US3297579A - Process for preparing a detergent composition containing sodium alkanesulfonate and soap - Google Patents

Description

United States Patent 11 Claims. (Cl. 252121) This is a division of application Serial No. 250,716, filed January 10, 1963, now Patent No. 3,228,980.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to .grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the preparation of alkanesulfonates. The alkanesulfonates and associated products of this invention are useful as chemical intermediates, surface active agents, detergents, and components of detergent compositions.

An object of the present invention is to prepare long carbon chain alkanesulfonates of the general formula C H CH CH SO M, wherein n is an integer from 6 to 19, M is H, Na, K, Li, NH or a substituted ammonium radical derived from a lower molecular weight amine or alkanolamine.

Another object of the present invention is to provide a process for preparing alkanesnlfonates having one less carbon atom than the parent a-sulfocarboxylic acid. A further object is to obtain a product comprising a major portion of the alkanesulfonate of one less carbon atom and a minor portion of a soap of two less carbon atoms, the latter simultaneously being formed by desulfonation in the process of the present invention.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims.

We have discovered that the preparation of alkanesulfonates by the thermal degradation of a-sulfocarboxylic acids requires the presence of sodium hydroxide in excess of that needed to completely neutralize the u-SlllfO- carboxylic acid.

In general according to the present invention a long carbon chain a-sulfocarboxylic acid is combined with an excess of sodium hydroxide over that required to completely neutralize the sulfocarboxylic acid, preferably an amount of the hydroxide representing a two to one ratio based on weight of the salt of the acid, the alkaline mixture is stirred under a nitrogen atmosphere while being heated to fusion temperature of the mixture, usually about 300 to 320 C., and the fluid mass allowed to cool. The product contains the sodium salt of an alkanesulfonate of one less carbon atom than the starting a-sulfocarboxylic acid. The product may be used directly in detergent formulations or the desired components may be separated therefrom as subsequently described.

The a-sulfocanboxylic acids are readily obtained by sulfonation; suitably with sulfur trioxide or chlorosulfonic acid, as indicated by the the following reaction:

wherein R is a long chain alkyl radical of 6 to 19 carbon atoms; of fatty acids such as pelargonic, obtained upon 3,297,579 Patented Jan. 10, 1967 of an even number of carbon atoms from lauric to behenic acid, or commercially available mixtures of long chain saturated fatty acids.

Reactions in the process of our invention are illustrated as follows, with R being the long chain alkyl radical of 6 to 19 carbon atoms.

RCH CH (SO H) CO H+NaOH RCH CH(SO Na)CO H-|-H O (2) RCH CH(SO Na)CO H+NaOH RCH CH(SO Na)CO Na|-H O (3) RCH CH(SO Na) CO Na +NaOH- RCH CH SO Na+Na CO (4) RCH CH(SO Na)CO Na+NaOH RCH=CHCO Na+Na SO +H O (5) RCH=CHCO Na+NaOH+H O+ RCO Na+CH CO Na+H (6) The initial reaction of the a-sulfocarboxylic acid with the hydroxide is the partial and complete neutralization of the acidic functions, illustrated in (2) and (3).

We have found that the thermal degradation of the products of Equations 1 to 3 proceeds as follows:

RCH2OH(SO;H)CO2H E RCHZCH2GO2H 03 (7) heat 2ROHzOH(SOaNa)CO2H RCHZCH(SO3NQ)CO2N2I ROH2CH(SO3H)O02H heat ROH CH(S0 Na)O02Na no reaction (9) Hence, contrary to prior art such as US. Patent No. 2,822,387 the thermal degradation of the half-salt (monosodium salt) of the a-sulfocarboxylic acid (Equation 8) gives as a product a mixture of the disodium salt, which oxidative cleavage of oleic acid, the individual fatty acids is stable under these conditions, and free a-sulfocarboxylic acid which degrades according to Equation 7 to give the parent fatty acid plus sulfur trioxide. It is obvious, therefore, that thermal degradation of the monosodium salt, RCH CH(SO Na)CO H, in the absence of alkali does not result in decarboxylation, but rather results in desulfonation.

