EP4734941A1 - Hydroxyalkanoate ester aqueous compositions - Google Patents

Abstract

The present application discloses aqueous compositions comprising one or more of a compound of formula (I), wherein R1, R2, and n are defined herein; and (ii) a surface-active agent (e.g., a surfactant, an emulsifier, or a combination thereof). The aqueous compositions are useful as cleansing formulations. The compound of formula (I) in the aqueous compositions improves viscosity, foam properties, and sensorics, and are particularly advantageous for low sulfate formulations or sulfate-free formulations.

Description

HYDROXYALKANOATE ESTER AQUEOUS COMPOSITIONS

BACKGROUND OF THE INVENTION

Cleansing compositions are used to provide cleansing of the hair and/or skin to remove dirt, sweat, sebum, and oils, and can also help to promote normal exfoliation and rejuvenation of the skin. The ingredients in such formulations are designed to help generate desirable viscosity, foam, and mildness. These desirable properties can be enhanced by the use of ingredients that modulate the foaming and viscosity properties of the formulation.

One class of formulations that is becoming increasingly important are “sulfate-free” formulations. These formulations contain only surfactants which do not contain a sulfate moiety. In the absence of the sulfate-containing surfactants it can be very challenging to develop beneficial sensoric characteristics such as desirable viscosity, significant and long-lasting foam, and good hand feel. In addition, many of the workhorse formulation enhancers (e.g., diethanolamides) are under duress due to toxicological issues, and the alternative solutions are challenged with the sulfate-free formulations. Additives that can improve sulfate-free formulations are of particular interest. One such additive is based on hydroxyalkanoate esters, which can be used to provide compositions that exhibit desirable viscosity and/or foaming action and improved sensorics, particularly for low sulfate or sulfate-free formulations.

SUMMARY OF THE INVENTION

The present application discloses an aqueous composition, comprising:

(i) one or more of a compound of formula I: each R¹ is independently an unbranched or branched (Ce-

12) alky I; each R² is independently a hydrogen, or an unbranched or branched (Ci-e)alkyl; and each n is independently 1 , 2, or 3;

(ii) a surface-active agent, which is a surfactant, an emulsifier, or a combination thereof, wherein the one or more of the compound of formula I is present at from 0.1 weight percent (“wt%”) to 15 wt%, wherein the surface-active agent is present at from 5 wt% to 30 wt%, wherein the weight percentage is based on the total weight of the aqueous composition, wherein the one or more of the compound of formula I and the surface active agent are different.

The aqueous compositions are useful in cleansing formulations that are low in sulfate or sulfate-free. The aqueous compositions are useful as shampoos, hair conditioners, shower gels, soaps, or other cleansing compositions.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

In general, cleansing formulations are complex chemical compositions composed of surfactants, emulsifiers and various other additives. Surfactants are large volume chemicals that constitute the predominant component in cleansing compositions, whether it be for home or professional use. The incorporation of one or more surfactants in cleansing compositions serves the purpose of reducing the interfacial tension between oil and water by adsorbing at the liquid-liquid and/or liquid-solid interface. When dissolved in water, surfactants provide cleansing compositions with the ability to remove soil from surfaces and further dispersion of said soil in the washing liquor. Chemically, each surfactant molecule is characterized by a hydrophilic head part, said hydrophilic head part being attracted to surrounding water molecules, and a hydrophobic tail part, said hydrophobic tail part repelling surrounding water molecules and simultaneously attaching itself to oil and grease in soil. As a result, these opposing forces loosen the soil and subsequently suspend it in the aqueous environment. In other words, surfactants disperse soil that normally does not dissolve in water by itself. Therefore, surfactants constitute the key component in cleansing compositions by detaching stains and further keeping the soil in the surrounding aqueous environment thereby preventing re-deposition of the soil onto the surface from which it has been removed. In the art, surfactants are generally of four types, namely anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.

As used herein, the term “anionic surfactant” refers to a surfactant that possesses at least one negative charge and no positive charge besides the associated counterion (M⁺). Anionic surfactants are those known to a person skilled in the art of detergent compositions. Nonlimiting examples of M+ include lithium, sodium, potassium, magnesium, calcium, barium, ammonium, or alkylammonium counterions. Nonlimiting examples of alkylammonium salts include monoethanolammonium salts, diethanolammonium salts, and triethanolammonium salts. Examples of such anionic surfactants include the following classes of surfactants: alpha-olefin sulfonates prepared by sulfonation of long chain alpha olefins such as sodium C12-C14 olefin sulfonate; acyl isethionates such as sodium cocoyl isethionate, sodium methyl lauroyl isethionate and sodium lauroyl isethionate; alkyl sulfosuccinates such as disodium lauryl sulfosuccinate; dialkyl sulfosuccinates such as dioctyl sulfosuccinate; alpha-sulfo fatty acid esters such as sodium methyl 2- sulfolaurate; alpha-sulfo fatty acid salts such as disodium 2-sulfolaurate; alkyl sulfoacetates such as sodium lauryl sulfoacetate; alkyl sulfonates such as C13-C17 alkane sulfonate, alkyl aryl sulfonates or linear alkyl benzenesulfonates such as sodium decyl benzenesulfonate; alkyl ether carboxylates such as sodium laureth-13 carboxylate, alkyl ether sulfosuccinates such as disodium laureth sulfosuccinate; alkylamidoalkyl sulfosuccinates such as disodium cocamido MIPA sulfosuccinate; alkyl sulfosuccinamates such as disodium stearyl sulfosuccinamate, acyl glutamates such as disodium cocoyl glutamate; acyl aspartates such as disodium M-lauroyl aspartate, acyl taurates such as sodium cocoyl taurate and sodium methyl cocoyl taurate; acyl lactylates such as sodium lauroyl lactylate; acyl glycinates such as sodium cocoyl glycinate; acyl sarcosinates such as sodium lauroyl sarcosinate; anionic derivatives of alkyl polyglucosides such as sodium lauryl glucoside carboxylate and sodium decylglucoside hydroxypropylsulfonate; alkyl sulfates such as sodium lauryl sulfate; alkyl ether sulfates such as sodium laureth sulfate; alkyl monoglyceride sulfates such as sodium coco monoglyceride sulfate.

