LOW VISCOSITY ALKYL DIPHENYL OXIDE SULFONIC ACID BLENDS

Abstract: This invention addresses methods and compositions for providing alkyl diphenyl oxide sulfonic acid blends at useful viscosities for use in surfactants such as DOWFAX - containing surfactants. The low viscosity alkyl diphenyl oxide sulfonic acid blend is made by admixing a fatty acid having a carboxylic chain length between 1 and 12 (for example, formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid into an alkyl diphenyl oxide sulfonic acid reaction product to provide between 5 weight percentage and 50 weight percentage of fatty acid in the admixture.

Description: where R is an alkyl radical having between 6 and 16 carbon atoms; and sulfonating said admixture with a sulfonating agent. 3 - An alkyl diphenyl oxide sulfonic acid blend having between 5 weight percentage and 50 weight percentage of a fatty acid with a carboxylic chain length between 1 and 12. 4 - An admixture composition of- formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid to provide between 5 weight percentage and 50 weight percentage of fatty acid in the admixture composition; and alkyl diphenyl oxide characterized by where R is an alkyl radical having between 6 and 16 carbon atoms Turning now to an overview of the Figures, Figure 1 shows the impact of various levels of octanoic acid upon the viscosity of a DOWFAX alkyl diphenyl oxide sulfonic acid surfactant blend. Figure 2 shows the impact of various levels of octanoic acid upon the viscosity of a DOWFAX alkyl diphenyl oxide sulfonic acid surfactant blend in the high viscosity range Figure 3 shows the comparative impact of acetic, valeric, octanoic, and decanoic fatty acids on the viscosity of a DOWFAX alkyl diphenyl oxide sulfonic acid surfactant blend. Figure 4 shows a ternary phase diagram showing significant liquid crystal phase regions for water, DOWFAX Detergent Acid, and fatty acid (acetic acid and octanoic acid). In further discussion of details in the preferred embodiments, alkyl diphenyl oxide sulfonate surfactants are a Friedel-Crafts reaction product of an olefin and diphenyl oxide using AICI 3 as a catalyst as indicated in Formula I. Formula l Olefin Diphenyl oxide is present in excess and is recycled. The reaction yields a mixture of monoalkyl diphenyl oxide and dialkyl diphenyl oxide. The ratio of monoalkylation to dialkylation can be optimized depending on the end use of the products. The next step in the process is the reaction of the alkylate with a sulfonating agent. This reaction (Formula II) is conducted in a solvent to dilute the reactant and to act as a diluent for the S0 3 used in the reaction. Formula II The reaction generally yields a mixture of monosulfonates and disulfonates according to Formulas III - VI. The level of disulfonation is determined by the end use of the product. Generally, the disulfonation level is above 80 percent. The predominant component in the commercial reaction mixture is the monoalkyl diphenyl oxide disulfonate (MADS) of Formula IV, with monoalkyl diphenyl oxide monosulfonate (MAMS) of Formula III, dialkyl diphenyl oxide monosulfonate (DAMS) of Formula V, and dialkyl diphenyl oxide disulfonate (DADS) of Formula VI essentially providing the remainder. Forrnula iπ Formula IV Alkyl diphenyloxide sulfonates and their traditional methods of preparation are well-known and reference is made thereto for purposes of describing this invention. Representative methods of preparation and handling are disclosed in U.S. Patents 2,990,375; 3,264,242, 3,634,272; 3,945,437; and 5,015,367. The commercially available species are predominantly (greater than 85 percent) disulfonates (the DADS and MADS described above) and are a mixture of mono- and di- alkyl with the percentage of dialkylation (the DADS and DAMS described above) being 5 to 25 and the percentage of monoalkylation (the MAMS and MADS described above) being 75 to 95 percent. Most typically, the commercially available species are 85 percent monoalkyl and 15 percent dialkyl. The traditional method taught by Steinhauer et al. (U.S. Pat. No. 2,990,375) outlines a series of steps, the first step comprising preparing an alkyldiphenyl ether by reacting an olefin or an olefin ha de, such as tπpropylenes, tetrapropylenes, pentapropylenes or dodecyl bromide, with diphenyl ether at