MXPA00005301A - An ortho ester-based surfactant, its preparation and use - Google Patents

Abstract

The present invention relates to a new ortho ester-based surfactant, where the hydrophobic and hydrophilic parts are connected by ortho ester linkages to the molecule. The ortho ester has formula (I), where R is hydrogen or an aliphatic group with 1-7 carbon atoms;R1 is hydrogen or an alkyl group with 1-5 carbon atoms;A1 is an alkyleneoxy group with 2-4 carbon atoms, the number of ethyleneoxy groups being at least 50%of the total number of alkyleneoxy groups;n1 is a number between 1 and 30;R2 is an aliphatic group with 5-22 carbon atoms;A2 is an alkyleneoxy group with 3-4 carbon atoms;n2 is a number between 0-30, provided that when R2 is an aliphatic group with 5-6 carbon atoms n2 is at least 1;R3 is selected from the group consisting of (A1)n1R1, (A2)n2R2 and an alkyl group with 1-6 carbon atoms, where A1, n1, R1, A2, n2 and R2 have the same meaning as mentioned above, or a di- or polycondensate via any of the free hydroxy groups of the ortho ester. The ortho ester surfactants are stable in alkaline solutions, but are readily hydrolysed in acidic solutions to yield products that are not surface active. They are suitable to be used as emulsifiers or dispersants.

Description

A SURFACTANT BASED ON ORTOESTER, ITS PREPARATION AND USE DESCRIPTION OF THE INVENTION The present invention relates to a novel surfactant based on orthoester, where the hydrophobic and hydrophilic parts are connected by orthoester bonds to the molecule. The surfactants are stable in alkaline solutions, but are rapidly hydrolyzed in acid solutions to produce products that are not surface active. Surfactants are used in a variety of applications and processes, but once their task is accomplished their presence is often undesirable. From an environmental point of view, it is of great advantage if the products that end up in the environment, are easily degradable, either biologically or by other means. Also, since surfactants have the ability to form emulsions and dispersions, which in most cases is the main reason for using them, they make it difficult to separate hydrophobic material from wastewater obtained in industrial processes.