The anionic surfactant may be chemically synthesized using conventional methods known to the person skilled in the art. The anionic surfactant may be commercially available from a wide variety of suppliers. The anionic surfactant can be sulfated, sulfonated, and/or carboxylated.

“Sulfated anionic surfactants” refers to anionic surfactants containing a -SO4’M⁺ group with M⁺ being absent or chosen from H⁺, Na⁺, K⁺ or other monovalent or multivalent cations. Examples of sulfated anionic surfactants include, but are not limited to, sodium lauryl sulfate and sodium laureth sulfate.

‘”Non-sulfate anionic surfactants” refer to anionic surfactants that do not contain a -SO4’M⁺ group, but are often sulfonates or carboxylates. Examples of non-sulfate anionic surfactants include, but are not limited to, alpha-olefin sulfonates prepared by sulfonation of long chain alpha olefins such as sodium C12-C14 olefin sulfonate; acyl isethionates such as sodium cocoyl isethionate, sodium methyl lauroyl isethionate and sodium lauroyl isethionate; alkyl sulfosuccinates such as disodium lauryl sulfosuccinate; dialkyl sulfosuccinates such as dioctyl sulfosuccinate; alpha-sulfo fatty acid esters such as sodium methyl 2-sulfo laurate; alpha-sulfo fatty acid salts such as disodium 2-sulfolaurate; alkyl sulfoacetates such as sodium lauryl sulfoacetate; alkyl sulfonates such as C13-C17 alkane sulfonate, alkyl aryl sulfonates or linear alkyl benzenesulfonates such as sodium decyl benzenesulfonate; alkyl ether carboxylates such as sodium laureth-13 carboxylate, alkyl ether sulfosuccinates such as disodium laureth sulfosuccinate; alkylamidoalkyl sulfosuccinates such as disodium cocamido MIPA sulfosuccinate; alkyl sulfosuccinamates such as disodium stearyl sulfosuccinamate, acyl glutamates such as disodium cocoyl glutamate; acyl aspartates such as disodium M-lauroyl aspartate, acyl taurates such as sodium cocoyl taurate and sodium methyl cocoyl taurate; acyl lactylates such as sodium lauroyl lactylate; acyl glycinates such as sodium cocoyl glycinate; acyl sarcosinates such as sodium lauroyl sarcosinate; anionic derivatives of alkyl polyglucosides such as sodium lauryl glucoside carboxylate and sodium decylglucoside hydroxypropylsulfonate.

As used herein, the term “nonionic surfactant” refers to a surfactant molecule bearing no electrostatic charge. Any of a variety of nonionic surfactants is suitable for use in the present invention. Examples of suitable nonionic surfactants include, but are not limited to, fatty alcohol ethoxylates, sorbitan ester ethoxylates, alkyl polyglucosides, polyglycerol esters, and fatty acid alkanol amides such as coconut fatty acid monoethylamide or coconut fatty acid monoisopropylamide.

Zwitterionic or amphoteric surfactants refer to an amphiphilic molecule containing a hydrophobic group and one or more hydrophilic groups wherein the molecule contains two opposite formal charges (often as a function of solution pH) and thus is a net neutral charge. Examples of zwitterionic surfactants include alkyl betaines such as coco betaine, lauryl betaine, myristyl betaine; alkylamidoalkyl betaines such as cocamidopropyl betaine, lauramidopropyl betaine, myristamidopropyl betaine, and oleamidopropyl betaine; alkylamidoalkyl sultaines including cocamidopropyl hydroxysultaine, lauramidopropyl hydroxysultaine, myristamidopropyl hydroxysultaine, and oleamidopropyl hydroxysultaine, cocamidopropyl sultaine, lauramidopropyl sultaine, myristamidopropyl sultaine, and oleamidopropyl sultaine; amphoacetates such as sodium lauroamphoacetate and sodium cocoamphoacetate; amphodiacetates such as disodium lauroamphodiacetate and disodium cocoamphoacetate; amphopropionates such as disodium lauroamphodipropionate and disodium cocamphodipropionate; amphohydroxypropylsulfonates such as sodium lauroamphohydroxypropylsulfonate and sodium cocoamphohydroxypropylsulfonate; and amino-acid based amphoteric surfactants as described in US Patent Application US20170081277 exemplified by the following formula: wherein R is selected from branched- and straight-chain, saturated, unsaturated, and polyunsaturated C3-C24 hydrocarbyl or substituted and unsubstituted C3-C8 cycloalkyl, R¹ is a C2-C8 divalent hydrocarbyl group, R² and R³ are each independently a Ci-Ce alkyl or alkenyl group, at least two of R1 , R2 or R₃ may connect with the N⁺ to form a heterocyclic ring, R⁴ is a C1- Cs hydrocarbyl group, X is O or NH, and Y- is CO2-, SO3-, SO4-, PO3-, or PO4-.

