SURFACTANTS DERIVED FROM AMINO ACIDS

Abstract

The present invention provides amino acid derivatives with surfactant properties. The amino acid may be natural or synthetic, or it may be obtained by a ring-opening reaction of a lactam, such as caprolactam. The amino acid may be functionalized to form a surfactant compound with advantageous surfactant characteristics. The compounds of the present invention have low critical micelle concentrations (CMCs) and a superior ability to reduce the surface tension of a liquid.

Description

[0001] This application claims priority over U.S. Provisional Application No. 62 / 967,175, filed on January 29, 2020, the description of which is incorporated herein by reference in its entirety. FIELD OF INVENTION

[0002] The present invention relates to amino acid derivatives and methods for their synthesis, wherein the amino acid derivatives have surfactant properties. BACKGROUND OF THE INVENTION

[0003] Surfactants (molecules with surface-active properties) are an important class of molecules with highly sought-after characteristics. Surfactants can be uncharged, zwitterionic, cationic, or anionic. Often, these compounds are amphiphilic molecules with a water-insoluble hydrophobic tail group and a water-soluble hydrophilic head group. These compounds can adsorb at an interface, such as an interface between two liquids, a liquid and a gas, or a liquid and a solid. In the case of a water-oil interface, the hydrophilic head group extends toward the water, while the hydrophobic tail... MA / IZ / ¿U¿¿ / U0O4U0 extends towards the oil. When added to water, the hydrophilic head group extends towards the water, while the hydrophobic tail extends towards the air. The presence of the surfactant disrupts the intermolecular interaction between water molecules, replacing it with weaker interactions between the water molecules and the surfactant. This results in reduced surface tension and can also serve to stabilize the interface.

[0004] At sufficiently high concentrations, surfactants can form aggregates to limit the exposure of the hydrophobic tail to the polar solvent. One such aggregate is a micelle, in which the molecules are arranged in a sphere with the hydrophobic tails inside the sphere and the hydrophilic heads on the outside to interact with a polar solvent. The effect a given compound has on surface tension and the concentration at which it forms micelles can serve as defining characteristics of a surfactant.

[0005] Surfactants are widely used in commercial applications in formulations ranging from detergents to hair care products and cosmetics. Compounds with surfactant properties are used as soaps, detergents, lubricants, wetting agents, foaming agents, and spreading agents, among others. Therefore, there is an ongoing need to identify and synthesize such compounds.

[0006] However, based solely on its structure, it can be difficult to predict whether a given compound would have surfactant properties, let alone other important characteristics such as interfacial adsorption dynamics, minimum achievable surface tension, and / or the ability to wet hydrophobic and / or oleophobic surfaces, which are also integral to whether the compound would become a useful surfactant. Certain amino acids and their derivatives, for example, are desirable as building blocks for surfactants, but selecting which amino acids to use is far from intuitive. The synthesis of such compounds adds another layer of difficulty due to differences in solubility attributable to different elements and fractions present in the same molecules. The need remains for highly effective surfactants that can be readily synthesized on a commercial scale via straightforward routes. SUMMARY OF THE INVENTION

[0007] The present invention provides amino acid derivatives that have surfactant properties. The amino acids may be natural or synthetic amino acids, or they may be obtained by ring-opening reactions of molecules such as lactams, for example, caprolactam. The amino acids may be functionalized to form compounds with surfactant properties. Characteristically, these compounds may have low critical micelle concentrations (CMCs) and / or the ability to reduce the surface tension of a liquid.

[0008] The present invention provides compounds of Formula I, hereinafter also referred to as the surfactant: r21 AmY O or Formula I where R1 and R2 can be the same or different, and are chosen from the group consisting of Ci-Ce alkyl, specifically Ci, C2, C3, C4, C5 or Ce; n is an integer from 2 to 5, specifically 2, 3, 4 or 5; and m is an integer from 9 to 20, specifically 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0009] Alternatively, the present invention provides compounds of Formula II, hereinafter also referred to as the surfactant: EITHER Formula II MA / IZ / ¿U¿¿ / U0O4U0 where R1 and R2 can be the same or different, and comprise at least one group selected from the group consisting of Ci-Cg alkyl, namely, Ci, C2, C3, C4, C5 or Ce.