In order to improve the degradation capacity of the surfactants and to make it easier to separate the hydrophobic material from the waste water, it has been suggested in European Patent EP-A1-0 742 177 and EP-A1-0 742 178 to use Hydrolyzable surfactants based on aldehyde and ketone. The surfactants, which contain acetal bonds, are stable in alkaline solutions but are hydrolyzed in acid solutions. Acetal-based surfactants are also described in European Patent EP-A3-0 054 366. However, to effect complete hydrolysis, the pH needs to be lower and the reaction time longer for the acetals, compared to the ortho-ethers. This will result in a higher consumption of chemicals, and will give either an aqueous phase with an unacceptably low pH to be sent to the wastewater treatment works or, if the wastewater is neutralized, the formation of large amounts of salt . In addition, there is only a small number of long chain aldehydes that are commercially available, and consequently the range of acetal based surfactants that is possible to obtain is limited. In addition, aldehydes are generally more difficult to produce than the corresponding alcohols, and are therefore more expensive. Orthoester-type surfactants have been described in European Patent EP-A1-564 402, where an orthoester group is used for the end-capping of non-ionic surfactants. The products obtained are low foaming, and can be used for example in machine washing dishes and bottle cleaning. These products, however, will benefit only marginally from better degradation, since a step of hydrolysis will produce compounds that are still active on the surface. The object of the present invention is to provide surfactants with at least as good emulsification and dispersion ability as conventional types of surfactants, which are also easily cleavable and more readily biodegradable. Their degradation products must also be environmentally friendly and not show any essential surface activity. In addition, this new type of surfactants must be easy to produce. Surprisingly, it has been found that surfactants based on an orthoester according to the formula O - (AxJmRi R - C - O - R3 (i: O - (A2) n2R2 where R is hydrogen or an aliphatic group with 1-7 carbon atoms; Ri is hydrogen or an alkyl group with 1 to 5 carbon atoms, preferably Ri is an alkyl group with 1 to 4 carbon atoms; Ai is an alkyleneoxy group having 2 to 4 carbon atoms, the number of ethyleneoxy groups of at least 50% of the total number of alkylenoxy groups; nor is it a number between 1 and 30, preferably between 2-25; R2 is an aliphatic group with 5-22 carbon atoms, preferably 8-22; A2 is an alkyleneoxy group with 3-4 carbon atoms; n2 is a number between 0-30, preferably between 0-20, with the proviso that when R2 is an aliphatic group with 5-6 carbon atoms n2 is at least 1, preferably at least 2; R3 is selected from the group consisting of (A?) N? R ?, (A2) n2R2 and an alkyl group with 1-6 carbon atoms, preferably 1-4, wherein Ai, nl r Rl r A2, n2 and R2 have the same meaning as described above; or a di- or polycondensate via any of the free hydroxyl groups of the orthoester; show the aforementioned properties. To strengthen the hydrophilic part of the molecule, the Ai groups may consist solely of ethyleneoxy groups. The surfactants of the formula I have a good emulsification and dispersion ability, and are preferably used in applications where the ability of rapid cleavage offers an advantage, for example, for hard surface cleaning, deinking, viscose processing, disinfection and in fiber and textile processes such as dyeing and scouring. These are also low foaming, which is an advantage in low applications. When they are used for cleaning hard surfaces they show comparable or better effects than traditional non-ionic, surface active alkylene oxide adducts. The emulsification ability of this type of surfactant is further demonstrated by the manufacture of an emulsion for a pesticide. This formulation is of stability comparable to a comparison obtained with an optimized nonionic emulsifier of the traditional type. The cleavage of orthoester-based surfactant is promoted to a high degree by decreasing the pH and increasing the temperature. The orthoester may also be used as an emulsifier / dispersant at a lower pH for example at a pH of 5, if the process is fast enough and consequently be cleaved at the same pH. When compared to the cleavage of an acetal-based surfactant at the same conditions, the orthoester-based surfactant is cleaved much more rapidly. The cleavage results in degradation products that lack the ability to behave as surfactants, for example, to form emulsions, which is demonstrated in Example 12. The rapid cleavage ability of the orthoesters of the present invention has a special advantage in application areas where the separation of an oily phase from the aqueous phase is desirable, for example, for the treatment of waste water, in the treatment of emulsions formed when cleaning hard surfaces, and in de-inking and in textile processes. The invention also relates to a process for the preparation of orthoester-based surfactants where the low molecular weight orthoesters are used as starting materials. These low molecular weight orthoesters are reacted with a hydrophobic component, which is an alcohol and preferably a hydrophilic component encased at the end, which is preferably a polyethylene oxide adduct. The molar amounts of the reactants are preferably 1-2 moles of the hydrophilic component per mole of orthoester and 1-2 moles of the hydrophobic component per mole of orthoester. By this process surface active orthoesters are obtained, where the hydrophobic and hydrophilic portions are each connected individually by orthoester bonds to the molecule. The orthoester-based surfactant of the present invention can be produced by the reaction of an orthoester of the general formula 0 -. 0 - R. R C - O - R4 117 O- R4 wherein R has the same meaning as in Formula I and R4 is an alkyl group with 1-6 carbon atoms, preferably 1-4, in one or more steps, with reagents having the formulas H0 (A _.) n? R? and HO (A2) n2R2, wherein Ri, R2, i, A2, ni and n2 have the same meaning as in Formula I, while the alcohols are evaporated with the formula R4OH, where R has the same meaning as described previously. The reaction is preferably carried out in the presence of an acid, for example methanesulfonic acid, p-toluenesulfonic acid or citric acid. The temperature is increased during the reaction and finally reaches 140 to 220 ° C. The alcohols R4OH, which are released during the reaction, are gradually evaporated from the reaction mixture. In the final phase of the reaction, vacuum is applied to eliminate the residual amounts of alcohols, with which the reaction is pushed to completion. Suitable examples of orthoesters II are methyl or ethyl orthoformate, methyl or ethyl orthoacetate and other low molecular weight orthoesters which are commercially available. The hydrophobic part of the molecule can be derived from an alcohol R2OH, or an alkoxylate thereof. The alcohol could be either synthetic or natural. Suitable examples of the alkyl group R2 are 2-ethylhexyl, octyl, decyl, cocoalkyl, lauryl, oleyl, rapeseed alkyl, and tallow alkyl. Other suitable R2 hydrocarbon groups are those obtained from the oxoalcohols, Guerbet alcohols, ethyl substituted alcohols with 2-4 groups having the formula -CH (CH3) - included in the alkyl chain. The alcohols can also be propoxylated or butoxylated. The hydrophilic part of the molecule is preferably derived from polyethylene glycols, which are encasquetaos at the end, preferably with a methyl or ethyl group, have a molecular weight of 100 and 2000. The choice of hydrophobic and hydrophilic parts and the relative amounts of them will vary of course between different applications, to meet your demands for a specific HLB, specific turbidity point, etc. In still another embodiment, the present invention relates to the use of an orthoester according to formula I in a process comprising a) emulsifying or dispersing a hydrophobic component in water at a pH of 6 or higher, preferably at a pH 7 or higher, in the presence of an orthoester according to the present invention, b) decreasing the pH or increasing the temperature of the emulsion or dispersion, or a combination thereof, and thereby breaking the emulsion or dispersion, and c) the separation of the hydrophobic component from the water.