As used herein, the term “cationic surfactant” refers to a surfactant that possesses at least one positive charge and no negative charge besides the associated counterion (Xj. They are most often quaternary ammonium species such as, but not limited to, alkyl quaternaries, benzyl quaternaries, ester quaternaries, ethoxylated quaternaries, and mixtures thereof, wherein the alkyl group has from about 6 to about 30 carbon atoms, with about 8 to about 22 being preferred. In certain embodiments the composition comprises cationic conditioning polymer including cationic cellulose and its derivatives (e.g., Polyquaternium -10), cationic guar and its derivatives, and that derived from the monomer diallyldimethylammonium chloride (Polyquaternium-6 and Polyquaternium-7).

The terms “emulsifying agent” or “emulsifier” refers to a compound that is soluble in both an oil or hydrophobic molecules and water. Emulsifiers enable oils and hydrophobic molecules to be uniformly dispersed in water as an emulsion.

The term “alkyl” means a hydrocarbon which may be unbranched or branched. Alkyl groups may be further defined with a carbon number, for example (C6-12). C6-12 means that the alkyl hydrocarbon can have 6 to 12 carbon atoms. Nonlimiting examples of alkyl groups include methyl, ethyl, isopropyl, hexyl, dodecyl, and the like.

The term “alkenyl” means an alkyl with one or more unsaturated bonds formed from the removal of two or more hydrogen atoms from a carbon atoms. Nonlimited examples of alkenyl are ethenyl, allyl, 2-butenyl, 1-butenyl, 1 -hexene, and the like.

The present application discloses an aqueous composition, comprising:

(i) one or more of a compound of formula wherein: each R¹ is independently an unbranched or branched (Ce-i2)alkyl ; each R² is independently a hydrogen, or an unbranched or branched (Ci-e)alkyl ; and each n is independently 1 , 2, or 3; (ii) a surface-active agent, which is a surfactant, an emulsifier, or a combination thereof, wherein the one or more of the compound of formula I is present at from 0.1 weight percent (“wt%”) to 15 wt%, wherein the surface-active agent is present at from 5 wt% to 30 wt%, wherein the weight percentage is based on the total weight of the aqueous composition, wherein the one or more of the compound of formula I and the surface active agent are different.

The aqueous compositions disclosed in the present application exhibit improved viscosity building properties, similar or better foaming action, and better sensorics compared to formulations without the one or more compounds of formula I.

In one embodiment or in combination with any other embodiment, the aqueous composition comprises less than 20wt%, 15wt%, or 10 wt%, or 9 wt%, or 8 wt%, or 7 wt%, or 6 wt%, or 5 wt%, or 4 wt%, or 3 wt%, or 2 wt%, or 1 wt%, or 0.5 wt%, or 0.1 wt%, or at 0 wt%, or from 0.1 -15wt%, or from 0.1 - 10wt%, or from 0.1 -5wt%, or from 0.1 -2wt%, or from 1 -20wt%, or from 1 - 15wt%, or from 1 -10wt%, or from 1 -5wt%, or from 2-20wt%, or from 2-15wt%, or from 2-10wt%, or from 2-5wt%, or from 5-20wt%, or from 5-15wt%, or from 5-10wt%, or from 10-20wt%, or from 10-15wt% of a sulfated anionic surfactant, based on the total weight of the aqueous composition. In one class of this embodiment, the aqueous composition is free of the sulfated anionic surfactant.

In one embodiment or in combination with any other disclosed embodiment, the sulfated anionic surfactant is (C6-3o)alkyl-S04’M⁺ or (Ce- 3o)alkenyl-S04’M⁺, wherein M+ is H⁺, Na⁺, K⁺, NH4⁺, (Ci-4)alkylH3N⁺, ((Ci- 4)alkyl)₂H₂N⁺, ((Ci-4)alkyl)₃HN⁺, or ((Ci-4)alkyl)₃N⁺. In one embodiment or in combination with any other disclosed embodiment, the sulfated anionic surfactant is (C6-3o)alkyl-S04’M⁺ or (C6-₃o)alkenyl-S04’M⁺, wherein M+ is H⁺, Na⁺, or K⁺. In one embodiment or in combination with any other disclosed embodiment, the sulfated anionic surfactant is sodium lauryl sulfate, sodium laureth sulfate, sodium myreth sulfate, sodium pareth sulfate, ammonium laureth sulfate.

In one embodiment or in combination with any other embodiment disclosed herein, the aqueous composition further comprises one or more of the following: (3) a conditioning agent; (4) an emollient; (5) a moisturizer; (6) a humectant; (7) a thickener; (8) a lubricant; (9) a chelating agent; (10) a filler; (11 ) a binding agent; (12) an antioxidant; (13) a preservative; (14) a ultraviolet light absorber; (15) a fragrance; (16) a dye; (17) a buffering agent; (18) an exfoliant; (19) a pH adjuster; (20) a solvent; (21 ) a viscosity controlling agent; or (22) an active ingredient including vitamins.

Examples of UV absorbers include organic and inorganic sunscreen actives.

