A mixture of DEFI and amide taurate and its preparation method

Abstract

This invention includes a method for preparing a mixture of DEFI and amide taurate (ATA), the method exhibiting excellent ATA yield and substantially no browning of the final ATA and DEFI mixture. The method allows for much greater flexibility in the DEFI to ATA ratio. This invention also relates to mixtures prepared by the method of this invention.

Description

Technical Field

[0001] This invention relates to compositions comprising a mixture of a directly esterified fatty acyl hydroxyethyl sulfonate (“DEFI”) and an alkylamide taurate (“ATA”), said alkylamide taurate being produced by the amidation of taurate (e.g., N-methyl taurate); further, it relates to a method for preparing the mixture in a single reactor, preferably in a DEFI reactor. The invention also relates to mixtures prepared by the method of the invention. Controlling the order of addition allows for processes to be carried out at temperatures lower than previously thought required to drive DEFI yields, which in turn allows for higher yields of ATA and substantially eliminates browning. The low-temperature reaction further allows for much greater flexibility in the production of desired blends of DEFI and ATA. Background Technology

[0002] A common anionic surfactant used in personal care and personal washing compositions is acylhydroxyethyl sulfonate. This compound is milder than soap but still retains the properties that consumers associate with good cleaning (e.g., foaming).

[0003] Acyl hydroxyethyl sulfonate surfactants are typically produced by the use of fatty acids (e.g., C10 to C16 fatty acids, such as lauric acid) and hydroxyethyl sulfonates (e.g., OHCH2CH2SO3). - Na + The direct esterification of ) is produced in a process commonly known as the "DEFI" process. The DEFI process is carried out in a single DEFI reactor.

[0004] Another commonly used anionic surfactant is alkylamide taurate (e.g., N-methyl taurate). Alkylamide taurate is also a well-known anionic surfactant that provides good foaming properties.

[0005] Typically, ATA can be produced by taurine or taurine salts (e.g., NH2CH2CH2SO3). - M + M + It can be made by reacting, for example, sodium or potassium counterions with appropriate fatty acids.

[0006] For example, sodium methylstearoyl taurate can be prepared by heating tri-pressure stearic acid, a sodium methyl taurate solution, and boric acid to 200°C while purging with subsurface nitrogen and distilling off water. In this process, as described in the literature, stirring is carried out at 195-200°C and atmospheric pressure for six hours, followed by three hours under a vacuum of 100 mmHg. The material is cooled, and the resulting product (a grayish-white waxy solid) is ground into a powder. The product is reported to contain 64.0% sodium methylstearoyl taurate as the active ingredient, 29.5% free fatty acids, 2.5% N-methyl taurate, and 4.0% other unspecified chemicals. The conversion rate of sodium methyl taurate is reported to be greater than 91%. Using coconut fatty acids instead of stearic acid results in a 97% conversion rate.

[0007] While DEFI and ATA can be manufactured separately and combined, it is more economical and efficient to prepare a mixture of the two in a single reactor (e.g., in a single DEFI reactor). However, reacting, for example, alkali metal hydroxyethyl sulfonate and N-methyl taurine with fatty acids in a DEFI reactor (to produce DEFI and ATA, respectively) results in relatively low yields of ATA and “browning” products. If the reaction temperature is not high enough, the DEFI yield is affected, but the same high temperature leads to ATA browning. Therefore, the total L value of the DEFI / ATA mixture is much lower (more browning) compared to that prepared according to the present invention.

[0008] U.S. Patent No. 6,562,874 to Ilardi et al. discloses, for example, compositions in which DEFI and ATA are formed in the same reactor. Specifically, Ilardi discloses a DEFI reaction (in which hydroxyethyl sulfonate is combined with a fatty acid) in which an amine (e.g., taurine) is used to partially replace the hydroxyethyl sulfonate (column 4, lines 49-57).

[0009] The applicant has reproduced Examples 26-31 of U.S. Patent No. 6,562,874 to Ilardi et al., Table 4, and has demonstrated that the yield is very low at temperatures typically required to drive DEFI reaction yields (e.g., 238°C in all examples). Various additional comparative examples further confirm that the bars are much darker at these temperatures.

