Patent Application
20100010251
The present invention relates to a process for the preparation of alkoxysulfates.
A large variety of products useful, for instance, as surfactants and chemical intermediates are prepared by the alkoxylation and subsequent sulfation of compounds having one or more nucleophilic groups. These include alkoxysulfates according to general formula (I).
In the general formula (I) R refers to any suitable group or groups, and X refers to oxygen, nitrogen or sulfur, such that R—XH is a nucleophile. R1 and R2 are, independently, hydrogen or an alkyl group and n corresponds to the number of alkoxy groups present in the molecule. Such a formula may also be used to indicate a mixture of alkoxysulfates. In this case, n refers to the average number of alkoxy groups per molecule. M is a metal.
Related compounds, of general formula (II), based on tertiary amines, are also of interest (see G. Jakobi and A. Löhr, Detergents and Textile Washing, Principles and Practice, VCH Publishers, Weinheim, Germany, 1987). These compounds, of general formula (II) are of use as zwitterionics or general amphoteric surfactants in household detergents and in enhanced oil recovery (EOR). In general formula (II) R0—N refers to a tertiary amine. Such molecules are not simple to produce using standard chemical methods.
Generally such molecules, or mixtures of molecules, of general formula (I) are produced by reacting the parent nucleophile or mixture of nucleophiles (general formula III), with a number of equivalents of the relevant alkylene oxide(s), in the presence of a catalyst, in order to produce a mixture of alkoxylates (general formula IV) containing an average number of alkoxy groups, n. The resultant alkoxylates can then be sulfated to provide the desired alkoxysulfate product mixture (I). Again, this product will be a mixture of compounds containing an average number of alkoxy groups, n.
The range of alkoxylates formed in the above-described alkoxylation reactions will depend on the starting material nucleophile(s) and the conditions and catalysts used for the alkoxylation. Known catalysts for alkoxylation include basic metal hydroxide compounds, such as potassium hydroxide. Acidic catalysts, such as Lewis acid and Brønsted acid catalysts are also known as alkoxylation catalysts. Alkoxylation processes catalyzed by phosphate salts of the rare earth elements have also been described in the art (e.g. U.S. Pat. No. 5,057,627 and WO 02/047817). A further class of alkoxylation catalysts comprises the so-called double metal cyanide catalysts described in WO01/04183 and WO02/42356.
In any product distribution of a particular average, n, there will be some products that are more desirable than others for a specific application. For certain applications, it is, therefore, often desirable to provide a product distribution with as narrow a range of n values as possible.
Alkoxy groups are included in detergent molecules in order to improve detergent properties, in particular to increase the calcium tolerance of a specific detergent.
The number, n, of alkoxy groups present will affect the detergent properties and a specific product (i.e. with a specific value or average value of n) may, therefore, be tailored around the requirements of the product. In many cases, it is desirable to form compounds of general formula (I) in which n is low, preferably 3 or below, and most preferably 1. These latter, most preferred, compounds are usually made by reacting the parent nucleophile, such as an alcohol, with the relevant alkylene oxide in an approximately 1:1 ratio in the presence of a catalyst. However, all such known processes lead to the formation of a distribution of products containing high levels of non-alkoxylated products as well as a range of products in which n is greater than 1, the levels and ranges being dependent on the character of the starting nucleophile, the alkoxylation reaction conditions and the nature of the employed alkoxylation catalyst.
The problems involved in the alkoxylation of nucleophiles are even more pronounced when the starting nucleophile, or mixture of nucleophiles, comprises one or more secondary or tertiary alcohol(s), and particularly so when the alkylene oxide is ethylene oxide. The product of the ethoxylation of a secondary or tertiary alcohol is a primary alcohol. Such a product is inherently more reactive than the parent secondary or tertiary alcohol. Therefore, when alkoxylating such an alcohol with approximately one equivalent of ethylene oxide, the product mixtures of alkoxylates, and thus, after sulfation, the alkoxysulfates, will contain relatively high levels of compounds where n is greater than 1 and also a large amount of product where n is 0 and a relatively low amount of the desired (n=1) product.
