CA2228950C - 2-substituted succinate esters - Google Patents

Abstract

This invention relates to a process for producing 2-substituted succinate esters of formula (I) by reacting (a) a dicarboxylic compound with a first alcohol R'O[CHR".CH2O]x H where x is 0 or an integer from 1-6 in the presence of a catalyst to form a hydrocarbyl ester or, when x = 1-6, a hydrocarbyloxy alkylene ester of maleic and/or fumaric acid and (b) the ester from step (a) with an alkaline earth metal alkoxide in the presence of a second alcohol R.OH to form the 2-substituted succinate ester of formula (I). The esters and paint formulations based thereon are also claimed.

Description

WO 98/00388 PCT/GB97/0i742 .2-SLIBSTITiITED SLJCCINATE ESTERS
This invention relates to a process for producing 2-substituted succinate esters with low colour and use of said ether esters as diluents in paint and polymer formulations.
One of the processes used hitherto to produce 2-substituted succinate esters is the combined transesterilication and Michael addition reaction of an alcohol or a monoether of a poiyoxyalkylene glycol as described in GB-A-552715 in which ether esters of hydl'Oxy$UCC1I11C aCld and unsaturated alcohols are prepared by reacting in a single step under anhydrous conditions an alkyl ester of malefic acid with an unsaturated alcohol in the presence of a magnesium alkoxide catalyst.
However, this method when repeated for instance with an octadienol/di methyl maleate system using magnesium methoxide as a catalyst gives products which have a deep red colour. It may be possible to overcome this colour problem in the products described in this prior art by distillation. However, such a method is unlikely to be practicable with the synthesis of esters contemplated in the present invention since they are all meant to have relatively low volatility and hence are not amenable to purification by distillation.
It has now been found that 2-substituted succinate esters, some of which are novel, can be produced in commercially viable yields and purity by using a two-stage process.
2o Accordingly, the present invention relates to a process for producing 2- substituted succinate esters of the formula (I) said pl-ocess comprising reacting a. a dicarboxyiic compound selected from the group consisting of malefic acid, malefic anhydride, tumaric acid and the dialkyl ester of malefic or fumal-ic acid with an alcohol R'O[CHR".CHZO].,.H where .r is 0 or an integer from I -O in the presence of a catalyst to form a hydrocarbyl SUBSTITUTE SHEET (RULE 26) ester or, when x = I-t~, a hydrocarbyloxy alkylene ester of lnaleic and/or fumaric acid and b. the ester from step {a) with an alkaline earth metal alkoxide in the presence of a further amount of the alcohol to form the 2-substituted succinate ester of formula (I) O
R
~ [OCH2.CHR"j~..OR' (I) [OCH2.CHR"jh.OR' O
I17 WhlCl7 R' is an unsaturated hydrocarbyl or allylicallty unsaturated hydrocarbyloxy atkylene group having at least S carbon atoms, 1o R" is H or an alkyl or an aikylene group having I-to 2 carbon atoms and, each of cr and h is same or different and has a value of 0 or is an integer from I -6.
By the expression "alkylene" as used herein and throughout the specification is meant a divalent hydrocarbyi group such as eg a -CHZ-(CHR")r CHZ-group wherein / = 0 or an integer and R" has the same notation as above.
R' is derived fi~oln the reactant alcohol R'O[CHR".CH20]xH where x is 0 or an integer from 1-6 which is used far making the succinate ester and can be an allylic hydrocarbyl or an allylic hydrocarbyloxy alkylene group. Thus, the reactant alcohol is an allylic alcohol and includes inter crlicr 2-ethyl-hex-2-en-1-oI;
