[0001] The present invention relates to an aqueous light duty liquid detergent formulation. In particular, the present invention relates to an aqueous light duty liquid detergent formulation including a water; a zwitterionic surfactant; and an alcohol ethoxysulfate surfactant of formula I wherein each R ¹ and R ² is independently a C1-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3" anion of formula I; and wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I.

[0002] Aqueous cleaning compositions, for example, floor care formulations, hard surface cleaning formulations and personal care formulations have a wide array of uses. For example, uses include cleaning hard surfaces such as floors, counters, walls, tables, and other things made of, for example, wood, stone, laminate, ceramic and plastic materials which need to be cleaned periodically of accumulated dirt, oil, grease, and other contaminants.

[0003] Aqueous light duty liquid detergent formulations are commonly used in hand dishwashing liquids, hard surface cleaners and some laundry applications. These aqueous light duty liquid detergent formulations typically include an anionic surfactant, which is the principal suds producer, along with a secondary surfactant. Alkyl ethoxy sulfate anionic surfactants (e.g., alcohol ethoxy sulfate surfactants) have established use in a variety of aqueous light duty liquid detergent formulations Conventional AES anionic surfactants; however, have been associated with undesirable 1,4 dioxane content. Regulators are increasingly restricting the amount of 1,4 dioxane that may be present in consumer products. For example, New York State has banned all but trace amounts of 1,4 dioxane in cleaning products. Typically, a consumer product must contain less than 10 parts per million by weight (ppm) of 1 ,4 dioxane to be compliant with the regulations. One contributor of the unintended incorporation of 1 ,4 dioxane in consumer products can be the inclusion of alkyl ethoxy sulfate anionic surfactants.

[0004] Inclusion of 1 ,4 dioxane in conventional AES surfactants is believed to occur at multiple points in time. A first point of 1 ,4 dioxane generation in conventional AES surfactants is believed to occur during the sulfation process of alcohol ethoxylates to make alcohol ethoxy sulfates. The alcohol ethoxylate intermediates for the production of conventional alcohol ethoxy sulfate surfactants are made via ethoxylation (i.e., the reaction of an alcohol with ethylene oxide) that typically results in a distribution of alcohol ethoxylate oligomers. It is believed that under the sulfation process conditions during the manufacture of conventional AES surfactants, 1,4 dioxane can form. A second point of 1,4 dioxane generation in association with conventional AES surfactants is believed to occur during handling and processing of the conventional AES surfactants. Handling and processing of conventional AES surfactants often involves acidic conditions at ambient, or elevated, temperature. Prolonged exposure to acidic environments for conventional AES surfactants and their alcohol ethoxylate precursors may result in the formation of 1,4 dioxane. Further, exposure to elevated temperatures (e.g., up to 280 °C) during processing, storage and/or handling may result in the decomposition of conventional AES surfactants resulting in the formation of dioxane.

[0005] Traditionally, 1,4 dioxane content in conventional AES surfactants and products incorporating such surfactants has been addressed by the use of stripping techniques. For example, where 1,4 dioxane concentrations are above a target threshold, a stripping process is employed to remove excess 1 ,4 dioxane from the conventional AES surfactants or product incorporating same. The stripping process is not only expensive and time consuming, but also is not a guarantee to meet the increasingly stringent regulatory requirements. Further, as 1,4 dioxane may form over time as a response to how the conventional AES surfactant or product is handled and further processed, any previously applied stripping techniques may be nullified by the generation of new 1 ,4 dioxane. As such, ensuring that a product comprising an AES surfactant is compliant with the appropriate regulations by the time it is sold to an end consumer is a difficult challenge.

[0006] Accordingly, there remains a need for aqueous light duty liquid detergent formulations having an anionic alcohol ethoxysulfate surfactant that resists forming 1,4-dioxane both during the sulfation process to form the surfactant and subsequently when the alcohol ethoxysulfate surfactant is exposed to elevated temperatures of up to 280 °C. [0007] The present invention provides an aqueous light duty liquid detergent formulation, comprising: water; a zwitterionic surfactant; and an alcohol ethoxysulfate surfactant of formula I wherein each R ¹ and R ² is independently a Ci-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3" anion of formula I; and wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I.

[0008] The present invention provides an aqueous light duty liquid detergent formulation, comprising: water; a zwitterionic surfactant; and an alcohol ethoxysulfate surfactant of formula I; wherein each R ¹ and R ² is independently a C1-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SOf anion of formula I; wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I; and wherein the alcohol ethoxysulfate surfactant of formula I contains < 9 ppm of 1,4-dioxane.

[0009] The present invention provides an aqueous light duty liquid detergent formulation, comprising: water; a zwitterionic surfactant; and an alcohol ethoxysulfate surfactant of formula I; wherein each R ¹ and R ² is independently a Ci-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO f anion of formula I; wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I; wherein the alcohol ethoxysulfate surfactant of formula I contains < 9 ppm of 1,4-dioxane; and wherein the alcohol ethoxysulfate surfactant of formula I has elevated thermal stability (preferably, enhanced thermal stability).