a temperature between 50° C and 100° C in the presence of the Fπedel-Crafts catalyst. The reaction mixture is washed with water to remove the catalyst, the phases separated, and the organic-rich phase subjected to distillation to obtain a fraction consisting of a mixture of monoalkylated diphenyl ether and dialkylated diphenyl ether. The number of alkyl substituents per diphenyl ether molecule can be controlled by adjusting the relative proportions of the reactants. Alternatively, the distillation can be performed so as to separate the monoalkylated and dialkylated diphenyl ethers from one another and from lower or higher boiling ingredients after which the monoalkylated and dialkylated diphenyl ether fractions can be combined at a desirable ratio. The mixture of monoalkylated and dialkylated diphenyl ethers is subsequently reacted with a sulfonating agent, such as chlorosulfonic acid, sulfunc acid, or sulfur tπoxide, in an inert solvent The general process of today uses reaction of an unsaturated hydrocarbon such as an alpha-olefin in the range of 6 to 16 carbons with diphenyl oxide in the presence of AICI 3 . Reaction of alpha-olefins in the higher range of 18-30 carbons with diphenyl oxide in the presence of AICI 3 holds some promise for fulfilling future surfactant needs The ratio of mono- to dialkylation is controlled by the ratio of olefin to diphenyl oxide. Recycled excess diphenyl oxide is purified and reused. The rate of the reaction and the yield are controlled by the amount of catalyst and temperature of the alkylation. Excessively high temperatures as well as excessive amounts of catalyst yield higher levels of dialkylation and tnalkylation. Low temperatures result in a low conversion of olefin. The ratios of concentration, catalyst and temperature are critical in keeping the reaction products consistent throughout the production cycle. The catalyst is removed from the process stream and the crude reaction mixture is then stripped of excess diphenyl oxide. Additional purification is optionally effected prior to the sulfonation reaction. Sulfonation is generally carried out in a solvent. The solvent provides value in distributing the sulfonating agent, preventing localized burning and yield loss of the reaction product, and acting as a heat removal medium in control of the reaction process temperature. Current commercial process routes use sulfur dioxide, methylene chloride, or air as reaction solvents. The air sulfonation process eliminates the need for the removal and recycle of the liquid reaction solvent and is amenable to onsite generation of S0 3 Liquid solvents require 7 the use of liquid S0 3 that is diluted into the solvent prior to addition to the sulfonation reactors. Sulfur tnoxide and chlorosulfonic acid are the two most common sulfonating agents. After sulfonation, (1 ) the sulfomc acid is separated from its diluent, (2) the anhydrous acid (HAA) is diluted with water, and (3) neutralization of the diluted acid is optionally executed with an alkaline base such as sodium hydroxide. The material is packaged and sold in drums or bulk shipments as the customer requires. The high viscosity of concentrated HAA derives from properties related to liquid crystal presence. This effect initiates at hydrophobe chain lengths above 6, is increasingly pronounced in observed samples to chain lengths of 16, and is expected to extend with greater significance to cases such as those which are contemplated via reaction of alpha- olefins in the higher range of 18-30 carbons with diphenyl oxide. Accordingly, a liquid crystal disrupter, or crystal structure breaker, is highly desirable as an additive for enabling useful viscosity in a useful HAA solids region (that is in an 60-95 percent solids range). In this regard, an additional component in the blend is most desirable which disrupts High Actives Acid (HAA) liquid crystal structure without imparting undesirable attributes to the resulting blend. In this regard, dimethylformamide (DMF) and methyl formamide (MF) effectively disrupt the liquid crystal structure in alkyl diphenyl oxide sulfonic acid blends used in deriving DOWFAX surfactants; but DMF and MF are not favored for use because of asserted health concerns. It has been discovered that addition of fatty acids, for instance, caprylic (octanoic) or launc