US3256155A - Dentifrice composition - Google Patents

Description

United States Patent 3,256,155 DENTIFRICE COMPOSITION Arno Cahn, Pearl River, N.Y., and Mark D. Konort, Haworth, and Meivin A. Goldberg, West Engiewood, N.J., assignors to Lever Brothers Company, New York, N.Y., a corporation of Maine N0 Drawing. Filed Apr. 11, 1962, Ser. No. 185,630

' 9 Claims. (Cl. 167-93) This invention relates to 2-hydroxyalkyl sulfates, alkali metal salts thereof, and to their method of preparation. The invention additionally relates to detergent and dentifrice formulations containing Z-hydroxyalkyl sulfates and their alkali metal salts as active ingredients.

The compounds of the formula wherein R is an alkyl group having from 8 to 18 carbon atoms, and M is selected from the group consisting of hydrogen and alkali metals have been discovered.

The novel compounds of this invention are excellent surface active agents and are useful in detergent formulations. Certain of the Z-hydroxyalkyl sulfates show excellent detergency without conventional inorganic builder salts, and show a moderate response to the conventional inorganic builder salts such as alkali metal sulfates, carbonates, silicates, phosphates, borates and mixtures thereof. Additionally, they show moderate activity as lime soap scum dispersants. Accordingly, the Z-hydroxyalkyl sulfates are useful in dishwashing detergents, non-soap bars, soap bars, bars containing mixtures of soaps and non-soaps, and to other applications known to those skilled in the art where surface active properties are desired.

A particularly useful and unexpected property of 2- hydroxyalkyl sulfates is realized in their use as dentifrice detergents. Most dentifrice formulations now commercially marketed contain surface active agents in low concentrations. The principal function of the surfactant is to provide an adequate foam level. Beyond providing foam, it is obvious that a desirable surfactant should not interfere with the flavor of the dentifrice formulation. Many of the commonly used dentifrice detergents, including sodium lauryl sulfate, have the disadvantage of giving an orange juice effect, an unpleasant flavor effect caused by interaction of citrus juice and the detergent.

the absence of an unpleasant flavor effect by interaction with citrus juice, is provided by using the 2-hydroxyalkyl sulfates of this invention in dentifrices as the active detergent.

In addition to the detergent, the dentifrices of this invention include an abrasive and other conventional ingredients such as binders, sweeteners, flavor, preservative, and humectant.

The compounds of thisinvention are prepared by hydrolyzing a lo hain L p x co p nd t p d the corresponding 1,2-diol, and subsequently sulfating the 1,2-,diol to produce the corresponding Z-hydroxyalkylsulfuric acid, which is then neutralized with an alkali metal hydroxide. v

The hydrolysis of the epoxy compound is carried out in a suitable solvent in the presence of 10% aqueous sulfuric acid as a catalyzing agent. Sulfation is preferably accomplished with chlorosulfonic acid by adding the chlorosulfonic acid dropwise while stirring a solution of the reaction mixture. The solvent used may be any solvent which is inert to attack by chlorosulfonic acid. Chlorinated solvents such as chloroform are especially advantageous. The chlorosulfonic acid and 1,2-diol should be mixed in approximately equimolar quantities. The synthesis of the compounds of this invention is summarized by the following equations:

The 1,2-epoxide starting materials may be prepared by conventional methods such as oxidation of olefin compounds derived from petroleum sources. Likewise, the 1,2-diol may be prepared according to other conventional methods such as hydrolysis of chlorohydrins andthe like.

It is apparent from the above discussion that an important step in the preparation of the compounds of this invention is the sulfation of the 1,2-diol. The use of chlorosul fonic acid as the sulfating agent produces the' EXAMPLE I Preparation of sodium Z-hydroxytetradecyl sulfate Tetradecane-1,2-diol was first prepared according to the following procedure: 1

A mixture of 42.4 g. (0.2 M) of 1,2-epoxytetradecane, 225 ml. of 1,4-dioxane and 40 ml. of 10% aqueoussulfuric acid was stirred and heatedato 50 C. A homogeneous solution was obtained at thistemperature and the reactionwas allowed to proceed for four and one-half hours. The resultant solution .was poured ,into 1500 ml. of ice water. A white precipitate was obtained and separated .by filtration. Thewetlresidue was dissolvedin 1500 ml. of boiling petroleum ether and the petroleum ether solution was decanted from .the aqueous-layer.- On cooling, the product, tetradecane-.1,-2-diol, precipitated out of the petroleum ether. ,After filtration and drying, the product weighed 30 g. and meltedsat 68.2-68.8" C. This corresponded to a %.,yield. v