[0010] The present invention provides an aqueous light duty liquid detergent formulation, comprising: water; a zwitterionic surfactant; and an alcohol ethoxysulfate surfactant of formula I; wherein each R ¹ and R ² is independently a C1-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3 anion of formula I; wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I; wherein the alcohol ethoxysulfate surfactant of formula I contains < 9 ppm of 1,4-dioxane; and wherein the aqueous light duty liquid detergent formulation contains < 1 wt%, based on solids weight of the aqueous light duty liquid detergent formulation, of an alcohol sulfate surfactant of formula II wherein each R ³ and R ⁴ is independently a Ci-16 alkyl group; wherein the sum of the carbon atoms is R ³ and R ⁴ is 7 to 17 and wherein A ⁺ is a cation balancing the negative charge on the -SO3" anion in formula II.

[0011] The present invention provides an aqueous light duty liquid detergent formulation, comprising: water; an organic solvent; a zwitterionic surfactant; and an alcohol ethoxysulfate surfactant of formula I; wherein each R ¹ and R ² is independently a C1-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3" anion of formula I; wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I; wherein the alcohol ethoxysulfate surfactant of formula I contains < 9 ppm of 1,4-dioxane; and wherein the aqueous light duty liquid detergent formulation contains < 1 wt%, based on solids weight of the aqueous light duty liquid detergent formulation, of an alcohol sulfate surfactant of formula II; wherein each R ³ and R ⁴ is independently a C1-16 alkyl group; wherein the sum of the carbon atoms is R ³ and R ⁴ is 7 to 17 and wherein A ⁺ is a cation balancing the negative charge on the -SCff anion in formula II.

[0012] The present invention provides an aqueous light duty liquid detergent formulation, comprising: 50 to 97 wt%, based on the weight of the aqueous light duty liquid detergent formulation, of water; 0.1 to 10 wt%, based on the weight of the aqueous light duty liquid detergent formulation, of the organic solvent; 0.1 to 10 wt%, based on the weight of the aqueous light duty liquid detergent formulation, of a zwitterionic surfactant; and 0.1 to 20 wt%, based on the weight of the aqueous light duty liquid detergent formulation, of an alcohol ethoxysulfate surfactant of formula I; wherein each R ¹ and R ² is independently a C1-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3" anion of formula I; wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I; wherein the alcohol ethoxysulfate surfactant of formula I contains < 9 ppm of 1,4-dioxane; and wherein the aqueous light duty liquid detergent formulation contains < 1 wt%, based on solids weight of the aqueous light duty liquid detergent formulation, of an alcohol sulfate surfactant of formula II; wherein each R ³ and R ⁴ is independently a C1-16 alkyl group; wherein the sum of the carbon atoms is R ³ and R ⁴ is 7 to 17 and wherein A ⁺ is a cation balancing the negative charge on the -SO3 anion in formula II.

[0013] The present invention provides a method of manually washing an article, comprising: providing an article, wherein the article is selected from the group consisting of at least one of dishware, glassware, flatware, pots, pans and delicate clothing; providing an aqueous light duty liquid detergent formulation of the present invention; manually contacting the article with the aqueous light duty liquid detergent formulation; and rinsing the aqueous light duty liquid detergent formulation from the article.

DETAILED DESCRIPTION

[0014] We have surprisingly found that alcohol ethoxysulfate surfactant of formula I wherein each R ¹ and R ² is independently a Ci-i6 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3" anion in formula I; and wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I resists forming 1,4 dioxane both during the sulfation process to form the alcohol ethoxysulfate surfactant of formula I and subsequently when the alcohol ethoxysulfate surfactant of formula I is exposed to elevated temperatures of up to 280 °C during processing, storage and/or handling.

[0015] We have also surprisingly found that alcohol ethoxysulfate surfactant of formula I; wherein each R ¹ and R ² is independently a C1-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3" anion in formula I; and wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I provides improved thickening of the aqueous light duty liquid detergent formulation relative to conventional AES surfactants and better suds mileage for cleaning surfaces in a higher oil load environment.

[0016] Unless otherwise indicated, ratios, percentages, parts, and the like are by weight (e.g., “ppm” means parts per million by weight).

[0017] The term “solids weight” as used herein and in the appended claims in reference to the aqueous light duty liquid detergent formulation and the alcohol ethoxysulfate surfactant of formula I means dry weight, i.e., excluding any water that may be present. [0018] Preferably, the aqueous light duty liquid detergent formulation of the present invention is a hard surface cleaning formulation. More preferably, the aqueous light duty liquid detergent formulation of the present invention is a hand dishwashing liquid.

[0019] Preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: water (preferably, 25 to 99 wt% (more preferably, 50 to 98 wt%; still more preferably, 60 to 97 wt%; most preferably, 65 to 80 wt%), based on weight of the aqueous light duty liquid detergent formulation, of water); a zwitterionic surfactant (preferably, 0.01 to 15 wt% (more preferably, 0.1 to 10 wt%; still more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on weight of the aqueous light duty liquid detergent formulation, of the zwitterionic surfactant); and an alcohol ethoxy sulfate surfactant of formula I (preferably, 0.01 to 35 wt% (more preferably, 0.1 to 20 wt%; still more preferably, 1 to 15 wt%; most preferably, 2.5 to 10 wt%), based on weight of the aqueous light duty liquid detergent formulation, of the alcohol ethoxysulfate surfactant of formula I) wherein each R ¹ and R ² is independently a Ci-16 alkyl group; wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17; wherein M ⁺ is a cation balancing the negative charge of the -SO3- anion of formula I; and wherein n is 1 in 95 to 100 mol% of the alcohol ethoxysulfate surfactant of formula I.

