NZ613224B2 - A process for the production of (meth)acrylic acid and derivatives and polymers produced therefrom - Google Patents

Abstract

method of extracting (meth)acrylic acid from an aqueous reaction medium into an organic phase in contact therewith is described. The aqueous reaction medium is formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic, and citramalic acid or mixtures thereof in aqueous solution and contains the base catalysed decarboxylation products of the base catalysed reaction. The method includes either the addition of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent or maintaining the level of base catalyst to dicarboxylic acid and/or pre-cursor at a sub-stoichiometric level during the extraction process. The method extends to a process of producing (meth)acrylic acid, its esters and polymers and copolymers thereof. conic, and citramalic acid or mixtures thereof in aqueous solution and contains the base catalysed decarboxylation products of the base catalysed reaction. The method includes either the addition of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent or maintaining the level of base catalyst to dicarboxylic acid and/or pre-cursor at a sub-stoichiometric level during the extraction process. The method extends to a process of producing (meth)acrylic acid, its esters and polymers and copolymers thereof.

Description

A PROCESS FOR THE PRODUCTION OF (METH)ACRYLIC ACID AND DERIVATIVES AND POLYMERS ED THEREFROM The present invention s to a process for the production 0: (Heth)acrylic acid (meaning herein acrylic acid or methacrylic acid) or derivatives such as esters thereo: by the decarboxylation 0“ selected acids in the presence 0: base catalysts and the extraction 0: the (meth)acrylic acid product from the reaction medium.

Acrylic acid. (AA) and. Methacrylic acid. (MAA) and. their esters, particularly methyl, ethyl and butyl esters, such as ethyl acrylate, butyl te, methyl methacrylate (MMA) and butyl methacrylate are important monomers in the chemical industry. Their main application is in the production 0“ polymers ‘or various applications. The most significant polymer applications are ‘or acrylic acid in superabsorbent polymers, and methacrylate and acrylate esters ‘or e coatings and for high optical clarity plastics produced by the casting, moulding or ion 0' thyl methacrylate (?MMA). In addition, many copolymers of AA and its esters and MAA or MMA are used; important copolymers are copolymers o: MMA with yl e, ethyl acrylate and butyl acrylate. Currently AA, MMA and MAA are produced entirely from petrochemical tionally, MMA has been produced industrially via the so—called acetone—cyanohydrin route. The process is capital intensive and produces MMA from acetone and hydrogen cyanide at a relatively high cost. The process is e "ected by forming acetone cyanohydrin from the acetone and hydrogen cyanide: dehydration 0" this intermediate yields methacrylamide sulphate, which is then hydrolysed to produce MAA. The intermediate cyanohydrin is converted with sulphuric acid to a sulphate ester of the methacrylamide, methanolysis of which gives ammonium bisulphate and MMA.

However, this method is not only expensive, but both sulphuric acid and hydrogen e require careful and ive handling to maintain a safe operation and the process produces large amounts of ammonium sulphate as a by-product. Conversion of this ammonium sulphate either to a useable fertilizer or back to sulphuric acid requires high capital cost equipment and icant energy costs.

Alternatively, in a further process, it is disclosed to start with an isobutylene or, equivalently, t-butanol reactant which is then ed to methacrolein and then to MAA.

An improved process that gives a high yield and selectivity and far fewer by-products is a two stage process known as the Alpha process. Stage I is described in WO96/19434 and relates to the use of 1,2-bis-(di-t-butylphosphinomethyl)benzene ligand in the palladium catalysed ylation of ethylene to methyl propionate in high yield and selectivity. The applicant has also developed a process for the catalytic conversion of methyl propionate (MEP) to MMA using dehyde. A suitable catalyst for this is a caesium catalyst on a support, for instance, . This two stage process although significantly advantageous over the competitive processes ble still nevertheless relies on ethylene feed stocks predominantly from crude oil and natural gas, albeit bioethanol is also available as a source of ethylene.

Acrylic acid is conventionally prepared by oxidation of propene which is derived exclusively from oil, gas or coal feedstocks.

For many years, biomass has been offered as an alternative to fossil fuels both as a potential alternative energy resource and as an alternative resource for chemical process feedstocks.

Accordingly, one obvious solution to the reliance on fossil fuels is to carry out any of the disclosed processes for the production of AA, MMA or MAA using a s derived feedstock.

In this regard, syngas (carbon monoxide and hydrogen) can be derived from Biomass and that methanol can be made from syngas.

Several Industrial plants produce methanol from syngas on this basis, for example, at Lausitzer ik GmbH Laboratorium für Umwelt und Brennstoffe Schwarze Pumpe in Germany and Biomethanol Chemie Holdings, Delfzijl, Netherlands. Nouri and Tillman, Evaluating synthesis gas based biomass to plastics (BTP) technologies, (ESA-Report 2005:8 ISSN 1404-8167) teach the viability of using ol produced from synthesis gas as a direct ock or for the production of other feedstocks such as dehyde. There are also many patent and nonpatent ations on production of syngas suitable for production of chemicals from biomass.

The production of ethylene by dehydration of biomass d ethanol is also well established with manufacturing plants in, especially, Brazil.

The production of nic acid from carbonylation of ethanol and the conversion 0; biomass derived glycerol to molecules such as acrolein and c acid is also well established in the patent ture.

Thus ethylene, carbon monoxide and methanol have well ished manufacturing routes from. biomass. The chemicals produced by this process are either sold to the same specification as oil/gas derived Heterials, or are used in processes where the same purity is required.

Thus in principle there is no barrier to ion 0: the so called Alpha process above to produce methyl propionate from Qiomass derived feedstocks. "n fact, its use 0; simple feedstocks such as ethylene, carbon Hmnoxide and methanol rather sets it apart as an ideal candidate.

In this regard, WOZOlO/O58ll9 relates explicitly to tie use 0: biomass feedstocks for the above Alpha process and the catalytic conversion 0: methyl propionate (M19) produced to M,A using formaldehyde. These M19 and formaldehyde feedstocks could come from a biomass source as mentioned above. r, such a solution still involves considerable processing and purification O“ the biomass resource to obtain the feedstock which processing steps themselves involve the erable use 0 "ossil fuels.

Further, the Alpha process requires mu'tip'e feedstocks in one location which can lead. to bi'ity issues. It would therefore be advantageous i: any biochemical route avoided le feedstocks or lowered the number 0; feedstocks.

WO 07758 Acrylic acid is conventionally prepared by oxidation I] propene which is derived exclusively from oil, gas or coal feedstocks.

Therefore, an improved alternative ssil fuel based route to acrylate monomers such as AA, MMA. and. MAA. is still required. 9C1/G%70lO/O59l76 discloses a process for the manufacture 0; aqueous solutions 0: acrylates and methacrylates respectively from solutiors o: malic and citramalic acids and their salts.

Carlsson et al. nd. fing. Chem. Res. 1994, 33, 1989—1996 has disclosed ic acid decarboxylation to MAA at high temperatures 0: 360°C and with a 1naximum. yield of 70% where a tion o: the acid is present as a base salt, for instance, sodium. itaconate. Unfortunately, Carlsson does not disclose any purification methodology to recover the MAA from the reaction Hedium. Carlsson discloses that the activity for the decomposition reaction increases with the concentration of the sodium salt relative to the free acid. Tte selectivity falls as the concentration 0; itaconic acid is raised in the on prior to decomposition.

US 4142058 discloses the extraction 0: methacrylic acid from acidic aqueous solutions using es o: MMA and e under counter current flow. The aqueous pqase goes to waste. US 3968;53 discloses the extraction 0“ acrylic and/or methacrylic acid from an aqueous phase using methylethyl ketone and xylenes. US 4956493 discloses extracting rylic acid from its aqueous solution WO 07758 using a saturated chain aliphatic hydrocarbon having 6 to 9 carbon atoms as a solvent. Xylene and toluene are said to be problematic. fl? /l0643 uses an organic solvent to extract methacrylic acid from. its aqueous solution and treats the organic extract with water to assist in the removal 0: close boiling acids citraconic and maleic acid from the t. US 4879412 and J? l93740/l989 discuss ,he treatment or the organic phase with a basic ion exchange resin ard US 5196578 discloses a similar process using amines. The processes are problematic because they introduce additional impurities and can lead to by— products that cause polymerisation of the methacrylic acid leading to equipment failure.

Those skilled in the art would realise that the conditions of the solution. generated. according' to the teaching' 0; on et al would not be suitable for subsequent t extraction because 0: the low concentration 0: MAA and the high concentration 0: base. Rasic salts 0‘ AA and MAA have high solubilities in water and very low solubilities in organic solvents.

Surprisingly, it has now been discovered that AA and MAA can be extracted from an aqueous decarboxy'ation on medium in the presence 0: a basic catalyst witq a singly ed yield. Furthermore, the extraCtion s allows the basic solutions after extraction to be recycled into the oxylation reaction so that a continuous decarboxylation and extraction process to generate AA and MAA from di and tri carboxylic acids can be achieved with a single addition 0: base, such that the base catalysed reaction may be conducted continuously.

A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the ation it contains was part of the common general knowledge as at the priority date of any of the claims. hout the description and claims of the specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

In one aspect, the present invention provides a method of ting (meth)acrylic acid from an aqueous reaction medium, the s reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic, and citramalic acid or es thereof in aqueous solution and containing the base catalysed decarboxylation products thereof comprising (meth)acrylic acid and/or (meth)acrylate base salt, the method comprising the steps of introducing an organic solvent to the said aqueous reaction medium for solvent extraction of the (meth)acrylic acid into an organic phase wherein there is added an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the c solvent.

In a further aspect, the t invention es a method of extracting (meth)acrylic acid from an aqueous reaction medium, the s reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof in aqueous on and containing the base catalysed decarboxylation products thereof comprising (meth)acrylic acid or (meth)acrylate base salt, the method comprising the steps of ucing an organic solvent to the aqueous reaction medium for solvent extraction of the (meth)acrylic acid into the organic phase wherein the level of base catalyst to the said at least one dicarboxylic acid and/or rsor thereof is ined at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during the extraction process.