acid, to highly concentrated surfactant sulfonic acid can greatly reduce the surfactant viscosity and improve handling characteristics of HAA. The use of such an additive to form particular blends enables the manufacture and use of concentrated acid forms of these surfactants. In an alternative embodiment, admixing the fatty acid with the alkyl diphenyl oxide prior to sulfonation also provides reduction of surfactant viscosity and improved handling characteristics in the HAA material Formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, and 8 dodecanoic (lauπc) acid all provide benefit in low viscosity HAA formulations as further described with reference to the sample data in the Examples and Figures. EXAMPLE 1 Samples containing straight-chain carboxylic acids from formic to launc acid were blended with a representative alkyl diphenyl oxide sulfonic acid surfactant with a 16-carbon hydrophobe side chain (DOWFAX Detergent Acid, 94 wt percent concentration) at levels of 10 wt percent carboxylic acid based upon DOWFAX amount. The viscosities of these samples were measured at 40 °C. The results are listed in Table 1 A Brookfield programmable rheometer, Model HDAV-III, was used to measure the viscosity of DOWFAX acid samples. The spindle size used was SC4-21 The viscosities of the samples were measured at 40 °C, a temperature at which the Thermosel temperature control stage was stable. Approximately 8 mLs of sample were placed into the rheometer chamber. The spindle was inserted into the chamber so that the sample covered to 1/8 inch of the spindle shaft The chamber was placed into the temperature control stage and the spindle connected to the rheometer. The rheometer was auto-zeroed. Stirring was started at 1 RPM and the sample was allowed to temperature equilibrate for ten minutes. After the ten minutes, the motor was stopped, the sample was allowed to sit for five minutes, then the motor was started again. A reading was taken after the spindle made 5 revolutions The stirring was increased and the torque recorded until the allowable torque range on the instrument was exceeded The equation below was used to convert torque to viscosity in units of cP Viscosity = 100/RPM * TK * SMC * Torque Torque constant (TK) = 2 Spindle Multiply Constant (SMC) = 5 TABLE 1 Structure - Viscosity Modification Attributes of Carboxylic Acid Additives in DOWFAX Detergent Surfactant [9.1 wt percent carboxylic acid, 85 5 wt percent DOWFAX Detergent, 5 4 wt percent water] Carboxylic Acid Viscosity, cP Common (Systematic) (@ 40 8 °C) Formic (methanoic) 7030 Acetic (ethanoic) 5847 Propanoic (propanoic) 4965 Butyric (butanoic) 5227 Valeric (pentanoic) 4970 Caproic (hexanoic) 6333 Enanthic (heptanoic) 6290 Capryhc (octanoic) 9360 Pelargonic (nonanoic) 9120 Capπc (decanoic) 15820 Laurie (dodecanoic) 18040 EXAMPLE 2 Samples containing a variety of concentrations (from 2 to 50 wt percent based upon DOWFAX acid amount) of a representative carboxylic acid, octanoic acid, were blended with a representative alkyl diphenyl oxide sulfonic acid surfactant with a 16-carbon hydrophobe side chain (DOWFAX Detergent Acid, or DD-HAA in Figures 1 and 2) at a variety of aqueous dilution levels (from 44 to 94 wt percent DOWFAX acid) Each sample was blended until homogeneous The viscosities of these samples were measured at 40 °C by the method indicated in Example 1 The results of these measurements are shown in Figures 1 and 2 Some of the samples (a) exhibited liquid crystal behavior with very high viscosities and (b) turned solid-like in consistency These samples typically exhibited viscosities exceeding the 10 upper measuring limit of the rheometer (1 ,000,000 cP), and these samples are shown as having viscosities of 1 ,000,000 cP in the Figures. The behavior of DOWFAX Detergent Acid containing no carboxylic acid ("0 wt percent OA") is shown for comparison purposes in both Figures 1 and 2. The onset of the liquid crystal phase in Figure 1 is apparent at the rapid rise of viscosity with decrease of solids in the 69 percent to 90 percent solids range (depending on the particular concentration of octanoic acid). Only at 30 percent octanoic acid is the liquid crystal phase evidently suppressed. EXAMPLE 3. Samples containing a variety of concentrations (from 2 to 30 wt percent) of four representative carboxylic