US3441612A - Hydroxyalkylamine oxide - Google Patents

Description

United States Patent O'ice 3,441,612 HYDROXYALKYLAMINE OXIDE Howard F. Drew, Wyoming, Ohio, assignor to The Procter & Gambia Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Original application Dec. 4, 1961, Ser. No. 156,993. Divided and this application Jan. 23, 1968, Ser. No. 699,787

Int. Cl. Ct97c 87/127,- C11d 1/40, 3/06 US. Cl. 260-584 3 Claims ABSTRACT OF THE DISCLOSURE Hydroxyalkyl amine oxides having improved hygroscopicity and thermal stability properties when employed in detergent compositions, particularly containing alkaline builders.

This is a division of copending application Ser. No. 156,993, filed Dec. 4, 1961.

This invention relates to novel tertiary amine oxide detergents and detergent compositions containing them.

In the constant improvement of organic detergent compounds, certain features have been found to be highly desirable. These features include resistance toward the ingredients imparting hardness to water, a high degree of detergency, and capacity for solubilization of hard water soaps, such as calcium soap. Although there are a number of organic detergents which have these characteristics, detergent compounds having additional desirable characteristics find a wider scope of application.

Thermal stability is a highly desirable property which is lacking in many detergents. Such stability is particularly desirable when detergents are subjected to heat during use or processing, as for example, in spray drying granular detergent compositions.

Another advantageous property for an organic detergent is a low degree of hygroscopicity which results in improved crystallinity. When detergent surfactants which are hygroscopic are used in bar or granular forms, desirable physical properties are impaired. Bars become soft and slimy and granules tend to cake and lose their free flowing and quick dissolving characteristics. For example, trialkylamine oxides have been found to be excellent detergent compounds but are so hygroscopic that they can be effectively used only in liquid detergent compositions.

It is the object of this invention to provide organic detergents and detergent compositions which have excellent detergency characteristics as well as improved mildness to the skin, improved thermal stability and a low degree of hygroscopicity.

It was found that these and other objects are achieved in a novel class of tertiary amine oxides having the structure set forth below and detergent compositions containing such compounds, preferably in solid form, as hereinafter more fully described.

The amine oxides of this invention are:

In the above formula R is a 2-hydroxyalkyl, 3-hydroxyalkyl or 3-alkoxy-2-hydroxypropyl radical in which the alkyl and alkoxy, respectively, range from to 18 carbon atoms in chain length, R and R are each methyl, ethyl, propyl or isopropyl. The class of compounds described above will hereinafter be referred to more simply as R R R N+O.

3,441,612 Patented Apr. 29, 1969 Examples of the compounds of this invention are dimethyl-Z-hydroxydodecylamine oxide, diethyl-3-hydroxydodecylamine oxide, dimethyl-Z-hydroxytetradecylamine oxide, dipropyl-3-hydroxyhexadecylamine oxide, propylmethyl-Z-hydroxyoctadecylamine oxide, diethyl-2hydroxyhexadecylamine oxide, diethyl-Z-hydroxytetradecylamine oxide, diisopropyl-Z-hydroxydodecylamine oxide, N,N-dimethyl-3-dodecoxy-2-hydroxypropylamine oxide, N,N-diethyl-3-tetradecoxy-2-hydroxypropy1amine oxide and methylethyl-3-hydroxydodecylamine oxide.

Tertiary amine oxides as a broad class of compounds are known. It was surprising to find, however, that the particular trialkylamine oxides containing particularlyplaced hydroxy groups as described above (i.e., a hydroxy group in the 2 or 3 position in R have such highly desirable properties for use as organic detergents, i.e., improved mildness, hygroscopicity and thermal stability characteristics.