[0010] A specific compound provided by the present invention is dodecyl 6-(dimethylamino)hexanoate N-oxide, having the following formula: MA / IZ / ¿U¿¿ / U0O4U0

[0011] In the above structures, the notation N—>0 is intended to convey a non-ionic bonding interaction between nitrogen and oxygen.

[0012] The above-mentioned features and other features of the invention, and the manner of achieving them, will become more evident and better understood with reference to the following description of the embodiments taken together with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Fig. 1 shows a graph of surface tension versus concentration measured at pH = 7 as described in Example 2, in which the Y-axis represents surface tension (γ) in millinewtons per meter (mN / m) and the X-axis represents concentration (c) in millimoles (mM).

[0014] Fig. 2 shows a graph of dynamic surface tension as change in surface tension versus time as described in Example 3, in which the Y-axis represents surface tension in millinewtons per meter (mN / m) and the X-axis represents surface age in milliseconds (ms). DETAILED DESCRIPTION OF THE INVENTION

[0015] As used herein, the phrase "within any range defined between any two values ​​above" literally means that any range may be selected from either of the two values ​​listed before that phrase, regardless of whether the values ​​are in the lower or upper range of the list. For example, a pair of values ​​may be selected from any two lower values, any two upper values, or any one lower and one upper value.

[0016] As used herein, the word alkyl means any saturated carbon chain, which can be a linear or branched chain.

[0017] As used herein, the term surfactant means that the associated compound is capable of reducing the surface tension of the medium in which it dissolves and / or the interfacial tension with other phases and, consequently, MA / IZ / ¿U¿¿ / U0O4U0 can be adsorbed at liquid / vapor interfaces and / or other surfaces. The term surfactant can be applied to this compound.

[0018] With respect to the terminology of inaccuracy, the terms "around" and "approximately" may be used interchangeably to refer to a measurement that includes the established measurement and also includes any measurement that is reasonably close to the established measurement. Measurements that are reasonably close to the established measurement deviate from the established measurement by a reasonably small amount, as readily understood and determineable by persons of ordinary skill in the relevant art. Such deviations may be attributed to measurement errors or minor adjustments made to optimize performance, for example. In the event that it is determined that persons of ordinary skill in the relevant art would not readily determine the values ​​for such reasonably small differences, the terms "around" and "approximately" may be understood to mean plus or minus 10% of the established value.

[0019] The present invention provides amino acid derivatives. The amino acids may be natural or synthetic, or may be obtained from ring-opening reactions of lactams, such as caprolactam. The compounds of the present invention have been shown to have surfactant properties and can be used as surfactants and wetting agents, for example. The present invention provides compounds of Formula I, as follows: R2I II τ OO Formula I where R1 and R2 can be the same or different, and are chosen from the group consisting of Ci-Ce alkyl, specifically Ci, C2, C3, C4, C5 or Ce; n is an integer from 2 to 5, specifically 2, 3, 4 or 5; and m is an integer from 9 to 20, specifically 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0020] In particular, the present invention provides compounds of Formula II, as follows: Formula II where R1 and R2 may be the same or different, and comprise at least one group selected from the group consisting of Ci-Ce alkyl, namely, Ci, C2, C3, C4, C5 or Ce.

[0021] A specific compound provided by the present invention is dodecyl 6-(dimethylamino)hexanoate N-oxide, which has the following formula: MA / IZ / ¿U¿¿ / U0O4U0

[0022] In the above structures, the notation N—>0 is intended to convey a non-ionic bonding interaction between nitrogen and oxygen.

[0023] These compounds can be synthesized by several methods. One such method involves opening a lactam to produce an amino acid having an N-terminus and reacting the N-terminus of the amino acid with an alkylating agent to obtain a tertiary amine. The resulting tertiary amine can then react with an alcohol under acidic conditions to provide an amino acid ester having an N-terminus. The N-terminus of the amino acid ester can then react with an oxidizing agent to produce an amine oxide.