According to the present invention, it is only in the presence of an excess of sodium hydroxide, as represented by Equation 4, that decarboxylation occurs to give the alkanesulfonate. The alkanesulfonate is the major product, but there is by-product formation of RCH= CHCO Na (Equation 5), which, in the presence of NaCH and H 0 (Equation 6) proceeds to form a soap having two less carbon atoms than the parent fatty acid.

The alkali, used in excess of neutralization (reactions 2 and 3), and that required in the simultaneous decarboxylation (reaction 4) and desulfonation (reactions 5 and 6) is preferably sodium hydroxide, although the process is considered operative when other alkali metal hydroxides such .as lithium hydroxide or potassium hydroxide are admixed with sodium hydroxide.

The process of our invention permits the formation of alkanesulfonates in an inexpensive manner. Sodium alkanesulfonates can be obtained in a pure state by the process of our invention, after separation from the byproduct soap, and are not otherwise obtainable except by more expensive reactions such as the well known Strecker reaction. The Strecker reaction depends upon the conversion of a long chain alcohol to the corresponding alkyl bromide and metathesis with sodium sulfite, usually in an autoclave under moderate pressure, as illustrated:

RCHzCHzOH HBr RCH CHZBr H20 (10) RCHaCHzBI Nazsoa RCHzCHzSOaNa NaBr (11) The long chain alcohol required in Equation can be obtained by hydrogenolysis or sodium reduction of esters of long chain fatty acids, but except in the case of pelargonic acid, C8H17CO2H, only fatty acids of an even number of carbon atoms are commercially available. Thus the process of our invention has the further advantage of producing otherwise unavailable long chain alkanesulfonates of an odd number of carbon atoms, from such commercially available fatty acids as lauric, myristic, palmitic, stearic, and behenic acids.

We have found that certain conditions for operating the process of our invention are necessary to obtain a good yield of desired product. The mixture of sodium hydroxide and the disodium salt of the cc-SllIfO fatty acid should be homogeneous throughout, hence, stirring is required; a nitrogen atmosphere inhibits oxidation and charring and carries otf water vapor and other volatile products; the weight ratio of sodium hydroxide to disodium salt is preferably not less than 2:1 to insure a fluid stirra'ble mass at the critical fusion temperature range of about 300320 C., approximating the melting point of sodium hydroxide; residence time in the molten state should be sufficient to insure completeness of reaction and yet avoid charring and volatile product formation, suitably from 10-30 minutes at 300320 C. for 2060 gram charges of the disodium salt; the alkaline fusion may be carried out in iron, steel, or thick walled glass vessels, preferably in glass if a neutralization or acidification step is carried out in the same vessel. The incorporation of water in the initial stage may assist thorough mixing but is not required.

The immediate fusion product, where conversion of the disodium salt has been complete, is a mixture of sodium alkanesulfonate, sodium soap, excess sodium hydroxide, sodium carbonate, sodium sulfite and sodium acetate. This mixture may be used directly in detergent formulations; or may be partially or completely neutralized with hydrochloric, sulfuric, phosphoric, polyphosphon'c, a long chain fatty acid, or an a-sulfo fatty acid, before entering into detergent compositions. If conversion of the disodium salt has been incomplete the immediate fusion product will necessarily contain the unconverted disodium salt of the oc-SlllfO fatty acid as an ingredient.

Examples of the fusion products of our invention formed by simultaneous decarboxylation and desulfonasodium octanesulfonate, sodium hendecanesulfonate, sodium tridecanesulfonate, sodium pentadecanesulfonate, sodium heptadecanesulfonate, and sodium henicosanesulfonate from the alkaline decarboxylation of disodium (1-S111fOPC1aI'gOI1Ht, disodium u-sulfolaurate, disodium a-sulfomyristate, disodium a-sulfopalmitate, disodium a-sulfostearate, and disodium a-sulfobehenate, respectively.

The properties of alkali metal alkanesulfonates and the unseparated fusion products are shown in Tables I and II.