It appears that only certain tertiary amine oxides have the aforementioned desirable characteristics; in these certain amine oxides, R R and R must be as described above. If the alkyl or alkoxy in R is longer in chain length than 18 carbon atoms or shorter in chain length than 10 carbon atoms, desired detergency is not obtained. Likewise, if R and R contain more than 3 carbon atoms, desired detergency characteristics are not obtained. The long chain R radical must contain a hydroxy group in the 2 or 3 position (i.e., the second or third carbon atom from the nitrogen) in order to achieve improved mildness, hygroscopicity and thermostability characteristics in accordance with this invention. When the hydroxy group in the R radical is in the l or alpha position, the resultant amine oxide compound has undesirable instability. The 3alkoxy-2-hydroxypropyl R radical has the following general formula:

wherein R ranges from 10 to 18 carbon atoms in chain length.

The Z-hydroxyalkyl, 3-hydroxyalkyl and the 3-alkoxy- Z-hydroxypropyl compounds have about the same reduced hygroscopicity characteristics as compared to the corresponding compound containing unsubstituted R alkyl group. The 3-hydroxyalkyl compound has about the same water solubility as the corresponding compound containing an unsubstituted R alkyl group whereas the water solubility of the 2-hydroxyalkyl compound is somewhat less than the solubility of the corresponding compound containing an unsubstituted R group.

In tertiary amine oxides of this invention, R can be derived from naturally occurring fats and oils or from synthetic sources such as olefins. Mixtures of amine oxides are very suitable wherein the alkyl or alkoxy in R varies in chain length in the C to C range, as for example, the alkyl or alkoxy groups derived from coconut fatty alcohol (or distilled coconut fatty alcohol). Those amine oxides in which the alkyl or alkoxy in R ranges from 12 to 14 carbon atoms are preferred.

The tertiary amine oxides of this invention can be prepared, in general, by oxidizing the corresponding tertiary amine. See, for example, British Patent 437,566. The corresponding tertiary amine, in general, can be prepared by alkylating, with an appropriate long chain alkyl compound, the appropriate secondary amine. If necessary, the long chain alkyl compound can be such (e.g., ketoalkane) that treatment (e.g., reduction) of the tertiary amine, prior to oxidation, will result in hydroxy 3 substitution at the desired location in the R group. The examples explain in detail such reactions. The preparation of alkyl glycidyl ethers (a source of the 3-alkoxy-2- hydroxypropyl R is described in Canadian Patent 582,404, issued Sept. 1, 1959 and U.S. Patent 2,989,547, issued June 20, 1961.

Compounds of this invention are useful per se as detergents and surface active agents. Desirably they are used with other materials to form detergent compositions, particularly solid form compositions as for example, bar, flake, granular or tableted granular compositions. (The tertiary amine oxides of this invention can also be used to make liquid detergent compositions.) Such detergent compositions can contain from about 5% to about 80% of the tertiary amine oxides of this invention and from about 95% to about 20% of anionic organic detergents, nonionic organic detergents, water-soluble inorganic alkaline builder salts, water-soluble organic alkaline sequestrant builder salts or mixtures thereof.

Granular or flake detergents preferably contain about 5% to about 50% of the amine oxides of this invention and from about 95% to about 50% normally solid, watersoluble inorganic alkaline builder salts, or water-soluble organic alkaline sequestrant builder salts. Bar formulations contain about 5% to about 50% of the amine oxides of this invention when used with anionic detergents, such as a soap base, and, if desired, alkaline inorganic or organic builders or inert fillers. Bar formulations can contain about 40% to about 80% of the amine oxides of this invention as the only detergent component, if desired, and the balance inert fillers or builders.

Anionic organic detergents used alone or in admixture include both the soap and non-soap detergents. Examples of suitable soaps are the sodium, potassium, ammonium and alkylol-ammonium salts of higher fatty acids (C -C Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium or potassium tallow and coconut soap. Examples of anionic organic non-soap detergents are: alkyl glyceryl ether sulfonates; alkyl sulfates; alkyl monoglyceride sulfates or sulfonates; alkyl polyethenoxy ether sulfates; acyl sarcosinates; acyl esters of isethionates; acyl N-methyl taurides; alkylbenzenesulfonates; alkyl phenol polyethenoxy sulfonates. In these compounds the alkyl and the acyl groups, respectively, contain to carbon atoms. They are used in the form of water-soluble salts, the sodium, potassium, ammonium and alkylolammonium salts, for example. Specific examples are: sodium lauryl sulfate; potassium N-methyl lauroyl tauride; triethanolammonium dodecylbenzenesulfonate.