[0010] Unexpectedly, the applicant has discovered that if only taurine is initially combined with fatty acids (allowing for the pre-production of ATA prior to the addition of most or all of the hydroxyethyl sulfonate), and the temperature is kept relatively low (e.g., 200°C or lower, preferably 180°C to 195°C), the resulting ATA is considered (unwilling to be bound by theory) to act as an emulsifier. Therefore, when most or all of the alkali metal hydroxyethyl sulfonate is added to ATA and the remaining fatty acids (to produce DEFI and the resulting DEFI / ATA mixture), the temperature of this part of the reaction can also be kept relatively low (e.g., 200°C or lower, preferably 180°C to 195°C). In this way, the yield of ATA (produced in the first part of the reaction) is much higher than when DEFI and ATA are produced simultaneously and completely (as in Ilardi), while (because the second part of the reaction to produce most or all of DEFI is carried out at a much lower temperature) browning of ATA is avoided, and the L value of the overall DEFI / ATA mixture is much higher than previously possible. Summary of the Invention

[0011] In one aspect, the invention therefore includes a method for preparing a mixture of DEFI and alkylamide taurine in a single reactor, wherein the alkylamide taurine is prepared in high yield (75% or higher, preferably 80% or higher), and wherein, after most or all of the DEFI is produced in a second part of the reaction, the ATA is substantially free of browning (e.g., as defined by an L value of 80 or greater, preferably 80 to 100, more preferably 80 to 96, for the DEFI / ATA mixture), wherein the method comprises:

[0012] a) Combining fatty acids (e.g., C8 to C22, preferably C10 to C18 fatty acids), taurine and / or taurate salts, and a catalyst at a temperature of 200°C or lower, preferably 180°C to 195°C, wherein the ratio of fatty acids to taurine and / or taurate salts is 1.2:1 to 10:1, preferably 1.5:1 to 8:1, more preferably 1.5:1 to 5:1; as described above, a small amount of alkali metal hydroxyethyl sulfonate (as used in step (b) below) may be present in the initial reaction, but it is very small (preferably less than 10%, typically less than 1% of the total hydroxyethyl sulfonate to be used (all or most of which is used in step (b))); and

[0013] b) After the reaction is complete (typically this will be about 1 to 2 hours, with an ATA yield of 80% or higher, preferably 81 to 100%, more preferably 82 to 95%), most or all of the alkali metal hydroxyethyl sulfonate is added to the mixture of alkylamide taurate and residual fatty acid at a temperature of 200°C or lower, preferably 180 to 195°C (after this second step, the final DEFI yield can be 45 to 85%, preferably 55 to 85%).

[0014] Typically, water is not used in the reaction except for any small amount of water introduced as part of the starting materials (e.g., basic N-methyl taurine and alkali metal hydroxyethyl sulfonate). Most of the water is removed during the reaction (e.g., when heated to 180°C to 200°C in steps (a) and / or (b)). In one form, the taurine or taurate used in step (a) is heated to 150°C (i.e., water is removed), even before being combined with fatty acids and under the aforementioned reaction conditions.

[0015] It can be noted that this method offers processing flexibility because the amounts of taurine and / or taurate (to produce ATA) or hydroxyethyl sulfonate (to produce DEFI) can be varied to produce different desired ATA to DEFI ratios. Thus, for example, as seen in the examples associated with Ilardi's references (reproduced examples 26-31), the DEFI to ATA ratio ranges from 14:1 to 22:1. In our examples, the ratio can range from 0.1:1 to 7:1, preferably from 0.5:1 to 5:1 (0.28:1 to 2.05:1). Therefore, using our method, a relatively much larger amount of ATA can be produced. Furthermore, as mentioned above, since the ATA produced in the first part of the reaction appears to act as an emulsifier, DEFI (which is mostly or entirely produced in the second part of the reaction) can be produced at a lower process temperature (i.e., the ATA acting as an emulsifier in the second part of the reaction facilitates the reaction of hydroxyethyl sulfonate and fatty acid at a lower temperature); the measured L value of the produced DEFI / ATA is 80 or higher, typically 80 to 96 (i.e., essentially no browning). Detailed Implementation

[0016] Unless otherwise expressly stated in the examples, all figures indicating amounts of materials or reaction conditions, physical properties of materials, and / or uses in this specification should be understood to be modified by the word “about”. Unless otherwise stated, all quantities are by weight of the final composition.

[0017] It should be noted that when specifying any range of concentrations or amounts, any particular higher concentration can be associated with any particular lower concentration or amount.

