WO2009038919A1

WO2009038919A1 - Methods of exchanging anions of tetraalkylammonium salts

Info

Publication number: WO2009038919A1
Application number: PCT/US2008/073583
Authority: WO
Inventors: Thanikavelu Manimaran; Alvin E. Harkins
Original assignee: Albemarle Corporation
Priority date: 2007-09-19
Filing date: 2008-08-19
Publication date: 2009-03-26
Also published as: CL2008002751A1; TW200920696A; AR070652A1

Abstract

Methods are provided for producing tetra-C1 -C20 alkyl or aryl-substituted Alkyl quaternary ammonium carbonates and bicarbonates. In methods of this invention, at least a tetra-C-1 -C20 alkyl or aryl-substituted alkyl quaternary ammonium bromide, a metal hydroxide, and a suitable solvent are combined, said metal hydroxide being present in a stoichiometric excess as to the quaternary ammonium bromide

Description

MONIUM SALT

BACKGROUND

[0001] The present invention relates to methods of exchanging the anion of a quaternary alkylammonium salt with a different anion, and more particularly to methods of exchanging the bromide ion of a quaternary tetraalkylammonium bromide with a different anion by removing the bromide ion as insoluble metal bromide. [0002] Quats are loosely defined as a group of compounds in which a nitrogen atom is joined to four organic radicals. Due to the net positive charge on the nitrogen atom in the quaternary ammonium compound, quats are always found associated with one or more anions. The associated anions are termed counterions, and the combination of the quaternary ammonium compound and the anion is termed a quat salt or "quat". [0003] Quats are a diverse group of compounds that find utility not only in the wood preservative/biocide industry, but also in such industries as hair care products, cleaning products, fabric softeners, pharmaceuticals, surfactants, deodorants, mouthwashes, preservatives, emulsifiers, cosmetics, and ore mining. Uses of quat compounds are described generally in U.S. Patent Nos. 3,301 ,815, 3,366,672, 4,365,030, and 4,444790, among others.

[0004] Methods for the production of quaternary ammonium compounds are generally known in the art. Basic chemistry texts teach that the end-product of the reaction of ammonia or of an amine with an alkyl halide is a quaternary ammonium salt. See, e.g., Noller, C. R., Textbook of Organic Chemistry, 2nd Ed., p.188 et seq., W. B. Saunders Co., Philadelphia (1961), and March, J., Advanced Organic Chemistry, 3rd Ed., pp.364, 365, John Wiley & Sons, New York (1985). Numerous other publications, for example U.S. Patent Nos. 5,308,363, 5,438,034, 5,523,487, 5,855,817, 6,784,317, 6,090,855, 6,485,790, and U.S. Patent Application Publication US 2003/0023108, report specific methods of producing quats having particular types of substituent groups and particular counter-anions.

[0005] Even in view of known methods for producing quats, there is a need for improved methods for production of quats, in particular, methods that are commercially applicable.

THE INVENTION

[0006] This invention meets the above-described needs by providing indirect synthesis methods that can be used to prepare a variety of tetra-Ci -C2₀ alkyl or aryl- su s i u e a y qua e compounds, e. ., di-Cs -C-₁₂, dimethyl alkyl quaternary ammonium carbonate and bicarbonate compounds. Methods of this invention comprise (a) combining at least a tetra-Ci -C₂o alkyl or aryl-substituted alkyl quaternary ammonium bromide, a metal hydroxide, and a solvent having a solubility of less than about 1 gram metal bromide per 1000 grams solvent, said metal hydroxide being present in a stoichiometric excess as to the quaternary ammonium bromide to produce at least a tetra-C-i -C₂o alkyl or aryl- substituted alkyl quaternary ammonium hydroxide; and (b) combining at least the tetra- Ci -C_2O alkyl or aryl-substituted alkyl quaternary ammonium hydroxide and carbon dioxide to produce at least tetra-Ci -C₂₀ alkyl or aryl-substituted alkyl quaternary ammonium carbonate. [0007] Applicants' methods can generally be illustrated as follows:

(!) - Xf(R¹ R²R³R⁴N)⁺]Br ^" + excess M(OH)_x + R⁵OH → x[(R¹R²R³R⁴N)⁺]OH + MBr_x + residual M(OH)_x + R⁵OH ; and