The examples of nonionic organic detergents are: polyethylene oxide condensates of alkyl phenols wherein the alkyl group contains from 6 to 12 carbon atoms (e.g., 5-octylphenol) and the ethylene oxide is present in a molar ratio of ethylene oxide to alkyl phenol in the range of 10:1 to :1; condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine wherein the molecular weight of the condensation products ranges from 5,000 to 11,000; the condensation product of from about 5 to moles of ethylene oxide with one mole of a straight or branched chain aliphatic alcohol containing from 8 to 18 carbon atoms (e.g., lauryl alcohol).

Water-soluble inorganic alkaline builder salts used alone or in admixture are alkali metal carbonates, borates, phosphates, polyphosphates, bicarbonates and silicates. (Ammonium or substituted ammonium salts can also be used.) Specific examples of such salts are sodium tripolyphosphate, sodium carbonate, sodium tetraborate, sodium pyrophosphate, sodium bicarbonate, potassium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, sodium sesquicarbonate, sodium monoand diortho phosphate and potassium bicarbonate. Such inorganic builder salts enhance the detergency of the subject amine oxides.

Examples of water-soluble organic alkaline sequestrant builder salts used alone or in admixture are alkali metal, ammonium or substituted ammonium amino polycarboxylates, e.g., sodium and potassium ethylenediaminetetraacetate, sodium and potassium N-(Z-hydroxyethyl)-ethylenediaminetriacetates, sodium and potassium nitrilotriacetates and sodium, potassium, and tri-ethanolammonium N-(2- hydroxyethyl)nitrilodiacetates. Mixed salts of these polycarboxylates are also suitable. Other organic alkaline sequestrant builder salts which can be used are: Hydroxyethyl ethylenediaminetriacetates; Z-hydroxyethylirninodiacetates; diethylenetriaminepentaacetates; 1,2-diaminocyclohexanetetraacetates. The alkali metal salts of phytic acid, e.g., sodium phytate are also suitable as alkaline organic sequestrant builder salts (see US. Patent 2,739,942).

Preferred detergent compositions contain about 10% to about 30% of the tertiary amine oxides of the invention and at least an equal amount of sodium tripolyphosphate. Desirably the amine oxides wherein the alkyl or alkoxy in R contains 12 to 14 carbon atoms are used in such preferred compositions. Particularly desirable is dimethyl-2-hydroxydodecylamine oxide which has good sudsing characteristics, being superior in this respect to dimethyldodecylamine oxide. It also is an effective suds enhancing (building) agent for anionic non-soap detergent compounds.

The detergent compositions of this invention can contain any of the usual adjuvants, diluents or additives, for example, ampholytic or zwitterionic detergents, cationic detergents, perfumes, anti-tarnishing agents, anti-redeposition agents, bacteriostatic agents, dyes, fluorescers, oxygen or chlorine bleaches, suds builders, suds depressors and the like.

The following are examples which illustrate the tertiary amine oxide compounds and compositions of this invention.

Example I 5 moles of dimethyl amine were liquified under anhydrous conditions using a Dry Ice-acetone condenser. 0.05 mole of anhydrous aluminum chloride was added to the dimethyl amine and a mixture was placed in a cold, glass autoclave liner (3 liter). One mole of C olefin oxide was added to the dimethylamine with mixing and cooling. The liner was placed ina cooled autoclave. After sealing the autoclave, the mixture was heated at 200 C. for three hours. The autogenic pressure was 300 to 400 p.s.i.g. After cooling the autoclave and flushing it with N the contents were dissolved in aqueous solution of 10% HCl to hydrolyze the resulting amine-aluminum chloride complex. The solution was made basic with solid KOH and the upper amine layer was removed for vacuum distillation. A 70% yield of distilled dimethyl-2-hydroxydodecylamine was obtained. Elemental analysis of the resulting amine was as follows:

Calculated: C, 73.3; H, 13.6; N, 6.1; O, 7.0. Found: C, 73.4; H, 13.3; N, 5.8; O, 7.2.