[0024] The amino acid may be natural or synthetic, or it may be derived from a ring-opening reaction of a lactam, such as propiolactam, butyrolactam, valerolactam, and caprolactam, for example. The ring-opening reaction may be an acid- or alkali-catalyzed reaction, and an example of an acid-catalyzed reaction is shown below in Scheme 1. MA / IZ / ¿U¿¿ / U0O4U0 SCHEME 1 EITHER

[0025] An amino acid may have as few as 2 or as many as 5 carbons between the N and C ends. The alkyl chain may be branched or linear. The alkyl chain may be interrupted by nitrogen, oxygen, or sulfur. The alkyl chain may be further substituted with one or more substituents selected from the group consisting of hydroxyl, amino, amido, sulfonyl, sulfonate, carboxyl, and carboxylate. The N-terminal nitrogen may be acylated or alkylated with one or more alkyl groups. For example, the amino acid may be 6-(dimethylamino)hexanoic acid.

[0026] The amino acid derivative can be synthesized as shown below in Scheme 2. As shown, 6-aminohexanoic acid is treated with formaldehyde in refluxing formic acid to give 6-(dimethylamino)hexanoic acid. The free carboxylic acid is then treated with an alcohol, such as dodecanol, in the presence of p-toluenesulfonic acid (PTSA) in toluene to give the corresponding ester, dodecyl 6-(dimethylamino)hexanoate. The N-terminus is then oxidized with hydrogen peroxide to give the amine oxide. SCHEME 2 MA / IZ / ¿U¿¿ / U0O4U0 EITHER

[0027] The compounds of the present invention exhibit surfactant properties. These properties can be measured and described by various methods. One method by which surfactants can be described is by the critical micelle concentration (CMC) of the molecule. The CMC can be defined as the concentration of a surfactant at which micelles form and above which all additional surfactant is incorporated into the micelles.

[0028] As the surfactant concentration increases, the surface tension decreases. Once the surface is completely coated with surfactant molecules, micelles begin to form. This point represents the CMC, as well as the minimum surface tension. Further addition of surfactant will not affect the surface tension. Therefore, the CMC can be measured by observing the change in surface tension as a function of surfactant concentration. One such method for measuring this value is the Wilhelmy plate method. A Wilhelmy plate is typically a thin iridium-platinum plate attached to a balance by a wire and positioned perpendicular to the air-liquid interface. The balance is used to measure the force exerted on the plate by wetting. This value is then used to calculate the surface tension (γ) according to Equation 1: Equation 1: γ = F / l cosΘ where 1 is equal to the wetted perimeter (2w + 2d, where wyd are the thickness and width of the plate, respectively) and cos Θ, the contact angle between the liquid and the plate, is assumed to be 0 in the absence of an existing literature value.

[0029] Another parameter used to evaluate the performance of surfactants is dynamic surface tension. Dynamic surface tension is the surface tension value for a particular surface or interface. In the case of liquids with added surfactants, this may differ from the equilibrium value. Immediately after a surface forms, the surface tension is equal to that of the pure liquid. As described earlier, surfactants reduce surface tension; therefore, the surface tension drops until an equilibrium value is reached. The time required to reach equilibrium depends on the diffusion rate and the adsorption rate of the surfactant.

[0030] One method for measuring dynamic surface tension is based on a bubble pressure tensiometer. This device measures the maximum internal pressure of a gas bubble that forms in a liquid by means of a capillary. The measured value corresponds to the surface tension at a certain surface age, the time from the start of bubble formation until the appearance of the maximum pressure. The dependence of surface tension on surface age can be measured by varying the rate at which the bubbles form.

[0031] Surfactants can also be evaluated by their wetting ability on solid substrates, measured by the contact angle. When a liquid droplet comes into contact with a solid surface in a third medium, such as air, a three-phase line is formed between the liquid, the gas, and the solid. The angle between the unit vector of surface tension, acting along the three-phase line and tangent to the liquid droplet, and the surface is described as the contact angle. The contact angle (also known as the wetting angle) is a measure of the wettability of a solid by a liquid. In the case of complete wetting, the liquid spreads completely over the solid. MA / IZ / ¿U¿¿ / U0O4U0 the solid and the contact angle is 0o. Wetting properties are typically measured for a given compound at a concentration of l-100x CMC; however, it is not a concentration-dependent property, therefore, wetting property measurements can be taken at concentrations that are higher or lower.