[0020] Preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: 25 to 99 wt% (more preferably, 50 to 98 wt%; still more preferably, 60 to 97 wt%; most preferably, 65 to 80 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of water. More preferable, the aqueous light duty liquid detergent formulation of the present invention, comprises 25 to 99 wt% (more preferably, 50 to 98 wt%; still more preferably, 60 to 97 wt%; most preferably, 65 to 80 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of water, wherein the water is at least one of distilled water, deionized water and industrial soft water. Still more preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises 25 to 99 wt% (more preferably, 50 to 98 wt%; still more preferably, 60 to 97 wt%; most preferably, 65 to 80 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of water, wherein the water is distilled and deionized. Most preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises 25 to 99 wt% (more preferably, 50 to 98 wt%; still more preferably, 60 to 97 wt%; most preferably, 65 to 80 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a water, wherein the water is distilled, deionized and industrial soft to avoid introduction of undesirable metal ions to the aqueous light duty liquid detergent formulation.

[0021] Preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: 0.01 to 15 wt% (more preferably, 0.1 to 10 wt%; still more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a zwitterionic surfactant. Preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: 0.01 to 15 wt% (more preferably, 0.1 to 10 wt%; still more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a zwitterionic surfactant; wherein the zwitterionic surfactant is selected from the group consisting of betaines, amine oxides, alkylamidoalkylamines, alkyl-substituted amine oxides, acylated amino acids, derivatives of aliphatic quaternary ammonium compounds and mixtures thereof. More preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: 0.01 to 15 wt% (more preferably, 0.1 to 10 wt%; still more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a zwitterionic surfactant; wherein the zwitterionic surfactant includes an amine oxide with a long chain group having 8 to 18 carbon atoms. Still more preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: 0.01 to 15 wt% (more preferably, 0.1 to 10 wt%; still more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a zwitterionic surfactant; wherein the zwitterionic surfactant includes a Cs is alkyl dimethylamine oxide. Yet still more preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: 0.01 to 15 wt% (more preferably, 0.1 to 10 wt%; still more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a zwitterionic surfactant; wherein the zwitterionic surfactant includes a Cio-i4 alkyl dimethylamine oxide. Most preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises: 0.01 to 15 wt% (more preferably, 0.1 to 10 wt%; still more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a zwitterionic surfactant; wherein the zwitterionic surfactant includes (preferably, is) a lauryl dimethylamine oxide.

[0022] Preferably, the aqueous light duty liquid detergent formulation of the present invention, comprises 0.01 to 35 wt% (preferably, 0.1 to 20 wt%; more preferably, 1 to 15 wt%; most preferably, 2.5 to 10 wt%), based on weight of the aqueous light duty liquid detergent formulation, of an alcohol ethoxysulfate surfactant of formula I wherein each R ¹ and R ² is independently a C1-16 alkyl group (preferably, a C1-15 alkyl group; more preferably, a C1-14 alkyl group; most preferably, a linear C1-13); wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17 (preferably, 10 to 16; more preferably, 11 to 15; most preferably, 12 to 14)(preferably, wherein R ¹ and R ² are linear alkyl groups); wherein M ⁺ is a cation balancing the negative charge of the -SOf anion in formula I (preferably, wherein M ⁺ is a cation selected from the group consisting of a nitrogen containing cation (e.g., an ammonium cation), a metal cation (e.g., an alkali metal cation, an alkaline earth metal cation), a boron containing cation and a phosphorous containing cation; more preferably, an ammonium cation, an alkali metal cation and an alkaline earth metal cation; still more preferably, an ammonium cation, a sodium cation and a calcium cation; most preferably, a sodium cation); and wherein n is 1 in 95 to 100 mol% (preferably, 96 to 100 mol%; more preferably, 97 to 100 mol%; most preferably, 97.5 to 100 mol%) of the alcohol ethoxysulfate surfactant of formula I (preferably, as determined using ¹³ C nuclear magnetic resonance characterization).