Sulfation of alkoxylates is generally carried out by reaction with SO3 in a falling film reactor, leading to the formation of alkoxysulfates (I). When sulfating the products of an alkoxylation reaction, the sulfation product will be a mixture of alkoxysulfates with a distribution of n values and will also contain sulfate(s), formed by sulfation of the residual (or unreacted) alcohol(s) present in the alkoxylation product mixture. The presence of the latter component(s) (i.e. formula (I), where n=0, X=oxygen) in the product mixture can be detrimental in terms of product characteristics such as calcium tolerance and, hence, detergency performance and also handleability, due to the high Krafft point and high melting point of the alcohol sulfate.
The formation of 1,4-dioxanes (also known as p-dioxanes) during sulfation is another problem encountered in the production of alkoxysulfates, limiting the flexibility of this process. The presence of the noxious p-dioxane is non-desirable in detergents, particularly in personal care products, such as shampoos. By the use of a falling film sulfation reactor and a swift and thorough neutralization technique the residence times of the alkoxylate and alkoxysulfate in (Lewis) acidic medium can be kept to a minimum. Hereby the SO3-catalyzed backbiting of the alkoxylate chain can be overcome, but only at an increased production cost.
Furthermore, the sulfation of alkoxylates of general formula (IV), wherein X is oxygen, particularly if the parent alcohol (III) is a secondary or a tertiary alcohol, and wherein R1 is hydrogen or an alkyl group and R2 is an alkyl group, by SO3 is difficult as it may give rise to olefin and sulfuric acid formation due to the occurrence of an acid-catalyzed elimination reaction. Such products are also undesirable constituents of the final product mixture.
It would be desirable to provide an alkoxysulfate composition of the general formula (I) or (II), wherein n is a low number, preferably 3 or below, and most preferably 1, and wherein said composition comprises a reduced amount of the by-products usually associated with the production of alkoxysulfates from nucleophiles, such as alcohols, by a two-step alkoxylation/sulfation process.
Furthermore, it would be desirable to provide a simple route to compounds of general formula (II).
Alkylene sulfates are known in the art as synthetic reagents in the preparation of surfactant molecules.
WO 96/35663 describes the preparation of oligomeric alkylene sulfates using ethylene sulfate.
Gautun, 0. R., et al. Acta Chemica Scandinavica, 1996, 50, 170-177 discloses the selective synthesis of aliphatic ethylene glycol sulfonates. This document describes the use of ethylene sulfate as a replacement for ‘epoxide synthons’ in the iterative addition of alkoxy groups in a surfactant molecule.
A similar use of ethylene sulfate is described in both Rist, Ø., et al. Molecules, 2005, 10, 1169 and Rist, Ø., et al. Synthetic Communications, 1999, 29(5), 749-754.
Known methods for alkoxysulfation using alkylene sulfates generally require the deprotonation of the organic compound having one or more active hydrogen atoms with a reagent such as sodium or sodium hydride. These reagents are expensive and difficult to handle. The present inventors have also found that reactions using these materials, in solvent systems known in the art, are generally low yielding.
It would, therefore, be desirable to provide an improved process for the alkoxysulfation of nucleophilic organic compounds using alkylene sulfates.
A process for the preparation of alkoxysulfates from organic compounds containing one or more nucleophilic groups by reacting said organic compound, in a water-miscible solvent selected from the group consisting of sulfur-containing solvents such as dimethylsulfoxide (DMSO) or sulfolane, or polar solvents such as tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMA) and hexamethylphosphoric triamide (HMPT), with an alkylene sulfate, in a non-water-miscible solvent selected from the group consisting of chlorinated solvents such as methylene chloride, chloroform, carbon tetrachloride, trichloroethane or chlorinated aromatics, such as chlorobenzene or dichlorobenzene, and non-chlorinated aromatics, such as toluene or xylenes, in the presence of a base selected from the group consisting of hydroxides, carbonates and hydrogen carbonates of alkali metals or alkaline earth metals.