[0018] To avoid ambiguity, the word "contains" is intended to mean "including," but not necessarily "composed of" or "consisting of." In other words, the steps or options listed do not need to be exhaustive.

[0019] The disclosure of the invention herein should be considered to cover all embodiments in the multiple dependent claims, regardless of the possibility that the claims may not have multiple dependents or redundancy.

[0020] This invention relates to a novel method for preparing mixtures of fatty acyl hydroxyethyl sulfonates (e.g., directly esterified fatty acyl hydroxyethyl sulfonates or “DEFI”) and alkylamide taurates. The method particularly allows for the preparation of ATA in higher yields (e.g., 80% or higher, preferably 82% or 85% and higher) while maintaining substantially no browning (as measured by the L value of the ATA / DEFI mixture) in the final mixture (because the ATA prepared in the first part of the reaction acts as an emulsifier and allows most or all of the DEFI produced in the second part of the reaction to be prepared at lower temperatures). In some aspects of the invention, the level of ATA is very high, such that the ratio of DEFI to ATA is, for example, 7:1 and smaller, such as 0.1:1 to 5:1.

[0021] The present invention also relates to a mixture of DEFI and ATA, wherein the final ratio of DEFI to ATA is from 0.1:1 to 7:1, preferably from 0.5:1 to 5:1, and wherein the L value of ATA confirms no browning (e.g., measured by an L value of 80 to 96 for the ATA / DEFI mixture). Preferably, the composition is prepared by the method of the present invention.

[0022] Finally, the present invention relates to a method in which, by controlling process parameters (especially the order of addition), a lower reaction temperature can be used (e.g., assuming some DEFI is prepared in the first step, then most of the alkali metal hydroxyethyl sulfonate is added in the second step; or if no DEFI is prepared in the first step, then all of the alkali metal hydroxyethyl sulfonate is added; DEFI is prepared in the second step at a lower temperature because ATA acts as an emulsifier), thereby providing reaction flexibility regarding the ratio of DEFI to ATA in the final mixture.

[0023] Specifically, the method of the present invention includes:

[0024] 1) In the first part of the method, fatty acids (e.g., C8 to C90) are... 22 Fatty acids), taurine and / or taurine salts (wherein the ratio of fatty acids to taurine and / or taurine salts is 1.2:1 to 10:1, preferably 1.5:1 to 8:1, more preferably 1.5:1 to 5:1) and a catalyst are combined at a temperature of 180°C to 200°C; and

[0025] 2) After the first part of the reaction is completed (usually within 1 to 2 hours), most or all of the alkali metal hydroxyethyl sulfonate is added to the mixture at a temperature of 200°C or lower, preferably 180°C to 195°C. Typically, no catalyst is used in the second step.

[0026] "Most or all" hydroxyethyl sulfonate means less than 10%, typically less than 1%, of all alkali metal hydroxyethyl sulfonates used in both steps (a) and (b), which is actually used in step (a). Step (a) is primarily about generating enough ATA to act as an emulsifier for the reaction in step (b), thereby allowing step (b) to proceed at a lower temperature than previously thought necessary.

[0027] The yield of ATA produced from the first step of the reaction process is typically 80% or higher, preferably 81% to 100%, and can be 82% to 95%. After the second step of the reaction, the yield of DEFI can be 45% to 95%, preferably 55% to 95%.

[0028] While not wishing to be bound by theory, it is believed that the ATA formed in the first part of the reaction (which is produced in relatively high yields and exhibits virtually no browning (as measured by the final L value of the ATA / DEFI mixture)) functions as an emulsifier, which in turn allows the second part of the reaction (producing DEFI when the majority or all, i.e., greater than 90% to 100% of the hydroxyethyl sulfonate, is added) to proceed at much lower temperatures. Therefore, the ATA in the mixture can be retained in high yields without subsequent browning, as described above.

[0029] Therefore, a key element of the method of the present invention (which in turn allows for the production of novel mixtures containing a relatively large amount of unbrowned ATA) is the preparation of ATA first by combining taurine and / or taurate with an excess of fatty acids at a relatively low temperature (180° to 200°C). That is, it is important to produce ATA in advance. As mentioned above, a small amount (less than 10%, preferably less than 5%, more preferably less than 1%) of hydroxyethyl sulfonate can be produced in step (a), but this is not the main function of step (a).