(II) - [(R¹R²R³R⁴N)⁺]OH^" + residual M(OH)_x + CO₂ + R⁵OH → [(R¹R²R³R⁴N)⁺]HCO₃ ^" +

[(R¹R²R³R⁴N)⁺I₂CO₃ ^2" + M₂(COs)_x + R⁵OH , wherein: the MBr_x in (I) and M₂(COs)_x in (II) precipitate in the solvent R⁵OH and are removed, e.g., by filtration; each of R¹, R², R³, and R⁴ is independently a Ci -C₂o alkyl or aryl-substituted alkyl group (e.g., R¹ and R² can be different Cs -C-₁₂ alkyl groups, and each of R³ and R⁴ can be methyl groups, etc.); R⁵ is a Ci -Ce alky! group; M is a mono-, bi-, or tri-valent metal, or an alkali metal; and x is 1 if M is monovalent, 2 if M is divalent, and 3 if M is trivalent. Thus, x is 1 for an alkali metal like Na or K. [0008] A Ci -C_2O alkyl or aryl-substituted alkyl, Ci -C₂o alkyl or aryl-substituted alkyl, dimethyl quaternary ammonium bromide can be combined with a stoichiometric excess of a metal hydroxide in a suitable solvent, e.g., a solvent having a solubility of less than about 1 gram metal bromide per 1000 grams solvent, to yield a Ci -C₂o alkyl or aryl- substituted alkyl, Ci -C₂o alkyl or aryl-substituted alkyl, dimethyl quaternary ammonium hydroxide intermediate in solution in the solvent. The hydroxy quat intermediate and residual metal hydroxide in solution are then combined with carbon dioxide to yield the carbonate/bicarbonate quat(s) and the insoluble metal carbonate. Suitable solvents include alcohols R⁵OH such as methanol, ethanol, isopropyl alcohol, propanol, butanol, isobutyl alcohol, and other Ci - C₆ alcohols. e . ., , , salicylate, oxalate, chloride, etc.) can be prepared from the intermediate ammonium hydroxide by combining with the corresponding acid.

[0010] Many Ci -C₂o alkyl or aryl-substituted alkyl, Ci -C₂o alkyl or aryl-substituted alkyl, dimethyl quaternary ammonium bromides are suitable reactants to prepare the intermediate hydroxy quat; for example, didecyldimethylammonium bromide is suitable.

The selections of the R¹ and R² substituents of the bromide quat reactant are determinative of the hydroxy quat intermediate, and therefore, of the carbonate quat product. Many other tetraalky quanternary ammonium bromides are also suitable for use in this invention, as will be known to those skilled in the art given the benefit of the teachings of this disclosure.

[0011] Exemplary methods are those wherein R¹ is a methyl, C₈ alkyl, C₉ isoalkyl, do alkyl, Ci₂ alkyl, Ci₄ alky!, Ci₆ alkyl, or benzyl group; R² is a Ci₀ alkyl, Ci₂ alkyl, Ci₄ alkyl, or C-₁₆ alkyl group; and each of R³ and R⁴ is a methyl group.

[0012] The metal hydroxide reactant can be a mono-, bi-, or trivalent metal hydroxide, or an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. The metal bromide first step reaction product will precipitate and is easily removed, i.e. by filtration or the like, yielding a hydroxy quat/solvent reaction product. The hydroxy quat can be separated therefrom by drying or the like, if desired.

[0013] The first reaction (I) can be conducted in a solvent which comprises a Ci -Ce alcohol, e.g., ethanol, or anhydrous ethanol. The reaction to form the hydroxy quat is typically an equilibrium reaction, but the use of a C₁ -C₆ alcohol solvent drives the reaction sharply to the hydroxy quat.

[0014] The amount of metal hydroxide reactant can be a stoichiometric amount with respect to the tetraalkyl quaternary ammonium bromide reactant. Therefore, on a theoretical basis and if the reaction were complete and unequilibrated, there would be no excess of metal hydroxide reactant upon completion of the intermediate reaction. In practice, yield when using a stoichiometric amount of metal hydroxide reactant will range from about 65% to about 95%, but will vary, dependent, in part, upon the particular metal hydroxide reactant.

[0015] Yield of the hydroxy quat can be further improved over conventional methods by utilization of a stoichiometric excess of metal hydroxide ranging from about 2% to about 50% excess. If an excess of metal hydroxide is used yield will be increased to from about 95% to about 99%, again varying as above. e unreac e me a y rox e s so u e in e y roxy qua so ven intermediate.