2-octen-1-0l; 1-octen-s-ol; 2,7-octadienol; 2-ethyl allyl alcohol; kept-3-en-2-ol; 4-methyl pent-3-en-2-ol; 4-t-butoxy but-2-en-I-of (also called 1,4-but-2-ene diol mono-tertiary butyl ether); 4-n-butoxy but-2-en-i-of (also called I,4-but-2-ene diol 1110110-n-bLltyl ether); clnnan7yl alcohol; and isophoroi.
The reactant alcohol, R'O[CHR".CH~O].,-H where x is 0 or an integer from I-G, call be prepared in several ways known to those skilled in the art. For instance, this reactant alcohol, eg an allylic alcohol, can be produced by the reduction of the corresponding a.,(i-unsaturated aldehyde eg by hydrogenation, which will generate a mixture of the allylic alcohol and its saturated analogue.
Some other allylic alcohols may be produced from conjugated dienes via the well known addition reactions. Furthermore, other allylic alcohois may be produced by initially formin~~ an unsaturated ester tiwm an olefin and a carboxylic acid followed SUBSTITUTE SHEET (RULE 26) WO 98/~0388 PCT/GB97/01742 by hydrolysis of the ester to a mixture of isomeric allylic alcohols. This latter reaction may, like some of the other reactions mentioned above, result in a mixture of products which includes inter crlicr the desired allylic alcohol, isomers thereof and saturated analogues thereof. The mixtures of allylic alcohol with the saturated J
analogue thereof and/or the isomers thereof can be then used as such, or, after further purification to isolate the desired allylic alcohol, to prepare the esters represented by formula (I) above.
Where the reactant alcohol is itself an allylic unsaturated hydroxy ether, ie x = 1-6, this may be derived by alkoxylation of an alcohol, eg allylic ether alcohol, 1 o suitably in the presence of a catalyst to form the hydroxy ether. Where a catalyst is used it should be such that it does not cause rearrangement of the allylic function and hence, amphoteric, basic or acidic catalysts may be used. The catalyst can be heterogeneous or homogeneous. Tlte alkoxylation step is suitably carried out in the presence of a base catalyst. Examples of base catalysts that may be used include alkali metal hydroxides such as sodium or potassium hydroxide and other metal salts such as potassium acetate.
The alkoxylation reaction to form the hydroxy ether of the allylic alcohol can be carried out using one or more of the epoxides which include ifrter alicz ethylene oxide, propylene oxide, butene oxide and butadiene mono-oxide. The 2o amount of epoxide used for this step would depend upon the number of alkoxy groups desired in the hydroxy ether. The amount of epoxide used is suitably in the range from 0.1 to 20 moles, preferably from 1 to 5 moles based on the allyIic alcohol reactant.
The alkoxylation reaction is suitably carried out at a temperature in the range from 50 to 180°C, preferably ti-om 60 to 140°C. The reaction pressure for this step is suitably autogenous but is preferably from 100 to 700 KPa.
The hydroxy ether formed in this step is suitably separated from the reaction mixture by neutralisation using eg magnesium silicate, then filtered to remove the neutralising agent and the salt of neutralisation so formed to leave 3o behind filtrate comprising the desired hydroxy ether.
The hydroxy ether so produced Call be used either as such without purification, or, optionally, after purification (eg by distillation) for the esterification stage.
Thus, the ?-succina.te esters of formula (I} are prepared by reacting in the first stage (a) the reactant alcohol with malefic acid or anhydride and/or fumaric SUBSTfTUTE SNEET (RULE 26~

