Amino acid surfactants

Abstract

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

Description

Amino acid surfactants Field This disclosure relates to uses of amino acid derivatives, where such derivatives possess surfactant properties. This disclosure also relates to the uses of a formulation comprising a surfactant. Background Surfactants (molecules with surface-active properties) are an important class of molecules with highly sought-after characteristics. Surfactants can be uncharged, bipolar, 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 extends toward the oil. When added to water, the hydrophilic head group extends toward the water, while the hydrophobic tail extends toward the air. The presence of the surfactant alters the intermolecular interaction between water molecules, replacing it with weaker interactions between water molecules and the surfactant.This reduces surface tension and can also help stabilize the interface. At sufficiently high concentrations, surfactants can form aggregates to limit the exposure of their hydrophobic tails to the polar solvent. One such aggregate is a micelle, in which the molecules arrange themselves into a sphere with their hydrophobic tails inside and their 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. 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 a constant need to identify and synthesize such compounds. However, based solely on its structure, it can be difficult to predict whether a given compound will 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 essential for determining whether the compound will become a useful surfactant. Certain amino acids and their derivatives, for example, are desirable as building blocks of surfactants, but selecting which amino acids to use is far from intuitive. The synthesis of these compounds adds another layer of difficulty due to differences in solubility attributable to the various elements and residues present in the same molecules. Highly effective surfactants that can be readily synthesized on a commercial scale via simple pathways remain essential.Document EP0826661A2 discloses hydrolytically cleavable active ingredient derivatives, hair treatment compositions containing them, and procedures for treating hair with the compositions. Summary This disclosure describes the uses of amino acid derivatives with surfactant properties as surfactants. The amino acids may be naturally occurring or synthetic, or they may be obtained through ring-opening reactions of molecules such as lactams, for example, caprolactam. Amino acids can 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. This disclosure provides surfactant uses of Formula II compounds, hereinafter also referred to as the surfactant: Formula II wherein X is an anion that can be selected from the group consisting of chloride, bromide, iodide, and hydroxide. One specific use intended in this disclosure is the use as a surfactant of 6-(dodecyloxy)-N,N,N-trimethyl-6-oxohexan-1-aminium iodide, which has the following formula: The aforementioned characteristics and other features of disclosure, and the manner of achieving them, will become more evident and better understood by reference to the following description of the achievements taken together with the accompanying drawings. Brief description of the drawings Figure 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 () in millinewtons per meter (mN / m) and the X-axis represents concentration (c) in millimoles (mM). Figure 2 shows a graph of dynamic surface tension as change of 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 the age of the surface in milliseconds (ms). Detailed description As used in this specification, the expression "within any defined interval between any two of the above values" literally means that any interval between any two of the values ​​listed before that expression may be selected, regardless of whether the values ​​are at the bottom or top 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. As used in this specification, the term "alkyl" means any saturated carbon chain, which may be linear or branched. As used in this specification, 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, can be adsorbed at liquid / vapor interfaces and / or other interfaces. The term "surfactant" may be applied to a compound of this type. With regard to the terminology of inaccuracy, the term "approximately" may be used to refer to a measurement that includes the stated measurement and also includes any measurement that is reasonably close to the stated measurement. Measurements that are reasonably close to the stated measurement deviate from the stated measurement by a reasonably small amount, as readily understood and determined by persons with ordinary knowledge of the relevant techniques. These deviations may be due to measurement errors or minor adjustments made to optimize performance, for example. In the event that persons with ordinary knowledge of the relevant techniques cannot readily determine the values ​​of such reasonably small differences, the term "approximately" may be understood to mean plus or minus 10% of the stated value. This disclosure provides surfactant uses for amino acid derivatives. The amino acids may be naturally occurring or synthetic, or they may be obtained from ring-opening reactions of lactams, such as caprolactam. These compounds have been shown to possess surfactant properties and can be used as surfactants and wetting agents, for example. This disclosure provides surfactant uses for Formula II compounds, as follows: Formula II wherein X is an anion that may be selected from the group consisting of chloride, bromide, iodide, and hydroxide. A specific compound provided for in this disclosure is 6-(dodecyloxy)-N,N,N-trimethyl-6-oxohexan-1-aminium iodide (surfactant 1), which has the following formula: These compounds can be synthesized by various procedures. One such procedure involves the opening of a lactam to produce an amino acid with an N-terminal group and the reaction of the N-terminal group of the amino acid with an alkylating agent to produce a tertiary amine. The resulting tertiary amine can then be reacted with an alcohol under acidic conditions to provide an amino acid ester with an N-terminal group. The N-terminal group of the amino acid ester can then be reacted with an alkylating agent under basic conditions to produce a quaternary amine. 