[0017] Hydroxy quat and any unreacted metal hydroxide can then be reacted with at least a stoichiometric equivalent of carbon dioxide to yield the quaternary ammonium carbonate(s), and if any unreacted metal hydroxide were present, the metal carbonate(s). The conversion of the metal hydroxide to the metal carbonate will proceed most rapidly of the two carbonations. The metal carbonate will precipitate and can be separated easily, i.e. by filtration or the like, leaving the stable carbonate/bicarbonate quat(s) or carbonate quat(s)/solvent reaction product. [0018] As illustrated, the carbonation step also produces the bicarbonate quat as a byproduct. The carbonate quat alone, or in combination with the bicarbonate quat, is suitable for use, e.g., in wood preservative systems. These carbonate quats or carbonate/bicarbonate quat compositions, do not require a metal coupler for stabilization in a wood substrate. Wood preservative systems can be metal-free. [0019] Mixing, adding, combining, and reacting of the components in the present invention can be accomplished by conventional means known to those of ordinary skill in the art. The order of addition of reactants or solvent in any individual step does not affect the method or process. Reactants and/or solvent can be added sequentially or simultaneously in any suitable reaction vessel. For example, the metal hydroxide may be dissolved in alcohol and the resultant mixture added to the bromide quat or the bromide quat may be dissolved in alcohol and the metal hydroxide added to the resultant mixture. Importantly, the method of the present invention is suitable for commercial scale production techniques and equipment, yet convenient for small scale work.

[0020] Typically, the reactants and solvent of the bromide quat to hydroxy quat reaction (I) will be stirred and heated to from about 2O⁰C. to about 70⁰C. and held at that temperature for a period of from about 1 hour to about 5 hours. The reaction mixture is then cooled, first to room temperature and then to about 0⁰C. where it is held for about 1 hour to about 2 hours. Any precipitated metal bromide is collected as is known in the art, i.e. such as by filtration.

[0021] An exemplary procedure according to this invention involves making a quaternary ammonium hydroxide solution by treating a quaternary ammonium bromide solution with KOH and precipitating KBr and converting the quaternary ammonium hydroxide in solution to the bicarbonate/carbonate. From the quaternary ammonium y roxi e in erme a e, severa o er qua ernary ammon um sa s e. p osp a es, carboxylates, other halides, etc.) can be prepared. 1- or 2-Butanol can be used as the solvent for making the quaternary ammonium bromide solution and water can be removed from the butanolic KOH solution in order to get low bromide values. While water is stripped off from the butanolic solution of KOH, KOBu is formed. The dried KOH solution is mixed with sub-stoichiometric amount (1.5 mol KOH/ mol bromide) of quaternary ammonium bromide solution to precipitate KBr. Quaternary ammonium butoxide/hydroxide solution is then treated with CO₂ gas to get the carboquat (carbonate/bicarbonate/butyl carbonate) solution in butanol. Excess KOH/KOBu in the ammonium hydroxide solution is precipitated as the carbonate with the CO₂ treatment and removed by filtration. Butanol from the carboquat solution is stripped off without water initially and then with water, treated with a small amount of 50% H₂O₂ to decolorize the yellow solution. The resultant clear carboquat solution (carbonate/bicarbonate) can then be diluted with enough water and 1 ,2-propanedioI to meet desired specifications.

[0022] Thus, in one aspect of this invention, a method is provided for preparing an about 50% aqueous tetra-Ci -C₂o alkyl or aryl-substituted alkyl substituted quaternary ammonium carbonate solution with low halide and good color. The method comprises (i) preparing a quaternary ammonium bromide solution from decyldimethylamine and 1- bromodecane in C₄ alcohol, (ii) azeotropically removing water from a butanolic solution comprising more than 1 mole of KOH/mole of quaternary ammonium salt with a suitable hydrocarbon such as hexane, (iii) combining the quaternary ammonium bromide solution from (i) and the butanolic solution from (ii) and removing precipitated KBr, e.g. by filtration, (iv) bubbling CO₂ gas through the solution obtained in (iii) to get carboquat solution in butanol after removing precipitated solids from excess KOH, and (v) solvent swapping carboquat solution from butanol to water followed by addition of 1 - 5 % hydrogen peroxide. Steps used to get low halide and good color include a) use of C₄ alcohol as the solvent, b) removal of water from alcoholic KOH solution and c) decolorization of the carboquat solution with hydrogen peroxide.