In one embodiment or in combination with any other embodiment, the thickener is xanthan gum, dehydroxyxanthan gum, guar gum, cassi gum, carrageenan gum, alginic acid and alginate gums, gellan gum, pectin, microcrystalline cellulose, cellulose derivatives (e.g., sodium carboxymethyl cellulose and hydroxypropyl methylcellulose), hydroxypropyl guar, synthetic alkali-swellable acrylate polymers (e.g., acrylates copolymer (tradename Carbopol® AQAU SF-1 from Lubrizol Corp., Brecksville, OH)), hydrophobically modified acrylate copolymers (e.g., acrylates C10-30 alkyl acrylates crosspolymer (Carbopol® 1382 from Lubrizol Corp., Brecksville, OH)), small molecule thickeners (e.g., cocamide MIPA, lauryl lactate, or sorbitan sesquicaprylate), inorganic salts such as sodium chloride, potassium chloride, sodium bromide, potassium bromide, ammonium chloride, ammonium bromide, and combinations thereof.

In one embodiment or in combination with any other embodiment, the aqueous composition further comprises 0.1 wt% to 5 wt%, or 1 wt% to 5wt%, or 2wt% to 5wt%, or 3 wt% to 5 wt%, or 4wt% to 5 wt%, or 0.1 wt% to 10wt%, 1 wt% 10wt%, or 2wt% to 10wt%, or 3wt% to 10wt%, or 4wt% to 10wt%, or 5wt% to 10wt%, or 6wt% to 10wt%, or 7wt% to 10wt%, or 8wt% to 10wt%, or 9wt% to 10wt%, or 0.1 wt% to 15wt%, 1wt% to 15wt%, or 2wt% to15wt%, or 3wt% to 15wt%, or 4wt% to 15wt%, or 5wt% to 15wt%, or 6wt% to 15wt%, or 7wt% to 15wt%, or 8wt% to 15wt%, or 9wt% to 15wt%, or 10wt% to 15wt%, or 0.1 wt% to 20wt% of an inorganic salt, based on the total weight of the aqueous composition. In one class of this embodiment, the inorganic salt is sodium chloride, potassium chloride, sodium bromide, potassium bromide, ammonium chloride, ammonium bromide.

In one embodiment or in combination with any other embodiment, the preservative is benzoic acid, lactic acid, salicylic acid, benzyl alcohol, caprylyl glycol, decylene glycol, ethylhexyl glycerin, gluconolactone, methylisothazolinone, phenoxyethanol, or combinations thereof.

Compositions containing the hydroxyalkanoate esters show enhanced viscosity and foaming behavior in low sulfate or sulfate-free systems with amphoteric co-surfactants. In addition, the formulations are stable and show excellent mildness. In one embodiment or in combination with any other embodiment, the active ingredient is one or more of the following: (i) an anti-aging ingredient, (ii) an anti-inflammatory agent, (iii) an antibacterial agent, (iv) an antifungal agent, (v) a plant extract, or (vi) one or more vitamins.

In one class of this embodiment, the one or more vitamins is vitamin E, vitamin C, vitamin B3, vitamin B5, vitamin B9, vitamin K, vitamin D, or combinations thereof.

In one embodiment or in combination with any other embodiment, the one or more compound of formula I is present at from 0.1 wt% to 14 wt%, or from 0.1 wt% to 12 wt%, or from 0.1 wt% to 10 wt%, or from 0.1 wt% to 8 wt%, or from 0.1 wt% to 7 wt%, or from 0.1 wt% to 6 wt%, or from 0.1 wt% to

4 wt%, or from 0.1 wt% to 3 wt%, or 0.1 wt% or 2 wt%, or 0.1 wt% or 1 wt%, or 0.1 wt% to 0.5 wt%, or 0.5 wt% to 1 wt%, or 0.5 wt% to 2 wt%, or 0.5 wt% to 4 wt%, or 0.5 wt% to 5 wt%, or 0.5 wt% to 6 wt%, or 0.5 wt% to 8 wt%, or 0.5 wt% to 10 wt%, or 1 wt% to 2 wt%, or 1 wt% to 4 wt%, or 1 wt% to 6 wt% or 1 wt% to 8 wt%, or 1 wt% to 10 wt%, or 2 wt% to 3 wt%, or 2 wt% to 4 wt%, or 2 wt% to 6 wt%, or 2 wt% to 8 wt%, or 2 wt% to 10 wt%, based on the total weight of the aqueous composition.

In one embodiment or in combination with any other embodiment, the compound of formula I is 2-ethylhexyl 3-hydroxybutyrate, or 1 -octyl 3- hydroxybutyrate. In one class of this embodiment, the compound of formula I is 2-ethylhexyl 3-hydroxybutyrate. In one class of this embodiment, the compound of formula I is 1 -octyl 3-hydroxybutyrate.

In one embodiment or in combination with any other embodiment, the pH of the aqueous composition is from 3 to 8, or from 4 to 7, or from 3 to 7, or from 3 to 6, or from 3 to 5, or from 4 to 8, or from 4 to 6, or from 4 to 5, or from

5 to 8, or from 5 to 7, or from 5 to 6, or from 5 to 7, or from 5 to 6.5, or from 6 to 8, or from 6 to 7. The pH of the composition can be adjusted to the desired level using any cosmetically acceptable organic or inorganic acid or base, such as citric acid, acetic acid, glycolic acid, lactic acid, malic acid, tartaric acid, hydrochloric acid, sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate or similar materials or combinations of the above. pH adjuster can be added in aqueous or nonaqueous form.