acid or esters thereof in the presence of a catalyst. The catalyst used in this step can be zinc acetate, dibutyl tin oxide, stannous oxalate, para-toluene sulphonic acid , or phosphoric acid. This reaction is suitably carried out at a temperature below I50°C, preferably from 100-130°C. The completion ofthe reaction is ascertained by GC analysis using a CP-SILS 50 m capillary column and a flame ionisation detector. Upon completion of the reaction, the unreacted materials are stripped out by steam stripping or by azeotropic distillation eg using an azeotroping agent such as eg cyclohexane. The catalyst may then be neutralised or removed as appropriate, the solids filtered and the ester in the filtrate recovered.
1 o The ester product from this step (a) is then further reacted in a step (b) with a further amount of the reactant alcohol in the presence of an alkaline earth metal alkoxide catalyst. The function of this step (b) is to enhance the amount of the desired 2-succinate ester in the product from step (a) at the expense of the maleates and firmarates in said product. The alkaline earth metal atkoxide may be 95 derived from the second reactant alcohol or from another alcohol. The alkaline earth metal.alkoxide is preferably magnesium alkoxide. The amount of alkaline eatrth metal alkoxide used must be sufficient to compensate for loss of catalyst due to its reaction with any residual acids or water present in the products from stage (a) of the reaction or the reactant alcohol. The reaction with the alkaline earth 20 metal alkoxide is suitably carried out at a temperature below 120°C, suitably in the range from 40 to 80°C: and step (b} is suitably carried out at atmospheric, subatmospheric or superatmospheric pressures. The pressures used are preferably in the range from atmospheric to 50 Kpa, more preferably from atmospheric to 5 KI'a. This division of the reaction into two states allows the use of relatively 25 milder conditions than has hitherto been possible and as a consequence affords an improved product which is less coloured.
The esters formed by this process may be a mixture of the desired esters of formula (I} and the corresponding unsaturated analogues comprising the malefic acid or fumaric acid esters. Thus, for example, reaction of 2-ethyl hexenol with 30 malefic acid or anhydride tbllo~ued by reaction of the product with magnesium alkoxide of 2-ethylhexenol as catalyst would give rise to a product which primarily , comprises 2-(2-ethyl hexenoxy)-di[2-(2-ethyl hexenyl)] succinate. Similarly, when octadienoxy ethanol is reacted with malefic acid or anhydride, followed by the reaction of this product with the magnesium alkoxide of octadienoxy ethanol as 35 catalyst. the resultant product comprises di-[(2-octadienoxy) ethyl]-2-[(2-SUBSTITUTE SHEET (RULE 26) WO 98/00388 PCTlGB97/01742 octadienoxy) ethoxy] succinate. Both of these are novel esters not reported hitherto. Similarly, when 2,7-octadienol is reacted with dimethyl maleate, followed by reaction of the resultant product with further aliquots of the reactant alcohol in the presence of magnesium alkoxide catalyst, the product obtained is 2-octadienoxy di-octadienyl succinate.
A feature of the two-stage process of the present invention is that it uses relatively milder conditions than a conventional Michael addition reaction.
For instance, no reflux conditions need be used during this step. Furthermore, the present process enables the proportion of the 2-substituted succinate ester in the 7 o reaction product to be enhanced considerably without leading to undesirable polymer formation or increasing the colouration of the ester product.
Moreover, the present process gives better yields of the desired 2-substituted succinate ester due to the milder conditions employed.
The esters of the present invention have (ow volatility and relatively low viscosity suitably below 1500 rnPa.s, thereby rendering them a suitable solvent component for curable paint and varnish formulations. These ether esters are especially suitable as the so called "reactive dilutents" for paint fornulations and in particular those containing alkyd resins. Reactive diluents are usually compounds or mixtures of compounds of relatively low viscosity, a relatively high boiling point (or low saturated vapour pressure) which act as solvents during the formulation and processing of the coating. An advantage of reactive diluents is that such diluents~can copolymerise with components of the alkyd resin. Hence reactive diluents may be used to replace part or all of the traditional solvents normally used in such formulations thereby reducing losses of the solvent to atmosphere on drying of the coatinb. Use of reactive diluents comprising esters of polyhydric alcohols which have been partially etherified with allyl alcohol are described in EP-A-0 253 474.
Alkyd resins are well known components of decorative paints {see, for example, "The Technology of Paints, Varnishes and Lacquers" by C R
3o Mar-tens(Ed.), published by Robert Krieger Publishing ( 1974) and can be prepared from polybasic acids or anhydrides, polyhydrie alcohols and fatty acids or oils.