The mixtures containing alkanesulfonate and soap, characterized in Table II, were obtained by adding to the alkaline reaction mixture only the amount of aqueous acid needed to neutralize the excess alkali metal hydroxide (cf. Example III), and filtering. Since the amount of water is minimized to prevent product loss, the filter cake of alkanesulfonate and soap also contains inorganic salt, but this presents no problem since builders for detergent compositions and soaps often contain salts such as Na SO K3PO4, N35P3010, (Etc- The alkanesulfonate is readily separated from the mixture by solvent partition techniques such as those described in Examples IIIVII. Slight acidification converts the soap to free fatty acid, but the alkanesulfonate is not affected. Typically, the inorganic salts are removed from an aqueous alcohol mixture and the fatty acid separated from the alkanesulfonate by extraction with acetone or ether.

Long chain alkanesulfonic acids were prepared in a pure state from the sodium salts by means of an ion exchange resin (cf. Example VIII). Properties of the alkanesulfonic acids are shown in Table III.

Isolation of the alkanesulfonic acids permits the ready preparation of salts with ammonia, low molecular weight amines and alkanolamines. These salts are more soluble than the corresponding sodium alkanesulfonates.

Table I shows an advantage in the process of our invention in the formation of sodium alkanesulfonates more soluble than the parent disodium salts of :x-sulfO acids; with the further advantage of a lower critical micelle concentration which means that the sodium alkanesulfonates of our invention are more effective surface active agents at lower concentrations than are the parent disodium salts of a-SlllfO acids.

TABLE I [Sodium Alkanesulfonates by Decarboxylation] Elemental Analyses, Percent Found/Theo. Critical Micelle Sodlum Kratit Concentration Alkane- Point,

sulfonate 0.

Percent 0 Percent H Percent S Percent Na Percent Mmolesll.

Kraift point and cmc. for parent disodium salts of a-SUlfO acids are as follows:

Kratlt CMC point, 0.

Percent Mmoles/l.

Naw-sullopalmitate 76 0. 25 6. 6 Naza-sulfostearate 91 0. 10 2. 5

TABLE II [Detergency and Foam of Sodium Alkanesulfonates and Fusion Products] Detergency, Measured in a Terg-O-Tometer,

60 0., as AR, the Increase in Reflectance Foam Height, RossMiles Test, 60 0., mm. After Washing Detergency 25% distilled 25% 300 .05%+.2% 25% distilled 25% 300 .05%+.2%

water ppm. builder water ppm. builder 5 Na alkanesulfouate:

C11. 27. 7 29. 2 29. 1 230 Fusion Products:

From disodium u.-sulfopalmitate 26. 0 28. 8 30. 0 250 From disodinm u.-sulfopalmitate d 24. 4 29. 0 27. 4 240 From disodium a-sulfostearate 31. 2 19. 7 28.1 240 From disodium a-sulfostearate 32.6 28. 5 28.9 220 From clipotassium a-sulfostearate s 33. 7 Related compounds:

Na a-suliopalmitate 15.9 29. 0

Na dodecyl sulfate.. 25. 7 21. 3 22. 0

Na, octadecyl sulfate 32. 6 31. 0 30. 4

a N85P Oro-N34PgOr-N22SO; builder.

b Na tridecanesulfonate has excellent wetting properties in the Braves test with a wetting time at 0.1% in distilled water of 5.4 secs. at C. compared to 13.3 secs. for Na dodecanesulfouate. Na tetradecanesulfonate is not soluble enough at 25" C .for eiiective wetting.

c 60% Na pentadecanesulfonate, 25% Na myristate, 15% inorganic salts.

d Inorganic salts removed.

a; 45% Na heptadecane sulfonate, 17% Na palmitate, 38% lnorganlc s ts.

