GB2365020A - Demulsifiying compositions - Google Patents

Abstract

There is provided a method for demulsifying a composition comprising an oil and water, the method comprising contacting the composition with a demulsifier compound of the formula <EMI ID=1.1 HE=41 WI=59 LX=437 LY=864 TI=CF> <PC>wherein: Y is a support substrate; R1, R2, R3 and R4 are independently selected from hydrogen and hydrocarbyl groups; wherein one of R3 and R4 is a group of the formula C(O)X in which X is a linking moiety attached to the support substrate Y, and the other of R3 and R4 ("the non-linked substituent") is selected from hydrogen and hydrocarbyl groups; L is a linker group or bond; n is an integer no less than 1. Preferably the compound is an alpha amino acid such as aspartic acid or glutamic acid.

Description

<Desc/Clms Page number 1> Method The present invention relates to a method for breaking an emulsion using a demulsifier compounds or a compositions containing them.

An emulsion is a mixture of two immiscible liquids, one of which is dispersed as droplets in the other.

Three major industries produce oily wastewater and waste oil emulsions: (i) petroleum and hydrocarbon production and refining, (ii) metals manufacturing and machining, and (iii) food processing. Other applications include cutting oils, paint and coatings, and also greases produced in commercial laundry effluent.

In the removal of an oily emulsion from a wastewater, the demulsification process (the process that breaks stable emulsions) is an important step. Efforts to limit adverse environmental impact of oil-containing wastewater have made water cleanup an important priority. The presence of emulsified oil contained in produced wastewater can be attributed to both natural and man-made surfactants.

The ability to rapidly demulsify from a waste liquor solution allows rapid recovery of fats, organic components, paint residues, greases and oils and provides for rapid passage of the aqueous effluent to a sewage treatment facility. Recycling and reclamation plants, as well as companies involved in environmental services, are often faced with the most complex and challenging emulsions.

Emulsification and demulsification processes are of particular importance in the petroleum industry. In the petroleum industry, emulsions are endemic, being generated during all stages of the crude oil purification and refining process. The separation efficiency of the emulsified organic materials is controlled by the stability of the dispersed systems.

Crude oil is invariably accompanied by water. The shear action at wellhead chokes and valves and the pressure drop across modern production pipelines may produce water- in-crude emulsions. For pipeline transportation of highly viscous crudes, an oil-water emulsion is often purposely prepared to reduce the viscosity of the crude and enhance

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pipeline flow. In desalting operations, fresh (wash) water is added in order to remove potentially corrosive water-soluble salts such as chlorides. Modern oil production requires removal of the last traces of water and water-soluble salts before refining begins, as well as treatment of effluent water to an environmentally acceptable level. This stage involves breaking water-in-oil (w/o) emulsions. Demulsification and desalting processes involving perturbation of the water/crude oil interface therefore constitute an important first step in refining operations.

The formation of water-in-crude oil emulsions from oil field crude is considered to be undesirable for a number of reasons, including pipeline corrosion and the additional cost of transportation via pipeline or tanker, and the poisoning of downstream refinery catalysts. To ensure smooth oil production operations, demulsifiers must be used. Chemical demulsification has long been established as the cheapest, most convenient and most effective method of breaking water-in-crude (w/o) emulsion. In chemical demulsification, chemicals known as demulsifiers are added to the water-in-crude oil emulsion. These demulsifiers are surface-active agents and develop high surface pressure at the crude oil/water interfaces. This results in replacement of rigid films of natural crude oil surfactants by a film, which is conducive to coalescence of water droplets.

The most common method of emulsion resolution in both oilfield and refinery applications is a combination of heat and application of chemicals designed to eliminate or neutralise the effects of emulsifying agents. Addition of suitable chemicals with demulsifying properties specific to the crude oil to be treated will generally provide quick, cost-effective and flexible resolution of emulsions. For the oil producer, the use of chemicals in emulsion breaking is attractive for a variety of reasons. The capital costs of implementing or changing a chemical emulsion breaking treatment are relatively small and can be accomplished without a shutdown. This feature is attractive because it means that emulsion breaking chemical treatments can be altered to react to changes in emulsion characteristics.

Once emulsions are formed, their stability is largely determined by molecular, electrical double-layer, steric and hydrodynamic forces. Emulsions are thermodynamically unstable and will separate naturally into their constituent phases in a given sufficient

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time. However, although these emulsions are thermodynamically unstable, they are kinetically very stable. Demulsification is a process to turn this relatively stable system into an unstable one.

The process of demulsification itself is complex and cannot be thought of as the reverse of emulsification. In chemical treatment, to destabilise the emulsions and improve the separation efficiency, surface-active materials are applied which modify the properties of the interface formed between the dispersed particle and continuous phase. Demulsification of emulsions typically occurs in two stages: flocculation and coalescence. Flocculation refers to the aggregation of droplets and coalescence involves the approach and combination of two or more droplets to form a larger drop. Demulsifiers are capable of being adsorbed (anchoring) preferentially at the oil-water interface and flocculating/coalescing the emulsion drops by changing the interfacial nature, which can be caused by electrostatic or bridging formation at the interface. The resistance to coalescence is determined by the structure and physical properties of the chemicals adsorbed at the interface. Also, factors such as the temperature, speed of agitation, bulk viscosity and presence of impurities can play an important role in the effectiveness of demulsification.

Typically in prior art systems the choice of chemical may be considered to be based on trial-and-error procedures. In most cases, a combination of chemicals is used in the demulsifier formulation to achieve both efficient flocculation and coalescence.

The formulation of commercial demulsifiers is based largely on empirical approaches. To date, thousands of chemical structures with surface active properties have been synthesised as demulsifiers in attempts to produce increasingly potent and universal materials, able to operate at low dosages, with reduced separation times, and producing very clean phase separation (of both phases). These include petroleum sulphonic acids/salts, fatty acid mono- and polyesters, alkoxylated fatty acids, mono- and polyols, and phenol-formaldehyde resins.

EP-A-0549918 discloses oil demulsifiers based on alkoxylates, for example monohydric or dihydric alcohols, such as ethylene glycol, diethylene glycol or butylene glycol, reacted with from 3 to 100 mol of ethylene oxide, propylene oxide or butylene oxide per

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hydroxyl group. These alcohol alkoxylates having demulsifying activity may also be used together with oxyalkylated polyalkylenepolyamines, which also have demulsifying activity.