In yet a further aspect, the t invention provides a process for the production of (meth)acrylic acid comprising the steps of:- forming an aqueous medium of at least one base st and at least one dicarboxylic acid ed from fumaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof; decarboxylating the at least one dicarboxylic acid in the ce of the at least one base catalyst under suitable conditions of temperature and pressure to produce (meth)acrylic acid and/or base salts thereof in the aqueous medium; introducing an organic solvent to the said aqueous medium for solvent extraction of the (meth)acrylic acid into an organic phase; wherein the level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor f is maintained at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during the extraction process.

In yet a further , the rpesent invention provides a process for the production of (meth)acrylic acid comprising the steps of:- forming an s medium of at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof; decarboxylating the at least one dicarboxylic acid in the presence of the at least one base st under le conditions of temperature and pressure to produce (meth)acrylic acid and/or base salts thereof in the aqueous medium; introducing an organic solvent to the said aqueous medium for solvent tion of the (meth)acrylic acid into an organic phase; comprising the step of adding an onal amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent.

In still a further aspect, the present invention provides a method of extracting (meth)acrylic acid from an aqueous reaction medium into an organic phase in contact therewith, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, itaconic, citraconic, nic or citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof sing (meth)acrylic acid or (meth)acrylate base salt and the organic phase comprises a suitable c solvent for the said acrylic acid wherein in the aqueous reaction medium the relative level of base st to the said at least one dicarboxylic acid and/or pre-cursor thereof is ined at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during at least part of the extraction.

In still a further aspect, the present invention provides a method of extracting acrylic acid from an s reaction medium, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof comprising (meth)acrylic acid and/or (meth)acrylate base salt, the method comprising the step of t extraction of the (meth)acrylic acid into an organic phase comprising an organic solvent in contact with the said s reaction medium wherein there is added an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous reaction medium containing the said base catalysed decarboxylation products f to enhance the solvent extraction of the (meth)acrylic acid into the organic phase.

According to a first aspect of the present invention there is provided a method of ting (meth)acrylic acid from an aqueous reaction medium, the aqueous reaction medium being formed from at least one base st and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic and citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation ts thereof including (meth)acrylic acid and/or (meth)acrylate base salt, the method comprising the steps of introducing an organic solvent to the said aqueous reaction medium for solvent extraction of the (meth)acrylic acid into an organic phase wherein the method is characterised in that there is added an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent. ably, the concentration of (meth)acrylic acid in the s phase extraction is at least 0.05 mol dm-3, more ably, at least 0.1 mol dm-3, most preferably, at least 0.2 mol dm-3, especially, at least 0.3 or 0.4 mol dm-3. In a batch reaction, this concentration applies to the reaction medium at the start of the extraction and in a continuous process applies to the starting point in the extraction. The concentration of acrylic acid at the end of the extraction will depend on the number of stages but will preferably be below 50%, more preferably 30%, most preferably 20% of the starting level.

Advantageously, concentrations of the (meth)acrylic acid at these levels result in better extraction into the organic phase.

Generally, the base catalyst molar concentration in the aqueous reaction medium. during the extraction 0; (meth)acrylic acid ,herefrom is S the overall acid concentration therein mol/mol, more preferably, the base st molar concentration S 75% mol/mol o: the overall acid concentration during the extraction, most preferably, the base catalyst molar concentration in the aqueous on medium. during the extraction 0: acrylic acid therefrom. is S the non (meth)acrylic acid acid concentration mol/mol, more especially, S 80% o: the non (meth)acrylic acid acid concentration mol/mol daring the extraction. ?referably, the molar level 0: base catalyst to the said at least one dicarboxylic acid and/or pre—cursor :hereo; is ined at a sub—stoichiometric level ir relation to the formation 0 the first acid salt thereo: during the extraction. process and the amount 0: dicarboxylic acid added is determined accordingly.

Suitable mixtures O“ dicarboxylic acid for the production o: methacrylic acid are itaconic, citramalic, citraconic and mesaconic acid, more preferably, itaconic, citramalic and citraconic acid. Suitable mixtures 0" oxy'ic acid for the production 0: acrylic acid are maleic, fumaric, and malic acid, more preferably, malic acid.

Advantageously, the tion does not require addition 0: any process al agents to the aqueous phase so that the aqueous phase can easily and e 'iciently be recycled into the decarboxylation reaction medium for further decarboxylation under base catalysed conditions followed by further extraction. In this way no or little onal base is ed to process jurther dicarboxylic acid to acrylic acid. ?qually the only acids added. to the systeH1 are those dicarboxylic acids and/or pre—cursor acids involved in the production 0; (meth)acrylic acid or those acids formed in the production process. No external inorganic acid is required.

According' to a second aspect o: the present invention there is provided. a method of extracting (meth)acrylic acid from an aqueous reaction medium, the aqueous reaction medium being ‘ormed trom at least one base catalyst and at least one dicarboxylic acid selected rom 'umaric, maleic, malic, itaconic, citraconic, mesaconic or citrama'ic acid or mixtures : in aqueous solution and containing the base catalysed decarboxylation products ; including (meth)acrylic acid or (mett)acrylate base salt, the method comprising the steps or introducing an organic solvent to the aqueous reaCtion medium for solvent tion 0: the (meth)acrylic acid into the organic phase characterised in that the level 0: base catalyst to the said at least one dicarboxylic acid and/or pre—cursor thereo* is maintained at a sub—stoichiometric level in relation to the jorma,ion or the Sirst acid salt thereo; during the tion process.

According' to a further aspect o: the present invention there is provided. a method of extracting acrylic acid from an s reaction medium into an organic phase in contact therewith, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected. trom. :umaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures :hereo: in aqueous solution and containing the base sed decarboxylation products thereo: including acrylic acid or (meth)acrylate base salt and the organic phase comprises a suitable organic so'vent jor ,he said (meth)acrylic acid characterised in that in the aqueous reaction medium the relative level 0" base catalyst to the said at least one oxylic acid and/or pre—cursor :hereo: is maintained at a sub—stoichiometric level in relation to the 'ormation o the Sirst acid salt thereo: during at least part of the extraction.

According to a still further aspect o; the present invention there is provided a method of extracting (meth)acrylic acid :fixmi an aqueous reaction , the aqueous reaction. mediunl being' formed. front at least one base catalyst and at least one dicarboxylic acid selected from. maleic, fumaric, malic, ic, citraconic, mesaconic or citramalic acid or mixtures thereo; in aqueous solution and containing the base catalysed decarboxylation. products thereo: including' (meth)acrylic acid and/or acrylate base salt, the method comprising the step 0: solvent extraction of the (meth)acrylic acid into an organic phase sing an c solvent in contac: with the said aqueous reaction medium wherein the method is terised in that there is added an additional amount 0: at least one ol ,he said dicarboxylic acids and/or a pre—cursor thereo to ,he said aqueous reaction medium containing the said base catalysed decarboxylation. products thereo: to enhance the solvent extraction 0: the acrylic acid into the organic phase. ?referably, the method 0: any aspect herein includes the step 0: separating the organic phase from. the aqueous phase after extraction followed by subsquent treatment 0; the organic phase to isolate the (meth)acrylic acid extraCted in the tion process from the organic solvent. A suitable treatment of the organic phase is distillation to obtain the (meth)acrylic acid.

It will be understood that the oxylic acid being a c acid can form a irs, and second acid salt : with a base and the term first acid salt should be understood accordingly and is th intended to refer to ,he salt with a second or furtqer acid group on the dicarboxylic acid or pre—cursor thereO“ but only the first acid salt that forms.

Advantageously, by maintaining the base at sab— stoichiometric first acid salt levels with respect to the level 0" dicarboxylic acid and/or pre—cursor in the aqueous medium/reaction medium the extraction of ,he (Heth)acrylic acid into the suitable organic solvent is improved. ?referably, in the case 0: decomposition O“ acids for the formation 0: MAA, the organic solvent is an external organic solvent with respect to the aqueous medium/reaction medium. ?referably, at least some onic acid is t in the s medium. Advantageously, this improves the extraction. However, the most suitable acid currently is itaconic acid due to its commercial availability or citramalic acid.

A suitable pre—cursor is one which can be re—cycled to produce one or more 0; the said oxylic acids.

Typically, the pre—cursor will decompose under suitable conditions 0: temperature and pressure to produce the said dicarboxylic acids. Accordingly, the pre—cursor may be regarded as a source 0: the dicarboxylic acid. "t will be appreciated. that a base catalyst is already present so that the pre—cursor decomposition. may advantageously be base catalysed under such suitable conditions. A suitable pre—cursor for the itaconic, citraconic, mesaconic or citramalic acids is citric acid which may be dehydrated and decarboxylated to produce at least one o: itaconic, citraconic, mesaconic acids or oxylated to produce citramalic acid. This reaction takes place under suitable conditions 0: ature and pressure and optionally in the presence 0: the base catalyst without the ity or a further separate catalyst. However, it has been found that adding citric acid to the aqueous medium/reaction medium prior to extraction also assists the extraCtion o; the methacrylic acid as the added acid whilst also nOt introducing an external reagent which itsel: needs to be removed. front the aqueous medium/reaction. mediunl because the citric acid can then be treated subsequently to generate more dicarboxylic acid and thence rylic acid in a continuous process. ing to a third aspect o: the present invention there is provided a process for the production or (mesh)acrylic acid comprising the steps 0;:— WO 07758 forming an aqueous medium 0: at least one base catalyst and at least one dicarboxylic acid se'ected rom 'umaric, maleic, malic, itaconic, citraconic, mesacoqic or citramalic acid or mixtures thereo:°I decarboxylating the at least one dicarboxylic acid in the presence of the at least one base catalyst under suitable conditions 0: temperature and pressure to e (meth)acrylic acid and/or base salts thereo; in the aqueous medium; introducing an c solvent to the said s medium for solvent extraction of the (meth)acrylic acid into an c phase; terised in that the level 0: base catalyst to the said at least one dicarboxylic acid and/or pre—cursor thereo; is maintained. at a sub—stoichiometric level in relation to the 'ormation 0' ,he Sirst acid salt thereo; during the extraction process.