EXPERIMENTAL SECTION

Abbreviations

AFC is Amphotaine FC (cocobutyramido hydroxysultaine); AOS is alpha olefin sulfonate; atm is atmosphere; °C is degree(s) Celsius; CAPB is cocamidopropyl betaine; CFEx is comparison formulation example(s); DecylGluc is decyl glucoside; DFA is dynamic foam analyzer; dH₂O is deionized water; DSLSS is disodium laureth sulfosuccinate; eq. is equivalent(s); Ex is example(s); FEx is formulation example(s); g is gram(s); h is hour(s); L is liter(s); min is minute(s); mL is milliliter; mmHg is millimeter(s) mercury; mol is mole(s); qs is quantum satis; rt is room temperature; s is second(s); SCI is sodium cocoyl isethionate; SLSarc is sodium lauroyl sarcosinate; SLES is sodium laureth sulfate; SLS is sodium lauryl sulfate; SMCT is sodium methyl cocoyl taurate; SLMI is sodium lauroyl methyl isethionate; soln is solution; TEA is triethylamine; temp is temperature; v is velocity; F| is viscosity;

Process for Preparation of the Compound of Formula I

Scheme 1 provides a process to make the compounds of formula I (i.e., hydroxyalkanoate esters) comprises: (a) contacting a lower alcohol ketoester of Formula 2 wherein R² is methyl or ethyl with the desired alcohol (R¹- OH) under transesterification conditions to form a ketoester of Formula 3, and (b) contacting the intermediate of Formula 3 with hydrogen and a catalyst to hydrogenate the ketone to form hydroxyalkanoate ester 1. Scheme 2 provides an alternative process for synthesizing the compounds of formula I (i.e., hydroxyalkanoate esters) wherein n is equal to one comprises: (a) contacting a diketene derivative of Formula 4 with the desired alcohol (R¹-OH), optionally in the presence of a catalyst, to form a ketoester of Formula 3 wherein n=1 , and (b) contacting the intermediate of Formula 3 with hydrogen and a catalyst to hydrogenate the ketone to form hydroxyalkanoate ester 1 wherein n=1.

3, n=1 1, n=1

Scheme 2

Example 1 : 2-Ethylhexyl acetoacetate

2-Ethylhexyl acetoacetate (from diketene)

2-Ethylhexan-1 -ol (1740 g; 13.36 mol; 1 .05 eq.) and TEA (64.4 g; 0.636 mol; 0.05 eq.) were added to a 5-L jacketed flask. The reaction mixture was heated to 50°C with a recirculating bath set at 60°C, and diketene (1073 g;

1 .28 mol) was added continuously at a rate of 5.5 mL/min. The temperature of the bath was reduced to 35°C to maintain a reaction temp, of between 55 and 60°C during the addition. After the addition was complete the mixture was distilled at 138°C/16 mm Hg to afford the title compound.

2-Ethylhexyl acetoacetate (by enzymatic transesterification of methyl acetoacetate)

To a reactor equipped with an overhead stirrer, a thermocouple, and a N₂ sparge tube was added 2-ethylhexanol (1000 g, 7.68 mol), methyl acetoacetate (891 .7 g, 7.68 mol, 1 .0 eq), and Novozym 435 (100 g). The mixture was heated (70°C) under an N₂ atm (90 h). The mixture was cooled to ambient temp, and the enzyme was removed by filtration. The filtrate was concentrated in vacuo to afford the title compound.

2-Ethylhexyl acetoacetate (from tert-butyl acetoacetate) A 1 L jacketed reactor was charged with tert-butyl acetoacetate (1 equiv., 2.35 mol, 372 g) and 2-EH alcohol (1 equiv., 2.35 mol, 306 g). The reactor was fitted with a head equipped with overhead stirrer (250 RPM), vacuum pump with controller, thermocouple, distillation arm and condenser, and a rubber septum. The reaction was stirred under vacuum pressure of 500 torr, sparged with N₂ at -100 SCCM, and heated to 130 °C. Reaction progress was monitored by withdrawing samples and analyzing by NMR; after 2 h the reaction was deemed complete and cooled to < 60 °C prior to being discharged from the reactor. The crude material was used in the next step without further purification.

Example 2: 2-Ethylhexyl 3-hydroxybutyrate

A 2L autoclave was charged with 2-ethylhexyl acetoacetate (1350g) and Catalyst (ES Cat 440 50% w/w basis, 38 g). The vessel was purged with N₂ (1000 psig) and vented. The vessel was then purged with hydrogen (2x300 psig), and agitation was started at 300 rpm. The vessel was then pressurized with hydrogen (900 psig), heated (80°C) and held at that temp until hydrogen uptake ceased (-2 h). The reaction mixture was filtered, and the filtrate was concentrated in vacuo to provide the crude product. The crude product was purified by distillation at 145°C and 16 torr to afford the title compound.