US-A-5445765 describes the use of alkoxylated polyethyleneimines as petroleum emulsion breakers.

US-A-4151173 describes the use of oil-soluble acylated polyoxyalkylene polyamines having useful demulsifying characteristics which are useful as additives for a variety of materials such as lubricants and liquid fuels, hydraulic fluids and the like.

EP-A-0696631 describes w/o demulsifiers prepared by reacting polyalkylene glycols with ethylene oxide and then esterifying the reaction products with a diacid anhydride. The diester products are reacted with vinyl monomers and additionally esterified with polyhydric materials.

US-A-5744046 describes the treatment of an aqueous medium which has been polluted with hydrocarbon compounds with a demulsifying composition comprising a mixture of polyglycerol esters.

WO-A-96/05272 describes the use of sulphosuccinic esters of long chain hydrocarbyl phosphoric acid esters as demulsifiers for crude oil.

US-A-4440092 describes the use of bis-esters of alkenylsuccinic acids and ethylene oxide/propylene oxide block polymers as useful demulsifiers for oil-water emulsions. The use of polyalkylene glycol derivatives of carboxylic acid acylating agents as demulsifying agents for w/o emulsions in liquid fuels and lubricants is described in US- A-3057890, US-A-3957854, and US-A-4216114.

US-A-5164116 describes the use of alkoxylated alkyl polyglycosides for breaking w/o petroleum emulsions. These are described as biodegradable, although no data is given.

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Many commercial demulsifiers are polymeric surfactants such as copolymers of polyoxyethylene and polyoxypropylene or alkylphenol formaldehyde resins or blends of different surface-active substances. Usually, commercial demulsifiers are blended mixtures of several components that have various chemical structures and polymeric materials, as well as a wide molecular weight distribution. In this case, each component of the demulsifier possesses a different partitioning ability and a different interfacial activity due to various chemical structures.

A particularly large number of prior art references describe the preparation of chemical demulsifiers for use in treating crude oils. This is principally because petroleum emulsions vary in their compositions and characteristics depending on a number of factors including geographic location and production method.

However, it is understood that there is no universal demulsifier. A demulsifier that works well with emulsions, particularly emulsions for one location may be ineffective for use in other locations. Because of the vastly differing compositions of crude oils, it is difficult to find a single demulsifying agent that is suitable for crude oils from all sources, and combinations of agents are generally used. Likewise, it is inaccurate to say that just because a demulsifier does not work well in a particular application that it is a poor demulsifier.

As noted, many emulsion breakers are very specific to certain areas and particular crude oil compositions. Most commercial emulsion breakers are formulations or blends of several chemicals. As the production field ages or as more wells are put into production, new chemicals or new blends may have to be put into the system. There is thus a continuing need for new demulsifiers to address the varying crudes and conditions under which they are produced.

The problem of the residual aqueous pollution arising from cutting-oil disposal may be tackled by designing separation operations able to make aqueous effluents almost free of organic materials. Oil-containing emulsions are typically used in applications such as solvent cleaning, metal-cutting oils, and well-bore drilling fluids. At the end of their useful working lives, the emulsions are disposed of typically by incineration. Incineration of emulsions with high water contents is expensive but the cost can be

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reduced by first breaking the emulsion and only incinerating the oil phase. Current technology for breaking these types of emulsions uses expensive and poorly biodegradable demulsification chemicals, typically block copolymers of polyethylene oxide), polypropylene oxide) followed by a mechanical separation process. There is thus a need for new demulsifier technology that presents a much lower adverse environmental impact than current technology.

Increasingly, the impact of industrial chemicals on the environment is coming under greater scrutiny. In Europe and Japan, environmental concerns have spurred ever more stringent legislation concerning chemical components in water treatment applications. The environmental impact of speciality chemicals for use in hydrocarbon production is receiving increased attention, especially in cases in which they find their way into the sea. The last 15 years has seen a heightened awareness and sensitivity to the environmental impact of the use and subsequent discharge of industrial chemicals. The safe application of a chemical ingredient requires knowledge of its impact in relevant environments including surface waters and soil. One way to ensure that a chemical's concentration in the environment will fall below the level of no harm, is to prevent it from reaching the environment in the first place. This can be achieved either by keeping the material in a closed system and never releasing the any effluent or by removing the material from the effluent in a waste treatment facility. Preferably, the material will be fully biodegraded in the waste treatment facility.

Knowledge of the biodegradability of a given chemical component allows greater confidence in the assessment of the potential environmental impact of that component. Biodegradation testing requires the exposure of the organic ingredient to the environment of interest and measuring its degradation. In the case of most water- soluble industrial chemicals, the environment of interest is a waste treatment facility. The rate of biodegradation of a chemical in the wastewater environment will determine how much of the chemical will be released to the external environmental. Biodegradability testing is generally done using a tiered approach. There are three generally recognised testing levels for aquatic biodegradability:

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# Ready biodegradability # Inherent biodegradability # Simulation testing Specific testing procedures have been agreed upon and can be found in the Organisation for Economic Co-operation and Development (OECD) guidelines for testing of chemicals.

Ready biodegradability tests (OECD 301A-E) are the simplest and most stringent. These tests utilise micro-organisms from sewage sludge. The chemical is tested at relatively high dose levels of 10 to 20 ppm, with no other source of organic nutrients and no acclimatisation of the micro-organisms to the test chemical. Ready bio-degradation in the marine environment is tested for in the OECD 306 test.

The level of biodegradation is measured by either oxygen uptake (BOD), COZ evolution, or by following the level of dissolved organic carbon (DOC removal) over the duration of the test.

If a chemical reaches a level of degradation of at least 60% within 28 days, and if that level is attained within 10 days of exceeding 10 % degradation, the compound can be considered readily biodegradable. If a compound meets these requirements, then there is a high probability that it will fully degrade in an aquatic waste treatment environment and no further testing is warranted.

If a chemical fails to meet the stringent requirements of ready biodegradability, it does not mean that the chemical is non-biodegradable. It simply means that further testing is required to establish biodegradability using less stringent tests such as inherent biodegradability (OECD 302A to C) and simulation tests (OECD 303A).