In any aspect herein, the organic solvent may be introduced to the aqueous medium before or a:ter decarboxylation. ?referably, the sub—stoichiometric level is maintained, a‘ter, it necessary, being implemented post reaction by added acid, during at least that part or the extraction process herein which is carried out after the decarboxylation step.

According' to a fourth aspect o: the present invention there is provided a process for the tion I] (meth)acrylic acid comprising the steps 0;:— forming an aqueous medium 0; at leaSt one base catalyst and at least one dicarboxylic acid se'ected rom 'umaric, maleic, malic, itaconic, citraconic, qic or citramalic acid or mixtures thereo:°I decarboxylating the at least one dicarboxylic acid in the presence of the at least one base catalyst under suitable conditions 0: temperature and pressure to produce (meth)acry;ic acid and/or base salts thereo; in the aqueous medium; introducing an organic solvent to the said aqueous medium for t extraction 0:5 the (meth)acrylic acid into an organic phase; characterised by tqe step 0: adding an additional amount 0: at least one o: the said dicarboxylic acids and/or a pre—cursor thereo‘ to the said aqueous medium, preferably, alter the decarboxylation step to enhance the solvent tion of the (meth )acrylic acid into the organic phase.

Advantageously, in accordance with some embodiments of the invention, it is also possible to in the 'evel 0' base st to the said at least one dicarboxylic acid and/or pre—cursor thereOt at a sub—stoichiometric level in relation to the 'ormation o the Sirst acid salt thereo; during the decarboxylation.

Suitable organic solvents for (meth)acrylic acid extraCtion e hydrocarbon ts or ated ts, particularly C4—Cm hydrocarbon solvents. The hydrocarbon solvents may be tic, aromatic, or part aromatic, saturated or unsaturated, cyclic, acyclic or part cyclic, linear or branched. The oxygenated solverts may be esters, ethers or ketones. Suitable solverts e toluene, benzene, ethylbenzene, xylere, trimethylbenzene, octane, heptane, hexane, pentare, cyclopentane, exane, cycloheptane, cyclOOCtare, cyclohexene, methylcyclohexane, methylethylketone, metryl methacrylate or mixtures thereof. "onic liquids which are immiscible with water may also be used.

A preferred mixture 0“ solvents for the extraction of MAA is a C4—Cm hydrocarbor solvent and MMA. A suitable mixture ns l—40% MMA, more lly, 5—30% MMA. with the balance made up 0: the hydrocarbon solvent(s). ?referred hydrocarbon solvents for this purpose are toluene and xylenes.

Nevertheless, it is preferred to use only C4—Cm hydrocarbons either alone or in mixtures with other hydrocarbons as the extractive solvent. '?referably, the relative (static) permittivity of tie arbon or each o: the hydrocarbons in a mixture 0“ hydrocarbons is less than 20, more preferably, less than 8, most preferab'y, less than 3 at 20°C and atmospheric pressure. Accordingly, hydrocarbons having relative (static) permittivity in the range 1.6 to 20 are preferred, more preferably in the range 1.7 to 8, most preferably, in the rarge 1.8 to 3 at °C and atmospheric pressure.

The preferred solvents and mixtures for extraction of AA have re1ative (static) tivity 0' 'ess than 20, more preferably, less than 10, most preferab'y, less than 7 at °C and atmospheric pressure. Typically, the relative (static) permittivity is at least 1.6, more typically, at leaSt, 2.0, most typically, at least, 2.3. Accordingly, solvents having relative (static) permittivity in the range 1.6 to 20 are preferred, more preferably in the range 2.0 to 10, most preferably, in the range 2.2 to 8 all at 20°C and atmospheric re.

The dicarboxylic acid(s) reactants and the base catalyst need not necessarily be the only compounds present in the s medium/reaction . The dicarboxylic acid(s) together with any other compounds present are generally dissolved in an aqueous solution for the base catalysed thermal oxylation. ?referably, the base catalysed decarboxylation of the at least one dicarboxylic acid takes place at less than 350°C, typically, less than 330°C, more preferably, at up to 310°C, mos, preferably at up to 300°C. In any case, a preferred lower temperature for the decarboxyLation process of the present invention is 200°C. red temperature ranges for the decarboxylation process 0: the present invention are between 200 and up to 349°C, more preferably, between 220 and 320°C, most preferably, between 240 and 310°C, especially between 240 and 290°C.

An ally red temperature range is 240 —275°C, most especially, 245—275°C 2012/050272 The base catalysed decarboxylation reaction takes place at a temperature at which the aqueous medium/reaction medium is in the liquid phase. Typically, the aqueous nedium/reaction medium is an aqueous solution. ?referably, the base catalysed decarboxylation takes place with the dicarboxylic acid reactants and preferably the base catalyst in aqueous solution.

Advantageously, carrying out the decarboxylation at lower temperatures prevents the tion 0" significant s 0: by—products which may be di 'iculL. to remove and may cause further purification and processing problems in an industrial process. Therefore, the s provides a. surprisingly improved. selectivity in this temperature range. Furthermore, lower temperature decarboxylation uses less erergy and thereby creates a smaller carbon footprint than high temperature decarboxylations. ?referably, the extraction step of the acrylic acid takes place at less than or equal to the decarboxylation temperatures detailed. above, more preferably however at less than 100°C, most ably, at less than 80°C, especially less than 60°C. In any case, a red lower temperature for the extractior step of the present invention is —lO°C, more preferably, 0°C. ?referred temperature ranges for the extraction step of ,he present ion are between —lO and up to 3m9°C, more preferab'y, between —lO and 100°C, most preferably, between 0 and 80°C, especially between 10 and 60°C, more especially 30—50°C.

The extraction step takes place at a ature at which the organic and aqueous phases are in the liquid phase.

Accordingly, the extraction step takes place at a pressure at which the organic and s phases are in the liquid phase, generally, extraction takes place at atmospheric pressure.

The dicarboxylic acids are available from non-fossil fuel sources. For instance, the itaconic, citramalic, citraconic or mesaconic acids could be ed from rsors such as citric acid or ric acid by dehydration and decarboxylation at suitably high temperatures or from aconitic acid by decarboxylation at suitably high temperatures. It will be appreciated that a base catalyst is already present so that the rsor may be subjected to base catalysed dehydration and/or decomposition. Citric acid and isocitric acid may themselves be produced from disclosed fermentation processes and aconitic acid may be produced from the former acids.

Accordingly, the process of the invention goes some way to providing a biological or substantially biological route to generate (meth)acrylates ly whilst minimising reliance on fossil fuels.

US5849301 discloses a process for production of malic and fumaric acids from glucose. US5766439 discloses a process for production of maleic acid. Malic acid is also available by extraction of products produced in agriculture such as apple juice.

To maintain the reactants in the liquid phase under the above temperature conditions the decarboxylation reaction o: the at least one oxylic acid is carried out at suitab'e pressures in excess 0 : atmospheric pressure.

Suitable pressures which will in the reactants in the liqLid phase in the above temperature ranges are greater than , more suitably, greater than 300psi, most suitably, greater than 450psi and in any case at a higher re than that below which the reactant medium will boil. There is no upper 'imit 0“ pressure but the skilled person will operate within practical limits and within apparatus rces, for instance, at less than ,000psi, more typically, at less than 5,000psi, most typically, at less than m000 psi. ?referably, the above decarboxyl ation reaction. is at a pressure 0: between about 200 and 10000psi. More preferably, the reaction is at a pressure 0: between about 300 and 5000 psi and yet more pre:ferably between about 450 and 3000psi.

In a. preferred. embodiment, the above reaction. is at a pressure at which the aqueous medium/reaction medium is in the liquid phase.

The above reaction. is at a temperature and. re at which the s medium/reaction medium is in the liquid phase.