[0032] In one method, an optical contact angle goniometer can be used to measure the contact angle. This device uses a digital camera and software to extract the contact angle by analyzing the contour shape of a sessile liquid droplet on a surface.

[0033] Potential applications for the surfactant compounds of the present invention include formulations for use as shampoos, hair conditioners, detergents, non-staining rinse solutions, floor and carpet cleaners, cleaning agents for graffiti removal, wetting agents for crop protection, adjuvants for crop protection, and wetting agents for spray coatings.

[0034] A person skilled in the art will understand that small differences between compounds can lead to substantially different surfactant properties, so that different compounds can be used with different substrates, in different applications. MA / IZ / ¿U¿¿ / U0O4U0

[0035] The following non-limiting modalities are provided to demonstrate the different properties of the different surfactants.

[0036] The compounds are effective as surfactants, useful for wetting or foaming agents, dispersants, emulsifiers and detergents, among other applications.

[0037] The compounds of the present invention may be useful in the applications described above, as well as some other special applications, such as in shampoos, detergents, hard surface cleaners, and a variety of other surface cleaning formulations.

[0038] The amount of the compounds described herein used in a formulation may be as low as 0.001% by weight, 0.05% by weight, 0.1% by weight, 0.5% by weight, 1% by weight, 2% by weight, or about 5% by weight, or as high as about 8% by weight, about 10% by weight, about 15% by weight, about 20% by weight, or about 25% by weight, or within any defined range between any two of the above values. EXAMPLES

[0039] Nuclear magnetic resonance (NMR) spectroscopy was performed on a 500 MHz Bruker spectrometer. The critical micelle concentration (CMC) was determined by the Wilhelmy plate method at 23 °C using a tensiometer (DCAT 11, DataPhysics Instruments GmbH) equipped with a Pt-Ir plate. Dynamic surface tension was determined using a bubble pressure tensiometer (Krüss BP100, Krüss GmbH) at 23 °C. The contact angle was determined using an optical contact angle goniometer (OCA 15 Pro, DataPhysics GmbH) equipped with a digital camera. Example 1: Synthesis of dodecyl 6-(dimethylamino)hexanoate N-oxide

[0040] 6-(Dimethylamino)hexanoic acid (11.99 g, 75.36 mmol) was dissolved in toluene (50 mL) in a round-bottom flask fitted with a Dean-Stark trap. Dodecanol (12.68 g, 75.36 mmol) and ptoluenesulfonic acid monohydrate (PTSA) (14.33 g, 75.36 mmol) were then added. The reaction was heated under reflux for 24 hours, until no more water was observed in the Dean-Stark trap. The solvent was removed under vacuum, and the resulting solid was washed with hexanes. The solid was dissolved in dichloromethane (200 mL) and washed with saturated sodium carbonate to give dodecyl 6-(dimethylamino)hexanoate in 51% yield. 1H NMR (DMSO) δ 4.00 (t, J = 6.5 Hz, 2H), 2.27 (t, J = 7.3 Hz, 2H), 2.13-2.16 (m, 2H), 2.01 (s, 6H), 1.54 - 1.53 (m, 6H), 1.27-1.18 (m, 20H), 0.86 (t, 3H) .

[0041] Dodecyl 6-(dimethylamino)hexanoate (1.0 g, 3.05 mmol) was dissolved in distilled water (80 ml). Then Hydrogen peroxide (50% solution, 1.04 g, 30.5 mmol) was added to MA / IZ / ¿U¿¿ / U0O4U0. The reaction was heated under reflux for 12 hours, and then the solvent was removed under vacuum. The resulting solid was washed with acetone to give the desired N-oxide in 90% yield. RMNXH (500 MHz, DMSO) δ 4.00 (t, J = 6.6 Hz, 2H), 3.30 - 3.26 (m, 2H), 3.18 (s, 6H), 2.31 (t, J = 7.4 Hz, 2H), 1.76 - 1.73 (m, 2H), 1.54 - 1.57 (m, 4H), 1.30 - 1.24 (m, 22H), 0.86 (t, J = 6.9 Hz, 3H). MA / IZ / ¿U¿¿ / U0O4U0 Example 2: Determination of the critical micelle concentration (CMC)