Meeting the ready biodegradability guidelines is the most desirable situation from the standpoint of cost (these tests are expensive) and from the acceptability of the results. Inherent biodegradability testing, for example, is much more expensive and time consuming than ready biodegradability testing. In addition, the results carry less weight in assessing environmental impact.

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An Inherent Biodegradation Test allows prolonged exposure of the test material to micro-organisms, a favourable ratio between test compound and biomass and other test conditions, which favour biodegradation. A compound giving a positive test result may be classified as being 'inherently biodegradable'; implying that it has the potential to degrade. However, its rapid and reliable biodegradation in the environment should not be assumed.

A Ready Biodegradation Test provides little opportunity for biodegradation and acclimatisation to occur within the confines of a strictly controlled test. It may therefore be assumed that a substance, which is 'readily biodegradable', will probably biodegrade rapidly in the environment.

The present invention alleviates the problems of the prior art.

Aspects of the present invention are described in the appended claims.

We have surprisingly found that a class of compounds including N-acylated amino acid derivatives disclosed in WO-A-99/59958 as corrosion inhibitors and/or scale inhibitors, provide unique demulsifying properties.

The present invention relates to a range of compounds useful for breaking emulsions. The compounds comprise N-acylated amino acid moieties appended onto suitable substrates (Y). We have found that these compounds have useful demulsification activity. Moreover, these adducts contain the additional advantage of being biodegradable. These properties can be used for, among other things, the clean up of oil-contaminated water. Furthermore, the compounds of the present invention have been found to be versatile in their solubility characteristics with regards dissolution in aqueous and/or hydrocarbon phases.

The present invention advantageously provides a demulsifying method comprises the use of a compound with enhanced environmental credentials. The present invention aims to provide a method utilising a water-soluble chemical demulsifier that is biodegradable.

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The present invention is directed specifically to the treatment of emulsions using compounds known as demulsifiers. Demulsifiers are normally amphipathic molecules Demulsifiers are normally amphipathic molecules containing a balance of hydrophilic and hydrophobic properties.

The term "demulsifier" as used in the present specification means a compound capable of preventing or retarding the formation of an emulsion or capable of breaking an emulsion down to form discrete, separable oil and water phases.

The term "demulsifying" as used in the present specification means a preventing or retarding the formation of an emulsion or breaking an emulsion down to form discrete, separable oil and water phases.

The term `moiety' is used as understood by those skilled in the art to mean part of a molecule, molecular fragment, or molecular structural fragment.

DEMULSIFIER COMPOUND The present invention provides a method for demulsifying a composition comprising an oil and water, the method comprising contacting the composition with a demulsifier compound of the formula

wherein: Y is a support substrate R1, R2, R3 and R4 are independently selected from hydrogen and hydrocarbyl groups wherein one of R3 and R4 is a group of the formula C(O)X in which X is a linking moiety

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attached to the support substrate Y, and the other of R3 and R4 ("the non-linked substituent") is selected from hydrogen and hydrocarbyl groups L is a linker group or bond n is an integer no less than 1 The present invention further provides use a demulsifier compound for demulsifying a composition comprising an oil and water, wherein the demulsifier compound is of the formula

wherein: Y is a support substrate R1, R2, R3 and R4 are independently selected from hydrogen and hydrocarbyl groups wherein one of R3 and R4 is a group of the formula C(O)X in which X is a linking moiety attached to the support substrate Y, and the other of R3 and R4 ("the non-linked substituent") is selected from hydrogen and hydrocarbyl groups L is a linker group or bond n is an integer no less than 1 The term "hydrocarbyl group" as used herein means a group comprising at least C and H and may optionally comprise one or more other suitable substituents. Examples of such substituents may include halo-, alkoxy-, nitro-, a hydrocarbon group, an N-acyl group, a cyclic group etc. In addition to the possibility of the substituents being a cyclic group, a combination of substituents may form a cyclic group. If the hydrocarbyl group comprises more than one C then those carbons need not necessarily be linked to each other. For example, at least two of the carbons may be linked via a suitable element or group. Thus, the hydrocarbyl group may contain hetero atoms. Suitable hetero atoms

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will be apparent to those skilled in the art and include, for instance, sulphur, nitrogen and oxygen.

In one embodiment of the present invention, the hydrocarbyl group is a hydrocarbon group.

Here the term "hydrocarbon" means any one of an alkyl group, an alkenyl group, an alkynyl group, an acyl group, which groups may be linear, branched or cyclic, or an aryl group. The term hydrocarbon also includes those groups but wherein they have been optionally substituted. If the hydrocarbon is a branched structure having substituent(s) thereon, then the substitution may be on either the hydrocarbon backbone or on the branch; alternatively the substitutions may be on the hydrocarbon backbone and on the branch.

PENDANT GROUP The compound of the present invention comprises a support substrate and one or more pendant groups. The pendant group(s) is of the formula

wherein R1, R2, R3, R4 and L are as defined above.

As described above R1, R2, R3 and R4 are independently selected from hydrogen and hydrocarbyl groups. One of R3 and R4 is a group of the formula C(O)X in which X is a linking moiety attached to the support substrate Y, and the other of R3 and R4 ("the non-linked substituent") is selected from hydrogen and hydrocarbyl groups In a preferred aspect of the present invention the non-linked substituent is a group of the formula C(O)OM wherein M is hydrogen or a water soluble metal cation Preferably the pendant group is an acylated amino acid. Preferably the pendant group is an acylated a-amino acid. More preferably the pendant group is an acylated a-amino

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acid wherein the amino acid is a naturally occurring a-amino acid, namely the amino acid is selected from including glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, tyrosine, tryptophan, cysteine, methionine, lysine, arginine, histidine aspartic acid, glutamic acid, asparagine, glutamine, serine and threonine.

Particularly preferred N-acylated amino acid derivatives of the present invention are N- acylated derivatives of the dicarboxylic amino acids aspartic and glutamic acids. Both D- and L- amino acid isomers and D,L- are effective in the subject invention. Natural amino acids (L-isomers) are preferred.