Sodium Z-hydroxytetradecyl sulfate was then prepared by dissolving 11.5 g. of the tetradecane-1,2-diol (0.05 mole) in a minimum amount of chloroform, and placing the solution in a 250 ml. 3-necked flask equipped with a mechanical stirrer and a dropping funnel. 5.9 g. of chlorosulfonic acid (0.05 mole) was added dropwise with stirring. Stirring was continued for minutes after the addition was complete. The acidic reaction mixture was poured with stirring into suflicient sodium hydroxide solution to bring the pH of the resulting mixture to 10-11. and water, the crude product was recrystallized from ehtanol, yielding 11.9 g. of 98% pure 2-hydr0xytetradecyl sulfate (72% of theory). Analysis of the product gave 9.43% S, while the calculated amount of S was 9.65%.

EXAMPLE II Tetradecane-1,2-diol was prepared as in Example I, except that tetrahydrofuran was used as a solvent in place of the 1,4-dioxane, the reaction mixture was refluxed and the reaction time was extended to six hours. Comparable yields of tetradecane-1,2-diol were obtained.

Tetradecane-1,2-dio1 was also prepared using acetone to replace tetrahydrofuran as the solvent, the remaining experimental details being th same as above. Comparable yields of tetradecane-1,2-diol were obtained.

EXAMPLE III Sodium 2-hydroxydecyl sulfate was prepared as follows: 6.6 g. of decane-1,2-diol (0.038 mole) was dissolved in chloroform and 4.9 g. of chlorosulfonic acid (0.041 mole) was added dropwise with stirring. After adding the chlorosulfonic acid, stirring was continued for an additional 1 /2 hours. The acidic reaction mixture was poured with stirring into sufiicient 20% sodium hydroxide solution to bring the pH of the resulting mixture to 10-11. After evaporation of the water and chloroform, the crude product was recrystallized from ethanol, yielding 6.1 g. of sodium 2-hydroxydecyl sulfate. The yield was 67% of the theoretical.

EXAMPLE IV Sodium 2-hydroxyoctadecyl sulfate was prepared as follows:

30.0 g. of octadecane-l,2-diol (0.105 mole) was dissolved in 300 ml. of chloroform and 12.8 g. of chlorosulfonic acid (0.11 mole) was added to the solution dropwise with stirring. The stirring was continued for two hours after addition was complete. The acidic reaction mixture was poured with stirring into suflicient 15% sodium hydroxide solution to bring the pH of the mixture to 10-11. After evaporation of the water and chloroform the crude product was recrystallized from ethanol, yielding 32.1 g. of sodium 2-hydroxyoctadecyl sulfate. The yield was 78.7% of the theoretical.

EXAMPLE V bring the pH of the resulting mixture to 10-11. After evaporation of the water andchloroform, the crude product was dissolved in hot ethanol, the undissolved sodium chloride filtered off, and the pure product recovered from the filtrate. The yield was 45.8 g.

After evaporation of the chloroform 4 EXAMPLE VI A series of the compounds of this invention was prepared by the method described in Example I. The detergency characteristics of these compounds were evaluated with a Terg-O-Tometer detergency test. Corresponding alkyl sulfates were evaluated by the same test, for purposes of comparison.

The Terg-O-Tometer test gives an empirical measurement of the amount of soil removed from the fabric under simulated washing conditions. Sample swatches of cloth soiled in a standard manner with a standard soil, are placed in a miniature washing machine, the Terg-O-Tometer apparatus, and are laundered in the presence of a measured amount of detergent and water of a standard hardness.

A Terg-O-Tometer apparatus is described in the Journal of the American Oil Chemists Society, volume 27, May 1950, pages 153159. After rinsing and drying, the reflectance of the cloths is measured and compared with the reflectance of the soiled cloths before washing. In the detergency tests referred to herein, the Terg-O-Tometer apparatus was maintained in a water bath adjusted to maintain the temperature of the washing solution at 120 F. :2 F. The paddle oscillation was brought to complete cycles per minute and the paddle oscillated through a 320 are.