[0023] Preferably, the alcohol ethoxysulfate surfactant of formula I contains < 9 ppm (preferably, < 8 ppm; more preferably, < 7 ppm; still more preferably, < 6 ppm; yet more preferably, < 5 ppm; still yet more preferably, < 4 ppm; yet still more preferably, < 3 ppm; still even more preferably, < 2 ppm; yet even more preferably, < 1 ppm; still yet even more preferably, < 0.25 ppm; most preferably, less than the detectable limit), based on solids weight of the alcohol ethoxysulfate surfactant of formula I, of 1,4-dioxane (preferably, wherein the 1,4-dioxane content is measured by liquid injection low temperature gas chromatography-mass spectrometry method for organic layer and liquid chromatographymass spectrometry method for aqueous layer). [0024] Preferably, the alcohol ethoxysulfate surfactant of formula I contains < 2 wt% (preferably, < 1.75 wt%; more preferably, < 1.5 wt%; still more preferably, < 1.25 wt%; yet more preferably, < 1.1 wt%; most preferably, < 1 wt%), based on solids weight of the alcohol ethoxysulfate surfactant of formula I, of an alcohol sulfate surfactant of formula II wherein each R ³ and R ⁴ is independently a Ci-i6 alkyl group (preferably, a Ci-i5 alkyl group; more preferably, a C1-14 alkyl group; most preferably, a linear C1-13); wherein the sum of the carbon atoms in R ¹ and R ² is 7 to 17 (preferably, 10 to 16; more preferably, 11 to 15; most preferably, 12 to 14)(preferably, wherein R ¹ and R ² are linear alkyl groups); and wherein A ⁺ is a cation balancing the negative charge of the -SO3" anion in formula II (preferably, wherein A ⁺ is a cation selected from the group consisting of a nitrogen containing cation (e.g., an ammonium cation), a metal cation (e.g., an alkali metal cation, an alkaline earth metal cation), a boron containing cation and a phosphorous containing cation; more preferably, an ammonium cation, an alkali metal cation and an alkaline earth metal cation; still more preferably, an ammonium cation, a sodium cation and a calcium cation; most preferably, a sodium cation).

[0025] Preferably, the aqueous light duty liquid detergent formulation of the present invention comprises an alcohol ethoxysulfate surfactant of formula I as described above, wherein the alcohol ethoxysulfate surfactant of formula I has elevated thermal stability. More preferably, the aqueous light duty liquid detergent formulation of the present invention comprises an alcohol ethoxysulfate surfactant of formula 1 as described above, wherein the alcohol ethoxysulfate surfactant of formula I has enhanced thermal stability. The term “elevated thermal stability” as used herein and in the appended claims means that the alcohol ethoxysulfate surfactant of formula I when heated to 110 °C contains < 9 ppm (preferably, < 8 ppm; more preferably, < 7 ppm; still more preferably, < 6 ppm; yet more preferably, < 5 ppm; still yet more preferably, < 4 ppm; even more preferably, < 3 ppm; still even more preferably, < 2 ppm; yet even more preferably, < 1 ppm; most preferably, < 0.5 ppm), based on solids weight of the alcohol ethoxysulfate surfactant of formula I, of 1,4-dioxane (preferably, wherein the 1,4-dioxane content is measured by liquid injection low temperature gas chromatography-mass spectrometry method for organic layer and liquid chromatographymass spectrometry method for aqueous layer). The term “enhanced thermal stability” as used herein and in the appended claims means that the alcohol ethoxysulfate surfactant of formula I when heated to 280 °C contains < 10 ppm, based on solids weight of the alcohol ethoxysulfate surfactant of formula I, of 1,4-dioxane (preferably, wherein the 1,4-dioxane content is measured by liquid injection gas chromatography-mass spectrometry method for organic layer and liquid chromatography-mass spectrometry method for aqueous layer). [0026] Preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: comprising 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of an organic solvent. Preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of an organic solvent; wherein the organic solvent is miscible with water. More preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of an organic solvent; wherein the organic solvent is selected from the group consisting of an aliphatic alcohol (e.g., Ci-6 alkanols, Ci-6 alkyl diols); a monoalkylene glycol ether (e.g., ethylene glycol propyl ether, ethylene glycol n-butyl ether, ethylene glycol t-butyl ether, propylene glycol propyl ether, propylene glycol n-butyl ether, propylene glycol t-butyl ether, propylene glycol methyl ether acetate, propylene glycol diacetate); a poly alkylene glycol ether (e.g., diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol n-butyl ether, diethylene glycol t-butyl ether, diethylene glycol hexyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol n-butyl ether, dipropylene glycol t-butyl ether, dipropylene glycol phenyl ether, dipropylene glycol methyl ether acetate, tripropylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol propyl ether, tripropylene glycol n-butyl ether, tripropylene glycol t-butyl ether) and mixtures thereof. Still more preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of an organic solvent; wherein the organic solvent is selected from the group consisting of isopropanol, ethanol, 2-(2-butoxyethoxy)ethanol, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol propyl ether, propylene glycol t-butyl ether, dipropylene glycol methyl ether, dipropylene glycol propyl ether, dipropylene glycol n-butyl ether and mixtures thereof. Yet more preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of an organic solvent; wherein the organic solvent includes ethanol. Most preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of an organic solvent; wherein the organic solvent is ethanol.

[0027] Preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a hydrotrope. More preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a hydrotrope; wherein the hydrotrope is selected from the group consisting of calcium, sodium, potassium, ammonium and alkanol ammonium salts of xylene sulfonic acid, toluene sulfonic acid, ethylbenzene sulfonic acid, cumene sulfonic acid and mixtures thereof. Still more preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a hydrotrope; wherein the hydrotrope is selected from the group consisting of sodium toluene sulfonate, potassium toluene sulfonate, sodium xylene sulfonate, ammonium xylene sulfonate, potassium xylene sulfonate, calcium xylene sulfonate, sodium cumene sulfonate, ammonium cumene sulfonate and mixtures thereof. Yet still more preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a hydrotrope; wherein the hydrotrope includes sodium xylene sulfonate. Most preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises: 0 to 10 wt% (preferably, 0.1 to 10 wt%; more preferably, 0.5 to 7.5 wt%; most preferably, 1 to 5 wt%), based on the weight of the aqueous light duty liquid detergent formulation, of a hydrotrope; wherein the hydrotrope is sodium xylene sulfonate.