As used herein acyl means carbon containing chains which may be straight, branched or cyclic; substituted or unsubstituted, saturated, monounsaturated (i.e., one double or triple bond in the carbon chain) or polyunsaturated (i.e., two or more double bonds in the carbon chain; two or more triple bonds in the carbon chain, one or more double bonds and one or more triple bonds in the carbon chain). Acetyl, propionyl, butyryl, pivaloyl, decanoyl, lauroyl myristoyl, palmitoyl, and stearoyl are examples of saturated, straight chain or branched acyl groups in this respect, while oleoyl and linoleyl are examples of unsaturated acyl groups. Aliphatic CZ_ZO acyl moieties that are preferred in the process of the invention are decanoyl, lauroyl (dodecanoyl), palmitoyl, and oleoyl or mixtures thereof. An especially preferred compound is the lauroyl group. Alternatively acyl moieties prepared from mixtures of fatty acids derived from tall oil fatty acids or beef tallow or similar including vegetable oils derived from, for example, sunflower oil, rapeseed oil, coriander oil, castor oil, soybean oil, cottonseed oil, peanut oil, may be used in the present invention. Alternatively, the acyl group may be derived from a diacid, for example, a dimer acid formed by dimerisation of unsaturated fatty acids such as linoleic or oleic acid or mixtures thereof.

In further preferred aspects the pendant group is selected from N-acylated amino acid derivatives including N-acylated amino acid amides, esters, and thioesters.

In a preferred embodiment the pendant group is an N-acyl amino acid amide or ester having the structure wherein an aspartic acid moiety may be functionalised in either its a- or (3- forms:

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Glutamic acid moiety may be similarly functionalised at the a- or y- carboxyl residues. We have found that the reaction products of N-acyl aspartic or N-acyl glutamic acid anhydrides and activated esters have particularly efficient demulsifying properties and the added advantage of good biodegradability.

In a preferred embodiment, the pendant group is a reaction product provided when an acylated aspartic or glutamic acid anhydride or suitable activated ester product is reacted further with a suitable nucleophilic group. Nucleophilic in this instance is meant to be functional groups (hydroxyl, amine, and thiol) which can effect the ring opening of the cyclic anhydride and or displacement of the activated ester function herein. Said reaction products exhibit excellent demulsifying performance when incorporated in a compound in the present invention as a pendant group.

LINKER GROUP/BOND L Group L may a linker group via which R4 is joined to the rest of the pendant group or L may be a simple bond joining R4 to the rest of the pendant group. In the latter embodiment the pendant group has the formula

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L may be a hydrocarbyl group as defined above. In a preferred aspect L is (CH2)m wherein m is from 1 to 5. More preferably L is (CHZ)m wherein m is 1 or 2.

M In a preferred aspect of the present invention the non-linked substituent of the pendant group is a group of the formula C(O)OM wherein M is hydrogen, a water soluble metal cation or an optionally substituted quaternary ammonium cation. When M is a water soluble metal cation, preferably M is a cation of an alkali metal or an alkaline earth metal SUPPORT SUBSTRATE Y Y is any suitable backbone moiety on which to append the pendant groups via X linkages.

Y can be straight or branched chain or cyclic or aromatic carbon chain structures containing hydroxyl (-OH), thiol (-SH) or amine (-NHR3) substituents, capable of reacting to form the products of the subject invention.

The number of pendant groups (n) present on the support substrate is an integer no less than 1. In other word the support substrate carries at least one pendant group. The maximum value for n will be the total number of available reactive substituents on the support substrate Y. It will be appreciated that these reactive substituents are only reactive prior to the link via X to a pendant group. In other words the available reactive substituents on the precursor of Y determines the maximum value of n.

Preferably n is from 2-10.

Optionally, Y may contain additional functionality (carboxyl, -COON, amine, -N(R4)-; ether, -0-; thioether, -S-; sulphonate, -S03H; phosphino, -P(R4)-; R4 = H or Cl-20 alkyl or C5_,2 aryl; and phosphonate, -P03H2), either in the backbone of Y or as pendant functionality.

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Moreover, by choice of the correct Y support one is able to moderate the biodegradability performance and also solubility and other solution characteristics such as partition coefficient between oil (hydrocarbon) and water phases.

A preferred embodiment of the present invention is where Y is polyoxyalkylene, polyalkyleneamine, or polyoxyalkyleneamine of formula:

In these aspects x is 1 to 20, Ry is H, alkyl or aryl, preferably H or Me z is 0 to 2 for the glycols n is 1, 2, 3 or 4, m is 1 to 20, R5 is H, alkyl or aryl.

The alkylene glycols included herein may be selected from diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, tetrapropylene glycol and polyethylene glycols, polypropylene glycols, and polybutylene glycols. The molecular weight of these compounds may be up to 5000, preferably 200- 3000, and most preferably 200-1600.

The alkylene glycol ester derivatives are readily prepared by reaction of the anhydride intermediate dissolved in a suitable inert solvent such as toluene or xylene, by adding the required amount of glycol and heating under reflux. Alternatively, the glycol may be used in excess as both reactant and as a solvent for the esterification reaction. Usefully, these reactions are carried out at temperatures of from 50 C to 150 C, preferably 100 C to 140 C, depending on the solvent or solvent mixture used.

Products formed by the addition of a suitable alkylene oxide such as ethylene oxide, propylene oxide and/or butylene oxide reactant to appropriate N-acylated amino acid derivatives of this invention are also preferred embodiments of this invention. Suitable

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N-acylated amino acid derivatives in this regard are the esters and amide or thioester derivatives of the present invention which contain free hydroxyl (-OH), thiol (-SH) or primary (-NHZ) or secondary (-NHR) amine groups capable of further reaction with alkylene oxides. In this way, a hydrophilic or hydrophobic polyoxyalkylene chain may be "grown" onto the molecule depending on the alkylene oxide used.

The amine reactants (representative of X-Y) may be widely diverse in chemical structure and include straight, branched chain and cyclic amines which can be unsubstituted or substituted with other functional groups, such as one or more ester groups, ether linkages, carbonyl groups, oxirane groups, carboxyl groups, thioether linkages, thiol groups and hydroxyl groups, and many others such as those described above. A few representative examples include ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, tetra propylenepentamine, and ethanolamines including monoethanolamine, diethanolamine and triethanolamine as well as polyalkyleneamines of molecular weight 200 to 1000 and the aminoglycols of which 2,2'-(ethylenedioxy) bisethyl-amine) is a particularly preferred example.