As mentioned above, the catalyst is a base catalyst. ?re‘erab'y, the catalyst comprises a source of OH’ ions. '?re‘erab'y, the base catalyst comprises a metal oxide, hydroxide, carbonate, acetate (ethanoate), alkoxide, hydrogencarbonate or salt 0: a decomposable di— or tri— carboxylic acid, or a quaternary ammonium compound 0; one of the above; " more pre‘erab'y a Group or Group metal oxide, ide, carbonate, acetate, alkoxide, hydrogencarbonate or salt of a di— or rboxy'ic acid or (meth)acrylic acid. The base catalys: may also se one or more amines. ably, the base st is selected from one or more 0: she jollowing: LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)% 3a (0‘1) 2, CSOH, Sr (OH) 2, RbOH, NH4OI‘ , Li2CO3, Na2CO3, K2CO3, Qb2CO3, , MgCO3, CaC03, SICO3, 3aCO3, (NH4)2CO3, LiHCO3, \TaHC03, KHCO3, RbHCO3, CSHCO3, Mg (HCO3) 2, C8. (HCO3) 2, Sr (HCO3) 2, 3a (HCO3) 2, NH4HCO3, Li20, Na20, K20, Rb20, C820, MgO, CaO, SrO, 3aO, Li(ORl), Na(OR1), K(OR1), Rb(OR’), Cs(OR1), Mg(ORl)2, Ca(OR1)2, smoahg, 3a(ORl)2, NH4(O'R1) where R1 is any C1 to C6 branched, unbranched or cyclic alkyl group, being optionally subs:ituted with one or more functional groups; NH4(RC02), Li(RCO2), Na(RC02), K(RCOQ, {b('{CO2), CS(RCO2), Mg(RCO2)2, C8.(RCO2)2, SI(RCO2)2 OI 5a(<COfl2, where RCO2 is selected from Halate, te, naleate, citramalate, mesaconate, citraconate, itaconate, citrate, oxalate and (meth)acrylate; (NHM2(COQRCOQ, Li2(CozRCOZ), Na2(COZRCOZ), K2(COZRCOZ), Rb2(CozRCOZ), CS2 (CO2QCO2) , Mg (CO2RCO2) , C8. (CO2QCO2) , Sr (CO2QCO2) , 3a(COZRC02), (NH4)2(C02RC02), where C02QC02 is selected from nalate, fumarate, maleate, citramalate, mesaconate, citraconate, ate and oxalate; (NHM3(COZR(C02)COfl, 2¥(CO2)CO2), Na3(CO2R(C02)CO2), K3(CO2R(CO2)CO2), 'Qb3(COZQ(CO2)CO2), 2R(COZ)COZ)I 93(COZR(CO2)CO2)2, Ca3(COZQ(CO2)CO2)2, Sr3(COZR(CO2)CO2)2, OZQ(CO2)CO2)2, (NH4LMCOZR(C02)C02), where COZR(C02)COZ is selected from citrate, isocitrate and aconitate; methylamine, mine, propylamine, butylamine, pentylamine, hexylamine, cyclohexylamine, aniline; and RANCH where R is selected from methyl, ethyl propyl, butyl. More preferably, the base is selected from one or more of the 'o"owing: LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2, 3a(OH)2, CSOH, Sr(OH)2, RbOH, NH4O , Li2CO3, Na2C03, K2CO3, , CS2CO3, MgCO3, CaC03, (N M2CO3, LiHCO3, NaHCO3, KHCOa RbHCO3, CSHCO3, Mg(HCOB)h ca(HC03)h Sr(HC03)h 3a(ECOB)h NH4HCO3, Li2 O, Na20, K20, Rb20, C820,; NH4 (RCO2) Li ) , , Na (-RCO2) , K(RCOZ) r Rb(RCO2), 2)I Mg(RCO2)2r Ca(RCOZ)% SI (-RCO2) 2 Of 3a (RCO2) 2, where RC02 is selected from malate, te, maleate, itaconate, citrate, oxalate, (meth)acrylate; (NH4)2(COZRCOZ), Li2(COgRCOZ), Na2(COg¥COZ), K2(C02RC02), Rb2 (CO2RCO2) , CS2 O2) , Mg (CO2-RCO2) , C8. (CO2RCO2) , SI (CO2RCO2 ), 3a (CO2RCO2) , (1\I‘4)2(CO2RCO2) , where CO2RCO2 iS selected from malate, tamarate, maleate, citramalate, mesaconate, citraconate, ate, oxalate; (Nan3(coz%(co2)cow, Li3(CO2R(CO2)CO2), Na3(CO2R(C02)CO2), K3(CO2R(CO2)CO2)r Rb3(CO2R(CO2)CO2)r CS3(CO2R(CO2)CO2)r 93(COZR(CO2)CO2)2I ca3(CO2R(CO2)CO2)2r Sr3(CO2R(CO2)CO2)% 38.3 (C02? (C02) C02) 2, (NH4)3(CO2R(CO2)CO2) , where CO2R(CO2)CO2 is selected from citr ate, isocitrate; tetramethylammonium hydroxide and tetraethylammonitm hydroxide. Most ably, the base is selected from one or more 0: the “ol'owing: NaOH, KOi, Ca(O{)2, CSOH, RbOH, NH4OH, Na2CO3, K2CO3, Rb2CO3, CS2CO3, MgC03, CaC03, (NH4)2CO3, NH4(RCO2) , Na (QCO2) , K(RCOZ) r Rb(RCO2), CS(RCO2), 2)2, Ca(RCO2)L Sr (QCO2) 2 or 3a (RCO2) 2, where RCO2 is selected from , fumarate, maleate, itaconate, citrate, oxalate, (meth)acrylate; (NH4)2(CO2RCO2), Na2(CO2RCO2), K2(C02?CO2), Rb2(COgRCOZ), CS2 (CO2RCO2) , Mg (CO2RCO2) , C8. (CO2QCO2) , (NH4) 2 (CO2RCO2) , where CO2RCO2 is selected from malate, VV()2012/107758 fumarate, e, citramalate, mesaconate, citraconate, itaconate, oxalate; (NH4)3(CO2R(C02)CO2), Na3(C02'R(C02)C02) , K3(COZR(COZ)COZ) , Rb3(CO2R(CO2)CO2)r CS3(C02R(COZ)COZ)I Mg3(CO2R(CO2)CO2)2, Ca3(CO2R(CO2)CO2)2, (Ni4LMCOZR(C02)C02), where COZR(C02)COZ is selected from citrate, isocitrate; and tetramethylammonium hydroxide.

The catalyst may be homogeneous or heterogeneous. In one embodiment, the catalyst may be dissolved in a li quid reaction phase. However, the catalyst may be suspended on a solid support over which the reaction phase may pass. In this scenario, the reaction phase is preferably mainta ined in a liquid, more preferably, an aqueous phase. ?referably, the ratio 1 e "ective mole 0: base OH’:acid for the decarboxylatioq reaction is between 0.00l—2:l, more preferab'y, 0.0l—l.2:l, most preferably, O.l—l: 1, especially, ’. Ry the e ec ,ive mole ratio 0: base OH’ is meant the nomiral molar con ,ent of OH’ derived from the nds concerned. 3y acid is meant the moles 0: acid. Thus, in tqe cas e 0:. a sic bas , th " c,iv mol ratios 0: base OH :acid will coincide with :hose 0: the compounds concerned but in the case of di or tribasic bases the e e mole ratio will not coincide with that (y' mole ratio 0' the compounds concerned.

Specifically, this may be regarded as the mole re tio o; sic base: di or tri carboxylic acid is preferably between 0.00l—2:l, more preferably, 0.0l—l.2:l, most preferably, O.l—lzl, especially, 0 .3—lzl.

As the deprotonation o: the acid to form the salt is only referring' to a first acid. deprOtonation. in the present invention, in the case 0: di or tribasic bases, the mole ratio of base above will vary ingly.

Optionally, the (meth)acrylic acid product may be esterified to produce an ester thereo;. ?otential esters may be selected from Cy4h2 alkyl or C2452 hydroxyalkyl, l, isobornyl, dimethylaminoethyl, tripropyleneglycol esters. Most preferably the alcohols or alkenes used or 'orming the esters may be derived from bio sources, e.g. biomethanol, bioethanol, biobutanol.

As mentioned above, the pre—cursor such as citric acid, isocitric acid or aconitic acid preferably decomposes under suitable conditions 0: temperature and pressure and optionally in the presence 0: base catalyst to one o: the dicarboxylic acids 0: the invention. le conditions for this decomposition. are less than 350°C, typically, less than 330°C, more preferably, at up to 310°C, most preferably at up to 300°C. In any case, a preferred lower temperature tor the decomposition is 180°C. ?referred temperature ranges for the rsor decomposition. are between 190 and up to 349°C, more ably, n 200 and 300°C, most preferably, between 220 and 280°C, especially between 220 and 260°C.

The pre—cursor decomposition reaction takes place at a temperature at which the aqueous on medium is in the liquid phase.

To maintain the reactants in the liquid phase under the above pre—cursor decomposition temperature conditions the decarboxylation on is carried out at suitable pressures in excess of atmospheric pressure. Suitable pressures which will maintain the nts in the liquid phase in the above temperature ranges are greater than , more suitably, greater than l80psi, most suitably, greater than 230psi and in any case at a higher pressure than that below which the reactant medium will boil. There is no upper limit 0“ pressure but the skilled person will operate within practical limits and within apparatus nces, for instance, at less than 10,000psi, more typically, at less than 5,000psi, most typically, at less than 4000 psi. ?referably, the pre—cursor decomposition on is at a re 0: between about 150 and 10000psi. More preferably, the reaction is at a pressure 0: between about 180 and 5000 psi and yet more preferably between about 230 and 3000psi. 211 a preferred. embodiment, the pre—cursor decomposition reaction is at a pressure at which the reaction medium is in the liquid phase. ?referably, the pre—cursor decomposition reaction is at a temperature and pressure at which the aqueous reaction medium is in the liquid phase.

According' to a further aspect o: the present invention there is provided a method 0: preparing polymers or copolymers o: (meth)acrylic acid or (meth)acrylic acid esters, comprising the steps 0; (i) preparation 0" (Heth)acrylic acid in accordance with the third or fourth aspect o: the present invention; (ii) optional esterification o: the (Heth)acrylic acid prepared in (i) to produce the (meth)acrylic acid ester; (iii) polymerisation O“ the (meth)acrylic acid prepared in (i) and/or the ester prepared in (ii), optionally with one or more comonomers, to produce polymers or copolymers thereor. ?referab'y, the (meth)acrylic acid ester 0: (ii) above is selected from C1—CQ alkyl or C2—CH hydroxyalkyl, y', isobornyl, dimethylaminoethyl, tripropyleneglycol esters, more preferably, ethyl, n—butyl, i—butyl, hydroxymethyl, hydroxypropyl or mettyl methacrylate, most preferably, methyl methacrylate, ethyl acrylate, butyl methacrylate or butyl acrylate.

Advantageously, such polymers will have an iable portion i: not all of the monom r r sidu s d riv d from a source other than fossil fuels.

In any case, preferred mers include for example, monoethylenically rated carboxylic acids and dicarboxylic acids and their derivatives, such as esters, amides and anhydrides. ?articalarly preferred comonomers are acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n—butyl acrylate, iso—butyl acrylate, t—butyl acrylate, 2— exyl acrylate, hydroxyethyl acrylate, iso—bornyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n—butyl rylate, iso—butyl methacrylate, l methacrylate, 2—ethylhexyl WO 07758 2012/050272 methacrylate, hydroxyethyl methacrylate, laury; methacrylate, glycidyl methacrylate, hydroxypropy; methacrylate, iso—bornyl H@:hacrylate, dimethylaminoethy; methacrylate, tripropy'eneg'ycol diacrylate, styrene, d— methyl styrene, vinyl acetate, isocyanates including toluene diisocyanate and p,p'—methylene diphenyl diisocyanate, acrylonitrile, butadiene, bLtadiene and styrene (M38) and ABS subject to any of the above mers not being tqe momomer selected from methacrylic acid or a methacrylic acid ester in (i) or (ii) above in any given copolymerisation o: the said acid monomer in (i) or a said ester monomer in (ii) with one or more 0: the comonomers . "t is 0‘ course also le to use mixtures 0" di 'erent comonomers. The comonomers themselves may or nay rot be ed by the same process as the monomers from (i) or (ii) above.