[0042] The critical micelle concentration (CMC) was tested. Based on the change in surface tension with concentration in water, the CMC was determined to be approximately 0.08 mmol. The minimum surface tension plateau value that this surfactant can reach is approximately 28 mN / m, specifically, 28 mN / m + 2.8 mN / m. Figure 1 is a graph of these results, showing surface tension versus concentration. From the graph, the surface tension at the CMC is equal to or less than 30 mN / m at a concentration of 0.08 mmol or higher. Example 3: Determination of dynamic surface tension

[0043] Dynamic surface tension was determined using a bubble pressure tensiometer, which measures the change in surface tension of a newly created air-water interface over time. Figure 2 presents a graph of surface tension versus time, showing that the compound fully saturated the surface in approximately 7.6 seconds. As can be seen from the graph, the dynamic surface tension is equal to or less than 40 mN / m at a surface age of 4900 ms or more. Example 4: Determination of wetting properties

[0044] In addition to surface tension and surface dynamics, the wetting properties of the compound were tested on various surfaces. For example, hydrophobic substrates such as HDPE exhibit surface wetting with a contact angle of 39.3°, much smaller than that of water. On oleophobic and hydrophobic substrates such as Teflon, the measured contact angle was much smaller than that of water, at 57.4° (Table 1). TABLE 1 Substrate CA of surfactant (°) Concentration CA of water (°) Teflon 57.4 10x CMC 119 Polyethylene-HD 39.3 10x CMC 93.6 Substrate CA of surfactant (°) Concentration CA of water (°) Nylon 21.7 10x CMC 50 Polyethylene terephthalate 24.5 10x CMC 65.3 Example 5: Shampoo formulation

[0045] In this Example, a formulation for use as a shampoo is provided. This formulation is useful for giving hair a soft and silky feel. The components of the formulation are shown below in Table 2. In addition, the formulation may include other oils and natural ingredients, as well as vitamins to appeal to the consumer, in an amount less than 1% by weight. TABLE 2 Component Function % by weight Surfactant Surfactant 0.1-10 Ammonium lauryl sulfate Foaming agent 10-25 Cocamidopropyl betaine Co-surfactant 0.1-5 Cocamide diethanolamine Foam booster 1-4 Xanthan gum or acrylate copolymer Thickener / rheology modifier 0-5 Citric acid pH stabilizer 0.1-0.3 Fragrance 0.02-0.1 Water 49.5-89 Example 6: Formulation for hair conditioner

[0046] In this Example, a formulation for use as a hair conditioner is provided. This formulation can be used to replace or reduce polyquaternium-10, polyquaternium-7, and dimethicone oils, while retaining the combability and silky-smooth feel provided by hair conditioners. The formulation is shown below in Table 3. MA / IZ / ¿U¿¿ / UOO4U0 TABLE 3 Component Function % by weight Surfactant Surfactant 0.1-10 Sodium cumene sulfonate Hydrotrope 1-3 Ammonium lauryl sulfate Surfactant 0.1-6 Ammonium laureth-3 sulfate Surfactant 0.1-6 Cocoamide diethanolamine Foaming agent 0.5-2 Propylene glycol oleate PEG-55 Emulsifier 0.01-1 Fragrance 0.02-0.1 Water 61.9-97.2 Example 7: Car wash detergent formulation for removing tough surface stains

[0047] In this Example, a formulation for use in car wash detergents for removing tough surface stains is provided. The formulation is shown below in Table 4. MA / IZ / ¿U¿¿ / U0O4U0 TABLE 4 Component Function % by weight Surfactant Surfactant 0.1-10 Dodecylbenzene sultanate or Ammonium lauryl sulfate Foaming / detergent agent 5-14 Monoethanolamine, diethanolamine or triethanolamine pH stabilizer <0.5 Cocoamide diethanolamine Foam stabilizer 0.1-2 Propylene glycol Solubilizing agent 0.05-1.6 Fragrance 0.02-0.1 Coloring agent 0-0.1 Water 71.6-95.0 Example 8: Formulation for a stain-free rinse or dry solution