The subsequent reaction of the N-acylated amino acid anhydrides or activated esters with polyoxyalkylene or polyamine or polyoxyalkylene amines of formula above gives rise to mono-, bis-, tris-, and poly-substituted amides and esters.

Other suitable supports (Y) include various polyols and carbohydrates including sugars and oligo- and polysaccharides, thiols, aminothiols, and substituted thioethers. Preferred polyhydric alcohols include one or a mixture of compounds such as glycerol, erythritol, pentaerythritol, dipentaerythritol, tripentaerythritol, glyceraldehyde, glucose, sucrose, 1,7-heptanediol, 1,10-decanediol and 1,2,3-hexanetriol and other similar carbohydrates Preferred polysaccharides for use as suitable supports (Y) include starches (amyloses, amylopectins), starch derivatives and starch blends, celluloses and cellulose derivatives, inulins, pectins, and various gums including locust bean gum and guar gum. Thus it is possible to use biodegradable polymeric materials based on renewable or on petrochemical sources. Other examples of such renewable sources are, polyhydroxybutyrates, polylactic acid, cellophane, casein and chitin polymers. Biodegradable polymeric materials produced from petrochemical resources are for

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example, aliphatic polyesters such as polycaprolactone and polybutene succinate, aromatic-aliphatic copolyesters and polyester amides.

A further embodiment of the present invention is that Y may consist of any of the common a-amino acids including glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, tyrosine, tryptophan, cysteine, methionine, lysine, arginine, histidine aspartic acid, glutamic acid, asparagine, glutamine, serine and threonine where the X linkage to be acylated consists of the a-amino group of the amino acid. Especially preferred embodiments of the present invention are where Y consists of those a-amino acids which contain additional (X) functionality in the aside chain such as tyosine, serine and threonine (X =OH); lysine, arginine, asparagine, glutamine (X = NHZ); proline and histidine (X = -NH-); and cysteine (X = SH). Alternatively, Y may consist of oligomers and polymers of any or all of the common a-amino acids such as polypeptides (including polyaspartic acid) and water soluble proteins or protein hydrolysates. In another embodiment of the present invention, the source of the amino acid or polypeptide or protein may come from use of the dilute waste streams from amino acid-using and/or amino acid-producing processes such that saleable demulsifier products may be produced from said waste streams.

Optionally, the support substrate Y may contain additional functionality either in the backbone of Y or as pendant functionality. The additional functionality may be provided by additional pendant groups as described herein. Known demulsifier molecules with suitably reactive X groups may also form appropriate Y backbone moieties. In fact, terminating the chains and molecules of such conventional demulsifier molecules with the N-acylated amino acid functionality by method of this invention leads to modified surface activity and consequently the ability to migrate to and modify the characteristics of an oil-water interface.

PREFERRED COMPOUNDS In will be appreciated from the above that a preferred compound of the present invention is of the formula

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wherein: R is the aside chain grouping of an a-amino acid, including glycine, alanine, valine, leucine, isoleucine, phenylalanine, tyrosine, cysteine, methionine, lysine, arginine, histidine, aspartic acid, glutamic acid, asparagine, glutamine, serine, tryptophan and threonine, Y is a support substrate R1, R2 are independently selected from hydrogen and hydrocarbyl groups, or R2 together with R is the heterocyclic ring of an imino acid, including proline, X is a linking moiety attached to the support substrate Y.

In the above aspects where R is the aside chain grouping of an a-amino acid, R may be selected from H (glycine), CH3(alanine), (CH3)2CH (valine), (CH3)2CHCH3 (leucine), CH3CH2CH(CH3) (isoleucine), C6H5CH2 (phenylalanine), p-HOC5H,CH2 (tyrosine), HSCH2 (cysteine), CH3S(CH2)3 (methionine), H2N(CH2)4 (lysine), H2NC(NH)NH(CH2)3 (arginine), HOOCCH2 (aspartic acid), HOOC(CH2)2 (glutamic acid), H2NOCCH2 (asparagine), H2NOC(CH2)2 (glutamine), HOCH2 (serine) and CH3CH(OH) (threonine),

In the above aspects where R2 together with R is the heterocyclic ring of an imino acid, the group R2-N-R may be

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In a highly preferred embodiment the compound of the present invention is derived from either of the dicarboxylic amino acids aspartic and glutamic acids. In this aspect the compound may be of the formula:

wherein m is 1 or 2 and R1 is a straight or branched chain alkyl or alkenyl residue containing 1 to 30 carbon atoms, for example 1 to 19 carbon atoms, or a cycloalkyl or aryl residue having from 5 to 12 carbon atoms; R2 is hydrogen or aryl or a straight chain alkyl or alkenyl residue having from 1 to 30 carbon atoms, for example 1 to 20 carbon atoms; M is selected from hydrogen, water-soluble alkali metal cations, water-soluble alkaline earth metal cations and optionally substituted quaternary ammonium cation; X is a linking moiety, preferably -O- or -S- or -N(R3)- (R3 is H or alkyl or alkenyl or aryl or alkylaryl) derived from hydroxyl (-OH), thiol (-SH) or amine groupings (-NHR3) on Y. In a highly preferred embodiment the compound of the present invention is of the formula

wherein n is from 1 to 13, preferably from 3 to 13, more preferably 3, 4, 8, 9, or 13.

In a highly preferred embodiment the compound of the present invention is of the formula

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wherein n is from 1 to 13, preferably from 3 to 13, more preferably 3, 4, 8, 9, or 13. COMPOSITIONS In tailoring the demulsifier formulation for a particular treatment, it may be preferred in many such treatments to combine the demulsifiers described in this invention with other known demulsifiers. The commercially available demulsifiers which can be used in a blend with the adducts described in this invention include oxyalkylated amines, alkylaryl sulfonic acid and salts thereof, oxyalkylated phenolic resins, polymeric amines, glycol resin esters, polyoxyalkylated glycol esters, fatty acid esters, oxyalkylated polyols, low molecular weight oxyalkylated resins, bisphenol glycol ethers and esters and polyoxyalkylene glycols, polyethyleneimine alkoxylates, mono- or oligoamine alkoxylates, alkoxylated alkylphenol/formaldehyde resins, co- or terpolymers of alkoxylated (meth)acrylates with vinyl compounds, condensates of mono- or oligoamine alkoxylates, dicarboxylic acids and alkylene oxide block copolymers where the condensates may furthermore be completely or partially quaternised at the nitrogen atoms. Other chemistries which are demulsifiers should work with the present invention include polyglycols, polyglycol esters, ethoxylated alcohols and amines, ethoxylated resins, ethoxylated phenol formaldehyde resins, ethoxylated nonyl phenols, polyhydric alcohols, and sulphonic acid salts. This listing is, of course, not exhaustive and other demulsifying agents or mixtures thereof will occur to one skilled in the art. Most demulsifiers that are commercially available fall into chemical classifications such as those enumerated above. The exact composition of a particular compound and/or its molecular weight is usually a trade secret, however. Despite this, one skilled in the art is able to select suitable demulsifiers using general chemical classifications provided.