Example 3: 1 -Octyl acetoacetate (by enzymatic transesterification of methyl acetoacetate)

To a reactor equipped with an overhead stirrer, a thermocouple, and a N₂ sparge tube was added 1 -octanol (1000 g; 7.68 mol), methyl acetoacetate (891 .7 g; 7.68 mol; 1.0 eq), and Novozym 435 (100 g). The mixture was heated (70°C) and sparged with N₂. Additional methyl acetoacetate (89 g; 0.77 mol; 0.1 eq) was added, and the reaction mixture stirred until completion of the reaction. The mixture was cooled to ambient temp, and the reaction mixture was filtered. The filtrate was concentrated in vacuo to provide the title compound. Example 4: 1 -Octyl 3-hydroxybutyrate

A 2L autoclave was charged with octyl acetoacetate (1300 g) and ruthenium on carbon (39 g). The vessel was flushed with N2 (3x -200 psig). The vessel was then purged with H2 (3x200 psig), and then pressurized with hydrogen (900 psig). The reaction mixture was agitated (1000 rpm) at a temp of 80°C for 6 h. The reaction mixture was filtered and the filtrate was concentrated in vacuo (80-130°C at 13 mm Hg) to provide the title product. Zein test

The purpose of zein test is to investigate the irritation potential (harshness) of a surfactant-based product. In the test, zein, a yellow corn protein that is similar to keratin present in the skin and hair, is denatured (solubilized) by an irritating product (e.g., the surfactant product diluted in a specific amount of water). The more zein dissolved by the surfactant-based product, the higher the predicted irritation potential.

Five grams of test item and dFW (45 g) were added to the test tube and mixed for 10 to 15 min or until the uniform dispersion was formed. Positive and negative controls were prepared in the same manner, using for the positive control: CAPB (10% soln) and for the negative control: dH₂O.

The pH of the test item and control solutions were measured and recorded.

One gram of Zein was added to the test item and controls solns. Solns were mixed for 60 min. Each filter paper, prior filtration, was weighted. Solns were filtered under the vacuum. Filtrates and filter papers were placed on the aluminum dishes and dried overnight at 45’C.

The day after the experimentation, the weight of the zein on the filter paper was measured for each test and control. The final weight of zein was calculated by subtracting the weight of the filter paper.

The percentage solid of zein dissolved was calculated, using following equation: (Total Zein (g) added to the solution — Total Zein after drying ) - Total Zein (g)add —ed - to th -e sol -ution ^x 100

The experiment is conducted in threefold (three independent measurements).

The results from the test indicate that both hydroxyalkanoate esters (Ex 2 and Ex 4) are considered mild because, when compared to the negative control, there are no significant differences.

Table 1.

Formulation Series 1

A basic sulfate-free shampoo formulation prototype was developed in order to highlight the benefits of hydroxyalkanoate esters. This formulation is comprised by a primary surfactant, an anionic compound, AOS, at 10 wt% active; a co-surfactant, normally an amphoteric one (CAPB or AFC), at 2 wt% active, which both constitute the main chassis at a ratio of 5:1 (AOS:CAPB or AFC). The hydroxyalkanoate ester is at 1 wt% active level. To enhance viscosity, 3 wt% of NaCI was added. And finally, as a pH adjuster, 50wt% aq citric acid was added until the pH was between 5.5 - 6.

All contents in Tables 1 below are given in wt. %, expressed as the 100% active compound, relative to the total weight of 10 the respective compositions, unless stated otherwise. Table 2.

The formulations were prepared under cold process, i.e., a simple mixture of the ingredients in the order above, with the help of a disperser (IKA Eurostar 200), finalized by the salt addition and pH adjustment. The final formulation has a yellowish color and no apparent odor.

Besides viscosity measurements and stability investigations, both versions of the sulfate-free shampoo (with CAPB or AFC) were submitted to foam analysis, intracellular lipids (sebum) removal test and Zein mildness test.

Viscosity (F|)

The viscosity of a formulation will depend on several factors: chassis ingredients (anionic/amphoteric/nonionic), concentration of chassis ingredients, ratio of chassis ingredients, salt level, adjuvants / other ingredients addition.

The viscosities were measured using an Anton Paar MCR 302 Rheometer.

The inclusion of the hydroxyalkanoate esters had a positive effect on viscosity in all cases. The results also indicate that the substitution of CAPB with AFC was beneficial for increasing viscosity in the case of formulations with hydroxyalkanoate esters. When CAPB was replaced by AFC, the viscosity of the formulation with Ex 2 was doubled and with Ex 4 was tripled (Table 2). Table 3.

Stability

A stability study is useful to predict the shelf-life of a product. The purpose of stability testing is to ensure that the cosmetic product maintains its intended physical, chemical and microbiological quality, as well as functionality and aesthetics when stored under appropriate conditions. All the sulfate-free formulations were also submitted to accelerated stability study, at rt and at 50°C, for a period of 12 weeks. By the end of the study, all formulations were considered stable, having no changes in viscosity, appearance nor pH.

Foam Analysis

The sulfate-free prototypes were submitted to foam analysis using a DFA by Kruss with camera module. The DFA measures the foamability of liquids and the stability of quickly decaying or long-lasting foam based on reproducible foaming and height detection. It also measures the liquid content and analyses the foam structure.

Foam generated by air sparging (0.3 L/min for 20s) through 50mL of a 0.1 wt% aqueous solution of the formulations. Foam measurements were conducted over a total time of 300s (including sparging time). Measurements were performed at rt.

The following parameters were taken into account:

• Vfoam Max = Maximum volume of foam

• BC Initial = Initial bubble count (“flash foam”) BC Final = Final bubble count (“foam stability”)

Table 4.