[0048] In this Example, a formulation for a spot-free rinse or drying solution is provided. The solution can be applied to the windows or body of a car after the main wash is completed. The formulation is shown below in Table 5. TABLE 5 Component Function % by weight Surfactant Surfactant 0.001-2 Water 98-99.999 Example 9: Formulation for a heavy-duty carpet cleaner

[0049] In this Example, a formulation for a heavy-duty carpet cleaner is provided. The cleaner is a high-foaming, deep-cleaning product. The formulation is shown below in Table 6. MA / IZ / ¿U¿¿ / U0O4U0 TABLE 6 Component Function % by weight Surfactant Surfactant 1-15 Dodecylbenzene sultanate or Ammonium lauryl sulfate Foaming / detergent agent 0.001-10 Sodium cumene sulfonate Hydrotrope 0.001-3 Monoethanolamine, diethanolamine or triethanolamine pH stabilizer 0.01-1 Water 74.95-99 Example 10: Formulation for a heavy-duty surface cleaner

[0050] In this Example, a formulation for a heavy-duty surface cleaner is provided. This cleaner can be used for manual or automatic surface cleaning machines. The formulation is shown below in Table 7. MA / IZ / ¿U¿¿ / U0O4U0 TABLE 7 Component Function % by weight Surfactant Surfactant 0.001-25 Dodecylbenzene sulfonic acid or Ammonium lauryl sulfate Foaming / detergent agent 0.001-10 Sodium cumene sulfonate Hydrotrope <0.5 Propylene glycol Solubilizing agent 0.01-5 Water 59.5-99.99 Example 11: Formulation of a concentrated detergent for graffiti removal

[0051] In this Example, a formulation for a concentrated detergent for graffiti removal is provided. The detergent can be used in a high-pressure hose. The formulation is shown below in Table 10 8. TABLE 8 Component Function % by weight Surfactant 4 Surfactant 0.001-15 Sodium cumene sulfonate Hydrotrope 0.001-3 Propylene glycol Solubilizing agent 0.01-5 Water 67-99.99 Example 12: Formulation for a wetting agent in aerosols

[0052] In this Example, a formulation for a wetting agent adjuvant in aerosols is provided. The aerosols can be used to apply pesticides or other crop protection agents. The provided formulation aims to reduce the amount of surfactant chemicals in pesticides and crop protection products (typically between 2 and 5%) by providing improved performance through excellent wetting and a low CMC, thus offering a more environmentally friendly option. The formulation is shown below in Table 9. TABLE 9 Component Function % by weight Surfactant Co-wetting agent 0.001-2 Pesticides and / or other crop protection agent(s) 0.1-10 Water 88-99.899 Example 13: Formulation of additives for spray paint

[0053] In this Example, a formulation for an additive for a water-based spray paint or coating is provided. The formulation is intended to provide good dynamic wetting of the spray droplets on surfaces after application, thereby preventing cratering in the paint and other similar problems. The formulation is shown below in Table 10. MA / IZ / ¿U¿¿ / U0O4U0 TABLE 10 Component Function % by weight Surfactant Wetting agent / flow leveling agent / slip control agent 0.001-5 Propellant gas Propellant 5-30 Oil-in-water emulsion Pigmentation 0.1-25 Tamol 731A Dispersing agent 1-4 Isopropanol (97-99% purity) Solvent / carrier 7-15 Efka SI2022 or SI 2723 Antifoaming agent 0.001-2 Water 19-86.9 ASPECTS

[0054] Aspect 1 is a compound of the following formula: Or where R1 and R2 can be the same or different, and comprise at least one group selected from the group consisting of Ci-C6 alkyl.

[0055] Aspect 2 is the compound of Aspect 1, wherein the compound is ΔZ-dodecyl 6-(dimethylamino)hexanoate oxide, which has the following formula:

[0056] Aspect 3 is the compound of Aspect 1 or Aspect 2, which has a critical micelle concentration (CMC) in water of approximately 0.08 mmol.