According' to a r aspect o: the present invention there is provided polyacrylic acid, polymethacrylic acid, po'yalky'acrylate, polymethylmethacrylate (?MMA) and polybutylmethacrylate homopolymers or copolymers formed from the method 0: preparing polymers or copolymers o: the above aspec:.

According to a still further aspect of the present ion there is provided a process for the production or mechacrylic acid comprising:— providing' a source 0; a pre—cursor acid selected from aconitic, citric and/or isocitric acid; performing' a decarboxylation and, i; necessary, a dehydration step on the source 0‘ pre—cursor acid by exposing the source thereo: in the presence or absence 0; base catalyst to a su ”ici ently high temperature to provide itaconic, mesaconic, citraconic and/or citramalic acid; and use of the itaconic, mes aconic, citraconic and/or citramalic acid ed in a process according to any 0; the other aspects o: the present invention to provide methacrylic acid and/or enhance extraction thereo: into an organic phase.

By a source 0: aconitic, citric and/Or isocitric acid is the acids and salts thereo:" meant such as groap or metal salts thereo: and includes ons of the pre— cursor acids and salts thereo: , such as s ons thereof.

Optionally, the salt may be acidified to liberate the free acid prior to, during or after the pre—cursor acid oxylation step. ?referably, the dicarboxylic acid(s) reactant(s) or the pre—cursors thereo o the present invention are exposed to the reaction conditions for a suitable time period to e "ect the required reaction, typical'y, 'or a time period of at least 30 seconds, more ab'y a: least about 100 seconds, yet more preferably at least about 120 seconds and most preferably at least about 150 seconds.

Typically, the dicarboxylic acid(s) reactant(s) or pre— cursors thereo: are exposed to the reaction ions :Olf a time period 0: less than about 2000 seconds, more typically less than about 1500 seconds, yet more typically less than about 1000 seconds. ?referably, the dicarboxylic acid(s) reactant(s) or the pre—cursors thereo o the present invention are exposed to the reaction conditions for a time period of between about 75 seconds and 2500 seconds, more preferably between about 90 seconds and 1800 seconds and most ably between about 120 s and 800 seconds. ?referably, the dicarboxylic acid(s) reactant(s) or the pre—cursors thereo o the present invention are dissolved in water so Lhau ,he reaction occurs under aqueous conditions. "t wil' be c'ear 'rom ,he way in which the above reactions are defined that if Lte pre—cursor is decarboxylated and, if necessary, dehydrated. in a on. mediuH1 then the reaction medium may simultaneously be e 'ecting base catalysed decarboxylation of the at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, nic, citramalic acid or mixtures ; ed from. the pre—cursor thereo: according to any aspect o: the invention. Accordingly, the decarboxylation and i; recessary, dehydration of ,he pre—cursor and the base catalysed oxylation of the at least one dicarboxylic acid may take place in one reaction medium i.e. the two processes may take place as a one pot process. However, tt is red i" the pre—cursor is decarboxylated and, if necessary, dehydrated substantially without base catalysis so that the decarboxylation and i; necessary, dehydration of tie rsor and the base catalysed decarboxylation of ,he at least one dicarboxylic acid take place in separate steps. 2012/050272 ?referably, the concentration 0: the dicarboxylic acid reactant(s) ill the decarboxylation reaction is at least 0.1M, preferably in an aqueous source thereo:; more preferably at least about 0.2M, preferably in an aqueous source thereo:; most preferably at least about 0.3M, preferably fill an aqueous source thereo:, especially, at least about 0.5M. Generally, the aqueous source is an aqueous on. ?referably, the concentration 0: the dicarboxylic acid reaCtant(s) in the oxy'ation reaction is less than about 10M, more preferably, 'ess than 8M, preferably in an aqueous source thereo:; more preferably, less than about 5M, preferably in an aqueous source thereo:; more preferably less than about 3M, ably in an aqueous source thereo;. ?referably, the concentration 0: the dicarboxylic acid reactant(s) in the decarboxylation reaction is in the range 0.05M—20, typically, OM, more preferably, O.lM—5M, most preferably, 0.3M—3M.

The base st may be dissolvable in a liquid , which may be water or the base catalyst may be geneous. The base catalyst may be dissolvable in the aqueous medium/reaction. mediunl so that reaCtion is e "ected. by exposing' the reactants to a temperature in excess of that at which base catalysed decarboxylation o; the reactant(s) to (meth)acrylic acid and/or the pre— cursor acids to the dicarboxylic acids will occur such as those temperatures given above. The catalyst may be in an aqueous solution. Accordingly, the catalyst may be qomogenous or heterogeneous but is typically homogenoas. ?referably, the concentration 0; the catalyst in the aqueous mediJm/reaction medium (including the decomposition 0" pre—cursOr acid medium) is at least 0.1M Or greater, preferably in an aqueous source :; more preferably at least about 0.2M, ably in an aqueous source "; more preferably at least about 0.3M. ?referably, the concentration 0; the catalyst in the aqueous mediLm/reaction medium (including the osition 0" rsor acid medium) is less tqan about 10M, more preferably, less than about 5M, more preferably less than about 2M and, in any case, preferably less than or equal to that which would amount to a saturated solution at the ature and pressure of the reaction. ?referably, the mole concentration of OH’ in the aqueous nedium/reaction medium or pre—cursOr acid decomposition is in the range 0.05M—20M, more preferably, O.l—5M, most preferably, 0.2M—2M. ?referab'y, the reaction conditions are weakly acidic. ?referab'y, the reaction pH is between about 2 and 9, more preferab'y between about 3 and about 6.

For the avoidance o: doubt, by the term itaconic acid, is meant the following compound 0 'ormula (i) COOH :</COOH For the avoidance o: doubt, by the term citraconic acid, is meant the following compound 0 "ormula (ii) COOH kCOOH (ii) For the nce of doubt, by tqe term nic acid, is mean, the jollowing compound 0' 'ormula (iii) HOOC \ COOH (iii) For the avoidance o: doubt, by the term citramalic acid, is meant the following compound 0 'ormula (iv) As mentioned above, the processes 0: the present invention may be homogenous or heterogeneous. In addition, the process may be a batch or continuous process.

Advantageously, one by—product ill the production (x: MAA may be hydroxy isobutyric acid (i %) which exists in equilibrium with the product MAA at the ions used for osition o: the dicarboxylic acids. Accordingly, partial or total separation o: the MAA from the products of the decomposition reaction shifts the equilibrium from H % to MAA thus generating further MAA during the extraction process or in subsequent processing 0: ,he solution aluer separation o: MAA. Optionally the solvent may be present during the decomposition reaction so that a portion at least of the rylic acid is extracted into the organic medium during the decomposition reaction.

Advantageously, one by—product in the production of AA may be hydroxy propionic acid ({?A) which exists in equilibrium with the product AA at the conditions used :OI decomposition of the dicarboxylic acids. Accordingly, partial or tOtal tion 0: ,he AA from the products 0; the decomposition on shilos the equilibrium from H?A to AA. thus generating further~ AA. ' the extraction process or in uent processing 0: the solution after separation (x? AA. Optionally the solvent may be present during the decomposition. reaCtion so that a portion at least 0: the c acid is extrac:ed into the c medium during the decomposition reaction.

Where a. compound (3 a "Ormula herein may exist ES more than one stereoisomer, for example a compound 0 "Ormula (iv) above, all stereoisomers are included withir the scope o: the invention. "n particular, R+ or S— 'OYHS O" citramalic acid as well as racemic detures thereo: are included within the scope o: the term alic acid.

All 0: the leatures contained herein may be combined with any of the above aspects, in any combination.

For a better understanding 0: the invention, and to show how embodiments o: the same may be d into e "ect, reference will now be made, by way 0: example, to the 'o'lowing ‘igures and examples in which:— Figure 1 shows the concentration dependence I] 0; the extraction 0: MAA into toluene; Figure 2 shows a plot of partition coe t ‘or a range o: acids against MMA on in toluene; Figure 3 shows a plot 0: relative partition coe 'icient for a range 0: acids with MMA. against MMA. fraction in :oluene; Figure 4 shows the e "ect or adding base and dicarboxylic acid on trans"er 0" MAA between aqueous and organic phases; Figure 5 shows the distribution 0“ acrylic acid between water and e; Figure 6 shows 1 a schematic view 0' suitable apparatus :or the base catalysed decomposition O“ dicarboxyiic acids.

Solvent Extraction The following experimental conditions were used unless indicated ise:— - O.lM Acids - 1:; vol:vol aqzsolvent - Room Temperature - 1 minutes agitation time; 5 min settling time ' Solvent is toluene unless where stated ' is by H?LC Comparative Example 1 A series of solvents were tested to examine the extent of transfer 0" methacrylic acid from an s solution using the above procedure. The results are shown in table 1.

Table 1 relative Average % (static) Transfer permittivity Mixed Xylenes Toluene {exane Benzene ?entane Cyclohexane This example shows that MAA present in the free acid form can be e"iciently extracted. into a range of solvents. ic hydrocarbons give the highest extraction e"iciencies.

Comparative Example 2 sic and dibasic acids likely to be present in aqueous solution following partial decomposition of mono and dicarboxylic acids expected to be found from decomposition 0' dibasic or tribasic acids were compared :Or their solubii ity in toluene.