It has now surprisingly been found that the reaction of alkylene sulfates with organic compounds containing one or more nucleophilic groups, including those having one or more active hydrogen atoms, can be improved by carrying out the reaction in a two-phase system such that the organic compound containing one or more nucleophilic groups, is dissolved in a water-miscible solvent and the alkylene sulfate is dissolved in a non-water-miscible solvent. Such a reaction system allows the reaction to be carried out in the presence of a cheap and easily handleable base selected from the group consisting of hydroxides, carbonates and hydrogencarbonates of alkali metals or alkali earth metals.
The term ‘alkylene sulfate’ as used herein refers to compounds of the general formula (V).
In general formula (V), R1 and R2 may be the same or different and are each, independently, selected from the group consisting of hydrogen and alkyl groups.
Typically, R1 and R2 are selected from the group consisting of hydrogen and short-chain alkyl groups. However, alkylene sulfates containing longer chain alkyl groups, such as those described in Rist, Ø., et al, Molecules, 2005, 10, 1169, which is herein incorporated by reference, may also be used.
As used herein, short-chain alkyl groups refers to alkyl groups of in the range of from 1 to 4 carbon atoms, preferably in the range of from 1 to 3 carbon atoms, more preferably in the range of from 1 to 2 carbon atoms, most preferably 1 carbon atom.
The choice of alkylene sulfate depends on the alkoxysulfate to be produced. Preferably, the alkylene sulfate is one in which R1 is hydrogen and R2 is hydrogen or a short chain alkyl group, more preferably R1 is hydrogen and R2 is hydrogen or a short chain alkyl group of in the range of from 1 to 2 carbon atoms. Most preferably, the alkylene sulfate is ethylene sulfate, i.e. R1 and R2 are both hydrogen, or 1,2-propylene sulfate, i.e. R1 is hydrogen and R2 is methyl.
Such alkylene sulfates may be produced by any method known in the art. A suitable method is described in FR 2664274, which is herein incorporated by reference.
The alkoxysulfates of the present invention are of the general formula (I) or (II).
In the general formula (I) R refers to any suitable group or groups, and X refers to oxygen, nitrogen or sulfur, such that R—XH is a nucleophilic organic compound containing one or more active hydrogen atoms, and M is a metal. R0—N is a tertiary amine and thus R0 refers to three groups. These groups may be the same or different and may be any group as defined herein for R. R1 and R2 are as defined above. Preferably, R refers to a group having a linear or branched hydrocarbyl backbone. Such a hydrocarbyl backbone, or the branches thereof, may contain non-hydrocarbyl substituents, such as groups containing oxygen, nitrogen or sulfur atoms.
The nucleophilic organic compounds of general formula (III) (R—XH) suitably utilized in the process of the present invention include (but are not necessarily limited to) alcohols, phenols, thiols (mercaptans), amines, polyols, carboxylic acids, carboxylic acid amides, and mixtures thereof. Generally, X represents either an oxygen, sulfur or (substituted, e.g. amino) nitrogen atom.
Among the suitable carboxylic acids, particular mention may be made of the mono- and dicarboxylic acids, both aliphatic (saturated and unsaturated) and aromatic, and their carboxylic acid amide derivatives. Specific examples include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, rosin acids, tall oil acids and terephthalic acid, and their carboxylic acid amide derivatives.
Among the suitable amines, particular mention may be made of primary, secondary and tertiary alkylamines and of alkylamines containing both amino and hydroxyl groups, e.g. N′N-di(n-butyl)-ethanol amine and tripropanolamine.