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 acid-catalyzed or alkali-catalyzed, and an example of an acid-catalyzed reaction is shown below in Scheme 1. The amino acid can have as few as 2 carbons or as many as 5 carbons—specifically, 2, 3, 4, or 5 carbons between the N- and C-terminus. The alkyl chain can be branched or linear. The alkyl chain can be interrupted by nitrogen, oxygen, or sulfur. The alkyl chain can also be substituted with one or more substituents selected from the groups consisting of hydroxyl, amino, amido, sulfonyl, sulfonate, carboxyl, and carboxylate. The N-terminus nitrogen can be acylated or alkylated with one or more alkyl groups. For example, the amino acid can be 6-(dimethylamino)hexanoic acid. The amino acid derivative can be synthesized as shown in Scheme 2 below. As shown, 6-aminohexanoic acid is treated with formaldehyde in refluxing formic acid to yield 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 alkylated with methyl iodide in the presence of sodium carbonate. SCHEME 2 The compounds in this disclosure exhibit surfactant properties. These properties can be measured and described using various methods. One method for describing surfactants is 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. 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 procedure 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 (y) according to Equation 1: Education where I is equal to the wetted perimeter (2w + 2d, where wyd are the thickness and width of the plate, respectively) and cos, the contact angle between the liquid and the plate, is assumed to be 0 in the absence of an existing bibliographic value. Another parameter used to evaluate surfactant performance is dynamic surface tension. Dynamic surface tension is the surface tension value for a given surface or interface. In the case of liquids with added surfactants, it 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, so it decreases until it reaches an equilibrium value. The time required to reach equilibrium depends on the diffusion rate and the adsorption rate of the surfactant. 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 using a capillary. The measured value corresponds to the surface tension at a given surface age, the time elapsed from the start of bubble formation until the maximum pressure is reached. The dependence of surface tension on surface age can be measured by varying the rate at which bubbles form. 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, which acts along the three-phase line and is 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, and the contact angle is 0°.Wetting properties are usually measured for a given compound at a concentration of 1-100x CMC, although it is not a concentration-dependent property and therefore wetting property measurements can be taken at higher or lower concentrations. In one procedure, an optical contact angle goniometer can be used to measure the contact angle. This device uses a digital camera and computer software to extract the contact angle by analyzing the contour shape of a sessile liquid droplet on a surface. Potential applications of the surfactant compounds in this disclosure include formulations for use as shampoos, hair conditioners, detergents, stain-free rinse solutions, floor and carpet cleaners, cleaning agents for graffiti removal, crop protection wetting agents, crop protection adjuvants, and wetting agents for aerosol coatings. An expert in the technique will understand that small differences between compounds can result in substantially different surfactant properties, so that different compounds can be used with different substrates, in different applications. The following non-limiting realizations are provided to demonstrate the different properties of the various surfactants. The compounds used in this disclosure are effective as surfactants, useful as wetting or foaming agents, dispersants, emulsifiers and detergents, among other applications. The compounds described in this disclosure may be useful in the applications mentioned above as well as in other special applications, such as surface treatments, for example, in personal hair care products, and may also be used to generate water-repellent surfaces. The amount of the compounds disclosed in this descriptive report used in a formulation may be as low as approximately 0.001% by weight, approximately 0.05% by weight, approximately 0.1% by weight, approximately 0.5% by weight, approximately 1% by weight, approximately 2% by weight or approximately 5% by weight, or as high as approximately 8% by weight, approximately 10% by weight, approximately 15% by weight, approximately 20% by weight, or approximately 25% by weight, or within any defined interval between any two of the above values. Examples Nuclear magnetic resonance (NMR) spectroscopy was performed on a 500 MHz Bruker spectrometer. The critical micelle concentration (CMC) was determined by the Wilhelmy plate procedure 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 6-(dodecyloxy)-N,N,N-trimethyl-6-oxohexan-1-aminium iodide 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 p-toluenesulfonic 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) 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), 1.5.