In tailoring the demulsifier formulation for a particular treatment, it may be preferred in many treatments to combine the demulsifier of the present invention with other demulsifiers. In this way, the environmental credentials of the complete additive

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package may be enhanced in order to give a totally biodegradable package. Alternatively, the use of combinations of products of the subject invention as blending components can enhance the biodegradability of the package. In addition, it may be advantageously possible to give a formulated product with a better Offshore Chemical Notification Scheme (OCNS) or Harmonised Offshore Chemical Notification Format (HOCNF) rating.

The emulsifiers of the present invention are preferably employed as solutions, for reasons of easier metering, for breaking emulsions. The solvents that can be used are water, and organic solvents such as, for example, toluene, xylene, c,_4 alcohols, THF, or light naphtha. The most preferred solvent system is water. The water content of the formulation generally ranges from 20 to 80, preferably 30 to 60, weight percent of the total formulation.

TREATMENTS It is impossible to predict in advance the proportions of demulsifier required to treat a particular emulsion due to the varied nature of emulsions. Moreover, differing pressures, temperature, concentrations of indigenous surfactants, etc., make sure that the exact proportions of demulsifier will vary greatly from treatment to treatment. In utilising the demulsifier of the present invention, the acylated derivatives of this invention may be used either alone or more preferably in mixtures; in combination with various other known additives. A formulation is usually prepared which may include other additives which provide additional function or enhancement to the effectiveness of the demulsifier package, such as dispersants, extreme pressure agents, detergents, corrosion and scale inhibitors, oxidation inhibitors, viscosity index improvers, cosolvents, surfactants, buffers, antifoams, biocides, oxygen scavengers and the like well known in the art. The composition and concentration of the actives in the formulation will be tailored for a specific treatment. The percentage of active demulsifier adduct in the formulation may range within wide limits, 5% to 90% is preferred, most preferred is 25% to 75% wlw.

The amount of demulsifier to be employed for breaking emulsions is usually 1 to 5000 ppm, preferably 1 to 1000 ppm, based of mass of the emulsion to be treated; although

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variations from this range are feasible and entirely permissible, since the amount to be used can readily be determined in any given instance by means of a few simple experimental tests, and thus any amount may be utilised to suit the needs of the particular occasion. The demulsification process may be carried out at ambient temperatures or at elevated temperatures advantageously from 30 to 130 C, preferably 40 to 80 C. Elevated temperatures tend to accelerate the demulsification effect. Other known breaking components can be added to the demulsifier solutions and the amounts of these additives are from 10-90%w/w, preferably 25-75%w/w, based on the weight of the solution.

The contacting of the emulsion with the product of this invention can be effected batch- wise or in a continuous manner in any suitable system allowing some form of stirring, agitation or intermixing. On a large scale, tanks with paddle mixers, pump-piping, systems and vortex mixers may be used. Other process variables such as temperature and salinity (ionic strength) of the aqueous phase may be optionally adjusted to enhance the destabilising effect of the composition.

The pH of the system under treatment after this invention may vary within relatively wide limits. For best results, the pH of the system should fall in the range of about 5 to about 10.

The wastewater to be treated can contain various types of oils including petroleum- based oils such as crude petroleum and refined oils such as fuel, mineral and lubricating oils, fixed oils such as animal fats and vegetable oils and the like. Besides oil and surfactants, the wastewater can also contain various residual components and application by-products including metal ions and metallic particles, corrosion inhibitors, water-in-oil breakers, electrolytes, stabilisers, biocides and thickeners, dyes, scavengers, pH adjusters, softeners, etc.

As will now be readily apparent to those skilled in the art, the demulsifiers of this invention may be employed for the treatment of a wide variety of oil/water emulsions including emulsions encountered in oil field operations or in industrial operations of various and sundry types, such as petroleum production and refining, mining, paper sizing operations, metal machining operations, and manufacture of chemicals,

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pharmaceuticals, personal care products, home care products, food processing and the like.

The invention will now be described in further detail with reference to the accompanying drawings in which: Figure 1 is a graph Figure 2a is a graph Figure 2b is a graph Figure 2c is a graph Figure 3a is a graph Figure 3b is a graph Figure 4a is a graph Figure 4b is a graph Figure 4c is a graph Figure 5 is a graph Figure 6a is a graph Figure 6b is a graph Figure 6c is a graph Figure 7 is a graph EXAMPLES Example 9 - Preparation of N-Lauroyl-L-Aspartic Acid Glycol Esters

General Synthetic Method

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N-Lauroyl-L-aspartic anhydride and the required amount of the desired glycol (molar ratio 2:1 or 1:1) dissolved in toluene solvent were added to a 250 ml stirred reactor and the mixture was heated under reflux for 1'/ hours.

The product was isolated by removal of the solvent in vacuo.