Among the suitable thiols, particular mention may be made of primary, secondary and tertiary alkane thiols having from 9 to 30 carbon atoms, particularly those having from 9 to 20 carbon atoms. Specific examples of suitable tertiary thiols are those having a highly branched carbon chain which are derived via hydrosulfurization of the products of the oligomerization of lower olefins, particularly the dimers, trimers, tetramers and pentamers of propylene and the butylenes. Secondary thiols are exemplified by the products of the hydrosulfurization of the substantially linear oligomers of ethylene as are produced by the Shell Higher Olefins Process (SHOP process). Representative, but by no means limiting, examples of thiols derived from ethylene oligomers include the linear carbon chain products, such as 2-decanethiol, 3-decanethiol, 4-decanethiol, 5-decanethiol, 3-dodecanethiol, 4-decanethiol, 5-decanethiol, 3-dodecanethiol, 5-dodecanethiol, 2-hexadecanethiol, 5-hexadecanethiol, and 8-octadencanethiol, and the branched carbon chain products, such as 2-methyl-4-tridecanethiol. Primary thiols are typically prepared from terminal olefins by hydrosulfurization under free-radical conditions and include, for example, 1-dodecanethiol, 1-tetradecanethiol and 2-methyl-1-tridecanethiol.
Among the phenols, particular mention may be made of phenol and alkyl-substituted phenols wherein each alkyl substituent has from 3 to 30 (preferably from 3 to 20) carbon atoms, for example, p-hexylphenol, nonylphenol, p-decylphenol, nonylphenol and didecyl phenol.
In a preferred embodiment, the nucleophilic organic compound (R—XH) is a hydroxyl-containing reactant.
In another preferred embodiment, the nucleophilic organic compound (R—XH) is selected from alcohols and carboxylic acid amides, and mixtures thereof.
The most preferred the nucleophilic organic compounds (R—XH) herein are alcohols. Suitable starting alcohols for use in the preparation of an alkoxylated alcohol composition herein include those known in the art for reaction with alkylene oxides and conversion to alkoxylated alcohol products, including both mono- and poly-hydroxy alcohols.
Acyclic aliphatic mono-hydric alcohols (alkanols) form a most preferred class of reactants, particularly the primary alkanols, although secondary and tertiary alkanols are also very suitably utilized in the process of the present invention. It is particularly useful to be able directly to form alkoxysulfates of secondary alcohols since secondary alcohols can be derived from relatively cheap feedstocks such as paraffins (by oxidation) or from short chain C6-C10 primary alcohols (by propoxylation). Suitable paraffins for producing secondary alcohols are, for example, those produced from Fischer-Tropsch technologies.
Preference can also be expressed for alcohols (R—OH) having from 9 to 30 carbon atoms, with C9 to C24 alcohols considered more preferred and C9 to C20 alcohols considered most preferred, including mixtures thereof, such as a mixture of C9 and C20 alcohols. As a general rule, the alcohols may be of branched or straight chain structure depending on the intended use. In one embodiment, preference further exists for alcohol reactants in which greater than 50 percent, more preferably greater than 60 percent and most preferably greater than 70 percent of the molecules are of linear (straight chain) carbon structure. In another embodiment, preference further exists for alcohol reactants in which greater than 50 percent, more preferably greater than 60 percent and most preferably greater than 70 percent of the molecules are of branched carbon structure.
Commercially available mixtures of primary monohydric alcohols prepared via the oligomerisation of ethylene and the hydroformylation or oxidation and hydrolysis of the resulting higher olefins are particularly preferred. Examples of commercially available alcohol mixtures include the NEODOL (NEODOL, as used throughout this text, is a trademark) alcohols, sold by Shell Chemical Company, including mixtures of C9, C10 and C11 alcohols (NEODOL 91 alcohol), mixtures of C12 and C13 alcohols (NEODOL 23 alcohol), mixtures of C12, C13, C14 and C15 alcohols (NEODOL 25 alcohol), and mixtures of C14 and C15 alcohols (NEODOL 45 alcohol, and NEODOL 45E alcohol); the ALFOL (ALFOL is a trademark) alcohols (ex. Vista Chemical Company), including mixtures of C10 and C12 alcohols (ALFOL 1012), mixtures of C12 and C14 alcohols (ALFOL 1214), mixtures of C16 and C18 alcohols (ALFOL 1618), and mixtures of C16, C18 and C20 alcohols (ALFOL 1620), the EPAL (EPAL is a trademark) alcohols (Ethyl Chemical Company), including mixtures of C10 and C12 alcohols (EPAL 1012), mixtures of C12 and C14 alcohols (EPAL 1214), and mixtures of C14, C16 and C18 alcohols (EPAL 1418), and the TERGITOL-L (Tergitol is a trademark) alcohols (Union Carbide), including mixtures of C12, C13, C14 and C15 alcohols (TERGITOL-L 125). Also suitable for use herein is NEODOL 1, which is primarily a C11 alcohol. Also very suitable are the commercially available alcohols prepared by the reduction of naturally occurring fatty esters, for example, the CO and TA products of Proctor and Gamble Company and the TA alcohols of Ashland Oil Company.