The reaction is represented by the following equation:

The dimethyl-2-hydroxydodecyl amine was oxidized with a 10% excess of hydrogen peroxide in a 1 to 3 mixture of water and ethanol at 60 C. After extracting the unreacted amine with petroleum ether, the aqueous phase was freeze dried to yield a pure white powdery amine oxide. The material was purified further by crystallization with acetone. The yield of amine oxide from this oxidation reaction and subsequent purification was A mixture of dimethyl-Z-hydroxyhexadecyl amine oxide and dimethyl-Z-hydroxyoctadecyl amine oxide was obtained from the above process using instead of the C olefin oxide a 6040 mixture of C1643 olefin oxide.

The corresponding diethyl and dipropyl compounds can be obtained by using molar equivalent amounts of diethylarnine or dipropylamine in the process of Example I.

20 parts of dimethyl-Z-hydroxydodecyl amine oxide are combined with 50 parts of sodium tripolyphosphate and 30 parts of sodium sulfate to form a solid form detergent composition which cleans well in a laundering operation and suds well in a dishwashing operation. The dishpan sudsing of dimethyl-Z-hydroxydodecyl amine oxide in such a composition is superior to that of sodium dodecylbenzene sulfonate in a like composition.

Example II 170 grams of 2undecanone, 22.5 grams of paraformaldehyde, 40.8 grams of dimethyl amine hydrochloride were mixed with 500 ml. of ethanol and stirred for 24 hours at 78 C. The reaction mixture was acidified and extracted with ethyl ether to remove the unreacted Z-undecanone. The mixture was then made alkaline and extracted again with ethyl ether to obtain 81 grams of 3-ketododecyl dimethyl amine. The reaction is represented by the following equation:

38 grams of LiAlH was dissolved in 600 ml. of anhydrous diethylether. 57 grams of the 3-lcetododecyl dimethyl amine obtained above was dissolved in 400 ml. of diethylether and added drop-wise to the LiA1H solution. This mixture was then stirred for an additional 1 /2 hours. The unreacted LiAlH was decomposed by the addition of ethyl acetate followed by water. The solution was filtered to remove solids. The filtrate split into aqueous and ether layers. The ether layer was evaporated on a steam bath to yield the hydroxy amine. This reaction is represented by the following equation:

0 1| 411 0 ill-Celine CHzCHzN(CH LLAJH4 A Calculated: Amine number, 244; hydroxyl number, 244. Found: Amine number, 240; hydroxyl number, 227.

45 grams of the dimethyl-3-hydroxydodecyl amine obtained above, was mixed with 8.5 grams of hydrogen peroxide (28.5 grams of a 30% aqueous solution) and 250 ml. of ethanol and 125 m1. of water. This mixture was stirred for 6 hours at 50 C. After cooling to room temperature the solution was diluted with 400 ml. of water and the remaining peroxide decomposed catalytically. The unreacted amine was removed with a triple ether extraction. The ethanol was largely removed from solution on a steam bath and the product was isolated by freeze drying. The amine oxide was recrystallized from acetone and had the following elemental analysis:

Calculated: percent C, 68.50; percent H, 12.73; percent N, 5.71. Found: percent C, 67.89; percent H, 12.40; percent N, 5.67.

The resulting dimethyl-3-hydroxydodecyl amine oxide was tested for hygroscopicity, being compared with the Z-hydroxydodecyldimethyl amine oxide of Example I and with an unsubstituted dimethyldodecyl amine oxide. The hygroscopicity was determined by exposing dry recrystallized material in a constant 50% relative humidity chambar at 70 F.