[0028] Preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises an additive. Preferably, the aqueous light duty liquid detergent formulation of the present invention, further comprises an additive selected from the group consisting of a salt, a builder, an enzyme, a corrosion inhibitor, an acid, a bleaching agent, an abrasive, an antimicrobial agent, a chelating agent, an additional surfactant, a pH adjuster, a buffering agent and mixtures thereof.

[0029] Preferably, the method of manually washing an article of the present invention, includes: providing an article, wherein the article is selected from the group consisting of at least one of dishware, glassware, flatware, pots, pans and delicate clothing (preferably, wherein the article is selected from the group consisting of at least one of dishware, glassware, flatware, pots and pans; more preferably, wherein the article is selected from the group consisting of at least one of dishware, glassware and flatware); providing an aqueous light duty liquid detergent formulation of the present invention; manually contacting the article with the aqueous light duty liquid detergent formulation; and rinsing the aqueous light duty liquid detergent formulation from the article.

[0030] Some embodiments of the present invention will now be described in detail in the following Examples.

Experimental Materials Synthesis SI: C12EO

[0031] A 3 liter (L) 3 -neck glass round bottom flask, equipped with an overhead stirred through the center neck, reflux condenser and-a heating jacket was used for the etherification of 1-dodecene and monoethylene glycol with the catalyst. To ensure good mixing, a pitch blade impeller was used for agitation. A reaction mixture of 551.7 grams (g) ethylene glycol and 505.8 g 1-dodecene was prepared and loaded in the reactor together with 61-g catalyst in powdered form at 23 °C. The impeller stirring rate was set to be at 400 revolutions per minute (“rpm”). The reactor was heated to 135 °C in over the course of 30 minutes, held at 135 °C for 18 hours and then the reactor was cooled down to 23 °C by shutting off the heater. The reaction mixture was separated into a monoethylene glycol and catalyst phase and an olefin phase using a separation funnel.

[0032] A distillation apparatus was constructed using a 1 -liter round bottom flask connected to a short path distillation head with a thermometer adapter and a condenser with a vacuum adapter at the outlet. The distillation flask was heated in an aluminum block by an IKA heated stir-plate. The distillation pot was charged with the combined olefin phase and then stirring and vacuum were applied. Significant boiling was observed but no condensate was observed or collected. The temperature of the heating block was raised to 75 °C and unreacted dodecane was collected at a distillation head temperature of 25 °C to 50 °C and a pressure of 13.3-40 pascals (Pa). The heating block temperature was raised gradually to 140 °C and an intermediate fraction containing both monoether alcohol ethoxylates and dodecenes was recovered while the head temperature increased from 50 °C to 75 °C at a pressure of 13 Pa. The C12EO was collected at a head temperature of 70 °C to 115 °C and a pressure of 6 Pa to 33 Pa. The heating block temperature was raised gradually to 200 °C and an intermediate fraction containing both monoether alcohol ethoxylates and diether was collected while the head temperature increased from 115 °C to 130 °C at a pressure of 6 Pa. The distillation was discontinued and the diether, which remained in the pot, was collected. The C12EO was carried to the next sulfation process to make sulfate anionic surfactant.

Synthesis S2: C14EO

[0033] A 300 mL Parr reactor with a heating jacket and controller was used for the etherification of 1-tetradecene and monoethylene glycol with a catalyst. To ensure good mixing, a pitch blade impeller was used for agitation.

[0034] The reaction mixture of 100.0 g monoethylene glycol and 100.0 g 1-tetradecene was prepared and loaded in the reactor together with 10.0 g powder form catalyst at 23 °C. The impeller stirring rate was set to be at least 600 rpm. The reactor was heated up to 135 °C in 30 minutes, held at 135 °C for 6 hours and then the reactor was cooled down to room temperature by shutting off the heater. The reaction mixture was separated by a separation funnel. The reaction mixture was separated into a monoethylene glycol and catalyst phase and an olefin phase using a separation funnel. Fifteen batches were generated and the olefin phases were collected and combined for distillation.

[0035] The same distillation apparatus as used in the Synthesis SI was used for distillation of the C14EO. The distillation pot was charged with the products in the olefin phase from multiple batch reactor runs and then stirring and vacuum were applied. Significant boiling was observed but no condensate was observed or collected. The temperature of the heating block was raised to 95 °C and unreacted 1 -tetradecene was collected at a distillation head temperature of 30 °C to 60 °C at a pressure of 27 Pa to 5 Pa. The heating block temperature was raised gradually to 170 °C and an intermediate fraction containing both monoether and tetradecene was recovered while the head temperature increased from 60 °C to 85 °C at a pressure of 7 Pa to 5 Pa. The C14EO was collected at a head temperature of 80 °C to 115 °C and a pressure of 8 Pa to 5 Pa. The distillation was discontinued when no more material would distill over with the pot temperature set at 170 °C.