[0057] Aspect 4 is the composite of any of Aspects 1-3, which has a plateau value of a minimum surface tension in water of approximately 28 mN / m.

[0058] Aspect 5 is the compound of any of Aspects 1-4, which has a surface tension in water equal to or less than 30 mN / ma at a concentration of 0.08 mmol or greater.

[0059] Aspect 6 is the composite of any of Aspects 1-4, having a surface tension in water equal to or less than 40 mN / ma and a surface age of 4900 ms or greater.

[0060] Aspect 7 is a method for synthesizing an amino acid-derived surfactant, comprising the steps of: (1) opening a lactam to produce an amino acid having an N-terminus; (2) reacting the N-terminus of the amino acid with an alkylating agent to produce a tertiary amine; (3) reacting the tertiary amine with an alcohol under acidic conditions to produce an amino acid ester having an N-terminus; and (4) reacting the N-terminus of the amino acid ester with an oxidizing agent to produce an amino acid-derived surfactant of the following formula: EITHER MA / IZ / ¿U¿¿ / U0O4U0 where R1 and R2 can be the same or different, and comprise at least one group selected from the group consisting of Ci-C6 alkyl.

[0061] Aspect 8 is the method of Aspect 7, wherein in step 1, the lactam is caprolactam.

[0062] Aspect 9 is the method of Aspect 7 or Aspect 8, wherein in step 2, the alkylating agent is formaldehyde or paraformaldehyde.

[0063] Aspect 10 is the method of any of Aspects 7-9, wherein in step 3, the alcohol is dodecanol.

[0064] Aspect 11 is the method of any of Aspects 7-10, wherein in step 3, the acid is ptoluenesulfonic acid.

[0065] Aspect 12 is the method of any of Aspects 7-11, wherein in step 4, the oxidizing agent is hydrogen peroxide.

[0066] Aspect 13 is a liquid composition comprising: a medium; and a surfactant of the following formula: Or where R1 and R2 can be the same or different, except for a selected group from the group that with: Ci-C6.

[0067] Aspect 14 is the composition in which the medium is water.

Claims

1. A compound of the following formula: where R1 and R2 may be the same or different, and comprise at least one group selected from the group consisting of Ci-Ce alkyl.

2. The compound according to claim 1, wherein the compound is dodecyl 6-(dimethylamino)hexanoate N-oxide, having the following formula:

3. The compound according to claim 1, having a critical micelle concentration (CMC) in water of approximately 0.08 mmol.

4. The compound according to claim 1, having a plateau value of a minimum surface tension of approximately 28 mN / m.

5. The compound according to claim 1, having a surface tension in water equal to or less than 30 mN / mM and a concentration of 0.08 mM or greater.

6. The compound according to claim 1, having a surface tension in water equal to or less than 40 mN / ma and a surface age of 4900 ms or more.

7. A method for synthesizing an amino acid-derived surfactant, comprising the steps of: (1) opening a lactam to produce an amino acid having an N-terminus; (2) reacting the N-terminus of the amino acid with an alkylating agent to produce a tertiary amine; (3) reacting the tertiary amine with an alcohol under acidic conditions to produce an amino acid ester having an N-terminus; and (4) reacting the N-terminus of the amino acid ester with an oxidizing agent to produce an amino acid-derived surfactant of the following formula: MA / IZ / ¿U¿¿ / U0O4U0 where R1 and R2 may be the same or different, and comprise at least one group selected from the group consisting of Ci-Cs alkyl.

8. The method according to claim 7, wherein in step 1, the lactam is caprolactam.

9. The method according to claim 7, wherein in step 2, the alkylating agent is formaldehyde or paraformaldehyde.

10. The method according to claim 7, wherein in step 3, the alcohol is dodecanol.

11. The method according to claim 7, wherein in step 3, the acid is p-toluenesulfonic acid.

12. The method according to claim 7, wherein in step 4, the oxidizing agent is hydrogen peroxide.

13. A liquid composition comprising: a medium; and a surfactant of the following formula: O where R1 and R2 may be the same or different, and comprise at least one group selected from the group consisting of Ci-Cg alkyl.

14. The composition according to claim 13, wherein the medium is water.