1 Inorganic salts removed.

72% K heptadecanesulfonate, 28% K palmitate.

h A built solution, 03% Na pent-adecanesulfonate, .01% Na myristate, 111% lime soap dispersing agent, 0.2% builder, gave 2. AR value (in hard water of 300 ppm.) 0126.6, and a foam height of 165 mm.

i A built solution in hard water, 03% Na heptadecanesulionate, .01% Na palmitate, .01% lime soap dispersing agent, .2% builder, gave a AR value of 30.0, foam height 60 mm.

ide reactions in the presence of excess alkali at high TABLE III [Alkanesuhonic Acids] 30 temperatures. An example 15 the followmg where x+y=l42 Critical Micelle B( E)X Z)y 3 2 N Alkane- Neutrali- Melting Krafit Concentration I sulfonic zation point, point, Acid Equivalent C. C.

Found/Theo. Percent Mmoles/l.

C1: 264.4/26 1 .4 63. 7-65 .098 2. s3 83:33:: 33233351? 333% its .235? 8113 OHflOHfl)XQHWHMHZSOQNQ+ News a Krafit point much lower than room temperature. Easily soluble to form concentrated solutions at 25 C. and below.

Table II shows that the sodium alkanesulfonates and 5 Q g 3 mvegtlcn f zffi gg afg gz The nature of our invention is further illustrated by an ii E 5 g i H SO and the the examples which follow. Examples 1 and II demon- If)ar.lcu at 3 1 Th strate that, in the absence of alkali, thermal degradation a f uc 2 150 3 g g fi g of an oc-SlllfO fatty acid or the monosodium salt thereof ii lsil r i iodiiiz nz in dis diumix-sulfd p:lmitate or di- -a desullfonzitlion with recovery of the parent fatty sodium u-sulfostearate, free of inorganic salts have AR $28 :Figgilg igg demonstrate the products and values in hard water of about 28-31 compared to 21.5 and 31.0 for sodium dodecyl and octadecyl sulfate EXAMPLE I respectively.

The sodium alkanesulfonates and alkanesulfonic acids f degmdatm f 'W f acid to P f of our invention are useful chemical intermediates as by desulfonano the absence f alkall exemplifiedby the following yp reactions: A solution of 10 grams of a-sulfopalmitic acid in 100 (13) P01 ml. of o-dichloro'benzene was heated 7 hours at a reflux Rcmcmsoma ROH CHzSOgOl temperature of 165-175 C. and then cooled to 5 C. (14) RCH2CH2S02C1 R/NH2 omerand filtered. The solid residue recrystallized from chloro- (15) form gave a 77% yield of palmitic acid, M.P. 60.7- R 0132011280201 A1913 RCHZOHZSOFC} 61.6 C., neutralization equivalent 258.0. (16 RCH2CHgSOgC1+ ROH RCHZCHzSOKR' EXAMPLE H (17) T hermal degradation 0 sodium u-sulfostearic acid to Rcmcrnsoma -cnmr stearzc acid A heavy walled glass resin flask was charged with 48 RCHZCESOSCHFC} grams of sodium wsulfostearic acid and 50 ml. of Water. The mixture was stirred continuously with a Hershberg (13) ncrr cmso n so; 3011101160311 stirrer, a stream of nitrogen gas was passed continuously (19) over the surface, and heat was supplied to slowly raise the RGHZOHZSOQH Em P temperature of the mixture to 285 C. The temperature was not raised beyond this point because sublimation onto RC CHB SOB ROHC B SOH I) 2 r 2 m I) a the upper portion of the resin flask took place. The The process of our invention is applicable to substituted sublimate is apparently the parent fatty acid formed in a-sulfo fatty acids sufiiciently stable against undesirable Equations 10 and 11. After cooling the mixture was extracted with boiling acetone. Crystallization of the acetone extract at gave stearic acid in a yield of 65%, M.P. 68.0-68.7%, neutralization equivalent 291.4, found by gas-liquid chromatography to be stearic acid of 95% purity.

EXAMPLE HI Alkali fusion of disodium a-sulfostearate A mixture of 60 grams of sodium a-sulfostearic acid and 120 grams of sodium hydroxide pellets in a heavy Walled glass flask, stirred with a Hershberg stirrer, was protected from oxidation by means of a slow stream of nitrogen and heated until the reactants entered a fluid phase at just above 300 C. Water was added to the cooled reaction mixture, excess alkali was neutralized with 50% H 50 the neutral mixture was filtered and the filtrate discarded. A portion of the solid residue was withdrawn. Analysis showed a soap-detergent composition of 45% sodium heptadecanesulfonate, 17% sodium palmitate, 38% inorganic salts. Detergent and foaming properties of the neutralized unseparated fusion product are shown in Table 2.