acids (acetic, valeric, octanoic, and decanoic acids) each were blended with a representative alkyl diphenyl oxide sulfonic acid surfactant with a 16-carbon hydrophobe side chain (DOWFAX Detergent Acid, 94 wt percent concentration). Each sample was blended until homogeneous. The viscosities of these samples were measured at 40 °C by the method indicated in Example 1. The results of these measurements are shown in Figure 3. The behavior of DOWFAX Detergent Acid containing no carboxylic acid (at "0 wt percent additive concentration" on the graph) is shown for comparison. Comparison of the data for all acids at concentrations above 0 percent in Figure 3 with the 0 percent case help to further illustrate the general viscosity reducing influence of fatty acids on an HAA such as the tested DOWFAX Detergent Acid The data of Figure 3 indicate a higher significance of fatty acid chain length toward viscosity reduction at the 5 weight percent fatty acid concentration. EXAMPLE 4: Samples containing various ratios of either acetic or octanoic acid, as representative carboxylic acids, of a representative alkyl diphenyl oxide sulfonic acid surfactant with a 16- carbon hydrophobe side chain (DOWFAX Detergent Acid), and water were prepared. Each sample was blended until homogeneous. Gross visual examination of each sample was made to identify the presence of a solid-like, liquid crystal phase. Data defining the composition of samples exhibiting such a highly viscous phase were plotted on a ternary 1 1 phase diagram to ascertain the phase boundary. Boundary regions for blends with either acetic acid or octanoic acid are shown in Figure 4 The ternary phase diagram of Figure 4 shows significant liquid crystal phase regions for water, DOWFAX surfactant acid, and two fatty acids (acetic acid and octanoic acid). The phase boundary is indicated where the viscosity measures 1 million centipoise or greater at room temperature and pressure. The high viscosity area underscores the importance of the method of addition in admixing the alkyl diphenyl oxide sulfomc acid surfactant and fatty acid blend of the described embodiments with water. It should be noted successful combination of HAA with water requires attentiveness to the issue of progression in component concentration with respect to phase control according to the depiction of Figure 4 In this regard, an alkyl diphenyl oxide sulfonic acid surfactant acid / fatty acid admixture should be added to water in use of the highly concentrated HAA in creating a surfactant for use and sale; water should not be added to the alkyl diphenyl oxide sulfonic acid surfactant acid / fatty acid admixture in use of the highly concentrated HAA in creating a surfactant for use and sale. In this regard, with reference to Figure 4, the addition of water to the alkyl diphenyl oxide sulfonic acid surfactant acid / fatty acid admixture can function to induce substantive liquid crystal formation in the admixture and render the admixture too viscous for use since the dilution of HAA with water effects entry into the liquid crystal region. EXAMPLE 5: Octanoic acid at a 10 weight percent concentration based upon expected levels of DOWFAX Detergent Acid was added to aikylate during a sulfonation reaction A control reaction containing no octanoic acid under identical conditions yielded DOWFAX Detergent Acid exhibited a viscosity of 40,200 cP. The product of the sulfonation reaction containing the 10 weight percent octanoic acid had viscosity of 3,100 cP. The beneficial results from use of fatty acids in the described embodiments indicate that fatty alcohols, fatty amines, or even linear alkanes in the C 6 - C 18 range warrant consideration and empirical study in contemplated embodiment blends. 12 We claim: 1. A method for viscosity control in an alkyl diphenyl oxide sulfomc acid, characterized by the step of: admixing a fatty acid having a carboxylic chain length between 1 and 12 into the alkyl diphenyl oxide sulfonic acid blend to provide between 5 weight percentage and 50 weight percentage of fatty acid in the admixture. 2. A method for preparation of an alkyl diphenyl oxide sulfonic acid blend characterized by the steps of : admixing formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid to provide between 5 weight percentage and 50 weight percentage of fatty acid in an admixture with an alkyl diphenyl oxide characterized by where R is an alkyl radical having between 6 and 16 carbon atoms; and sulfonating said admixture with a sulfonating agent. 