As mentioned above, secondary alcohols are also a preferred class of reactants for use herein. Examples of secondary alcohols suitable for use herein include 2-undecanol, 2-hexanol, 3-hexanol, 2-heptanol, 3-heptanol, 2-octanol, 3-octanol, 2-nonanol, 2-decanol, 4-decanol, 2-dodecanol, 4-tridecanol, 2-tetradecanol, 2-hexadecanol, 2-octadecanol and mixtures thereof.
Mixtures of alcohols comprising primary and secondary alcohols are also suitable for use herein.
In particular, oxidation products arising from Fischer-Tropsch derived paraffins (which may include mixtures of primary and secondary alcohols), as described in WO2009/058654, which is herein incorporated by reference, are particularly suitable for use herein.
In one embodiment of the present invention R—XH may be an alcohol (i.e. X=oxygen) and comprise one or more polyether chain(s), such as present in polyalkylene glycols, e.g. glycerol-based polypropylene glycols. The present invention is particularly useful for the preparation of compounds with one or more mono-ethoxylated polypropylene glycol chain(s), which can be formed by the hydrolysis of the alcohol ethoxysulfate(s) formed by reaction of the compounds having one or more polypropylene glycol chain(s) with ethylene sulfate.
In a particularly preferred embodiment of the present invention, R comprises a linear or branched hydrocarbyl backbone containing no non-hydrocarbyl substituents.
Regardless of the composition of R, R—XH may be a primary, secondary or tertiary nucleophilic organic compound. It is of particular advantage to apply the present invention when R—XH is a secondary or tertiary, preferably secondary, alcohol.
As stated above, when the nucleophile is a tertiary amine of the formula R0—N, R0 refers to any three groups as defined herein for R, with the proviso that R0—N is a tertiary amine. Tertiary amines of particular interest include tri-alkyl amines, where each alkyl group may be the same or different. Preferably, each alkyl group contains in the range of from 1 to 20 carbon atoms. In one particularly preferred group of trialkylamines the nitrogen atom is substituted with two methyl groups and one alkyl group containing 12 to 18 carbon atoms.
As used herein, M refers to a metal. Preferably the metal is an alkali metal, even more preferably the metal is selected from sodium, lithium and potassium, most preferably the metal is sodium.
In a further embodiment of the present invention, R—XH may be of general formula (VI). That is R—XH comprises a nucleophilic organic compound containing an active hydrogen atom, which has already been alkoxylated.
Herein, R3 refers to any suitable group, such that R3—XH is a nucleophilic organic compound having one or more active hydrogen atoms. The skilled person will readily understand that in this embodiment, R3—XH may be any organic compound as defined above for R—XH, with the exception, of course, of the embodiment wherein R3—XH is of the general formula (VI).
R4 and R5 are each, independently, hydrogen or an alkyl group, preferably hydrogen or a short-chain alkyl group. As used herein, short-chain alkyl groups refers to alkyl groups of between 1 and 4 carbon atoms, preferably between 1 and 3 carbon atoms, more preferably between 1 and 2 carbon atoms, most preferably 1 carbon atom. Preferably, R4 is hydrogen and R5 is selected from the group consisting of hydrogen and a short-chain alkyl group having between 1 and 2 carbon atoms (i.e. an methyl or ethyl group).