With the agitators in position on the machines, the detergent was added in the desired amount to the washpot of themachine. 1250 ml. of water having a hardness of 180 parts per million CaCO (60 parts magnesium and parts calcium calculated as calcium carbonate), were added. The machine was started and the solution agitated until the detergent was dissolved. Four pieces of soiled cloth approximately 4 /2 inches by 6 inches were addedv and the washing was continued for twenty minutes, after which the test swatches were removed from the solution and hand squeezed. The washpot was refilled with clear rinse water of the same hardness used for washing at a temperature of 120 F. :2 F. and, with the agitators running, the cloths were rinsed for five minutes. The cloths were then removed, hand squeezed, and ironed dry. The reflectance of the cleaned cloths was measured with a Hunter reflectometer using the green filter.

The Terg-O-Tometer test was carried out in duplicate. The reflectance Values in the table below represents the average of the actual reflectance reading taken from 8 cloth swatches. Each of the Z-hydroxyalkyl sulfates and the alkyl sulfates was evaluated alone and in the presence of tetrapotassium pyrophosphate, a conventional builder. Table I summarizes the results obtained.

TABLE I.COMPARISON OF DETERGENCY OF SODIUM QIIfIIJCIEKALTSSULFATES AND SODIUM ZHYDROXYALKYL Reflectance Readings, Hunter Reflectometer with Green Filter C ompound 0.025% by Level, weight of 0.05% by compound weight plus 0.05% by weight of 'IKPP 1 Sodium dodeeyl sulfate 42'. 9 43.8 Sodium tetradeeyl sulfate. 40. 2 48. 4 Sodium hexadecyl sulfate. 41.8 47. 8 Sodium octadecyl sulfate 40. 7 42. 3 Sodium 2-hydroxydodecyl suliat 41. 7 43. 7 Sodium Z-hydroxytetradecyl sulfatc 43.8 43. 2 Sodium 2-liydroxyhexadoeyl sulfate 47. 0 49. 5 Sodium 2-hydroxyoctadecyl sulfate 46. 1 46. 2 Sodium 2-hydroxylalkyl (Cu-C15) Sulfate-.. 41. 3 45.0 Dodeeylbenzenesulfouate; sodium salt... 40. 7 46. 2 TKPP l 42. 0 Water 40. 2 Soil Cloth-Initial Average 39. 7

1 Tetrapotassium pyrophosphate.

The data of Table I shows that- Z-hydroxyalkyl sulfates are superior to the corresponding alkylsulfates, particularly inthe absence of a phosphate builder. Maximum detergency in-theZ-hydroxyalkyl sulfate series is obtained EXAMPLE VII'I' To many individuals, citrus juice has: an: undesirable bitter taste when. ingested. shortlyafter their teeth: have higher lky] carbon. chain l h h i h alkyl been cleaned with a dentifrice containing sodiumlauryl sulfate series. Since compounds of longer carbon chain ulfiate 'or one of th m ny other Widely used dentifrice lengths are, in general, milder towards the skin that shorter detergellts- This effect is well known. Patent .No. chain compounds a distinct advantage i hi regard 2,812,284 describes a comb1nat10n of sodium lauryl sulsides with the Z-hydroxyalkylsulfates. fate a a vg g g t ag" a which provl es an accepta e 0am an w ic at e same time,

EXAMPLE VII does not evidence the orange juice flavor effect.

A series .of 2-hydroxyalkyl sulfates was prepared and A panel of 8 to 9 subjects sensitive to this elfect was tested for mildness or lack of irritation potential toward asked to use unmarked samples of various dentifirices, the skin by means of the Repeat Animal-Patch test. This some containing sodium lauryl sulfate. and somecontaintest measures the primary irritation potential, that is, the ing one of a series of Z-hydroxalkylsulfates. In the test, inverse of mildness, of toilet bars and detergents. the subjects brushed their teeth; waited? for fiveminutes The test is conducted by applying patches saturated with and then ingested orange juice. Where no objectionable the test solution: to young,.adult,Swiss albino mice, usually taste was found in the orange juice: by the subject, the four for each test. The mice are; patched with the test subject listed the, dentrifrice: as being; acceptable. solutions for 75 minutes each day forv four successive days. 2 The formulae ofthe various; dentifricesinvestigated Six applications with friction are made during the 75'- a-re given. below; Each dentri frice contained an abraminute period. The treated area is maintained moist sive and other conventional dentifrice ingredients in adduring the patch period by covering with a rubber dam. dition to the detergent being tested:

Toothpaste; percent Ingredient- A B e" 'D' E Dicalcium phosphate dihydrate 50. 78. 50. 61 50. 49. 22 50. 78 Other inorganic abrasives 5.4'2 5.41 5.39 f 5110 f 5. 42 Binder 0. 51 4 0:50 i 0. 50. 0.49. 0.51 Humectant 23:02; 22.94 1 22.88" 22:40 2210 Sweetener 0.13: 0:13. i 0113; 0513- I 0; 13 Water 18.90: 18.82 p 18177 18.66 v 18.90 Flavor 0189 0.89 0-88 0.86 I 0.89 Detergent 0.30 0.65 0.95 3.00 17.16 Preservative 0.05 0.115 g I 0. 05 v 0.05 1'00. 00 10000 100.00 10000 100.00

After the fourth patch, the animals are sacrificed, the treat- Toothpaste Formula F ed areas excised, and the tissues prepared for histological Ingredient: Per ent analysis araffin imbedding; slides stained with Eosin- Dicalcium phosphate dihydrate 49.33 Methylene Blue). 45 Alumina 0.25

The criterion of mildness is based on the degree of Binder 0.9.5 epidermal destruction incurred after repeated exposure to Hurnectant r 22.25 the test preparation at high concentrations. The exag- Sweetener 0.12 gerated levels are necessary since the epidermis usually Water 24.89 remains intact when treated with most detergents at use Flavor 0,88 concentrations. Detergent 1.25

Mildness ratings based on the degree of epidermal Preservative 0.08 erosion observed histopathologically are as follows: I 0No epidermal erosion (very mild) Tooth powder Formula G 10000 1--Small areas of eroslon (falr mlldness) Ingredient: Percent 2-25% to 50% ep d n (moderatelyirrltatmg) Insoluble sodium metaphosphate 7254 30v r 50% epidermal eroslon (strongly lrntatmg) Dicalcium Phosphate dihyd'rate 1913 The 2-hydroxyalkyl sulfates were tested by this procedure, Magneslum Silicate 4101 together with a corresponding series of sodium alky-l sul- Blndel' 0150 fates, both as 2% aqueous solutions. Results of this test sweeienef are listed in Table II. Wettmg agent 1x00 Flavor TABLE II Compound: Mildness rating Detergent (1.95 Sodium decyl sulfate 1 100100 Sodium dodecyl sulfate 3 p Sodium tetradecyl lf t 0 The foamlng. abil ty of the dentfrlce described above Sodium he'xadecyl lf t 0 was also evaluated 1n terms of. foam quality and. foam Sodium, 2 h d d .1 lf t Q volume. The foam volume was measured by transferring sodium z hydroxydodecyl lf te 1 a two-gram sample of the dentifrice mm. a 50 mlbeaker Sodium 2 hydroXyt6t1-adecy1 Sulfate 1 contalnlng 5 ml. of distilled water. The mlxture was Sodium Lhydroxyhexadecyl sulfate 1 stirred gently. untll thoroughly dispersed and then trans- Difierences between 0 and: 01 are not considered significant in this test.

ferred to a ml. graduated cylinder- The beaker was washed with 15 mlt of water and. the washings added to 7 the cylinder. The cylinder was then turned 25 times and permitted to rest for five minutes, after which the foam volume was read.

The results of the orange juice flavor effect evaluation 8 ing from C to C was prepared according to the method outlined in Example V. The detergency characteristics of this composition were compared with those of the mixed C -C Z-hydroxyalkyl sulfate of Example V,

and the foam evaluation are given in Table III below. 5 using the Terg-O-Tometer test outlined in Example VI.

TABLE III Orange Juice Effect, Foam Level, per- Number of panelists Dentitrlce Base Detergent, Type cent by weight;

Accept- Unaccept- Quality Volume, able able ml.

Sodium 2-hydroxytetradecyl sulfate 0. 30 6 2 21 Sodium 2-hydroxydodecylsulfate 0. 65 9 0 20 {Sodium 2-hydroxydodecylsulfate 0.65 6 3 36 Sodium 2-hydroxytetradecyl sulfate 0.30 Sodium 2-hydroxydodeeyl sulfate 0.30 7 1 46 {Sodium Z-hydroxytetradecyl sulfate 0. 65

Sodium Z-hydroxydodecyl sulfate. 3. 0O 6 2 37 Sodium lauryl sulfate 1.16 0 s 45 Sodium 2-hydroxyoctadecyl sulfate 1.25 9 0 3 Sodium 2-hydroxydodecyl sulfate. 0.65 7 1 38 {Sodium 2-hydroxytetradecyl sulfate 0. 30