Table 1 - Analytical Data for N-Lauroyl-L-Aspartic Acid Glycol Esters Product Structural Glycol n Observed (theoretical) Va Type Used Acid Value %C %H %N (cm 1) mmol H+/ I A PEG 13 1.672 - - - 1734 600 1.68 11 B PEG 13 1.075 57.52 9.19 1.39 1736 600 1.12 56.80 9.19 1.57 III A PEG 8-9 2.029 59.63 9.04 2.53 1744 400 2.00 59.57 9.18 2.81 IV B PEG 8-9 1.192 57.16 9.11 1.67 1736 400 1.43 57.42 9.20 2.00 V B PEG 4 1.676 57.38 8.75 2.35 1728 200 2.03 58.63 9.22 2.85 V1 A PEG 4 2.443 59.44 8.88 3.15 1764 200 2.53) 60.89 9.19 3.55 br VII A PEG 3 2.700 60.28 9.07 3.65 1760 150 2.68 61.26 9.20 3.76 br a: Nujol mull, KBr plates; br = broad. b: Acid value was determined as mmol H+/g by titration in isopropanol using 0.1 M LiOMe and Thymol Blue indicator (0.4% in dioxane). General Demulsification Procedure: A 50:50 mixture of the aqueous phase and the hydrocarbon phase are added to a graduated torpedo tube. The standard test uses a total volume of 100 ml, but any aqueous phase: hydrocarbon ratio can be evaluated in this test. The demulsifier is then dosed into the system upon a total fluids basis by weight. The two-phase mixture is mixed by vigorous shaking by hand for 10-15 seconds. The colour and clarity of the hydrocarbon and aqueous phases, and the appearance of the interface are then recorded at 60-second intervals over a period of time up to 10 minutes. The torpedo tubes are kept at room temperature between examinations.

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Example 2 -Demulsification Tests of Sunflower Oil/Tap Water at Neutral pH [pH 7, 250 ppm Additive) The products of Example 1 were tested for demulsification activity at 250 ppm active concentration in a system containing sunflower oil/tap water at neutral pH. This system is representative of conditions in the food processing industry. The results are given in Table 2 and are represented graphically in Figure 1.

Table 2 Time Separated Amount of Aqueous Phase (ml) (secs) Control I II III IV V VI VII 0 0 0 0 0 0 0 0 0 60 42 2 13 24 40 4.5 7 6 120 42 10 26 37 42 12 21 20 180 44 14 34 41 42 20 37 25 240 44 17 39 42 43 32 44 35 300 45 23 41 43 50 36 46 36 360 25 41 45 37 47 38 420 26 43 50 41 50 40 480 27 45 42 42 540 30 45 44 45 600 35 46 45 Example 3 - pH Dependence of Demulsification Efficiency in SunflowerlTap-Water [250 ppm additive The pH dependence of the demulsification activity of products III, IV and V at 250 ppm active concentration were compared in the sunflower oil/tap water system at pH 4, 7 and 9. Results are given in table 3 and are represented graphically in Figures 2a-c.

Table 3 - pH Dependence of Demulsification Activity Time Separated Amount of Aqueous Phase (ml) (sets) pH 4 pH 7 pH 9 Control III IV V Control III IV V Control III IV V 0 0 0 0 0 0 0 0 0 0 0 0 0

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60 25 17 42 9 15 42 42 8 15 46 42 10 120 37 34 42 20 25 42 46 20 25 48 42 20 180 42 42 42 27 28 42 46 25 37 48 43 25 240 44 44 42 33 33 44 47 29 44 48 43 35 300 46 46 42 37 36 47 48 34 48 43 38 360 48 42 39 38 48 48 37 48 44 39 420 48 42 40 48 50 42 48 44 40 480 48 42 42 48 48 44 44 540 48 43 44 48 48 44 46 600 48 44 46 48 48 44 46 Example 4 - Concentration Dependence of Demulsification Efficiency in SunflowerlTap Water The concentration dependence of demulsifier products III and IV were compared in the sunflower oil/tap water system at neutral pH. The results are given in Tables 4 and 5 respectively, and are illustrated graphically in Figures 3a and 3b.

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Table 4 - Concentration Dependence of Demulsification Efficiency for Product 111 Time Separated Amount of Aqueous Phase (ml) (secs) Control 10 ppm 25 ppm 50 ppm 250 ppm 500 ppm 750 ppm 1000 m 0 0 0 0 0 0 0 0 0 60 42 10 15 20 15 4 4 3 120 42 25 30 38 30 10 20 8 180 44 35 37 42 35 20 28 20 240 44 39 42 43 37 25 32 25 300 45 42 42 45 40 30 44 30 360 43 42 46 42 40 420 45 42 46 42 42 480 46 43 46 42 42 540 46 43 46 42 44 600 48 46 48 42 44

Table 5 - Concentration Dependence of Demulsification Efficiency for Product IV Time Separated Amount of Aqueous Phase (ml) (secs) Control 10 ppm 25 ppm 50 ppm 250 ppm 500 ppm 750 ppm 1000 m 0 0 0 0 0 0 0 0 0 60 42 10 8 8 42 47 50 50 120 42 25 20 25 44 180 44 33 33 33 46 240 44 38 37 36 46 300 45 40 42 37 48 360 42 42 37 48 420 43 45 38 48 480 45 46 38 48 540 46 46 39 48 600 47 46 39 48 Example 5 - Comparison of the Demulsification Efficiency of Acylated PEG Derivatives versus Underivatised PEGs The demulsification activity of selected N-acylated aspartic acid derivatives of PEGs were compared against the corresponding underivatised PEG in the sunflower oil/tap water system at 250 ppm and neutral pH. The results for this experiment are given in Table 6 and are illustrated graphically in Figures 4a-c.

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Table 6 Time Separated Amount of Aqueous Phase (ml) (secs) Control I II PEG III IV PEG V VI PEG 200 400 600 0 0 0 0 0 0 0 0 0 0 0 60 42 2 13 10 24 40 20 4.5 7 20 120 42 10 26 31 37 42 39 12 21 37 180 44 14 34 44 41 42 44 20 37 44 240 44 17 39 46 42 43 45 32 44 46 300 45 23 41 46 43 50 45 36 46 46 360 25 41 47 45 46 37 47 46 420 26 43 47 50 46 41 50 46 480 27 45 47 46 42 46 540 30 45 47 46 44 46 600 35 46 47 46 45 46 Example 6 - Demulsification of a `Stabilised' Emulsion The ability of the product IV to demulsify a detergent-stabilised emulsion on sunflower oil/tap water was investigated at 250 ppm, neutral pH. The results are given in Table 7 and are illustrated graphically in Figure 5.