The maximum foam volume, initial bubble count (flash foam) and final bubble count (foam stability) of the formulations with hydroxyalkanoate ester were similar or higher in comparison to the same formulation without hydroxyalkanoate ester. Indicating a larger foam volume, a flash foam with high bubble count (small bubbles) and stable foam can be generated via addition of hydroxyalkanoate ester to the formulation.

Intracellular Lipids (Sebum) Removal Test

The purpose of this study is to determine how the application of the sample affects intracellular lipids at the cellular level on sebocytic cells in vitro. Lipid droplets are found in all eukaryotic organisms, the accumulation of lipid droplets is a normal function of cells. The lipid surface of the skin is derived from keratinocytes and sebocytes. Thus, the sebaceous glands secrete lipids to the surface of the stratum corneum. The intracellular lipid assay consists of culturing cells in the absence (negative control) and in the presence of the product. After the incubation time, an oil red staining, a diazo lysochrome dye which allows lipid staining, help us to determine the difference in levels of intracellular lipids of the product versus the negative control. Briefly, the cells are cultured in absence and presence of the product. Sample diluted in cell culture media to the pre-determined concentrations is added to the cells and incubated for 24 h. Intracellular lipids are determined using the Oil red dye. Table 5. Absorbance (OD) as measure for sebum lipid removal.

The sample induces a significant decrease in levels of intracellular lipids compared to Negative control.

From the results with hydroxyalkanoates, it was found that with the CAPB chassis the sample induces a significant decrease in levels of intracellular lipids compared to negative control and the comparative example without hydroxyalkanoates. A lower value of sebum removal indicates better cleansing properties.

Formulation Series 2

A basic sulfate-based shampoo formulation prototype was developed in order to highlight the benefits of hydroxyalkanoate esters. This formulation is comprised of anionic surfactants SLES (5.6wt%) and SLS (4.8wt%); a cosurfactant, normally an amphoteric one (e.g., CAPB 1.20 wt%) active. The hydroxyalkanoate ester is at different active levels (0-3 wt%). And finally, as a pH adjuster, 40-50wt% aq citric acid was added until the pH was between 5.5 - 6.5. NaCI was added stepwise to the formulations in order to see the impact on the viscosity.

All contents in Tables 6 below are given in wt%, expressed as the 100% active compound.

Table 6.

Table 7 provides the results of the foam analysis using the previously described procedure. The initial bubble count (flash foam) and final bubble count (foam stability) of the formulations with hydroxyalkanoate ester are higher in comparison to the same formulation without hydroxyalkanoate ester.

Indicating a flash foam with high bubble count (small bubbles) and stable foam can be generated via addition of hydroxyalkanoate ester to the formulation.

Table 7.

Influence of salt on formulation Stability and Viscosity

Increasing the viscosity of sulfate surfactant-based formulation is easily done by addition of NaCI, due to salt thickening effect. NaCI was gradually added to the formulations, and at each step the viscosity was measured using a Brookfield Viscometer (DV-I Prime, SPDL 3 or 7; 1 to 100 rpm).

Table 8.

Formulation Series 3

A basic sulfate-free shampoo formulation prototype was developed in order to highlight the benefits of hydroxyalkanoate esters. This formulation is comprised anionic surfactants AOS (15 wt%) active; two co-surfactants, an amphoteric one CAPB (5 wt%) active and a nonionic one (DecyGluc 2wt%). The hydroxyalkanoate ester is at different active levels (0-3 wt%). And finally, as a pH adjuster, 40-50wt% aq citric acid was added until the pH was between 5.5 - 6.5.

All contents in Tables 9 below are given in wt%, expressed as the 100% active compound.

Table 9.

Table 10 provides the results of the foam analysis using the previously described procedure. The maximum foam volume, initial bubble count (flash foam) and final bubble count (foam stability) of the formulations with hydroxyalkanoate ester were higher in comparison to the same formulation without hydroxyalkanoate ester. Indicating a larger foam volume, a flash foam with high bubble count (small bubbles) and stable foam can be generated via addition of hydroxyalkanoate ester to the formulation. Table 10.

Table 11 provides the results of the NaCI stability and viscosity study, using the previously described procedure.

Table 11.

Formulation Series 4

A basic sulfate-free shampoo formulation prototype was developed in order to highlight the benefits of hydroxyalkanoate esters. This formulation is comprised by four surfactants, SLSarc (1 .8wt%), DSLSS (5.41 wt%), SCI (3.18wt%) and CAPB (4.55wt%). The hydroxyalkanoate ester is at different active levels (0-3 wt%). And finally, as a pH adjuster, 40-50wt% aq citric acid was added until the pH was between 5.5 - 6.5.

All contents in Tables 12 below are given in wt%, expressed as the 100% active compound.

Table 12.

Table 13 provides the results of the foam analysis using the previously described procedure. The maximum foam volume, initial bubble count (flash foam) and final bubble count (foam stability) of the formulations with hydroxyalkanoate ester were higher in comparison to the same formulation without hydroxyalkanoate ester. Indicating a larger foam volume, a flash foam with high bubble count (small bubbles) and stable foam can be generated via addition of hydroxyalkanoate ester to the formulation.

Table 13. Table 14 provides the results of the NaCI stability and viscosity study, using the previously described procedure. Table 14.

Formulation Series 5

Table 15 provides another series of formulations that were prepared and studied.

Table 15.