As used herein, the number m corresponds to the number of alkoxy groups present per molecule and is preferably in the range of from 1 and 70, more preferably in the range of from 1 and 50, even more preferably in the range of from 1 to 20. Alternatively, general formula (V) may be used to indicate a mixture of compounds. In this case, m refers to the average number of alkoxy groups per molecule and may be any number greater than zero and no more than 70, preferably no more than 50, even more preferably no more than 20.
In each case, the number of alkoxy groups (m) may refer to a single type of alkoxy group or a mixture of two or more alkoxy groups. Such a mixture of alkoxy groups may include both random and block co-polymers of the alkoxy groups.
The process of the present invention provides a method for the preparation of alkoxysulfates containing a reduced level of at least one undesirable by-product, that is the level of one or more of the by-products usually associated with a two-step alkoxylation/sulfation process for the formation of alkoxysulfates from the corresponding organic compounds having one or more active hydrogen atoms. Such by-products include the residual (also known as unconverted or free) organic compounds having one or more nucleophilic groups themselves, the sulfates thereof (i.e. compounds of general formula (I), wherein n=0) and 1,4-dioxanes, e.g. depending on the nature of the alkoxylate chain 2,3,5,6-tetraalkyl-1,4-dioxane, 2,5-dialkyl-1,4-dioxane or 1,4-dioxane. The latter noxious compound, 1,4-dioxane (also known as p-dioxane), may be formed upon acid-catalyzed ethoxylation and/or upon sulfation of a terminal ethoxylate.
Preferably the amount of residual (free) organic compound having one or more nucleophilic groups in the alkoxysulfate composition prepared herein is no more than 40%, preferably no more than 30%, more preferably no more than 20%, even more preferably no more than 10% by weight of the alkoxysulfate composition.
Preferably, the level of 1,4-dioxanes, i.e. depending on the nature of the alkoxylate chain 2,3,5,6-tetraalkyl-1,4-dioxane, 2,5-dialkyl-1,4-dioxane or 1,4-dioxane, present in the alkoxysulfate composition prepared herein is no more than 100 ppm, preferably no more than 10 ppm, more preferably no more than 5 ppm by weight of the alkoxysulfate composition.
In the process of the present invention, the organic compound containing one or more nucleophilic groups, is dissolved in a water-miscible solvent, selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMA), hexamethylphosphoric triamide (HMPT) and sulfur-containing solvents. Preferably, the water-miscible solvent is selected from the group consisting of sulfur-containing solvents. More preferably, the water-miscible solvent is selected from the group consisting of sulfur-containing solvents, which comprise a sulfoxide or sulfone group. Even more preferably, the water-miscible solvent is selected from the group consisting of DMSO and sulfolane. Most preferably, the water-miscible solvent is DMSO.
The required alkylene sulfate is dissolved in a non-water-miscible solvent, selected from those in the group consisting of chlorinated solvents such as methylene chloride, chloroform, carbon tetrachloride, trichloroethane or chlorinated aromatics, such as chlorobenzene or dichlorobenzene, and non-chlorinated aromatics, such as toluene or xylenes. Preferably, the non-water-miscible solvent is selected from the group consisting of chlorinated hydrocarbons, such as methylene chloride, chloroform and trichloroethane. More preferably the non-water-miscible solvent is selected from the group consisting of methylene chloride and chloroform. Most preferably, the non-water-miscible solvent is methylene chloride.
The base may be selected from the group consisting of hydroxides, carbonates and hydrogen carbonates of alkali metals or alkaline earth metals. It is particularly convenient if the base is selected from alkali metal hydroxides, which are cheap, easy to handle and readily available. Preferably, the base is selected from sodium, lithium or potassium hydroxide. Most preferably, the base is sodium hydroxide.
The process of the present invention may be carried out by first adding the base to the organic compound having one or more active hydrogen atoms and dissolved in a water-miscible solvent. The base and the organic compound may then be reacted together for a period of time of at least 10 minutes, preferably at least 20 minutes, more preferably at least 30 minutes. The period of time is suitably no more than 10 hours, preferably no more than 5 hours, even more preferably no more than 2 hours. Such a process will effect at least partial deprotonation of an organic compound having at least one active hydrogen atom.