Each acid, initially at 0.1M solution in water was separately tested ‘or solubility in volume I] an equal 0; e. The results are shown in table 2 Table 2 Fraction Transferred to Acid Toluene/% Tonobasic ,AA 54.4 CT 40.ll % 4.21 '?Y O dibasic I C 0 MC 0.64 MAA rylic Acid CT Crotonic Acid i % Hydroxyisobutyric Acid BY Byruvic Acid C taconic Acid C esaconic Acid This example shows that the di and 'tricarboxylic acids use u' in the process for the production 0: MAA are not soluble in toluene, one solvent which can be employed :or the extraction o: MAA. Furthermore H % ‘ormed in equilibrium with MAA is not extracted ir icant proportions and c acid. formed. as an unwanted. by— produc: is also not extracted into toluene.

Comparative Example 3 A. series 0 di "erent concentrations (If MAA 111 aqueous solution. were extracted. into toluene (1:1 by volume vs aqueous solution). The percentage lity is shown in table 3.

Table 3 [MAA] in % extracted at starting aq 1:1 :oluene to soln/M aq soln C0“p Ex 3a 0.00743 12.69% C0“p Ex 3b 0.0148 20.07% C0“p Ex 3c 0.02878 26.76% C0“p Ex 3d 0.05829 37.09% Corp Ex 3e 0.1215 52.00% Corp ix 3: 0.2479 60.51% C0“p Ex 3g 0.3 63.60% Corp Ex 3h 0.4778 68.67% C0“p Ex 3j 0.7559 73.72% C0“p Ex 3k 0.9576 76.71% The 'raction erred increa ses with the cor centration o: MAA. The data from table 3 were plotted according to the equation: [MAAJtol = K[MAA]2aq and the value K in the equation was ted as 14.6.

The results are plo:ted in ‘igure This example shows that the extrac:ior o: MAA into toluene is concentration dependent. For e 'icient extraction, concentrations above 0.1M are preferred. ative Example 4 Aqueous solutions were prepared 0: each of the dicarboxylic acids exemplified in comparative example 2.

VV()2012/107758 These were extracted with an equal volume of solvent mixtures o: toluene and methyl Hethacrylate (MMA). The resultant degrees of extraction are shown in table 4 Table 4 Fraction 0: A in A/Toluene olvent ixture :C ?Y MAA H % CT -_ 0 .64 0 54.4 4.21 40.11 0 .72 0 58.85 4.8 46.72 0-29 .5 0.3 63.0; 5.14 49.88 0-81 .26 0.7 67.25 6.38 53.62 1-69 13. 02 70.3; 4.82 56.56 2-89 20. 56 OOLprbL/ONH .17 .07 74.28 5.76 61.15 m4-34 27 .82 .01 76.77 7.32 64.67 6-56 38. 06 .17 79.42 19.71 68.07 m9-57 47 .19 .57 81.42 21.47 70.86 m13-1 56 .33 .05 83.02 23.32 73.21 17-58 63. 45 10.71 84.28 23.9 75.05 This e shows that MMA ca 1 be added to toluene to improve the extraction e 'iciency o : MAA. However an optimun1 MMA level is observed above which dicarboxylic acids and H % are extracted in signi:ficant amounts.

In order to compare the solubili:ies in the organic ts in terms of ion coe 'icients each sample was converted. to a partition coe 'icient based on the equation: [MAA] Sm = K[MAA] Zaq The data are presented in figure 2 Only MAA, Crotonic acid and hydroxyisobutyric acid have significant solubilities in any 0: the solvent phases.

The solubility of the components increases with the ‘raction O“ MMA in every case.

The relative partition coe 'icients may a lso change with composition. Figure 3 compares the ratio 0' ?artition Coe 'icient tor MAA with Lhao jor each of the other acids.

Thus the comparative es show that selectivity is higher it pure toluene is used. However use 0: some MMA allows a higher tration 0: MAA t o be extracted whilst lowering selectivity.

Comparative Example 5 The extraction 0: a solution 0: 0.1M MAA in aqueous solution into an equivalent volume 0 : toluene was determined atter addition 0“ 0.05 sodium hydroxide. The amoun, o: MAA. trans‘erred tell trom. 48% to 26%. The results are shown in ,he Sirst two rows of table 5 Examples 1—3 Su"icient itaconic acid to give a 0.;M on was added to the MAA + sodium hydroxide contairing aqueous solution 0; ative example 5 and the MAA :er dramatically improved to 4m.7% extraction into toluene . The data are shown in table 5. The experiment was repeated with citraconic or Hesaconic acids instead 0' "taconic acid.

Very similar results were obtained.

Table 5 Concentration of MAA in %Trans: aqueous Added into solution/M NaOH/M Added Acid/M Toluene —.:.-.3x1 OOBo-Ito LiJ' O 6 O —_II':a<:or1iC AcidN —4. - 7 __CfiraoonlicAclid --8 —L‘lL‘JL‘J UMP OOO l Examples 4—30 and Comparative Examples 6—9 O.lM trations 0: various di and tricarboxylic acids added to an aqueous on 0: 0.1M MAA containing di"eren, levels 0: NaOH were extracted with an equal volume 0: toluene.

The quantity 0: MAA extracted fell much more slowly as sodium hydroxide concentration increased, in tqe presence 0; one o: the added carboxylic acids than in the absence of added. di/tri carboxylic acid. The e ec, was most marked with citric and mesaconic acids. Table 6 shows the experimental data, which are presented graphically in figure 4.

Table 6 HM _-8transfer - _:'-_ —4-59 “E—l-53 11—“ 307 LiJ N kOOO\] O H :aconic 20.88 LiJ N 0.125 :aconic 17.68 LiJ N O H (II :aconic 3.84 O 01",_>\J'U (D N O '_l'tracoqic .58 H. N O .71 . :‘J >< .06 _J N \> .29 _J_i N LA) .52 _J_i N 14> .05 _J'J N U‘I .21 _*J N ow Citracoqic 8.12 Cor_>"G L41 00 —Mesacoric _*J N \1 Mesacoric _J N 00 0.05 ric _J_i N 0 Mesacoric 'LJ N N O Mesacoric Li] N N H ——0.125 J'LJ N N N mx w oBN "0 *6 3X 9 —- mx N a “3X 25 0.05 Citric “3X 26 rLJ N N \1 citric ill3X 28 ——0.125 3X 29 0.15 Citric LJ N U) Q citric Examples 31—34 Table 7 rates the 'use 0: higher organic phase to phase ratios leading to higher degrees I] aqueous 0: extraction 0: a solution of 0.3M MAA.

Table 7 aqztoluene v/v %transfer 3X 31 Examples 35—39 Table 8 further shows that the use 0“ serial extractions can increase the MAA Lrans"er still J rther. The starting solution was 0.3M MAA in water.

Table 8 aqztoluene v/v %transfer ‘. vo 3x 31 lzl 63.6 ’.2 vo EX 32 l:2 72.0 EX 35 2 X 1 80.2 l:3 vol Ex 33 1:3 75.9 EX 36 1:2 + lzl 84.9 3 ‘ ‘ Ex 37 x 88.1 l:4 vol EX 34 1:4 84.9 Ex 38 2 X ’:2 88.0 EX 39 4 X :1 92.4 Example 40 In a further experiment 0.01M citramalic acid decomposition was conducted with reaction ‘low in order to test the use of toluene extraCtion during the reaction; in this experiment, the flow of aqueous solution of dicarboxylic acid was mixed with an equal rate 0' "low or toluene before entering the reactor. Conditions were as s: 0.01M Citramalic acid (CM) in water with 50 mM NaOH, 2000 psi at variable ature, with a fixed nce time of 480 seconds. "nitia' ‘low consisted of CM and. NaOH dissolved. in water and 'toluene in a 50:50 VV()2012/107758 ratio by volume. The yields 0: products in the two phases detected by H?LC analysis are displayed in table 9.

Ana'ysis O“ the organic phase indicated an absolute MAA yie'd. o: 3.42 %, with no Other products detected. The yie'd O" MAA detected in the aqueous phase was 34.61 %, therejore the partition coe"icient jor MAA between the toluene and aqueous phases = 28.5 after cooling to ambient temperature. Thus the solvent may be added to the aqueous phase before the decomposition. period. as well as after cooling.

Table 9 Detected ' Detected s e ?hase ?hase Q) U) U) Balance Conversion Z0 O \1 H U) gs N Key:— C taconic Acid MC Mesaconic Acid CC Citraconic Acid { % Hydroxyisobutyric Acid BY c Acid Examples 41—46 and Comp Ex 10 Solutions 0: a Hfixture o: dibasic acids and Hethacrylic acid were prepared in water containing 0.‘M 0“ each acid.

Sodium ide was added to each solution at a di 'erent concentration as shown in table 10. The aqueous solution was extracted. with an equal volume or ,oluene at room temperature. The quantity in the organic and aqueous layers are shown in the table.

Table 10 _____-__ Comp Ix 0 0.052 0.048 __-_-_-_'x 0-048 0-052 -2_-_‘_-_ 0-050 0-050 -3_-_‘_-_ 0-052 0-0—-4—m 0.05:- ——-_-_l_ 0-050 “mm“ 0-05:— In the presence 0: 0.3M 0: combined dicarboxylic acids, the addition 0: base has no e "ect on the concentration or MAA extracted. "n ‘act, by comparisor with data in example 5, and 'table 5, it is s that the amount extracted was the same as for a or ‘ree of dicarboxylic acid and base. This shows the e"ec,iveness of the presence of the dicarboxylic acid in preventing the loss 0: organic solvent solubility in the presence 0; base.

Comparative Txample ll ons 0: acrylic acid. in water were extracted. with toluene under the same conditions as in ative example 3 except that the acid was changed from MAA to AA.

The starting concentrations and the quantity extracted into toluene are shown in table 11.

Table ll ———_a—75fi i*0*X ‘ ‘ A» :‘IX CO C——_ —_—_‘‘ A» p :‘IX OO J ' I] "G ————"GN 3' The relative concentration between the aqueous and organic phases is plotted according to the equation [AAUq] = K[AAmfi and shown in figure 5.