‘Viscosity too high to measure

Formulation Series 6

Tables 16 and 17 provides another series of formulations that were prepared and studied.

Table 16.

Table 17.

Formulation Series 12

A basic hair conditioner formulation prototype was developed in order to highlight the benefits of hydroxyalkanoate esters. This formation is comprised of a cationic surfactant (2wt%), fatty alcohols (5wt%) and the hydroxyalkanoate ester (1wt%).

Procedure for Preparation of the Conditioner

The required amount of Incroquat Behenyl TMC-85 (2 wt%) and Cetearyl Alcohol (5 wt%) were weighed and added to dH₂O (125g). The contents were mixed with an IKA T25 Easy clean digital Disperser/Homogenizer at 5000 RPM at 75°C until everything was dissolved. The pH was checked and adjusted using a 10 wt% aq. citric acid and a 40wt% aq NaOH if the pH exceeded the acceptable pH range (4 - 4.5)). The mixture was weighed and halved into two beakers. To one beaker (CFEx 8) water was added until the formulation was 90g. To the other beaker (FEx 18) Ex 2 (1g) was added and dH₂O until the formulation was 90g. Both the contents of CFEx 8 and FEx 18 were independently mixed using the IKA T25 at 10000 RPM. After sufficient mixing, pH was checked again and adjusted if necessary, water was added until the mixture reached 100g and mixed one last time. The mixer was moved around in the beaker to ensure homogenization due to the high viscosity of both mixtures; CFEx 18 was clearly more viscous relative to FEx 8 without Ex 2.

Table 18 provides the ingredients and wt% for each component.

Table 18.

Claims

CLAIMS What is claimed is:

1 . An aqueous composition, comprising:

(1 ) one or more of a compound of formula I:

5 wherein: each R¹ is independently an unbranched or branched (Ce-

12) alky I; each R² is independently a hydrogen, or an unbranched or branched (Ci-e)alkyl; and each n is independently 1 , 2, or 3;

(2) a surface-active agent, which is a surfactant, an emulsifier, or a combination thereof, wherein the one or more of the compound of formula I is present at from 0.1 weight percent (“wt%”) to 15 wt%, wherein the surface-active agent is present at from 5 wt% to 30 wt%, wherein the weight percentage is based on the total weight of the aqueous composition, wherein the one or more of the compound of formula I and the surface active agent are different, and wherein the surfactant and the emulsifier are different.

2. The aqueous composition of claim 1 , wherein the aqueous composition comprises less than 15 wt% of a sulfated anionic surfactant.

3. The aqueous composition of claim 2, wherein the sulfated anionic surfactant is (C6-3o)alkyl-S04’M⁺ or (C6-3o)alkenyl-S04’M⁺, wherein M+ is H⁺, Na⁺, K⁺, NH₄ ⁺, (Ci-₄)alkylH₃N⁺, ((Ci-₄)alkyl)₂H₂N⁺, ((Ci-₄)alkyl)₃HN⁺, or ((C1- ₄)alkyl)₃N⁺.

4. The aqueous composition of claim 3, wherein the sulfated anionic surfactant is sodium lauryl sulfate, sodium laureth sulfate, sodium myreth sulfate, sodium pareth sulfate, ammonium laureth sulfate, or a combination thereof.

5. The aqueous composition of claim 1 , wherein the aqueous composition is free of a sulfated anionic surfactant.

6. The aqueous composition of any one of claims 1 -5, wherein the aqueous composition further comprises, one or more of the following: a conditioning agent; an emollient; a moisturizer; a humectant; a thickener; a lubricant; a chelating agent; a filler; a binding agent; an antioxidant; a preservative; a ultraviolet light absorber; a fragrance; a dye; a buffering agent; an exfoliant; a pH adjuster; a solvent; a viscosity controlling agent; or an active ingredient.

7. The aqueous composition of claim 6, wherein the active ingredient is one or more of the following: (i) an anti-aging ingredient, (ii) an anti-inflammatory agent, (iii) an antibacterial agent, (iv) an antifungal agent, (v) a plant extract, or (vi) one or more vitamins.

8. The aqueous composition of any one of claims 1 -7, wherein the aqueous composition further comprises 0.1 wt% to 10 wt% an inorganic salt, based on the total weight of the aqueous composition.

9. The aqueous composition of claim 8, wherein the inorganic salt is sodium chloride, potassium chloride, sodium bromide, potassium bromide, ammonium chloride, ammonium bromide.

10. The aqueous composition of any one of claims 1 -9, wherein the pH of the aqueous composition is from 3 to 8, or from 4 to 7, or from 3 to 7, or from 3 to 6, or from 3 to 5, or from 4 to 8, or from 4 to 6, or from 4 to 5, or from 5 to 8, or from 5 to 7, or from 5 to 6, or from 5 to 7, or from 6 to 8, or from 6 to 7.

1 1 . The aqueous composition of any one of claims 1 -10, wherein the aqueous composition is a shampoo, a hair conditioner, a shower gel, a soap, or any cleansing composition.

12. The aqueous composition of claim 11 , wherein the aqueous composition is a shampoo.

13. The aqueous composition of any one of claims 9 or 10, wherein the aqueous composition is free of a sulfated anionic surfactant.

14. The aqueous composition of any one of claims 1 -13, wherein the compound of formula I is 2-ethylhexyl 3-hydroxybutyrate, or 1 -octyl 3- hydroxybutyrate.