US-A-s 819 720 describes methods of preparing such alkyd formulations. Alkyd coating compositions usually contain large amounts of~solvents (eg mineral spirits and aromatic hydrocarbons). , The compositions of the present invention are highly suitable for use as SUBSTITUTE SNEET (RULE 26) reactive diluents. The relative ratios of reactive diluent to the alkyd resin in a formulation can be derived from the ranges quoted in published EP-A-0 305 006.
In an example in which the reactive diluent replaces aII of the traditional solvent, the ratio of reactive diluent to alkyd resin is suitably in the range from I-50 : 99-50 parts by weight, eg 5-50 : 95-50, preferably from S-25 : 9S-75 and more preferably from 5-15 : 95-85 parts by weight. On the other hand, where used in a conventional paint formulation, such a diluent can replace all or part of a traditional solvent such as white spirit. The formulations may contain further components such as catalyst, drier-, antiskinning agent, pigments, pigment stabilisers, rheology 1 o controllers (e.g. for sag control), UV and oxidation stabilisers, flow additives, microgels (e.g. to enhance hardness) and other additives. The formulations may also need to include water scavengers such as trialkyl orthoformates, molecular sieves or zeolites inhere the reactive diluent used is susceptible to hydrolysis such as eg some of the ether ester derivatives. Furthermore, where such water scavengers are used it may be necessary to use them in combination with compatible pigment stabilizers. Where a drier (siccative) is used this may further contribute towards the solvent content of the formulation.
For formulations comprising an oxidatively curing alkyd resin and a siccative/drier such as cobalt complexes, impurities. which can have a co-ordination affinity for the siccative drier such as cobalt complexes can affect adversely the drying speed and stabtltty of the paint. Examples of such impurities include malefic acid and triethyl amine. In particular, it has been found desirable to minimise the acidity of the ester mixture used as reactive diluent in such formulations to a value of ~ 700U ppm, preferably ° s00U ppm, more preferably < 1000 ppm w/w of KOH.
It has also been found that when a mixture of esters, ie the succinates, fumarates and maleates, is used as a reactive diiuent in such formulations comprising an oxidatively curing alkyd resins, the properties/performance of the diluent can be varied by changing the relative proportions of the three esters present in such a diiuent. For example, mixtures with a relatively lower amount of 3o maleates exhibit better hardness and dtyng properties compared with those having relatively higher amounts ol'such maleates. Moreover, it has also been observed that formulations comprising these esters display a decreased tendency towards wrinklinb. This renders them particularly suitable when using formulations comprising high solid systems/one-coat paints have to be applied to generate a greater thickness of the relevant coating without impairing the ability of such SUBSTITUTE SHEET (RULE 26) PCTlG~97/01742 thicker layers to harden through.
For some uses it is preferable that the free alcohol content of the diluent is minimised in order to facilitate drying of the formulation.
A feature of the present invention is that ether esters of formula (I) when used as reactive diluents in paint or coating formulations, especially those COtnpl-islltg alkyd resins, enhance the performance of these formulations. In particular, where a mixture of products comprising ether esters of the present invention derived by reacting an allylic alcohol or a hydroxy ether thereof with malefic acid/anhydride or tumaric acid is used as reactive diluent, they enhance their performance when compared with that of the unsaturated esters when used alone.
A further aspect of the present invention is that such esters when used in a relatively pure state do not cause any haze in the formulation. Where there is likely to be a risk of such haze formation, eg due to the presence of impurities such as eg resins or polymers formed during the synthesis of the esters used or during storage of SLICK fOrlnulatIOilS, it is beneficial to use inhibitors such as eg butylated hydroxy-toluene (2,6-butoxy-4-methyl phenol) or 2,4.6-teal-butyl phenol. Such inhibitors not only have the advantage of preventing haze formation but also render the formulations safer to handle by inhibition of other unwanted reactions in the formulation such as eg peroxidation.
Uses of the molecules of this invention include the partial or total replacement of traditional hydrocarbon-based solvents in solvent-borne alkyd paints used for primer, undercoat and topcoat decorative applications as well as in industrial applications such as alkyd primers and UV-cure.
The molecules of this invention are also suitable for use as co-monomers, for example in vinyl acetate-based polymers used in emulsion paints. In this case, the molecules of this invention impart a temporary plasticisation to the paint flm, before air-curinD to a hard finish. They can, therefore, facilitate the partial or total replacement of coalescent solvents.
In addition, the molecules could be used in water-based paints based on acrylic and alkyd resins, in addition to, or instead of, coalescent solvents.
The present invention is further illustrated with reference to the following Examples.
EXA1VIPLE 1: General Method Reaction of an allelic ether-alcohol with a maleate The lbllowing apparatus was assembled:

