apparatus were kept at the temperature there indicated.

(a) Into the reaction vessel 230 g. (0.92 mol) ester was charged and heated to 65 C. Then, within 100 minutes, 96 g. (1.3 mol) sulfur trioxide, diluted with 20- fold quantity of air, were blown into the ester. As soon as this sulfur trioxide quantity had been taken up, 125 g. of ester per hour were added drop by drop and so much sulfur trioxide air mixture introduced that per mol ester 1.3 mols sulfur trioxide air mixture were taken up. 177 g. reaction mixture per hour flowed off from the apparatus. From time to time the receiver was changed and the degree of Sulfonation and color values determined. The degree of sulfonation lay during the entire reaction between 82 and 83.5%. However, the depth of the color increased continuously and after 6 hours of voperation reached a nal value.

(b) The test described under (a) was repeated. However, the temperature was increased to 85 C. The degree of sulfonation of the product amounted to 94-95%. The color intensity increased during the course of the carrying out of the test.

(c) The ester was sulfonated with the same sulfur-trioxide excess as under (a) and (b). However, the temperatures in the individual reaction vessels were adjusted to 50, 60, 70, 80, and 80 C. respectively. The degree of sulfonation of the product was 95 Samples of the product resulting after 6 hours of carrying out of the processes 'were bleached with 2% H2O2 (used as 40% aqueous solution) for 8 hours at 30-40 C. Unbleached, as well as bleached products, werel neutralized in order to measure the color values of both. It was found that the colorvalues of the crude products obtained according to (a) and (b) could not be reliably measured'in a 4 cell. The product produced according to (c) had, in neutralized condition, measured as 5% solution in a 2 cell, the following Lovibond color values:

Yellow: 27, red: 24, blue: 5.0.

The products neutralized after the bleaching with 2% H2O2 showed as 5% aqueous solution of the sulfonate in a 4" cell the following Lovibond color values:

In 126 g. of a hardened palm-kernel-fatty acid ethyl ester (iodine number=0.2) 52 g. sulfur trioxide, diluted with a 20-fold air quantity were introduced in the course of one hour. The temperature was uniformly increased skilled artisan.

from 20 to 80 C. and the introduction velocity of the sulfur trioxide kept uniform during the entire time. After introduction of .the sulfur trioxide quantity indicated, the product was still kept for minutes at 80 C. The crude acid sulfonation product was bleached with 3% lof its weight quantity of H2O2 (used as 40% aqueous solution) for 8 hours at 30-40 C., and then neutralized with 8% soda lye. With a 5% sulfonate solution, the following Lovibond color values were measured in a 4 cell:

Yellow: 1.3, red: 0.4, blue: 0.0.

The degree of sulfonatiou of the Iproduct amounted to 95.7%.

Example 10 In the manner described in Example 9, 113 g. hydrogenated palm-kernel-fatty-acid (iodine number=0.4) were sulfonated except that the starting temperature amounted to 35 C. A product with a degree of sulfonation of 97% was obtained. The product, bleached as described in Example 3, had the following Lovibond color values:

Red: 27, yellow: 22, blue: 1.2.

While the invention has been described in detail with reference to certain specific embodiments, various changes and modifications will become apparent to the The invention is, therefore, only intended to be limited by the appended claim-s or their equavalents wherein We have endeavored to claim all inherent novelty.

We claim:

1. In the process for the sulfonation of a member selected from the group consisting of unsubstituted saturated fatty acids, unsubstituted saturated fatty acid esters, and mixtures thereof containing 6 to 28 C atoms in the fatty acid radical by reaction with gaseous sulfur trioxide, the improvement which comprises initially contacting said group member at a temperature between about 30 and 70 C. with about 65-90% of a 1.1-1.8 molar quantity,

of gaseous sulfur trioxide based on the fatty acid radicals to be sulfonated in at least one rst sulfonation step, and thereafter contacting said group member in at least one l@ additional sulfonation step with lthe balance of said molar quantity of sulfur dioxide at a temperature between about -95 C.

2. Improvement according to claim 1 in which said first sulfonation step is effected at a temperature between about 40-65 C. and said additional sulfonation step is effected at a temperature between about -90" C.

3. Improvement according to claim 1 in which said sulfonation steps are effected at said temperatures and with said amounts of sulfur trioxide -in separate series connected reaction zones.

4. Improvement according to claim 3 in which said group member is passed substantially continuously in series through said zones,v and 1in which the sulfur trioxide is separately added lto said zones.

5. Improvement according to claim 1 in which said sulfur trioxide is used in admixture with an inert gas.

6. Improvement according to claim 1 in which said group member is an ester of a fatty acid with a lower alcohol.

7.v Improve-ment according to claim 1 in which a total quantity of l.21.6 mols of sulfur trioxide per mol of fatty acid radical to be sulfonated is used and in which 70-85% of this sulfur trioxide quantity is added in the first sulfonation step.

8. Improvement according to claim 7 in which said group member contains 12--18 carbon atoms in a fatty acid radical.

9. Improvement according to claim 7 in which said group member is an ester of a fatty acid with a lower alcohol.

10. Improvement according to claim 1 in which said sulfonation is efected in the absence of a solvent.

References Cited by the Examiner UNITED STATES PATENTS 1,926,442 9/ 1933 Gunther et al 260-400 2,691,040 10/ 1954 Bloch et al 260-400 v2,878,271 3/1959 Little et al. 260-400 CHARLES B. PARKER, Primary Examiner.

DANIEL D. HORWITZ, Examiner'.

Claims (1)

1. IN THE PROCESS FOR THE A SULFONATION OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF UNSUBSTITUTED SATURATED FATTY ACIDS, UNSUBSTITUTED SATURATED FATTY ACID ESTERS, AND MIXTURES THEREOF CONTAINING 6 TO 28 C ATOMS IN THE FATTY ACID RADICAL BY REACTION WITH GASEOUS SULFUR TRIOXIDE, THE IMPROVEMENT WHICH COMPRISES INITIALLY CONTACTING SAID GROUP MEMBER AT A TEMPERATURE BETWEEN ABOUT 30 AND 70*C. WITHABOUT 65-90% OF A 1.1-1.8 MOLAR QUANTITY OF GASEOUS SULFUR TRIOXIDE BASED ON THE FATTY ACID RADICALS TO BE SULFONATED IN AT LEAST ONE FIRST SULFONATION STEP, AND THEREAFTER CONTACTING SAID GROUP MEMBER IN AT LEAST ONE ADDITIONAL SULFONATION STEP WITH THE BALANCE OF SAID MOLAR QUANTITY OF SULFUR DIOXIDE AT A TEMPERATURE BETWEEN ABOUT 75-95*C.

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