Synthesis S3: C12EO Sulfate

[0036] All chemical manipulations were conducted under a dry nitrogen atmosphere. Prior to the experiment all glassware was heated in a laboratory oven to remove residual water. A 2-L three-neck round bottom flask was loaded with dichloromethane (500 mL) and C12EO prepared according to Synthesis SI (40 g, 0.173 mol, 1.0 equivalents). The reaction flask was equipped with an overhead mechanical stirrer, additional funnel, and thermocouple.

Next, chlorosulfonic acid (12.7 mL, 0.191 mol, 1.1 equivalents) was carefully loaded into the additional funnel. The reaction flask was then submerged into an ice-bath and allowed to cool for 20 minutes, down to 0 °C. Once the reaction was cooled, chlorosulfonic acid was added to the reaction flask dropwise, at a rate of approx. 1.0 mL per minute, over approximately 20 minutes. During the addition of chlorosulfonic acid the reaction temperature did not exceed 5 °C. After the addition, the reaction was allowed to react, and the temperature was kept between 0 and 5 °C, for 3 hours. At this time, the reaction was neutralized by slow dropwise addition of an aqueous NaOH solution (18.0 g NaOH in 500 mL of water, 0.9 molar). The rate of addition was slow enough to not exceed 5 °C over the course of addition. The solution became basic after the addition of -300 mL of 0.9 molar NaOH solution. Dichloromethane was then carefully removed from the biphasic reaction in vacuo. During the removal of the dichloromethane, a large amount of foam was observed. Upon removal of the dichloromethane, the remaining aqueous solution was placed in a freeze drier/lyophilizer to yield the secondary alcohol ethoxylate sulfate product, C12EO Sulfate, as a whiteish solid (61.9 grams).

Synthesis S4: C14EO Sulfate

[0037] All chemical manipulations were conducted under a dry nitrogen atmosphere. Prior to the experiment all glassware was heated in a laboratory oven to remove residual water. A 2-L three-neck round bottom flask was loaded with dichloromethane (500 mL) and C14EO prepared according to Synthesis S2 (50 g, 0.193 mol, 1 .0 equivalents). The reaction flask was equipped with an overhead mechanical stirrer, additional funnel, and thermocouple. Next, chlorosulfonic acid (14.2 mL, 0.213 mol, 1.1 equivalents) was carefully loaded into the additional funnel. The reaction flask was then submerged into an ice-bath and allowed to cool for 20 minutes, down to 0 °C. Once the reaction was cooled, chlorosulfonic acid was added to the reaction flask dropwise, at a rate of approximately 1.0 mL per minute, over approximately 20 minutes. During the addition of chlorosulfonic acid the reaction temperature did not exceed 5 °C. After the addition, the reaction was allowed to react and the temperature was kept between 0 °C and 5 °C, for 3 hours. At this time, the reaction was neutralized by slow dropwise addition of aqueous NaOH (18.0 g in 500 mL of water, 0.9 molar). The rate of addition was slow enough to not exceed 5 °C over the course of addition. The solution became basic after the addition of about 400 mL of 0.9 molar NaOH solution.

Dichloromethane was then carefully removed from the biphasic reaction in vacuo. During the removal of DCM, a large amount of foam was observed. Upon removal of DCM, the remaining aqueous solution was placed in a freeze drier/lyophilizer to give the secondary alcohol ethoxylate sulfate product (68.6 grams).

Synthesis S5: ALEO1 Sulfate

[0038] ALEO1 sulfate was prepared from ALEO1 in the same manner as described in Synthesis S3.

Synthesis S6: SA3EO Sulfate

[0039] SA3EO sulfate was prepared from SA3EO in the same manner as described in Synthesis S3.

EQ Distribution of Surfactants

[0040] The distribution of EO adducts in the surfactants listed in TABLE 1 was determined by NMR or UHPLC-MS as noted using the methodology set forth below with the results provided in TABLE 1. Nuclear Magnetic Resonance EQ Distribution Characterization (NMR) [0041] Samples of surfactant to be analyzed were prepared by dissolving the surfactant in deuterated dimethyl sulfoxide containing 0.025 M chromium (III) acetylacetonate. Nuclear magnetic resonance ( ¹³ C NMR) spectra of the samples were then collected on a Bruker AVANCE 400 MHz spectrometer equipped with a 10 mm cryo-probe set to 25 °C, with the following parameters: a 90°-pulse, inverse-gated decoupling, a 1.38 second acquisition time, and a 6.4 second recycle delay. 2048 scans were collected. The data was processed in MNOVA, and the chemical shifts were referenced to the solvent peak at 39.52 ppm. A DEPT- 135 experiment was also acquired with the same parameters, but with a 2.0 second recycle delay, and 2048 acans. The ratios of different EO adducts are calculated by integrating and comparing the intensity of the ethylene oxide alcohol end groups from about 60-61 ppm, the ethylene oxide backbone groups from about 69-70 ppm, the ethylene oxide end group ether peak from about 71-72 ppm, the unreacted primary alcohol peaks from about 60-61 ppm, and the unreacted secondary alcohol peaks from about 65-66 ppm.