[0030] The fatty acids used are typically C8 to C9. 22 C8 to C are preferred 16 Fatty acids. Fatty acids are often combined with taurine (e.g., 2-aminoethanesulfonic acid) having the following structure:

[0031] RNHCH2CH2SO3H

[0032] in:

[0033] R can be, for example, hydrogen or methyl; or taurine, where the hydrogen on the sulfate group is replaced by a counterion, such as a sodium or potassium counterion. Theoretically, a mixture of acid and salt can be used.

[0034] Fatty acids are used in excess, and are used broadly in ratios of 1.2:1 to 10:1, preferably 1.5:1 to 8:1.

[0035] As described above, it is generally preferred to have a very small amount of water. Water is typically part of the starting materials (e.g., sodium N-methyltaurate and sodium hydroxyethyl sulfonate), and most of the water is removed during the reaction (e.g., by heating at 180°C to 190°C). In one form of the invention, the water in sodium N-methyltaurate is preferably removed by heating at 150°C before reacting with the fatty acids to form ATA.

[0036] Catalysts are typically used in the first part of the reaction, but not always. Catalysts can be added in the second part. It is preferable to use a catalyst in the first part of the reaction to maximize the yield of ATA.

[0037] This reaction can be carried out using a wide variety of catalysts. Suitable catalysts include polyvalent metal ion salts or organic or inorganic compounds, strong acids, and mixtures thereof. Alkali metal oxide catalysts can be used. Examples include zinc oxide, magnesium oxide, and calcium oxide. Zinc oxide is a preferred catalyst and can be used in this invention. However, faster-acting catalysts are preferred. Among fast organic catalysts is zinc hydroxyethyl sulfonate. Particularly preferred inorganic zinc compounds are selected from zinc sulfate, zinc aminosulfonate, and zinc oxide acidified with aminosulfonic acid or sulfonic acid. Mixtures of the above compounds can also be used.

[0038] Based on the combined weight of the charged reactants, the catalyst is present in amounts from about 0.01% to about 2% (calculated as, for example, zinc or other metal ions). Preferably, the amount of catalyst added is from about 0.01% to 1%. Higher amounts of catalyst, especially those containing zinc, are undesirable due to their adverse effects on product quality, such as color.

[0039] The first part of the reaction is run to completion after the combination of taurine and / or its salt (and alkali metal hydroxyethyl sulfonate, if available), fatty acids, and a catalyst. This typically takes 1 to 2 hours.

[0040] At this point, ATA is formed at a yield of 80% or higher, preferably 81% to 90% and higher.

[0041] At this point, most or all (greater than 90% to 100%) of the alkali metal hydroxyethyl sulfonate is added to the reaction chamber (containing ATA and excess fatty acids, and any possible trace amounts of DEFI). Due to the presence of ATA, the reaction between the hydroxyethyl sulfonate and the excess fatty acids still in the reactor is more efficient in this second part of the reactor and can occur at lower temperatures (e.g., 200°C or lower). This means that the ATA present in the reactor, and after the final reaction, will not brown. This is measured using the L scale, where the L value of the final DEFI / ATA mixture is greater than 80, preferably 80 to 96, more preferably 90 to 96.

[0042] Since a large amount of non-browning ATA can be produced, the DEFI to ATA ratio can be kept relatively low. Therefore, the DEFI to ATA ratio can be from 0.1:1 to 7:1, preferably from 0.4:1 to 7:1, and more preferably from 0.5:1 to 5:1.

[0043] As described above, the present invention also provides the opportunity to precisely control what ratio of DEFI to ATA can be used.

[0044] Scheme and Implementation

[0045] Scheme for measuring the value of "L"

[0046] The color of the product was evaluated using the Hunter Lab Color Scale. This is a color scale well-known to those skilled in the art (see the “Application Note” from Hunter Lab, “Insight on Color,” Volume 8, Issue 9, where, for example, formulas for L, a, and b are defined). On the Hunter scale, the key parameter is the L value, which is a measure of reflectance of luminance.

[0047] The L value of the ATA / DEFI product mixture is obtained through visual evaluation / comparison, and the color of the ATA / DEFI product mixture is matched with a standard color chart with Hunter Lab Color Scale L, a, and b values. As mentioned above, this is routine and well-known to those skilled in the art of color measurement.