Additional tests by a 200 member test panel made to The following Table V gives the reflectance readings evaluate the flavor of the 2-hydroxya1kyl sulfates as toothobtained after washing the soiled cloths in water of paste surfactants indicated that dentifrices containing the 180 ppm. hardness. Z-hydroxyalkyl sulfates of this invention have an overall flavor which is generally acceptable. TABLE V EXAMPLE XI R n t R di An important property of toothpaste detergents is the miffif ifi g j ability to produce foam. The following test procedure with Green Filter was used to measure the foaming ability of toothpaste formulations containing the 2-hydroxyalkyl sufate of this Cmnpound Level e o zgrg 1 invention: 0.05% by compound Two gram samples of an experimental toothpaste foreight gins 0. 05%

yweight mulation similar to Toothpastes A-E described in Exg i ample VIII, containing 1% and 1.5% detergent were each 4 introduced into a 50 ml. beaker containing 5 ml. of dis- 40 gogium g-lilly$Olfy1alEI3i1 oil-C15) sulfate... 44.5 47.5 tilled water. The toothpaste was thoroughly dispersed ggg g gggi gg g;;;;g1 gf---- 21% 23:; by gentle stirring, and the dispersion was then transferred 44.0 to a 100 ml. graduated cylinder. The beaker was washed it: with 15 m1. of distilled water and the washings also transferred to the cylinder. The cylinder was then in- 1Tetmpomssiumpymphosphate vetted 25 times and allowed to rest for five minutes before reading the foam volume. The experimental results from a series of tests run in this manner are summarized We claim: i T bl IV. 1. A dentifrice composition comprising an abrasive and TABLE IV a compound having the formula Foaming agent: Foam volume, ml.

1% sodium lauryl sulfate OH 1.5% sodium 2-hydroxydodecy1 sulfate 36 I 1.5% sodium 2-hydroxytetradecyl sulfate 80 R CHCHzOSOsM 1.5% sodium 2-hydroxyhexadecyl sulfate 20 EXAMPLE X wherein R is alkyl having from 8 to 18 carbon atoms and M is selected from the group consisting of hydrogen and Mixtures of the 2-hydroxyalky1 sulfates of this inventhe a1ka1imeta1s have been found ueful toothpaste deterg 2. The dentifrice composition of claim 1, wherein the For example, on comparison with a commercial toothcompound is z hydroxydecyl sulfam Paste, a toothpasteFontammg 125% of z'hydroxydPdecyl 3. The dentifrice composition of claim 1, wherein the sulfate was marginally less acceptab'le beclause it was compound is LhYdroxYdodecYl Sulfate. considered slightly deficient in foam, Toot pa f 4. The dentifrice composition of claim 1, wherein the 'tallllng 115% of sPdlum 2hydroxytetradecyl 2 1? compound is 2-hydroxytetradecyl sulfate. developed more copious than ff wlt e 5. The dentifrice composition of claim 1, wherein the dodecxl analog but a Shgh,fly blue; g g fi compound is sodium Z-hydroxydodecyl sulfate. effect However by usmg mlxmre o i e 6. The dentifrice composition of claim 1, wherein the dcdecyl analog g tetra S t g com-pound is sodium 2-hydroxytetradecyl sulfate. toothpaste was a l a 15 g z 7. A dentifrice composition comprising an abrasive and regagd Q q l i r i is; z z g a a mixture containing Z-hydroxydodecyl sulfate and of t 6 orange 6 a e p Z-hydroxytetradecyl sulfate in aratio between about 30:65 total level of only 0.95% detergents. and 30 EXAMPLE XI 8. A dentifrice composition comprising an abrasive and A sodium Z-hydroxyalkyl sulfate, wherein the alkyl a. mixture containing Z-hydroxyclodecyl sulfate and p r i n was a mixture having carbon chain lengths rang- 7 2-hydroxytetradecyl sulfate in a ratio of about 30:65.

9. A dentifrice composition comprising 'an abrasive and a mixture containing Z-hydroxydodecyl sulfate and 2-hydroxytetradecy1 sulfate in a ratio of about 65:30.

References Cited by the Examiner UNITED STATES PATENTS Hall 167-93 Kuever 167-93 Stayner 252-461 Kooijman et a1 252-161 JULIAN S. LEVI'I'I, Primary Examiner.

J. GREENWALD, F. CACCIAPAGLIA, 'JR.,

Examiners.

Claims (1)

1. A DENTIFRICE COMPOSITION COMPRISING AN ABRASIVE AND A COMPOUND HAVING THE FORMULA