The surfactant is normally used as an emulsifier or dispersant at a pH of 9 or higher, but could also be used up to a pH of about 6. The waste water obtained as a result of the operation of the surfactant in step a is then treated in accordance with b. The pH of the emulsion or dispersion is preferably reduced to a pH of between 4 and 6. If necessary, the temperature can be high, preferably at 20 to 60 ° C to further promote the cleavage. In some circumstances with the pH during emulsification is low enough, it may be sufficient to raise the temperature. The lower the pH and the higher the temperature the faster the cleavage will occur. In most circumstances it may be more convenient to lower the pH instead of raising the temperature above room temperature, since the latter will often require a large input of energy. The aforementioned process can be used in a variety of applications. A major application is the cleaning of hard surfaces, for example in connection with vehicle cleaning and the cleaning of storage tanks and tank trucks, where the ortho ester surfactant is used at alkaline pH as an emulsifier or dispersant for the fluid or hydrophobic powder .. When the surface has been cleaned, the waste water is acidified, whereby the surfactant is cleaved. This causes the emulsion or dispersion to break, and the hydrophobic material to be separated from the waste water. In an analogous manner, the hydrophobic ink obtained in a deinking process, the excess of the hydrophobic dye, a textile dyeing process and the dust of a textile scouring process, could be emulsified or dispersed by the surfactants, and subsequently removed from the process water. Orthoester surfactants also benefit from a better biodegradation capacity than the corresponding conventional nonionic surfactants. When subjected to a neutral or slightly acidic pH in a pipe treatment plant, the ortho ester surfactants are cleaved to produce non-toxic substances that are essentially non-active surface. These substances could be more easily biodegraded than an intact surface active molecule. A comparison between a traditional non-ionic surfactant and an orthoester surfactant according to the present invention (see Example 14) shows that the latter is more readily biodegradable. The present invention is further illustrated by the following Examples.

Example 1 1. 5 moles of a linear primary alcohol of 9 to 11 carbon atoms (Dobanol 91 of Shell), 1.5 moles of diethylene glycol monoethyl ether ethoxylate (diethylene glycol monoethyl ether + 2 moles of ethylene oxide), 1 mole of triethyl orthoformate and 0.2% w / w of methanesulfonic acid were mixed together at room temperature. The temperature of the reaction mixture was gradually raised, and finally, after about 4 hours, a temperature of 150-200 ° C was reached. The ethanol, which was released during the reaction, was continuously distilled. In the final phase of the reaction, vacuum was applied to facilitate the elimination of ethanol. A total of 30.8 g of ethanol was collected, which corresponds to 92% of the theoretical amount. The distillate was analyzed by 1 H NMR and the product was analyzed by 1 H-NMR and 13 C-NMR. According to the analyzes there was no triethyl orthoformate left unreacted.

Example 2 1.05 moles of propoxylate of 2-ethylhexanol (2-ethyl-hexanol + 13 moles of propylene oxide), 1.05 moles of diethylene glycol monoethyl ether ethoxylate (diethylene glycol monomethyl ether + 18 moles of ethylene oxide), 1.0 mole were mixed of triethyl orthoformate and 1% w / w of anhydrous citric acid, and a reaction was carried out under the same conditions as in Example 1. A total of 10.2 g of ethanol was distilled, which corresponds to 92% of the theoretical amount. The same analyzes as in Example 1 were performed. No unreacted triethyl orthoformate was found.