It is apparent that the 3-hydroxydodecyl and the 2- hydroxydodecyl compounds are markedly less hygroscopic than the unsubstituted dodecyl compound. The thermal stability of the compounds of this invention are indicated by decomposition temperatures of the 3-hydroxydodecyl and the 2-hydroxydodecyl compounds of 145 C. and 130 C. respectively as compared to C. decomposition temperature of unsubstituted dimethyldodecyl amine oxide.

The dimethyl-3-hydroxydodecyl amine oxide and the dimethyl-Z-hydroxydodecyl amine oxide were tested for detergency properties. These amine oxides were substantially equivalent in detergency to sodium dodecyl'benzenesulfonate. The determination was made by washing naturally soiled cloth (desired print cloth) swatches in an 0.1% aqueous solution of a mixture of 20% of an organic detergent compound (amine oxide being tested or alkylbenzenesulfonate standard) 50% sodium tripolyphosphate and 30% sodium sulfate. The composition had a pH of 10 and the washing was done at F. for 10 minutes using wash water of 7 grains per gallon hardness. The detergency effectiveness was deter-mined by measuring the percentage of lipid soil remaining on a standard size swatch (on a dry basis) after the washing operation. The percentage of lipid soil remaining after washing with the amine oxide test composition was compared with the percentage after washing with the alkylbenzenesulfonate standard composition. On the basis of the percent residual lipid soil, the lower the percent, the better the detergency performance. A Tergotometer was used for the washing operation. (Tergotometer testing is described in Detergency Evaluation and Testing by I. C. Harris, Interscience Publishers, Inc. (1954) page 60.)

Diethyl-2-hydroxytetradecylamine oxide, diisopropyl- 3-hydroxyhexadecylamine oxide and dimethyl-Z-hydroxyalkylarnine oxide wherein the alkyl is derived from coconut fatty alcohol can be made by processes similar to those described in Examples I and II. These compounds will have substantially equivalent thermal stability and hygroscopicity characteristics and the detergency eflicacy will be slightly less than that of the hydroxydodecyl compounds.

Example III 1,818 grams of dodecyl glycidyl ether was charged into a two liter autoclave. Air was purged from the head space with dimethyl amine. The autoclave was then heated to 390 F. A pressure of 450 p.s.i. was obtained in the autoclave by charging dimethyl amine into the autoclave using nitrogen pressure. A dimethyl amine bleed valve was adjusted during the reaction of the ether with the dimethyl amine to keep a constant pressure and temperature. After one hour, the autoclave was cooled. The resultant N,N- dimethyl-3-dodecoxy 2 hydroxypropylamine contained about 25% dissolved dimethylamine which was stripped 01f at 175 F. at mm. Hg pressure. The amination reaction is represented by the following equation:

012E250 CH -CH-CHz Hmon 1 61211950 CH2CH-CH2N( 01-13) 1000 grams of this tertiary amine was mixed with 2789.3 grams of water, heated to 180 F. and mixed with 462 grams of 25% aqueous solution of hydrogen peroxide. The mixture was vigorously agitated. The resultant mixture was aged overnight at about 170 F. to decompose excess peroxide.

The resultant N,N-dimethyl-3dodecoxy-Z-hydroxypropylamine oxide absorbed only 0.3% water after one week of storage in an open vessel at room temperature and conditions. Only 22% water was absorbed upon extreme storage conditions of 90 F. and 80% relative humidity for 7 days. This amine oxide exhibited excellent detergency and sudsing characteristics and has excellent thermal stability.

N,N-diethyl-3-tetradecoxy-2-hydroxypropylamine oxide and N,N-dimethyl-3-hexadecoxy-2-hydroxypropylamine oxide can be prepared by processes similar to that described in Example II. These compounds have improved characteristics similar to those of the dodecyl compound.