In this embodiment of the reaction, the alkylene sulfate dissolved in a non-water-miscible solvent is then added to the mixture of the base and the organic compound having one or more active hydrogen atoms dissolved in a water-miscible solvent. The addition may occur as one single addition or it may occur portion-wise or drop-wise.
In an alternative embodiment of the present invention, the organic compound having one or more active hydrogen atoms and dissolved in a water-miscible solvent is mixed with the alkylene sulfate dissolved in a non-water-miscible solvent and then the base is added to the mixture.
The reaction may be carried out at any suitable temperature or pressure. Preferably, the reaction is carried out at a temperature of at least −10° C., more preferably at least 0° C., even more preferably at least 10° C. Preferably, the reaction is carried out at a temperature of at most 100° C., more preferably at most 70° C., even more preferably at most 40° C.
Preferably, the reaction is carried out at a pressure of at least 10 kPa, more preferably at least 25 kPa, even more preferably at least 50 kPa. Preferably, the reaction is carried out at a pressure of at most 500 kPa, more preferably at most 250 kPa, even more preferably at most 150 kPa
In a most preferred embodiment the reaction is carried out at ambient temperature and atmospheric pressure.
Reaction of an organic compound containing one or more nucleophilic groups with an alkylene sulfate, according to the present invention, will predominantly form the alkoxysulfate according to general formula (I) or (II), wherein n=1. Thus, when applying the present invention, the formation of a distribution of molecules is avoided, and a single step procedure is used to replace a two-step procedure comprising two problematic reaction steps.
Furthermore, the reaction is carried out using bases that are cheap, readily available and easy to handle.
Following formation of the alkoxysulfate(s) according to the present invention, further chemical transformations may be carried out. For example, the alkoxysulfate(s) may be converted to alkoxysulfonates by reaction with sodium sulfite, or the alkoxysulfate(s) may be subjected to hydrolysis under acidic or neutral conditions to form alkoxylate(s).
The present invention will now be illustrated by the following non-limiting examples.
NEODOL 45, a C14/C15 primary alcohol composition, is commercially available from The Shell Chemical Company. NEODOL 67, a C16/C17 primary alcohol composition is commercially available from The Shell Chemical Company). Heavy Detergent Feedstock—HDF is a C14-C18 paraffin (GC analysis gives typically 25 wt % tetradecane, 24 wt % pentadecane, 23 wt % hexadecane, 21 wt % heptadecane and 6 wt % octadecane, of which approximately 7 wt % are predominantly methyl-branched C14-C19 paraffins; GC×GC analysis gives 240 mg/kg total mono-naphthenes, 0 mg/kg total di-naphthenes and 10 mg/kg total mono-aromatics).
The use of sodium hydride in a variety of inert solvents such as dimethylformamide (DMF), tetrahydrofuran (THF), acetonitrile, p-dioxane has been reported to give generally satisfactory conversions for ethoxysulfation of alcohols (also known as ethylsulfation), although low conversions have also been observed and reported for one type of primary alcohol by Rist, Ø., et al., Molecules, 2005, 10, 1169. We have surprisingly found the (relatively expensive) reagent sodium hydride (NaH) gave generally low-moderate yields (10-40%) in the ethoxysulfation of primary and secondary alcohols such as NEODOL 45, NEODOL 67, and the mixture of secondary alcohols derived from C14-C18 paraffin, also known as Heavy Detergent Feedstock (HDF).
NEODOL 23, a C12/C13 primary alcohol composition, is commercially available from The Shell Chemical Company. Hexadecanol and 2-undecanol are available from Aldrich and 4-tridecanol is available from Chemical Samples Co, Columbus, Ohio, USA.