Example 3 1.5 moles of 2-ethylhexanol, 1.5 moles of a polyethylene glycol blocked with monomethyl having an average molecular weight of 550, 1 mole of triethyl orthoformate and 0.2% w / w of methanesulfonic acid were mixed. The same procedure as in Example 1 was followed. A total of 18.2 g ethanol was collected, which corresponds to 98% of the theoretical amount. The same analyzes as in Example 1 were performed. No unreacted triethyl orthoformate was found. According to the NMR analysis more than 70% of the product consists of three active surface components specified below. The number of ethoxy groups that has not been substituted is denoted by x, the number of 2-ethylhexyl groups per y, and the number of polyoxyethylene groups capped at the end by z.

Example 4 The procedure is the same as in Example 1, except that 2-ethylhexanol + 2.4 moles of propylene oxide and polyethylene glycol blocked with monomethyl having a molecular weight of 550 are used as the hydrophobic and hydrophilic components, respectively. The same analyzes as in Example 1 were performed. No unreacted triethyl orthoformate was found.

Example 5 The procedure is the same as in Example 1, except that n-octanol and polyethylene glycol blocked with monomethyl having an average molecular weight of 350 are used, as the hydrophobic and hydrophilic components, respectively. The same analyzes as in Example 1 were performed. No unreacted triethyl orthoformate was found.

Example 6 0.152 moles of hexadecanol, 0.152 moles of polyethylene glycol blocked with mono-methyl having an average molecular weight of 750, 0.101 moles of triethyl orthoformate and 0.15% w / w of anhydrous citric acid were mixed together. The temperature of the reaction mixture gradually rose from 22 ° C to 155 ° C over the course of 30 minutes. The ethanol, which was released during the reaction, was continuously distilled. When the temperature had reached 155 ° C, the pressure was slowly reduced to 3 mbar and remained there for 20 minutes to facilitate the elimination of ethanol. A total of 13.7 g of ethanol was collected, which corresponds to 99% of the theoretical amount. The distillate was analyzed by H-NMR and the product was analyzed by 1 H-NMR and 13 C-NMR. According to the analyzes there was no unreacted triethyl orthoformate, and 60% of the product mixture consists of three active surface components corresponding to those specified in the table of Example 3.

Example 7 The procedure is the same as in Example 6, except that 2-ethylhexanol + 2 moles of propylene oxide and polyethylene glycol blocked with monomethyl having an average molecular weight of 550 are used, as the corresponding hydrophobic and hydrophilic components. The same analyzes as in Example 6 were performed, no unreacted triethyl orthoformate was found.

Example 8 The procedure is the same as in Example 6, except that the linear primary alcohol of 9 to 11 carbon atoms (Dobanol 91 of Shell) and polyethylene glycol blocked with monomethyl having an average molecular weight of 470 are used as the hydrophobic components and hydrophiles respectively. The same analyzes as in Example 6 were performed. No unreacted triethyl orthoformate was found.

Example 9 The biodegradability of the orthoester based surfactant described in Example 1 was investigated by the "closed bottle test" as described in OECD Test 301D. The surfactant reached 82% biodegradation after 82 days, and is therefore classified as easily biodegradable.

Example 10 To evaluate the cleaning efficiency of the formulations containing an orthoester-based surfactant of the present invention, the following cleaning test was used: alumina plates (41 x 15 mm) coated with carbon-14-labeled triolein (glycerol triolate). Amersham) were placed in a fastener and washed in a Terg-O-Tometer by rotating the fasteners back and forth through the surfactant solution at a speed of 50 rpm for a period of 50 minutes. The test was performed at 20 and 40 ° C, using formulations I, II and III in the following Table, where I is a reference formulation containing a traditional nonionic surfactant. The formulations were diluted with tap water 1: 100 before use. After the cleaning step the fasteners were submerged for 5 seconds in tap water maintaining a temperature of 20 ° C.

The plates were transferred to flasks containing scintillation liquid (Ultima Gold from Packard) with the ability to dissolve the fat, and were shaken at 300 rpm for 20 minutes. The plates were removed from the flasks, and the liquid was analyzed for radioactivity on a scintillation analyzer (Tri- Carb 1900CA from Packard). The result is reported as the% fat washed compared to the coated plates that have not been washed according to the previous procedure.