EXAMPLES

[0023] The following examples are illustrative of the principles of this invention. It is understood that this invention is not limited to any one specific embodiment exemplified herein, whether in the examples or the remainder of this patent application. EXAMPLE 1 - Preparation of Quaternary Ammonium Bromide Solution [0024] A dry 500 ml_ flask fitted with a condenser was charged with a mixture of 93g (0.5 mol) of N,N-dimethyldecylamine, 111g (0.5 mol) of 1-bromodecane and 135 g of 1-butanol. The mixture was heated to reflux using an electric mantle. Heating was turned off after 4 hrs. The clear light yellow solution of the quaternary ammonium bromide was analyzed, Analysis showed 12.7 wt% bromide, 0.19 wt% free amine and 59.4 wt% quaternary ammonium salt.

[0025] A solution of 93.5g (0.5 mol) of decyldimethylamine in 65g of 2-butanol was taken in a flask and heated to 105 C and stirred magnetically. 1-Bromodecane (111.5g) was added in drops over 2 hrs and the mixture heated at 105 C for additional 4 hrs. The clear yellow solution (269g) was analyzed and found to have 70.6 wt% quaternary salt, 13.27 wt% bromide and 0.88 wt% free amine.

EXAMPLE 2 - Preparation of Carboquat Solution in Butanol [0026] A 250 mL flask was charged with 10g (150 mmol) of potassium hydroxide pellets containing about 15 wt% water, 5Og of 1-butanol and 25g of hexane. The flask was fitted with a Dean-Stark trap and a reflux condenser. The mixture was refluxed and water removed as an azeotrope was collected in the trap. The mixture was refluxed till there was no increase of the aqueous phase in the trap. To this solution, 6Og (~90 mmol) of quaternary ammonium bromide solution was added in drops at ambient temperature and magnetically stirred. The mixture was then cooled in an ice- bath for an hour. Solids precipitated were filtered under suction and washed with 20 mL of hexane. The slightly turbid filtrate was filtered again to get a clear solution. Carbon dioxide gas was bubbled through this solution for an hour. Precipitated solids were removed by filtration through Whatman filter paper to get 100 g of a clear yellow solution of carboquat in 1-butanol. Analysis showed the carboquat solution had 33.2% quaternary ammonium salt and 345 ppm of bromide.

EXAMPLE 3 - Preparation of Aqueous Carboquat Solution

[0027] A 106g sample of a carboquat solution (34.8 wt%) in 1-butanol containing 230 ppm of bromide was taken in a 500 mL flask and concentrated to about 6Og under vacuum at 70 C using a rotary evaporator. Deionized water (4Og) and 1 ,2-propanediol

(6g) were added to the mixture and concentrated to about 65g using the rotary evapora or. i u ion wi g o wa er an concen ra ion o a ou g was repea e three times. The resulting pale yellow solution was mixed with 3 g of 50 wt% hydrogen peroxide solution and diluted with water to 74g. The clear colorless solution obtained had a Gardner color of 1 and contained 294 ppm of bromide (130 ppm as chloride) and 51.0 wt % of quaternary ammonium salt. Specification for carboquat: Quaternary Salt = 48.5 to 51.5 wt%; Gardner Color = <4; Halide = <300 ppm as chloride.

[0028] It is to be understood that the reactants and components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to being combined with or coming into contact with another substance referred to by chemical name or chemical type (e.g., another reactant, a solvent, or etc.). It matters not what chemical changes, transformations and/or reactions, if any, take place in the resulting combination or solution or reaction medium as such changes, transformations and/or reactions are the natural result of bringing the specified reactants and/or components together under the conditions called for pursuant to this disclosure. Thus the reactants and components are identified as ingredients to be brought together in connection with performing a desired chemical reaction or in forming a combination to be used in conducting a desired reaction. Accordingly, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense ("comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, combined, blended or mixed with one or more other substances, components and/or ingredients in accordance with the present disclosure. Whatever transformations, if any, which occur in situ as a reaction is conducted is what the claim is intended to cover. Thus the fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, combining, blending or mixing operations, if conducted in accordance with this disclosure and with the application of common sense and the ordinary skill of a chemist, is thus wholly immaterial for an accurate understanding and appreciation of the true meaning and substance of this disclosure and the claims thereof. As will be familiar to those skilled in the art, the terms "combined", "combining", and the like as used herein mean that the components that are "combined" or that one is "combining" are put into a container with each other.