Comparative Examples 1 to 7 and Examples 8 to 12 of the present invention are carried out according to the following process unless otherwise indicated in Table 1: Under a nitrogen atmosphere the alcohol, solvent-1 and the base were reacted for 1 h under the conditions detailed in Table 1, in order to form a sodium alkoxylate mixture. Ethylene sulfate (available from Eastar Chemical Corporation, Sacramento, Calif., USA) dissolved in solvent-2 was added to the stirred sodium alkoxylate mixture at such a rate that the designated temperature could be maintained. The reaction mixture was then stirred at the indicated temperature overnight. At the times indicated in Table 1, small samples were taken. These samples were hydrolysed by treatment with 6NH2SO4 at 90° C. for less than 1 h and subsequently analysed by gas chromatography (GC).
GC was carried out on a Hewlett-Packard HP6890 apparatus with the following column: Varian-Chrompack capillary column CP-SM 5CB (low-bleed), length 50 m, internal diameter 0.25 mm, film thickness 0.4 μm and with the following temperature program: 125° C. (5 min); 125-325° C. (10° C./min); 325° C. (5 min). Flame ionization detection and an internal normalization method of quantification were employed.
NEODOL 67 (74.8 g, 300 mmol) and dichloromethane (60 ml) were added to a 3-necked round-bottomed flask (2-liter) equipped with a mechanical stirrer, a nitrogen inlet tube, a thermocouple and a dropping funnel (500-ml). Under a nitrogen atmosphere, a 50% suspension of sodium hydroxide (1.5 mol, 5.0 equivalents with respect to NEODOL 67) in dimethyl sulfoxide (DMSO) was added and the mixture was stirred for 15 minutes. The mixture was cooled to 15° C. and a solution of ethylene sulfate (48.4 g, 390 mmol, 1.3 equivalents with respect to NEODOL 67) in dichloromethane (400 ml) was added drop-wise at such a rate the reaction temperature did not exceed 25° C. (˜1.5 ml/min). After complete addition the mixture was stirred at room temperature for an additional 2 hours. The conversion was 69%+/−5%, due to broad overlapping peaks in the GC method, described in Examples 1-12 (Table 1).
To the reaction mixture was added demineralised water until phase separation occurred (˜80 ml). The phases where separated and the upper phase was discarded. To the viscous lower layer was added demineralised water (250 ml). Two phases were formed. The clear and mobile lower layer was separated and extracted with demineralised water (2×250 ml). The three combined viscous aqueous phases were filtered over a glass filter (porosity 4), then saturated with sodium chloride and subsequently extracted with isopropyl alcohol (5×250 ml). The combined isopropyl alcohol layers were concentrated on a rotary evaporator and the residue was dried by azeotropic distillation with toluene (2×250 ml) to yield 88.1 g of a white solid, sodium NEODOL 67 ethoxysulfate (˜90% purity; the remainder being NEODOL 67). The yield of isolated sodium NEODOL 67 ethoxysulfate was 200 mmol (67%).
12c
54e
22d
aEthylene sulfate is available from Eastar Chemical Corporation, Sacramento, Ca, USA and has been used without purification.
bMeasured by GC after hydrolysis in 6N sulphuric acid at 90° C. for <1 h (wt % of 1EO-adduct on alcohol intake).
cTrace (<1%) of 2EO derivative also present.
d2EO and 3EO derivatives also observed in GC after hydrolysis.
e45-67% conversion according to 1H NMR.
These conversions of ethoxysulfation of primary and secondary alcohols to form alcohol ethoxysulfates are generally higher than those obtained using a two-step process of ethoxylation using 1 equivalent (eq.) of ethylene oxide, followed by sulfation. No distribution of alcohol ethoxylates and subsequently of alcohol ethoxysulfates, including alcohol sulfate itself, is formed.
Under a variety of conditions, as summarised in Table 1, the ethoxysulfation of primary and secondary alcohols has been studied.
A versatile economically feasible process has been discovered for the production of alkoxysulfates by reacting a nucleophilic compound (e.g. an alcohol) with an 1,2-alkylene sulfate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 08160155.1 | Jul 2008 | EP | regional |