This example shows that orthoester surfactants are as good cleansers for hard surfaces as the non-ionic surfactant used as a reference.

Example 11 The wetting ability of the orthoester-based surfactants according to the present invention was estimated by the contact angle measurements. The solutions used were the formulations I (reference), II and III that were used in Example 10. The formulations were used undiluted. The contact angle was measured against a hydrophobic polymeric material (Parafilm PM-992 from American Can Company) with a Ramé-Hart NRL C.A. The measurements were made after 1 minute, and each value is the average of 10 measurements. The results are summarized in the following Table.

The results show that the wetting ability of the orthoester-based surfactants according to this invention is comparable to the wetting ability of the reference compound.

Example 12 A comparison is made between the orthoester-based surfactant produced according to Example 1, a surfactant blocked at the end with orthoester and an acetal-based surfactant, with respect to its ability to emulsify at different pH values. The oil phase used in all the experiments is n-decane, and the aqueous phase consists of different buffer solutions. Red Sudan B is added as a dye for the emulsion. The surfactants used are: A) Surfactant based on orthoester, according to Example 1 B) A linear primary alcohol of 10 to 11 carbon atoms + 8 moles of ethylene oxide which is blocked at the end with triethyl orthoformate (synthesized according to the procedure described in the European Patent EP- A-0 564 402) C) The acetal between n-decanal and glycerol ethoxylated with 4 moles of ethylene oxide (synthesized according to the procedure described in European Patent EP-A1-0 742 177).

Process : 7. 5 ml of n-decane, 7.5 ml of buffer solution, 0.3 g of surfactant and 2 drops of Sudan Red B are placed in a sealable test tube, which is manually adjusted for one minute before the first measurement. The emulsion is allowed to separate, and after 3 minutes the degree of separation is measured as a / b x 100, where a is millimeters of clear lower phase, and b is millimeters of clear aqueous phase before emulsification. Between the measurements the test tubes are continuously stirred at 1000 rpm in the horizontal position by an IKA-VIBRAX-VXR device. Before each new measurement the test tube is manually stirred for 30 seconds to completely re-emulsify the mixture. The test is performed at 22 and 50 ° C. For the 50 ° C test the n-decane and the buffer is heated before the surfactant is added. unrealized test At 22 ° C surfactant A is easily hydrolysed at pH values lower than 5, which results in a loss of surface activity causing the emulsions to separate. At 50 ° C the hydrolysis is rapid in this pH range, producing separation times of less than 15 minutes. As expected, hydrolysis is slow at alkaline pH. To obtain an acceptable hydrolysis time for C, 100% H2SO4 was added. This resulted in a time of more than 3 hours, while for an addition of 5% of H2SO4, it took more than 72 hours. The emulsion produced with surfactant B is only marginally affected by pH. Still after 11 days at a pH of 2 and 22 ° C, only a separation of 11% is obtained. This is expected since the surface activity of B does not disappear when the orthoester link is broken. These previous results show the superiority of surfactant A over surfactant B and C with respect to the ease of hydrolysis at acidic pH values.

Example 13 To further investigate the separation of the emulsion, obtained at a pH of 5, two other types of oils were emulsified by the same surfactants A and C, which were used in Example 8. For a comparison with a conventional non-ionic surfactant, it was used an alcohol of 9 to 11 carbon atoms + 4 moles of ethylene oxide (surfactant D). The oils used were refined soybean oil, produced by Karlshamn) and diesel (diesel), and the aqueous phase consists of a buffer solution of pH 5.

Procedures At room temperature 200 ml of oil, 300 ml of buffer and 6 g of surfactant are placed in a 500 ml reactor equipped with a mechanical stirrer of the propellant type. The reactor has an outlet in the bottom. The mixture is stirred vigorously at about 500 rpm for 90 minutes. The emulsion that is formed is allowed to stand for 5 minutes, after which 250 ml of liquid are drained through the lower outlet for about 1 minute. The sample is left for 3 hours, after which the volume of oil and / or emulsion is measured. The result is presented as% v / v with reference to the total volume of the sample. The values obtained are collected in the following table.