The ent straight line fit has a Hmch lower slope than for example 3, indicatirg that AA much prefers the aqueOLs layer.

Comparative Txample 17 In order to increase the solubiliuy or the AA in the organic layer a higher polarity is 'ikely to be required.

The extraction 0: a 0.1M aq AA solttion was studied with an equal volume 0: a mixture between toluene and butanone. llll!!!!!!!!llag!!!!!!!lMaleic Acrylic ne acid acid 65. 56 There is a very large increase in the extent of extraction as the butanone concentration increases, although the selectivity or extraction falls. It is likely that a mixture containing sodium salts will show a much improved separation between acrylic acid solubility and maleic acid lity and that an appropriate choice 0: solvent 0; intermediate polarity will allow su iciently e "ective a separation that the acrylic acid car be turther puritied by e.g. distillation. ?reparative ?xamp'es — Experiments conducted using the Flow Reaction use the procedure as outlined below.

Flow Reaction ?rocedure A reactant Seed solution was prepared sing itaconic, citraconic, mesaconic acid or alic acid at a concenoraoion o: 0.5 M and SOdiqu hydroxide also at a concenoraoion o: 0.5 M. The itaconic acid used (>=99 %) was obtained from Sigma Aldrich (Catalogue number: L2,920— WO 07758 4); citraconic acid (98+ %) was obtained from Alfa Aesar (L044l78); mesaconic acid (99 %) was obtained from Sigma Aldrich (Catalogue number: l3,lO4—O). The citramalic acid solution. is ed. by dissolving solid )— citramalic acid (commercially available from VWR "nternational) with sodium hydroxide catalyst in nano—pure water to the ed concentration.

The deionised water used ‘or solvation 0 ,he WaOH was first degassed via sonication in an Ultrasound Bath (30 KHz) for a period 0: 5 minutes.

This reactant feed solution was fed into the reactor system via a Gilson 305 H?LC pump module listed with a Gilson 10 SC pump head. Tue rate at which the reactant feed solution was pumped irto the reactor syStem depended on the residence time required and the volume 0: ,he reactor. The feed rate was also dependent on the density or ,he reaction media which in turn depended on the reaction temperature.

The reactant feed solution was pumped to the reactor via 1/16" internal diameter stainless steel (SS 316) pipe (Sandvik). The reactor consisted o: a straight seCtion o; 1/2” SS 316 pipe, d. in an aluminiuni block fitted with two 800W Watlow heater cartridges. The transition 0; the SS 316 piping ‘rom 1/16" to 1/2” was achieved with Swagelok SS 316 reducing unions and required an intermediate step 0: 1/8” pipe (i.e. l/l6" pipe to 1/8” pipe to 1/2” pipe).

The voltme o: the reactor was calculated theoretically, and confirmed from. the di"erence in weight when the reactor was filled with water and wren it was dry; for the experiments described, the volume 0: the r was 19.4 cm?. After the 1/2” pipe ’reactor’, the piping was reduced back down to 1/16”, before meeting a Swagelok SS 316 1/16" cross—piece. At this cross—piece, a thermocouple (type K) was used to monitor the temperature 0: the exit feed.

Reactor volume (used for residence time) is d as the volume 0: the 1/2" section 0: pipe between the two 1/2" to 1/8” reducers located immediately before and after the aluminium block.

The t mixture is finally passed through a heat exchanger (a lquth O: 1/8" pipe within a 1/4" pipe through which cold water was passed in contra flow) and a manual Tescom jack—Bressure Regulator throagh which back— pressure (pressure throughout the whole system. between this point and the pump head) was generated: the pressure employed was 3000 psi for all ments described.

Samples were collected in vials before being ed for analysis.

The required temperature for reaction was achieved using a thermostat listed with a Gefran controller (800 ?), which mediated power applied to the two Watlow cartridge heaters. Each set 0: experiments involved working at a single temperature wrile g' residence time between runs. The required flow rate "or the first run was set at the Gilson pump module. The pump was then le t or a period 0: around 20 minutes, pumping only sed water, in order for the heat—,ransfer between the aluminium block to have become consistent. The heat—transfer was deemed to have achieved equilibrium when the temperature indicated by the thermocouple located at the reactor exit feed position did not change (accurate to L 0C) for a period 0; more than 5 minutes. At this Stage tqe inlet 0: the pump was transferred from the container 0; deionised water to the container 0: the prepared nt mixture. The total volume of the apparatus ding reactor) was approximately double that o: the reactor itsel: ; this was previously d t rmin d xp rim ntally. For a particular flow rate, the reactant mixture was left pumping :Olf approximately three tim s th r quir d p riod for it CO have begun emerging from the final , in order ":0 ensure that a steady—state o: on had been achieved.

After this time a 20 ml sample o: the apparatus exit solution was collected for analysis. Both the rate OI- co'lection 0" the exit solation and the rate at which the reaction solution was ed were recorded against time in order to Hmnitor tqe consistency o; the pump e 'iciency. Following samp'e collection from a particular run, the pump inlet was switched back to the container 0; deionised water, and the ow rate was increased to its maximum for a period 0“ approxima':ely l0 minutes to ensure that all remaining material from ,he us run had been purged from the system. This procedure was then repeated for the subs qu nt r sid nc tim to be investigated.

Analysis Quantitative analysis 0: products was achieved using an Agilent 1200 series H?nC system. equipped with a multi wave—length UV detector. ?roducts were ted using a ?henomenex Rezex QHM Hmnosaccharide H+ (8 %) column held at 75 OC, protected by a guard column. The method used was isocratic, implementing a 0.4 mlmin’l flow rate 0: aqueous VV()2012/107758 0.005 M H2804 Inobile phase. The compounds ned in t s were found to have optimum JV ance at the shortest wavelength capable of the MWD or of 210 nm (bandwidth 15 nm). All product compounds were calibrated for their UV detection, by correlating their UV absorbance against a range 0; concentra tions. Linear response rang s w r d t rmin d for each conpound, and the most compatible range 0: concentrations found for all compounds of inserest was between 5 X 10’3 and :_ x 10’3 M. Thus, adequate quantitative detectior o; most products was achieved with a l to 100 di'uti OH 0" SB.mples obtained from the apparatus before H?LC analysis (a dilution 0: l to 100 would mean that when starting witq a 0.5 M reaction solution, any prodJct generated in a yield 0: between 20 0 O — 100 6 would fa'l within the linear response range 0; concentrations). Where compounds fell outside this linear response range (e.g. a yield 0: less than 20 o\O ), a second H?LC analysis was conducted using a dilution of l to 10.

Any samples which were not accurately quantified using the l to l0 on method were considered to be trace in concentration and therefore negligible. ?rocedure The following procedure was d out. The reagent mixture sing acid and sodium. hydroxide was first prepared. The required flow rate to achi v th r sid nc time was calculated using the reactor volume and the density 0: water (calculated from temperature).

Figure 6 shows a schematic represen :ation of ,he apparatus tor the present invention. Reac:ion so' ution ‘8 was located in receptacle 20 which was connected to inlet 16.

The inlet was connected via conduit 22 to the nt pump 2 which was operable to pump the solution 18 to the r tube 24 tube which was housed in a heater cartridge 26 which extended circum‘erentially along the reactor 24 . The t 22 between the pump 2 and the reactor 24 proceeded from the pump via a valve 28 :or operation control, pressure r 30 and pressure relie; valve 32. In addition, a trip switch 34 was connected to the pressure monitor 30, reactant pump 2 and a temperature monitor 14. The temperature monitor 14 was located in condtit 22 immediate'y atter reaCtor 24 and before outlet 6. In addition, after the monitor 14, the conduit proceeded to the out'et via a "iloer 36, heat exchanger 8 and back pressure regulator 4. At the outlet 6, the product was collected in colleCtion receptacle 38.

The reactor 24 also included a temperature control unit , 12 to l the temperature 0: the reactor 24. The apparatus also included a quenching system which includes a separate inlet 40 for quench water 44 in quench water receptacle 42. The inlet 40 was connected to the outlet 6 via conduit 46 which ed a separate quench pump 48 followed by a valve 50 for control 0: the quench water.

The quench water conduit 46 met the reaction condLit 22 immediately atter the ature monitor ‘4 o: the reactor 24 and be‘ore ‘ilter 36 to quench ary reaCtion after the reactor. The quench pump 48 and temperature controller unit l0, l? were also connected to trip switch 34 for necessary shut down when the trip criteria are met.

The reactor pump 2 was turned on and deionised water was pumped into the system. The back pressure regulator 4 was gradually adjusted to th r quir d pr ssur (3000 psi).

The pump operation e 'iciency was checked at 5 ml Irirfl by recording time taxen to colleCt a volume 0" 70 ml 0" water from system outlet 6. > 90 % e 'iciercy was acceptable.

The pump flow rate is then set to that required for the run.

The water supply (no t shown) to the heat exchanger 8 was set to a low—moderate flow, depending' on the reaction temperature and pump ‘low rate :Or the experiment.

The heater thermos:at ’O titted with a temperature controller 12 was se o to ,he required temperature for the run.

Onc th r quir d t mp rature had been d (as indicated. by thermostat lO), reactor outlet temperatare was monitored by the reactor temperature monitor 14 until the value (accurate to l 0C) was observed to remain static for‘ a period. 0: at least 5 minutes (this y took approximately 20 minutes).

The pump inlet 16 was switched from the deionised water ner (nOt shown) to th pr par d r ag nt mixture container 18 (this requires stopping the pump "low or a :ew seconds).The in itial volume 0: reagent mixture in container 18 was recorded.

Calculations can indicate the period before product solution will begin to emerge from the syStem outlet 6.

However, in practice, this was confirmed by tqe visual and audible ce 0: gas s exiting the apparatus (generated from the decomposition of reagents). This was allowed to continue for a period tqat is x3 the period taken for the product solution. to emerge. This ensured that the product mixture is homogenous.