SUBSTITUTE SHEET (RULE 26) A five-litre flanged flask with an insert pipe for a nitrogen sparge, a thermowell for thermocouple, and a Dean and Stark apparatus with double-walled condenser. The v flask was heated with an electric heating mantle which was controlled with a eurothenn controller connected to the thermocouple. The nitrogen sparge pipe was inserted so that the nitrogen flow agitated the flask contents and provided mixing during the course of the reaction. The nitrogen flow also served to entrain out the liberated methanol and farce the reaction to completion.
To the flask was added dimethyl maleate (914.3g), 2,7-octadienol (2375g) and stannous oxalate ( 31.2g). The mixture was sparged with nitrogen for I 0 minutes to remove air and tl~e nitrogen flow was then reduced to a level which ensured efficient mixing. The mixture was then heated in stages to I30°C ( e.g.
80°C for 10 minutes, then 100°C for 10 minutes and then 120°C for 10 minutes).
The progress of the reaction was monitored by collection of the methanol collected in the Dean and Stark apparatus. In order to drive the reaction to completion the temperature was raised to 140°C after 7hrs at 130°C. When 90%
ofthe methanol had been collected, the reaction mixture was sampled hourly and analysed by GC.
The reaction was adjudged complete when the level of the "half ester" (methyl octadienyl maleate/fumarate) fell to below 0.3% w/w and this took approximately 31 hours. At this point the heating was switched off and the reaction mixture allowed to cool to~room temperature. The product from the reaction was then decanted from any solids in the reaction flask. This product was then charged to a heated decanter (40°C) with an equal volume of S% w/w aqueous sodium hydroxide solution. The mixture was stirred for 20 minutes and then allowed to separate and the lower aelueous phase decanted. This base wash was repeated and the remaining organic phase was washed with saturated brine until the adueous phase reached a steady pH. The organic phase was then heated (100°C) under reduced pressure (~. S00 Pa (~~- S mBar)) on a rotatory evaporator to remove residual water and the majority of the excess octadienol. After cooling, the product was filtered and transferred to a 5-litre three-necked round-bottomed quickft flask . This flask was equipped with a still-head condenser and reciever flask (Perlcin triangle), a thermocouple, a stream inlet pipe, and a eurotherm , controlled heating mantle. The apparatus was evacuated to 4000 Pa (40 tnBar) and tire product heated to (20°C'.. The sulsply of steam was then connected and the , residual traces of octadienol were removed. The purification was judged complete when the volume of the heads product aqueous phase to increased more than 5 SUBSTITUTE SHEET (RULE 26) times that of the organic phase. Af3er cooling down the product was then treated with activated carbon (1%wlw, 100°C 2Hrs, < X00 Pa (< 5 m$ar)) on a rotatory evaporator. The cooled mixture was filtered through dried Ceiite"~ to obtain the final product which had the following analyses:
OH number - 4 mg KC)H/g (titration) total acid - 46 ppm KOH/g (titration) malefic acid / anhydride - < lOppm (HPLC) Futnaric acid ~ ~ < 1 Oppm (HPLC) .
tin - ~ l0ppm (atomic absorption) ~ o sodium - <20ppm ( atomic absorption, detection limit) chlorine - ~:lOppm (atomic absorption detection limit) Gt'. "t:PSiIS" column - c~ctadienyl methyl fumaratelmaleate , (0.11% w/w) - di-(2,7-uctadienyl) maleat~e (73% wlw) t 5 1 - di-(?,7-octr3dienyl) fumarate (3?% w/w) - 2-(2,?-octadienoxy) di-(3,7-octadienyl) tuccinate ( ~% w!w) The GC assignment was supported by GGIMS and a'H nrrar and'''C nmr studies.
The GGJMS used a VG Trio-1000, r~perated accordins~ to the manufacturers 2o inctructi«ns under the fnllc~wing conditions:
- GC'. column 35mx0.33mm 13B5 (0.35 micron film) - temperature programme 40°C (3 mins) a IOC/min to X20°C:(IUrnins) - ipjectiun 1 micrulitre ( 1% solution in acetone) on 25 column 40°C~
- ammonia chemical ionisation (C1) - scan rankle :50-s0U
- scan rate ! /s It was round that the deduction of~molecular wei?hts from the Cl spectra is rather 30 Less straijhtfarward than is usual on account of~(a) extensive rearrangements of tirmarates in particular- ~=wing [M+ ~J rind [M+24J~ ions in addition to the usual [M+ 1 J ~ and [M+ 1 ~) ions and (b) extensive tra~mentation exhibited by same species. As a result the GC peaks were assi~_ned by interpretation. In addition to the assigned peaks an additional species was identified which was assigned to a 35 lzctone. These assignrnerats wea-e confirmed by 'H and r'C nmr. Table 1 gives tentative assignments of the observed ~~'t; nmr peaks. It should be noted that the two isomeric octadienols ( 2,7-octadienol and 1,7-octadien-3-ol) though not separable by the GC method used can be identified by nmr and are recorded in the nmr assign znent Tabie 1. The correspondence to the GC was confirmed again by integration of the nmr spectrum of several samples in which the composition varied. The lactone found by GC/MS was also observed in the nmr and quantified at approximately 6.2% (tenative structure given in TabIeI).