- 1.53 (m, 6H), 1, 27-1, 18 (m, 20H), 0, 86 (t, 3H). Dodecyl 6-(dimethylamino)hexanoate (1.0 g, 3.05 mmol) was dissolved in acetonitrile (10 mL). Sodium carbonate (0.388 g, 3.66 mmol) was then added, and the reaction was stirred at room temperature for 10 minutes. Methyl iodide (0.57 mL, 9.16 mmol) was added, and the reaction mixture was heated at 40 °C for 24 hours, then cooled to room temperature. The mixture was filtered and concentrated to give 6-(dodecyloxy)-N,N,N-trimethyl-6-oxohexan-1-amino iodide as a yellow solid in 92% yield. 1H NMR (DMSO) 4.00 (t, J = 6.7 Hz, 2H) , 3.3.- 3.22 (m, 2H) , 3.04 (s, 9H) , 2.34 (t, J = 7.4 Hz, 2H) , 1.7.- 1.63 (m, 2H) , 1, 6.- 1, 46 (m, 4H), 1, 3.- 1, 20 (m, 20H), 0, 86 (t, J = 6, 9 Hz, 3H). Example 2: Determination of the critical micelle concentration (CMC) 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 1 mmol. The minimum surface tension plateau value that this surfactant can reach is approximately 33 mN / m, specifically 33 mN / m ± 3.3 mN / m. Figure 1 shows the surface tension versus concentration. From the graph, the surface tension is approximately 34 mN / m at the CMC and approximately 33.8 mN / m at a concentration of 1.0 mmol or higher. Example 3: Determination of dynamic surface tension Dynamic surface tension was determined using a bubble pressure tensiometer, which measures the change in surface tension over time at a newly created air-water interface. Figure 2 presents a graph of the results as surface tension versus time, showing that the surface tension in the time interval between 1 ms and 75 ms drops rapidly from approximately 55.5 mN / m to approximately 39.9 mN / m. In the time interval between 75 ms and 50,410 ms, the surface tension drops slowly from approximately 39.9 mN / m to approximately 34 mN / m, asymptotically approaching the saturation value of the surface tension at the CMC. Example 4: Determination of wetting properties In addition to surface tension and surface dynamics, the wetting properties of the compound were tested on different surfaces. For example, hydrophobic substrates, such as HDPE, exhibit surface wetting with a contact angle of 32°. On oleophobic and hydrophobic substrates, such as Teflon, the measured contact angle was much smaller than that of water, 67.1° (Table 1). Table 1 Example 5: Shampoo formulation 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. Additionally, the formulation may include other oils and natural ingredients, as well as vitamins, to appeal to the consumer, in quantities less than 1% by weight. Table 2 Example 6: Formulation for hair conditioner This example provides a formulation for use as a hair conditioner. This formulation can be used to replace or reduce polyquaternium-10, polyquaternium-7, and dimethicone oils, while maintaining the manageability and silky feel provided by hair conditioners. The formulation is shown below in Table 3. Table 3 Example 7: Formulation for car wash detergents to remove tough surface stains In this example, a formulation is provided for use in car wash detergents for the removal of tough surface stains. The formulation is shown below in Table 4. Table 4 Example 8: Formulation for a rinse or drying solution that leaves no residue This example provides a formulation for a spot-free rinse or drying solution. The solution can be applied to the vehicle's windows or bodywork after the main wash is complete. The formulation is shown below in Table 5. Table 5 Example 9: Formulation for a heavy-duty carpet cleaner This example provides a formulation for a heavy-duty carpet cleaner. The cleaner is a deep cleaner that produces a large amount of foam. The formulation is shown below in Table 6. Table 6 Example 10: Formulation for a heavy-duty surface cleaner This example provides a formulation for a heavy-duty surface cleaner. This cleaner can be used in manual or automatic surface cleaning machines. The formulation is shown below in Table 7. Table 7 Example 11: Formulation of a concentrated detergent for graffiti removal This example provides a formulation for a concentrated detergent for graffiti removal. The detergent can be used with a high-pressure hose. The formulation is shown below in Table 8. Table 8 Example 12: Formulation for a wetting agent in aerosols This example provides a formulation for a wetting adjuvant in aerosols. 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 by 2-5%) 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 Example 13: Formulation of additives for spray paint This example provides a formulation for an additive for a water-based spray paint or coating. The formulation is intended to provide good dynamic wetting of the spray droplets onto surfaces during application, thereby preventing paint cratering and other similar problems. The formulation is shown below in Table 10. Table 10

Claims

1. Use as a surfactant of a compound of the following formula: wherein X is an anion selected from the group consisting of chloride, bromide, iodide, and hydroxide.

2. Use according to claim 1, wherein the compound is 6-(dodecyloxy)-N,N,N-trimethyl-6-oxohexan-1-aminium iodide, having the following formula:

3. Use according to claim 1 or claim 2, wherein the compound has a critical micelle concentration (CMC) of approximately 1 mmol in water.

4. Use according to any one of claims 1 to 3, wherein the compound has a plateau value of a minimum surface tension of approximately 33 mN / m.

5. Use in accordance with any of Claims 1 to 4, wherein the compound has a surface tension in water equal to or less than 33.8 mN / mA and a concentration of 1.0 mmol or higher. 6.Use according to any of claims 1 to 5, wherein the compound has a surface tension in water equal to or less than 39.9 mN / mA and a surface age of 75 ms or greater.

7. Use of a formulation comprising a compound as defined in any of claims 1 to 6 as shampoo, detergent, stain-free rinse solution, floor and carpet cleaner, cleaning agent for graffiti removal, crop protection wetting agent, crop protection adjuvant, or wetting agent for spray coatings, wherein the compound is a surfactant.

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