The remainder of the neutralized unseparated fusion product was slightly acidified and treated with a mixture of equal volumes of ethanol, diethyl ether, and water. The lower aqueous layer containing inorganic salts was discarded. An equal volume of water added to the ethanoldiethyl ether system caused separation of an ether layer which was dried and evaporated. Recrystallization from acetone of the residue from the ether layer gave palmitic acid, M.P. 60.2-60.5 yield 25%.

Crystallization of the main product from the aqueous ethanol phase gave sodium heptadecanesulfonate, yield 65%. The two products were thus obtained in a total yield of 90%.

EXAMPLE IV Alkali fusion of disodium a-sulfopalmitate A mixture of 48 grams of disodium a-sulfopalmitate and 100 grams of sodium hydroxide was stirred and heated to the fusion temperature under a nitrogen atmosphere. The fused cake was cooled below 100 C., water was added, the mixture was neutralized and slightly acidified with sulfuric acid, diluted with ethanol and heating to boiling. Inorganic salts were removed by filtration. Crystallization of the aqueous alcohol filtrate at 0 C. gave a mixture of sodium alkanesulfonate and fatty acid. Extraction with boiling acetone gave myristic acid, yield 20%. Crystallization of the acetone filtrate gave sodium pentadecanesulfonate, yield 55% EXAMPLE V Alkali fusion of dis dium a-sulfomyristate Sodium hydroxide, 53 grams, was added to a paste made from 27 grams of disodium a-sulfomyristate and 30 ml. of hot water, in a heavy walled glass vessel stirred with a Hershberg stirrer. The reactants were heated and stirred under a nitrogen atmosphere at 300 C. for 15 minutes. The fused cake was cooled below 100 0., water was added, and the mixture was made slightly acid with sulfuric acid. The crude solids were filtered off, washed, treated with boiling 95 ethanol, and filtered, recovering insoluble unconverted starting material as sodium asulfomyristic acid in a yield of 30%.

The product crystallized from the alcoholic solution and washed with ether was sodium tridecanesulfonate in a yield of 39%, with the analysis shown in Table I. Infrared analysis of a Nujol mull showed S0 absorption at 1260-1150 cm.- and 1070 cm.- and the absence of COO- at 1580 emf and CO at 1740-1750 CITIFI.

Addition of water to the combined alcohol filtrate and ether washings caused phase separation. Lauric acid was isolated from the ether layer and identification was confirmed by a gas-liquid chromatogram.

8 EXAMPLE v1 Alkali fusion in steel Sodium hydroxide, 70 grams, was added to a paste of 38 grams of disodium a-sulfopalmitate with 50 ml. of hot water in a steel resin flask. The mixture was stirred with a Hershberg stirrer and heated under a nitrogen atmosphere to above the fusion point. Water was added, excess alkali was neutralized with sulfuric acid, the mixture was filtered, and the solid residue was washed and treated with ethanol. The alcoholic solution was decolorized with carbon and filtered. Crystallization at 25 C. gave a 20% yield of a mixture of sodium pentadecanesulfonate and myristic acid.

EXAMPLE VII Alkali fusion of disodium a-sulfopelargonate Sodium hydroxide, 50 grams, was added to a paste of 25 grams of sodium a-sulfopelargonic acid and 50 ml. of water in a heavy walled glass vessel. The mixture was stirred with a Hershberg stirrer and heated under nitro-' gen to the fusion temperature. The fusion mixture was cooled, water was added, excess alkalinity was neutralized with sulfuric acid and the mixture was filtered. The clear filtrate was extracted with butanol, the butanol layer was evaporated, the residue was dissolved in 95 ethanol, decolorized, and filtered. Crystallization at 0 C. gave a 30% yield of crude sodium octanesulfonate, purified by recrystallization from ethanol, with the analysis shown in Table I. Identification was confirmed by infrared absorption.