Sodium lauryl ether sulfate analysis by UHPLC-MS

[0042] Ultra high performance liquid chromatography-mass spectrometry (UHPLC-MS) conditions:

[0043] Procedure: The compositions containing commercial surfactants were analyzed by ultra-high performance liquid chromatography mass spectrometry (UHPLC-MS) with electrospray ionization (ESI). For the analysis, stock solutions were prepared at concentrations of 25 ppm in a 50/50 mixture of methanol/water. The alcohol ethoxylate samples were diluted 1:100 in 50/50 methanol/water in duplicate and vortexted for a few seconds. Then they were diluted 1:10 in 50/50 methonol/water to give a final dilution of 1:1,000. Ethal® LA-4 was the standard used for the commercial 1-mole sodium laureth sulfate and Ethal® LA-7 was the standard used for the commercial 3 -mole sodium laureth sulfate. Calibration standards were prepared at 10 ppm, 5 ppm, 2 ppm and 1 ppm in 50/50 methanol/water.

[0044] Alkyl sulfates were diluted from the 1:1,000 preparation in 50/50 methanol/water to give a final solution of 1:20,000. POLYSTEP® B-N-5 was used as the standard for the alkyl sulfate analysis. Standards were prepared in 50/50 methanol/water at concentrations of 5 ppm, 2 ppm, 1 ppm and 0.5 ppm.

[0045] The samples were analyzed using a Waters ACQUITY® UPLC system equipped with a Waters BEH Cl 8 1.7 pm 1 x 50 mm column. Mass spectrometry was conducted using a Waters LCT Premier TOF Mass Spectrometer with ESI. Measurements were conducted in both positive and negative ion mode. Each sample preparation was injected three times for analysis. The ratios of the different EO adducts were calculated by the peak area and are reported in TABLE 1. TABLE 1

[0046] At least 95 mol% of the oligomers of the products of Syntheses S4 and S5 had an n of 1 and no more than 5 mol% the oligomers have an n of > 2. Specifically, > 98 mol% of the oligomers of the products of Syntheses S4 and S5 had an n of 1 and < 2 mol% of the oligomers had an n of > 2.

1,4-Dioxane Content of Surfactants

[0047] The 1,4-dioxane content in the surfactants listed in TABLE 2 was determined by liquid injection low temperature gas chromatography-mass spectrometry (GC-MS) method for organic layer and liquid chromatography-mass spectrometry (LC-MS) method for aqueous layer as noted using the methodology set forth below with the results provided in TABLE 2. [0048] Gas chromatography-Mass spectrometry (GC-MS) conditions for organic layer 1,4-dioxane measurement:

[0049] Standards were prepared by adding dioxane in tetrahydrofuran (“THF”) and diluting down to 0.1-100 ppm.

[0050] Samples were prepared by mixing 3.3 g from the organic (DCM) layer of the crude process mixture and 6.7 g of THF, the solution was then allowed to shake for about 20 minutes. The solids were then centrifuged to the bottom and the supernatant was vialed in an autosampler vial. Spiked samples were prepared by spiking dioxane standard in THF into separate samples at 5-10 ppm.

[0051] Liquid chromatography-mass spectrometry (LC-MS) conditions for aqueous layer 1,4-dioxane content measurement:

[0052] Samples were injected neat or diluted with water 1:4. Standards were prepared by preparing a dioxane in THF stock solution and the diluting down with water to 0.1-100 ppm. Calculation of Dioxane Content Relative to Solids

[0053] The ppm of dioxane content relative to solids content in the sample is calculated according to equation 1.

Concentration of Dioxane in Solution l^or ppM )*Total Reaction Volume (L)

- — -

Theoretical Yield of produc ⁷ - — x 10 t (mg) ⁶

TABLE 2

[0054] The gas chromatography results for the SA3EO sulfate surfactant indicate the secondary alcohol with an average of 3 moles of ethylene oxide per molecule contained 2 ppm of 1,4-dioxane in the organic phase at 110 °C and indicates the potential for structures having n > 2 to produce 1,4-dioxane. Interestingly, when the inlet temperature was increased to 280 °C, the dioxane content of SA3EO sulfate increased from 2 ppm to 1,471 ppm 1,4-dioxane in the organic phase. This result indicates that sulfated surfactants having n > 2 may develop observable 1,4-dioxane at 110 °C, but also that such surfactants may be unstable at elevated temperatures of 280 °C which could result in significant 1,4-dioxane formation. Similarly to SA3EO sulfate, gas chromatography results for the ALEO1 sulfate surfactant indicate the formation of > 9 ppm of 1,4-dioxane relative to the solids at 110 °C. Further, the ALEO1 sulfate surfactant also exhibited a large generation of 1,4-dioxane (259 ppm) at 280 °C, suggesting that the ALEO1 sulfate surfactant lacks stability at high temperatures. The inventive C12EO sulfate surfactant with > 95 mol% having n of 1 and < 5 mol% having n > 2 demonstrates a low 1,4-dioxane content. Surprisingly, the inventive C12EO sulfate surfactant also demonstrates an extremely low 1,4-dioxane content and falls below the limit of detection (LOD) of the GC and LC methods. Using the LOD as a basis, this indicates that the dioxane content for the C12EO sulfate is < 1.6 ppm relative to solids, at 110 °C.