At the outlet 6, 20 ml of product solution was collected and the time taken for this collection was recorded. A final time and volume reading was also taken for the reagent mixture.

After product collection, the pump inlet was transferred back to the deionised water ner, and the pump was set to ”prime mode” (maximum flow rate) and le L or a period 0“ approximately 10 minutes.

The flow rate 0: the pump was then set to the required value for the subsequent run.

Again the reactor outlet ature was monitored ard was considered steady when the value did. change 1 not for a period 0: at least 5 minutes (this usually took approximately 10 minutes).

This experimental method was repeated until all required runs for the experiment had been performed.

After all runs had been completed, tqe deionised water was pumped into the system with the pump on prime mode and the heater (thermostat) was switched 0 When the reactor outlet ature had dropped below 80 O C, the pump was switched o and the water supply to the heat exchanger was also ceased.

Methacryiic Acid Extraction Solutions prepared according to the preparative procedure above were extracted with an equal volume 0: toluene. In ,he Sirst set 0: ments no extra acid was added. In the second set the acid used for the original high temperature decomposition was added such that the total concentration 0“ dicarboxyiic acids nic, onic, mesaconic, Citramalic) plus oxyisobutyric acid equalled 0.5M, which was the starting concentration :or the original decomposition. The results in table LO show that addition. 0: acid has a very large impact on the amount extracted at the high concentrations 0: base present.

Table 10 Example IExample Example Example Example Example 49 Example 50 _-__--- Original Feed conc/M 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Acids Mass Balance 99.23% 96.50% 85.89% 79.31% 71.51% 97.82% 89.81% No added Acid Acid Added .21% 29.43% 28.31% 28.04% 27.90% 30.56% 29.74% Comparative ?xamp'e l7 The e 'iciercy o: MAA. extraction into a mixture 0: 2— butanone and ne in the ratio 75:25 was studied. The presence 0: xylene in this organic mixture partly restricts tte solubility of butanone in the aqueous phase, which is a significant issJe where butanone is used alone as the organic phase; at this particular ratio, the bution coe t for MAA is reported to be a maximum 0: approximately K = 7.00.23 In this case it was found. that roughly 80 % o: MAA. was extracted. into the organic phase, which appeared extremely desirable; however, other dicarboxylic acids concerned in the decomposition experiments (i.e. ZC, CC etc..) also showed a slight a 'inity to the organic phase 0: up to ll %.

Attention is ed to all papers and documents which are filed concurrently with or us to this specification in connection with this application and which are open to public inspection with this specification, and. the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and gs), and/or all of the steps 0: any method or process so disclosed, may be combined in any combination, except combinations where at least some 0: such feauures and/or steps are mutually exclusive.

WO 07758 Each feature disclosed. in this specification (including any accompanying claims, abstract and gs) may be replaced by alternative features serving the same, equivalent or similar e, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each e disclosed is one example only 0: a generic series 0: equivalent or similar features.

The invention. is not restricted. to the details 0: the foregoing embodiment(s). The invention extends to any novel one, or any novel conbination, of the features disclosed in this specification (includirg any accompanying claims, abs:ract and drawings), or to any novel one, or any novel combination, of the steps 0; any method or process so disclosed.

The

Claims (26)

claims defining the invention

1. A method of extracting (meth)acrylic acid from an aqueous on medium, the aqueous reaction medium being formed from at least one base st and at least one dicarboxylic acid selected from maleic, fumaric, malic, ic, onic, mesaconic, and citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof comprising (meth)acrylic acid and/or (meth)acrylate base salt, the method comprising the steps of introducing an organic solvent to the said aqueous reaction medium for solvent extraction of the (meth)acrylic acid into an organic phase wherein there is added an additional amount of at least one of the said dicarboxylic acids and/or a rsor thereof to the said aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent.

2. A method according to claim 1, wherein the concentration of (meth)acrylic acid in the aqueous phase extraction is at least 0.05 mol dm-3.

3. A method according to claim 1 or claim 2, wherein the molar level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor thereof is maintained at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during the extraction s and the amount of dicarboxylic acid added is determined accordingly.

4. A method according to any one of the preceding claims, n the dicarboxylic acid and/or a rsor thereof is selected from citric, itaconic, citramalic, citraconic and mesaconic acid or mixtures thereof.

5. A method according to claim 4 wherein the dicarboxylic acid and/or a pre-cursor thereof is selected from citric, ic, citramalic and citraconic acid or mixtures thereof.

6. A method ing to any one of claims 1 -3, wherein the dicarboxylic acid is selected from , fumaric, and malic acid or mixtures thereof.

7. The method according to claim 6, wherein the dicarboxylic acid is selected from malic acid or mixtures thereof.

8. A method of extracting (meth)acrylic acid from an s reaction medium, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, ic, onic, mesaconic or citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof comprising (meth)acrylic acid or (meth)acrylate base salt, the method sing the steps of introducing an organic solvent to the aqueous reaction medium for solvent extraction of the (meth)acrylic acid into the organic phase wherein the level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor thereof is maintained at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during the extraction process.

9. A method according to any one of the preceding claims wherein in the case of the (meth)acrylic acid being methacrylic acid, the organic solvent is an external organic solvent with respect to the reaction medium.

10. A method according to any one of the preceding claims, wherein the dicarboxylic acid is selected from citramalic or ic acid.

11. A process for the production of (meth)acrylic acid comprising the steps of:- forming an aqueous medium of at least one base catalyst and at least one dicarboxylic acid selected from c, maleic, malic, itaconic, citraconic, nic or citramalic acid or es thereof; oxylating the at least one dicarboxylic acid in the presence of the at least one base catalyst under suitable conditions of temperature and pressure to produce (meth)acrylic acid and/or base salts thereof in the aqueous medium; introducing an organic solvent to the said aqueous medium for solvent extraction of the (meth)acrylic acid into an organic phase; wherein the level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor thereof is maintained at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during the extraction process.

12. A process for the production of acrylic acid comprising the steps of:- forming an aqueous medium of at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, ic, citraconic, mesaconic or citramalic acid or mixtures thereof; decarboxylating the at least one oxylic acid in the presence of the at least one base catalyst under suitable conditions of temperature and pressure to produce (meth)acrylic acid and/or base salts thereof in the aqueous medium; introducing an organic solvent to the said s medium for solvent extraction of the (meth)acrylic acid into an c phase; comprising the step of adding an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous medium to e the solvent extraction of the (meth)acrylic acid into the organic solvent.

13. A method or s according to any one of claims 1-12, wherein the organic solvents for (meth)acrylic acid extraction comprise hydrocarbon solvents or oxygenated solvents.

14. The method or process according to claim 13 wherein the c solvents comprise C4–C20 hydrocarbon solvents.

15. A method or process according to claim 13 or claim 14, wherein the solvents comprise toluene, benzene, ethylbenzene, xylene, trimethylbenzene, octane, heptane, hexane, e, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclohexene, methylcyclohexane, methylethylketone, methyl methacrylate or mixtures thereof; or ionic liquids which are immiscible with water.

16. A method or process according to any one of claims 13 to 15, wherein the mixture of solvents for the extraction of MAA is a C4-C20 hydrocarbon solvent and MMA.

17. A method of preparing polymers or copolymers of (meth)acrylic acid or (meth)acrylic acid esters, comprising the steps of (i) preparation of (meth)acrylic acid in accordance with any one of claims 11-16; (ii) optional esterification of the (meth)acrylic acid prepared in (i) to e the (meth)acrylic acid ester; (iii) polymerisation of the (meth)acrylic acid prepared in (i) and/or the ester prepared in (ii), optionally with one or more comonomers, to produce rs or copolymers thereof.

18. Polyacrylic acid, polymethacrylic acid, polyalkylacrylate, polymethylmethacrylate (PMMA) and polybutylmethacrylate homopolymers or mers formed from the method of claim 17.

19. A process for the production of methacrylic acid comprising:- providing a source of a pre-cursor acid selected from aconitic, citric and/or isocitric acid; performing a oxylation and, if necessary, a ation step on the source of pre-cursor acid by exposing the source f in the presence or e of a base catalyst to a sufficiently high temperature to provide a dicarboxylic acid selected from itaconic, mesaconic, citraconic and/or citramalic acid; and using the dicarboxylic acid ed in a process according to any one of claims 1-16.

20. A method of extracting (meth)acrylic acid from an aqueous reaction medium into an organic phase in contact therewith, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof comprising (meth)acrylic acid or (meth)acrylate base salt and the organic phase comprises a suitable organic solvent for the said (meth)acrylic acid n in the aqueous reaction medium the ve level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor thereof is maintained at a oichiometric level in relation to the formation of the first acid salt f during at least part of the extraction.

21. A method of ting (meth)acrylic acid from an aqueous reaction medium, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic or citramalic acid or es thereof in s solution and containing the base catalysed decarboxylation ts thereof comprising (meth)acrylic acid and/or (meth)acrylate base salt, the method comprising the step of solvent extraction of the acrylic acid into an organic phase comprising an organic solvent in contact with the said aqueous reaction medium wherein there is added an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous reaction medium containing the said base sed decarboxylation products thereof to enhance the solvent extraction of the (meth)acrylic acid into the organic phase.

22. A method or process according to any one of claims 1-16 comprising the step of separating the organic phase from the aqueous phase after extraction followed by subsequent treatment of the organic phase to isolate the (meth)acrylic acid extracted in the extraction process from the organic solvent.

23. A method or process according to any one of claims 1-16 and 20-22 wherein the organic solvent is introduced to the aqueous medium before or after decarboxylation.

24. A method or process according to any one of claims 1-16 and 20-23 wherein the sub-stoichiometric level of base is maintained, after, if necessary, being implemented post reaction, during at least that part of the tion process which is carried out after the decarboxylation step.

25. A method or process according to any one of claims 1-16 and 20-24, wherein the sub-stoichiometric level of base is maintained throughout the reaction and extraction.

26. A method or process according to any one of claims 1 to 16 and 20 to 25, substantially as herein described with reference to any of the Examples and/or associated