The tertiary amine oxides of this invention can be used in eifective detergent compositions having improved hygroscopicity and thermal stability characteristics. They have the following formulas:

Granular detergent: Percent Dimethyl-2-hydroxydodecyl amine oxide 17.5

Sodium sulfate 23 Sodium tripolyphosphate 50 Sodium silicate 6 Water 3.5 Granular detergent:

Diethyl-2-hydroxydodecyl amine oxide Sodium dodecylbenzenesulfonate (the dodecyl group being derived from tetrapropylene) 10 Sodium nitrilotriacetate 35 Sodium sulfate 40 Water 5 Granular detergent:

Dipropyl-3-hydroxy tetradecyl amine oxide 10 Condensation product of one mole of nonyl phenol and nine moles of ethylene oxide 10 Sodium pyrophosphate 50 Sodium carbonate 3 Trisodium phosphate 3 Sodium sulfate 24 Granular detergent: Parts Dimethyl-Z-hydroxydodecylamine oxide 1 Potassium ethylenediaminetetraacetate 2 Granular detergent:

Dimethyl-3-hydroxydodecylamine oxide 1 Potassium pyrophosphate 5 Spray-dried granular detergent: Percent N,N-dimethyl-3-dodecoxy 2 hydroxypropylamine oxide Sodium dodecylbenzenesulfonate Sodium tripolyphosphate 50 Sodium sulfate 15 Sodium silicate 5 Moisture 10 8 Milled toilet bar: Percent Diethyl-3-hydroxytetradecylarnine oxide 10 Sodium coconut oil soap 15 Sodium tallow soap 6O Triethanolammonium ethylenediaminetetraacetate 5 Moisture Framed toilet bar:

Dirnethyl-2-hydroxydodecylamine oxide 5 Sodium dodecylbenzenesulfonate 57 Glyceryl tristearate 38 Scouring cleanser Silica flour Detergent consisting of 85% trisodium ph0S-' phate and 15% dimethyl-3-hydroxyhexadecylamine oxide 15 To show the improvement in mildness of the compounds of this invention ove-r trialkylamine oxides without a hydroxy group in the long chain R radical, dimethyldodecylamine oxide and dimethyl-Z-hydroxydodecylamine oxide were tested in accordance with the guinea pig immersion test. This test consists of immersing guinea pigs having shaved underside up to their thorax in a 0.2% solution of the material being tested at 37 C., for a 4 /2 hour period per day for three consecutive days. The animals are graded three days after the last immersion. The grades are the average of the results on not less than three animals. A 1 to 10 scale is used to rate the effects of the prolonged exposure of the test solution on the animals skin. Grade 10 represents ideal or perfect skin (soft, smooth and flexible) and the effect of a theoretically perfectly mild detergent compound; grade 1 represents severely irritated skin. Other values represent graduations of severity between these extremes. Grade 1 in the guinea pig immersion test indicates severely thickened, dry, cracked and bleeding skin, i.e., extreme irritation. (Grade 1 in exaggerated tests on human subjects would indicate severe redness and dryness of the skin. Exaggerated exposure tests on guinea pigs are much more extreme than those conducted on human subjects.) There is a good correlation between the results of the tests on guinea pigs and the results of normal use tests on humans; the guinea pig immersion test can be relied on to grade the relative mildness of detergent compounds toward the human skin. In guinea pig immersion tests dimethyldodecylamine oxide had a grade of 2, while dimethyl-2-hydroxydodecylamine oxide had a grade of 5. I

What is claimed is:

1. Tertiary amine oxide compounds having the formula R R R N+O, wherein R is 2-hydroxyalkyl or 3- hydroxyalkyl in which the alkyl ranges in chain length from 10 to 18 carbon atoms and R and R are each selected from the group consisting of methyl, ethyl, propyl and isopropyl radicals.

2. The compound of claim 1 wherein R is 2-hydroxydodecyl and R and R are each methyl.

3. The compound of claim 1 wherein R is 3-hydroxydodecyl and R and R are each methyl.

References Cited UNITED STATES PATENTS 8/1930 Guenther et al. 260-563 X 7/1962 Whitman 260-584 X U.S. Cl. X.R. 252-l52