Table 7 Time (secs) Separated Amount of Aqueous Phase (ml) 0.1 % Teepol 0.1 % Teepol + 250 ppm IV 0 0 0 60 7 20 120 13 45 180 20 47 240 25 49 300 29 50 360 33 50 420 35 50 480 36 50 540 37 50 600 38 50 Example 7: Demulsification of Fuel Oil/Brine Mixtures The pH dependence of the ability of products III, IV, and V to demulsify a fuel oil/brine mixture was investigated. This mixture is perhaps representative of mixtures common in the oil and gas industry. The results are given in Table 8 and are illustrated in

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Figures 6a-c.

Table 8 - Diesel Fuell3% NaCl Solution [250 ppm additive] Time pH 4 pH 7 pH 9 (secs) control I11 IV V control 111 IV V control III IV V 0 0 0 0 0 0 0 0 0 0 0 0 0 60 10 3 3 6 15 1.4 9 1.5 12 1.5 3 1.5 120 42 10 13 23 48 9 48 6 42 7 14 8 180 50 30 33 35 50 38 50 22 50 26 38 18 240 42 50 38 48 35 46 49 31 300 50 48 46 50 41 360 46 44 420 45 480 48 540 48 600 48 Example 8: Biodegradability Study The biodegradability of the product of example VII was assessed in an OECD 301D Closed Bottle Test. The data is presented in Table 9 and graphically in Figure 7.

Table 9 Day % Biodegradability Reference (10 mg/l) Product VII (10 mg/I) 0 0 0 5 54 38 7 59 45 11 60 48 14 65 52 18 66 57 21 65 64 25 65 59 28 63 64 All publications mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the described methods and system of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in

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connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in chemistry or related fields are intended to be within the scope of the following claims.

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Claims (10)

1. CLAIMS 1. A method for demulsifying a composition comprising an oil and water, the method comprising contacting the composition with a demulsifier compound of the formula

   wherein: Y is a support substrate; R1, R2, R3 and R4 are independently selected from hydrogen and hydrocarbyl groups wherein one of R3 and R4 is a group of the formula C(O)X in which X is a linking moiety attached to the support substrate Y, and the other of R3 and R4 ("the non-linked substituent") is selected from hydrogen and hydrocarbyl groups; L is a linker group or bond; and n is an integer no less than 1.
2. 2. Use a demulsifier compound for demulsifying a composition comprising an oil and water, wherein the demulsifier compound is of the formula

   wherein: Y is a support substrate;

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   R1, R2, R3 and R4 are independently selected from hydrogen and hydrocarbyl groups wherein one of R3 and R4 is a group of the formula C(O)X in which X is a linking moiety attached to the support substrate Y, and the other of R3 and R4 ("the non-linked substituent") is selected from hydrogen and hydrocarbyl groups; L is a linker group or bond; and n is an integer no less than 1.
3. 3. The invention according to any one of the preceding claims wherein the hydrocarbyl group is a hydrocarbon group.
4. 4. The invention according to any one of the preceding claims wherein the non- linked substituent is a group of the formula C(O)OM wherein M is hydrogen or a water soluble metal cation.
5. 5. The invention according to any one of the preceding claims wherein the pendant group is an acylated amino acid.
6. 6. The invention according to any one of the preceding claims wherein the pendant group is an acylated a-amino acid.
7. 7. The invention according to claim 5 or 6 wherein the amino acid is a naturally occurring a-amino acid.
8. 8. The invention according to claim 7 wherein the amino acid is aspartic acid and or glutamic acid.
9. 9. The invention according to any one of the preceding claims wherein L is (CHZ)m wherein m is from 1 to 5.
10. 10. The invention according to claim 9 wherein m is 1 or 2.

    The invention according to any one of the preceding claims wherein In a preferred aspect of the present invention the non-linked substituent of the pendant group is a group of the formula C(O)OM wherein M is hydrogen, a water soluble metal

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    cation or an optionally substituted quaternary ammonium cation. When M is a water soluble metal cation, preferably M is a cation of an alkali metal or an alkaline earth metal.

    The invention according to any one of the preceding claims wherein Y is derived from a straight chain, branched chain, cyclic or aromatic carbon chain structure containing hydroxyl (-OH), thiol (-SH) or amine (-NHR3) substituents, capable of reacting to form the products of the subject invention.

    The invention according to any one of the preceding claims wherein n is from 2- 10.

    The invention according to any one of the preceding claims wherein Y is polyoxyalkylene, polyalkyleneamine, or polyoxyalkyleneamine of formula:

    wherein: . x is 1 to 20, Ry is H, alkyl or aryl, preferably H or Me z is 0 to 2 for the glycols n is 1, 2, 3 or 4, m is 1 to 20, R5 is H, alkyl or aryl.

    The invention according to claim 1 or 2 wherein the compound is of the formula

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    wherein: R is the aside chain grouping of an a-amino acid, Y is a support substrate R1, R2 are independently selected from hydrogen and hydrocarbyl groups, or R2 together with R is the heterocyclic ring of an imino acid, X is a linking moiety attached to the support substrate Y.

    The invention according to claim 1 or 2 wherein the compound is of the formula:

    wherein m is 1 or 2 and R1 is a straight or branched chain alkyl or alkenyl residue containing 1 to 30 carbon atoms, for example 1 to 19 carbon atoms, or a cycloalkyl or aryl residue having from 5 to 12 carbon atoms; R2 is hydrogen or aryl or a straight chain alkyl or alkenyl residue having from 1 to 30 carbon atoms, for example 1 to 20 carbon atoms; M is selected from hydrogen, water-soluble alkali metal cations, water-soluble alkaline earth metal cations and optionally substituted quaternary ammonium cation; X is a linking moiety, preferably -O- or -S- or -N(R3)- (R3 is H or alkyl or alkenyl or aryl or alkylaryl) derived from hydroxyl (-OH), thiol (-SH) or amine groupings (-NHR3) on Y.

    The invention according to claim 1 or 2 wherein the compound is of the formula:

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    wherein n is from 1 to 13, preferably from 3 to 13, more preferably 3, 4, 8, 9, or 13.

    The invention according to claim 1 or 2 wherein the compound is of the formula:

    wherein n is from 1 to 13, preferably from 3 to 13, more preferably 3, 4, 8, 9, or 13.

    A method as substantially hereinbefore described with reference to any one of the Examples.

    A use as substantially hereinbefore described with reference to any one of the Examples.