[0048] Repeating Examples 26-31, Inventive Examples 1-4, and Additional Comparative Examples 1-2 from the references

[0049] To demonstrate how processing affects the yield and the mixtures of the present invention that can be prepared, the applicant recorded the following in Table I:

[0050]

[0051] The invention is prepared as follows:

[0052] Invention example procedure;

[0053] In a four-necked 250 ml round-bottom flask equipped with a mechanical stirrer, condenser, solvent trap / receiver, and thermocouple / nitrogen (N2) inlet, add sodium N-methyltaurate (12.5 g, 55% solution, 1 equivalent). Set the N2 flow rate to 0.2 L / min (LPM). Heat the N-methyltaurate solution to approximately 150 °C to remove water. Raise the reaction temperature to approximately 190 °C and add lauric acid (42.89 g, 5 equivalent) and zinc oxide (0.7 g, 0.2 equivalent). Stir the reaction mixture at 190 °C for 1 hour.

[0054] Add sodium ethanesulfonate (19.03 g, 3 equivalents) to the above reaction mixture. Stir the reaction mixture at 195°C for another 2 hours (3 hours of heating in total).

[0055] As shown in Table 1, the temperature (reproduced from U.S. Patent No. 6,562,874 to Ilardi et al.) for each of Examples 26-31 was 238°C. At these temperatures, the yield of ATA (produced in the same reactor as DEFI) never exceeded 68.4% (Example 28). While lower temperatures are generally expected to yield lower yields, the method of the present invention allows us to both increase the yield and avoid browning of the ATA / DEFI mixture.

[0056] The following examples use the procedure of Ilardi et al., US6,562,874, except that the reaction temperature is 190°C. Both ATA and DEFI yields were low.

[0057]

[0058] This confirms that, as mentioned above, the yield using previous single-step methods (such as in Ilardi) is significantly lower than the yield using the method of the present invention.

[0059] In contrast, in our Invention Examples 1-4, N-alkyl taurine was added to the reactor before most or all of the sodium hydroxyethyl sulfonate. It can be seen that the yield improved to a range from 82 to greater than 95. Furthermore, when the hydroxyethyl sulfonate was subsequently added, the reaction temperature could be maintained below 200°C, and there was essentially no browning (L values ​​all greater than 94.5).

[0060] In contrast, Comparisons 1 and 2 were carried out in a one-step reaction at a higher temperature. Although the yield was superior to the examples in US 6,562,874 (at least based on "ATA yield %"), the L values ​​were significantly lower. These examples thus show that the L values ​​are significantly lower when higher temperatures are used. Specifically, the L values ​​are 53.85 and 42.1. Lower L values ​​mean darker products (browning). In the inventive examples, the L values ​​are in the nineties.

Claims

1. A method for preparing a mixture of directly esterified fatty acyl hydroxyethyl sulfonate and alkylamide taurate, comprising: a) In the first part of the method, C8 to C 22 Fatty acids, taurine and / or taurate salts, and a catalyst are combined at a temperature of 200°C or lower, wherein the ratio of fatty acids to taurine and / or taurate salts is from 1.2:1 to 10:1; and b) After the first part of the reaction is completed, add more than 90% to 100% of the alkali metal hydroxyethyl sulfonate to the mixture at a temperature of 200°C or lower.

2. The method according to claim 1, wherein the ratio of fatty acid to taurine and / or taurate is 1.5:1 to 8:

1.

3. The method according to claim 2, wherein the ratio of fatty acid to taurine and / or taurine is 1.5:1 to 5:

1.

4. The method according to any one of claims 1-3, wherein the catalyst is a polyvalent metal ion salt of an organic or inorganic acid, a strong acid, or a mixture of both.

5. The method according to any one of claims 1-3, wherein the catalyst is a metal oxide catalyst.

6. The method according to claim 5, wherein the catalyst is ZnO, MgO or CaO.

7. The method according to any one of claims 1-3, wherein the reaction temperature in step a) is a temperature of 180°C to 195°C.

8. The method according to any one of claims 1-3, wherein the alkali metal hydroxyethyl sulfonate added in step b) is added at a temperature of 180°C to 195°C.

9. The method according to any one of claims 1-3, wherein the alkylamide taurine does not brown, as defined by an L value of 80 to 96 based on the mixture of directly esterified fatty acyl hydroxyethyl sulfonate and alkylamide taurine.

10. Use of the method of any one of claims 1-9 for controlling the ratio of directly esterified fatty acyl hydroxyethyl sulfonate to alkylamide taurate in the final mixture.

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