3. The method of Claim 2 wherein a plurality of said fatty acids are admixed in said admixing step with said alkyl diphenyl oxide blend. 4. A method for preparation of an alkyl diphenyl oxide sulfonic acid blend characterized by the steps of: admixing formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid to provide between 5 weight percentage and 50 weight percentage of fatty acid in an admixture with an alkyl diphenyl oxide sulfomc acid blend characterized by 13

Claims: where R is an alkyl radical having between 6 and 16 carbon atoms. 5. The method of Claim 4 wherein a plurality of said fatty acids are admixed admixed in said admixing step with said alkyl diphenyl oxide sulfonic acid blend. 6. The method of either of Claims 4 or 5 wherein the alkyl diphenyl oxide sulfonic acid blend prior to admixing of said fatty acid is characterized by: between 5 to 25 weight percent 14 between 75 to 95 respective weight percent greater than 85 weight percent 7. The method of either of Claims 2 or 3 wherein the alkyl diphenyl oxide blend prior to admixing of said fatty acid is characterized by: between 5 to 25 weight percent between 75 to 95 respective weight percent 15 8. An alkyl diphenyl oxide sulfomc acid blend having between 5 weight percentage and 50 weight percentage of a fatty acid with a carboxylic chain length between 1 and 12. 9. An admixture composition of: formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid to provide between 5 weight percentage and 50 weight percentage of fatty acid in the admixture composition; and alkyl diphenyl oxide characterized by where R is an alkyl radical having between 6 and 16 carbon atoms 10. The admixture composition of Claim 9 having a plurality of said fatty acids 11. An alkyl diphenyl oxide sulfomc acid blend characterized by: formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid to provide between 5 weight percentage and 50 weight percentage of fatty acid in the blend; and alkyl diphenyl oxide sulfomc acid characterized by 16 where R is an alkyl radical having between 6 and 16 carbon atoms. 12. The blend of Claim 11 having a plurality of said fatty acids. 13. The blend of either of Claims 11 or 12 wherein the alkyl diphenyl oxide sulfonic acid blend without consideration of the weight of said fatty acid is characterized by: between 5 to 25 weight percent 17 between 75 to 95 respective weight percent greater than 85 weight percent 14. The method of either of Claims 2 or 3 wherein the alkyl diphenyl oxide blend without consideration of the weight of said fatty acid is characterized by: between 5 to 25 weight percent between 75 to 95 respective weight 18 15. A method for preparation of a surfactant characterized by the steps of: admixing formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid to provide between 5 weight percentage and 50 weight percentage of fatty acid in an admixture with an alkyl diphenyl oxide characterized by where R is an alkyl radical having between 6 and 16 carbon atoms; sulfonating said admixture with a sulfonating agent; blending the sulfonated admixture into water; and neutralizing the blend of water and sulfonated admixture. 16. A method for preparation of a surfactant characterized by the steps of: admixing formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid to provide between 5 weight percentage and 50 weight percentage of fatty acid in an admixture with an alkyl diphenyl oxide sulfonic acid blend characterized by between 5 to 25 weight percent 19 between 75 to 95 respective weight percent greater than 85 weight percent blending the sulfonated admixture into water; and neutralizing the blend of water and sulfonated admixture; where R is an alkyl radical having between 6 and 16 carbon atoms. 20 VISCOSITIES OF AQUEOUS DILUTIONS OF DOWFAX DETERGENT CONTAINING VARIOUS LEVELS OF OCTANOIC ACID ADDITIVE 30 40 50 60 70 80 90 100 DD CONCENTRATION, WT % SOLIDS

Inventors: GALLAGHER TIMOTHY J, WALLICK DAVID E, GALLAGHER, TIMOTHY, J., WALLICK, DAVID, E.
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 2000
Main classification: B01F17
IPC codes: B01F17, C07C43, C07C53, C07C303, C07C309