Likewise a "combination" of components means the components having been put oge er n a con a ner.

[0029] While the present invention has been described in terms of one or more preferred embodiments, it is to be understood that other modifications may be made without departing from the scope of the invention, which is set forth in the claims below.

Claims

What is claimed is:

1. A method of preparing at least a tetra-Ci -C₂₀ alkyl or aryl-substituted alkyl substituted quaternary ammonium carbonate, comprising:

(a) combining at least a tetra-Ci -C-2₀ alkyl or aryl-substituted alkyl quaternary ammonium bromide, a metal hydroxide, and a solvent having a solubility of less than about 1 gram metal bromide per 1000 grams solvent, said metal hydroxide being present in a stoichiometric excess as to the quaternary ammonium bromide to produce at least a tetra-Ci -C₂o alkyl or aryl-substituted alkyl quaternary ammonium hydroxide; and

(b) combining at least the tetra-C-i -C₂o alkyl or aryl-substituted alkyl quaternary ammonium hydroxide and carbon dioxide to produce at least the tetra-C_ϊ -C₂o alkyl or aryl-substituted alkyl quaternary ammonium carbonate.

2. The method of claim 1 wherein the solvent comprises a Ci -Ce alcohol.

3. The method of claim 1 wherein the solvent comprises methanol, ethanol, isopropyl alcohol, propanol, butanol, or isobutyl alcohol.

4. The method of claim 1 wherein at least one tetra-Ci -C₂o alkyl or aryl-substituted alkyl quaternary ammonium bicarbonate is also produced.

5. A method of preparing at least a di-Ci -C₂o alkyl or aryl-substituted alkyl substituted dimethyl quaternary ammonium carbonate, comprising:

(a) combining at least a di-Ci -C₂o alkyl or aryl-substituted alkyl substituted dimethyl quaternary ammonium bromide, a metal hydroxide, and a solvent having a solubility of less than about 1 gram metal bromide per 1000 grams solvent, said metal hydroxide being present in a stoichiometric excess as to the quaternary ammonium bromide to produce at least a di-Ci -C₂o alkyl or aryl-substituted alky! substituted dimethyl quaternary ammonium hydroxide; and (b) combining at least the di-Ci -C₂o alkyl or aryl-substituted alkyl substituted dimethyl quaternary ammonium hydroxide and carbon dioxide to produce at least the di-Ci -C₂o alkyl or aryl-substituted alkyl substituted dimethyl quaternary ammonium carbonate.

6. The method of claim 5 wherein the solvent comprises a Ci -C₆ alcohol.

7. The method of claim 5 wherein the solvent comprises methanol, ethanol, isopropyl alcohol, propanol, butanol, or isobutyl alcohol.

8. The method of claim 5 wherein at least one di-Ci -C₂o alkyl or aryl-substituted alkyl substituted dimethyl quaternary ammonium bicarbonate is also produced.

9. A method for preparing an about 50% aqueous tetra-Ci -C₂Q alkyl or aryl-substituted alkyl substituted quaternary ammonium carbonate solution comprising:

(i) preparing a quaternary ammonium bromide solution from decyldimethylamine and 1 -bromodecane in C₄ alcohol,

(ii) azeotropicaily removing water from a butanolic solution comprising more than 1 mole of KOH/mole of quaternary ammonium salt with a suitable hydrocarbon such as hexane,

(iii) combining the quaternary ammonium bromide solution from (i) and the butanolic solution from (ii) and removing precipitated KBr, e.g. by filtration,

(iv) bubbling CO₂ gas through the solution obtained in (iii) to get carboquat solution in butanol after removing precipitated solids from excess KOH, and

(v) solvent swapping carboquat solution from butanol to water followed by addition of 1 - 5 % hydrogen peroxide to produce at least the about 50% aqueous tetra- Ci -C_2O alkyl or aryl-substituted alkyl substituted quaternary ammonium carbonate solution.

10. The method of claim 9 wherein at least one tetra-Ci -C₂₀ alkyi or aryl-substituted alky! substituted quaternary ammonium bicarbonate is also produced.