Interestingly, the inventive C12EO sulfate, when the inlet temperature is increased to 280 °C, the 1,4-dioxane content of the material is still less than 1 ppm (i.e., 0.58 ppm), which indicates that the inventive C12EO sulfate has increased thermal stability relative to the comparative materials.

Comparative Examples CF1-CF4 and Examples F1-F5 Light duty liquid detergent formulation

[0055] Light duty liquid detergent formulations of Comparative Example CF1-CF4 and Example F1-F5 were prepared by mixing together the components in the weight proportions noted in TABLE 3 adjusted to pH 8 (as necessary) with sodium hydroxide.

TABLE 3

Performance Testing

Flash foam (hand shake method)

[0056] The flash foam performance of the light duty liquid detergent formulations of Comparative Examples CF1-CF4 and Examples F1-F5 was assessed by loading into a glass vial (30 mL, 25 mm dia. x 95 mm height) 10 g of 0.1 wt% of the light duty liquid detergent formulation in 15 dH hard water (3: 1 Ca ²⁺ :Mg ²⁺ ). The formulations were shaken up and down for 20 seconds at a rate of about 2 shakes per second. The foam height generated from the solution was measured using a ruler after sitting for 1 minute, 3 minutes or 5 minutes. The results are provided in TABLES 4 and 5. TABLE 4

TABLE 5

Foam performance (stirring method)

[0057] The foam performance of the light duty liquid detergent formulations of Comparative Examples CF1-CF4 and Examples F1-F2 was assessed by preparing 0.1 wt% test solutions of the light duty liquid detergent formulations in 15 dH hard water (3:1 Ca ²⁺ :Mg ²⁺ ). A 100 mL portion of the test solution was transferred to the testing cylinder of a Kruss Dynamic Foam Analyzer (DFA100) Instrument. Foam was generated with a 4,000 rpm mixing speed for 80 seconds, with a 5 sec oscillation period. After mixing, foam height and bubble count were continuously monitored for five minutes. The results of the foam analyses are provided in TABLE 6.

TABLE 6

Viscosity

[0058] The viscosity of the light duty liquid detergent formulations of Comparative

Examples CF2 and Examples F1-F5 was measured on a Hamilton MICROLAB STAR liquid handler (Hamilton Robotics) using the Total Aspiration and Dispense Monitoring (TADM) system. The results are provided in TABLE 7.

ABLE 7

Suds mileage

The suds mileage performance of the light duty liquid detergent formulations of Comparative Examples CF1-CF2 and Examples F1-F5 was assessed using the following procedure. A test vial (30 mL, 25 mm dia. x 95 mm height) was charged with 10 g of a 0.1 wt% solution of the light duty liquid detergent formulation in 15 dH hard water (3:1 Ca ²⁺ :Mg ²⁺ ) and 0.012 g of olive oil to form the test solution. The test solution was then mixed in the closed test vial at 500 rpm for 2 minutes at room temperature in an Electrothermal RS-5000 reaction station with a PTFE coated magnetic stir bar. The test vial was then shaken up and down for 20 seconds at a rate of 2 up/down shakes per second. The foam height was then immediately measured with a ruler (Initial). The test solution is then stirred at 500 rpm for 1 hour at 46 °C on the reaction station. The test vial was then shaken up and down for 20 seconds at a rate of 2 up/down shakes per second. The foam height was then measured by ruler (Hl). Finally, the test solution was stirred at 500 rpm for an additional 30 minutes at 46 °C on the reaction station. The test vial was then shaken up and down for 20 seconds at a rate of 2 up/down shakes per second. The foam height was then measured by ruler (H2). The suds retention equals (H2/Hl)*100. The first olive oil dose results are provided in TABLE 8. A second set of test vial was prepared which included an additional 0.012 g dose of olive oil (for a total of 0.014 g of olive oil) and the foam procedure was repeated. The second olive oil dose results are provided in TABLE 9.

TABLE 9

Oily soil cleaning

[0059] The oily soil cleaning performance of the light duty liquid detergent formulations of Comparative Examples CF1-CF2 and Examples F1-F2 was determined using tiles presoiled with red palm oil (DM-97, Center For Testmaterials, Netherlands). Test solutions were prepared as a 1.0 wt% solution of the light duty liquid detergent formulation in 15 dH hard water (3:1 Ca ²⁺ :Mg ²⁺ ). The test solutions were heated to 35 °C. A portion of the heated test solution (2 mL) was placed on a small area of the pre-soiled tile (approx. 1.5 cm x 4.5 cm). The treated tile was placed in an oven at 35 °C in an oven and left to soak for 15 minutes. The tile was then removed from the oven. The test solution was quickly removed and the tile was rinsed twice with deionized water. The percent cleaning was determined by measuring the tile color change from before and after cleaning. The results are provided in TABLE 10.

TABLE 10