EXAMPLE VIII A lkanesulfonic acids A solution of the sodium alkanesulfonate in 50% ethanol was heated with a portion of an ion exchange resin sulfonic acid (Dowex 50W-X8 in the acid form) to facilitate solution and passed through a one foot column of the resin with a bed volume of 300 ml. The aqueous ethanol solution after ion exchange was evaporated to dryness. The residue was twice crystalllized from chloroform to give the alkanesulfonic acid in a pure state with the constants listed in Table III.

We claim:

1. A process for the preparation of a detergent composition containing as the essential active ingredients a sodium alkanesulfonate and a soap, said alkanesulfonate being present in about a 2.4:1 to 28:1 weight ratio with respect to said soap, comprising combining the disodium salt of an a-sulfocarboxylic acid having the general formula R CO NZ.

wherein R is selected from the group of straight carbon chain alkyl radicals having 11, 13, and 15 carbon atoms, respectively, and, based on said salt, about a 2:1 to 2.5 :1 weight ratio of sodium hydroxide to give an alkaline mixture, stirring said mixture and heating said mixture to fusion temperature under a nitrogen atmosphere until the reaction is substantially complete, cooling the reaction mixture to below C., neutralizing excess alkali in the reaction mixture with an aqueous mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, and polyphosphoric acid, and drying the neutralized reaction mixture to give a dry detergent composition containing a sodium alkanesulfonate and sodium soap of the general formulas and R CO Na, respectively, wherein R is selected from the group of straight carbon chain alkyl radicals having 11, 13, and 15 carbon atoms, respectively.

2. The process of claim 1 in which R is hendecyl and the acid is aqueous phosphoric acid.

3. The process of claim 1 in which R is tridecyl and the acid is aqueous sulfuric acid.

4. The process of claim 1 in which R is pentadecyl and the acid is aqueous polyphosphoric acid.

5. A process for the preparation of a detergent composition comprising combining the disodium salt of an cc-SlllfOCZlIbOXYllC acid of the general formula wherein R is an alkyl radical having 6 to 19 carbon atoms, and, based on said salt, about a 2:1 to 2.5:] weight ratio of sodium hydroxide to give an alkaline mixture, stirring said mixture and heating said mixture to fusion temperature under a nitrogen atmosphere until the reaction is substantially complete, cooling the reaction mixture to below 100 C., neutralizing excess alkali in the reaction mixture with an aqueous mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid and polyphosphoric acid, and filtering and drying the neutralized reaction mixture to obtain a solid detergent composition containing as the essential active ingredients a sodium alkanesulfonate of the for mula R CH CH SO Na and a soap of the formula R CO Na wherein R remains the same as in the parent disodium salt, said sodium alkanesulfonate being present in about a 2.4:1 to 2.811 weight ratio with respect to said soap.

6. The process of claim 5 in which the aqueous mineral acid is aqueous sulfuric acid.

7. The process of claim 6 in which R is hexyl.

8. The process of claim 6 in which R is nonyl.

9. The process of claim 6 in which R is hendecyl.

10. The process of claim 6 in which R is tridecyl.

11. The process of claim 6 in which R is pentadecyl.

References Cited by the Examiner UNITED STATES PATENTS 2,822,387 2/1958 Bloch 260-513 LEON D. ROSDOL, Primary Examiner.

A. T. MEYERS, I. GLUCK, Assistant Examiners.

Claims (1)

1. A PROCESS FOR THE PREPARATION OF A DETERGENT COMPOSITION CONTAINING AS THE ESSENTIAL ACTIVE INGREDIENTS A SODIUM ALKANESULFONATE AND A SOAP, SAID ALKANESULFONATE BEING PRESENT IN ABOUT A 2.4:1 TO 2.8:1 WEIGHT RATIO WITH RESPECT TO SAID SOAP, COMPRISING COMBINING THE DISODIUM SALT OF AN A-SULFOCARBOXYLIC ACID HAVING THE GENERAL FORMULA