The amount of oil and / or emulsion in a sample reflects the hydrolysis ratio of the surfactants. The results obtained clearly show that the use of scissor-based surfactant A, cleavable, facilitates the separation of the oily phase from emulsions containing vegetable oil, as well as oil-based oil. The separation ratio at pH 5 is substantially higher using this orthoester-based surfactant compared to the use of the acetal-based surfactant C. When conventional non-ionic surfactant D is used, the rate or separation ratio is still slower.

Example 14 A formulation for a pesticide containing an ortho ester surfactant is compared to a standard formulation containing a traditional nonionic surfactant. ml of each formulation were emulsified in 95 ml of water, and the emulsions were transferred to 100 ml test tubes. The separation of the emulsions was noted as% v / v of clear upper phase at certain time intervals. The results are summarized in the following table.

The formulation containing the orthoester-based surfactant produced an emulsion that was of comparable stability to the emulsion obtained by formulation II, which contains a traditional non-ionic surfactant. However, the orthoester-based surfactant has the advantage of being more easily cleaved to non-active surface compounds, and therefore has a better environmental profile than the conventional non-ionic surfactant. The biodegradation capacity of the orthoester based surfactant according to the "closed bottle test" was 37% after 28 days and 41% after 42 days, while for the corresponding conventional surfactant it was degraded 18% after 28 days. days and 35% after 112 days.

Claims (10)

1. An orthoester characterized because it has the formula 0 -. 0 -. 0 - (A?) N? R? R - C - O - R3 (I) I O - (A2) n2R2 where R is hydrogen or an aliphatic group with 1-7 carbon atoms; Ri is hydrogen or an alkyl group with 1 to 5 carbon atoms; Ai is an alkyleneoxy group with 2 to 4 carbon atoms, the total number of ethyleneoxy groups is at least 50% of the total number of alkylenoxy groups; nor is it a number between 1 and 30; R2 is an aliphatic group with 5-22 carbon atoms; A2 is an alkyleneoxy group with 3-4 carbon atoms; n2 is a number between 0-30, with the proviso that when R2 is an aliphatic group with 5-6 carbon atoms, n2 is at least 1; R3 is selected from the group consisting of (A?) N? R ?, (A2) n2R2 and an alkyl group with 1-6 carbon atoms, where Ai, nl r Ri, A2, n2 and R2 have the same meaning as described above; or a di- or poly-condensate via any of the free hydroxyl groups of the orthoester.

2. An orthoester according to claim 1, wherein Ri is an alkyl group with 1 to 4 carbon atoms.

3. A confectionery orthoester with claims 1-2, where nx is a number between 2-25 and n2 is a number between 0-20.

4. An orthoester according to claims 1-3, wherein n2 is 0, R2 is an aliphatic group with 8-22 carbon atoms and Ai is an ethyleneoxy group.

5. A process for the preparation of an orthoester according to any of claims 1-4, characterized in that it is prepared by the reaction of an orthoester of the general formula 0 - R4 R - C - O - R4 (ir I O - R4 where R has the same meaning as in any of claims 1-4, and R is an alkyl group with 1-6 carbon atoms, in one or more steps, with reagents having the formulas H0 (A?) n? R ? and HO (A2) n2 2. wherein Ri, R2, Ai, A2, ni and n2 have the same meaning as in any of claims 1-4, while the alcohols are evaporated with the formula ROH, where R4 has the Same meaning as described above.

6. The use of an orthoester having the formula I, according to claims 1-4, as an emulsifying and / or dispersing agent.

7. The use of an orthoester according to claim 6, in a process of cleaning, scouring, dyeing and deinking, and in the formulation of a pesticidal composition.

8. The use of the orthoester according to claims 6 or 7 in a process comprising: a) emulsifying or dispersing a hydrophobic component in water at a pH of 6 or higher, in the presence of an orthoester according to claims 1- 4, b) decreasing the pH or increasing the temperature of the emulsion or dispersion, or a combination thereof, and thereby breaking the emulsion or dispersion, and c) separating the hydrophobic component from the water.

9. The use of an orthoester in a process according to claim 8, wherein the temperature in step b is elevated to between 20 and 60 ° C.

10. The use of an orthoester in a process according to claims 8-9, wherein the pH in step B is between 4 and 6. acid solutions to give products that are not surface assets. These are suitable for use as emulsifiers or dispersants.