SUBSTITUTE SHEET (RULE 26) WD 98/00388 PCTlGB97/01742 M O~ N

O M cn ~ N

.--.01 ~ M M

N N M M

t~ N vO t~

N ~' ~ O

~fi~t >, _ a ~

c~ ~ ,n U 00~f'i ~ d' Q ~ _ _ i cV

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coSriU

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N

N N cV

M rnQ

M cn x 0 0 ~ ~ ~
~

fJ ~ . _ .--~ x N M N r'~ N
x U ~ co- U

~

N r~ (-dN Z

U c~ CJ '-"" ~o N

II II

rmn y rj in rn '~ x rft rn f M
U n rnVr fJ ~. fV,'fV

~- x M N ~

_ U 'fi U Wit- M

fJ ~ rn rf1 00 N cn ' cn N
V

'n m U N N N

N
rn~ N

vD x ~n t~ x x N ~ cn U ~ U ~ ~ ' ~ ~ i Ii t ~ N Iw N
N rn i ap a~

r~,w c i .
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cG cc3 _ -~..,._.~ ~ a> N ~
~-.

Q y cue ~ ~ v ~ ~

N is Li~ Z. ii f.~
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SUBSTITUTE SHEET (RULE 26) N

U

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N W ~ N c1 ~ ~ ~ " ~ N <tO

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~

N
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N

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c'~ p~ ._.. 00 ~ (, r..cV

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U

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-.t ~ .

> ~ N ~ U

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'n CJ a~ . s..... . ~.O
N

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U o0 SUBSTITUTE SHEET (RULE 26) The mixed ester product from step (a) comprising a relatively low amount of the 2-succinate ester is reacted in a step (b) with a second reactant alcohol in the presence of a magnesium alkoxide catalyst as follows:
Sten (b1: Ailyloxysnccinnte Enhstncement - General method All apparatus used was dried ( 100°C: oven) before: use and the litluid reagents were be dried ( <0.05%w/w water - molecular sieves 3a). The total acid number (TAN) of the ester reagent was measured.
To a conical flask was charged a pear shaped magnetic follower;
The mixed ester product from step (a) - 546.68 t o 2,7-Octadienol - 414.8~g magnesium ethoxide#t - 4.8588 #~ jassuming that 1 mole ofacid is neutralised by D mole of magnesium ethoxide, 1 ppm ICOHI;~; is = f x i U'" I Mol lit of K4N moles KOHIg 7 5 1 x D (?''' /56.13 males Kf3Hlg The molecular weight of~magnesium ethoxide = 1 14.44 So TAN of l ppm K(aH will require l 14.44 x 1 x 10-''156.1 I/g If the sample weighs Y scrams, if~the sample TAN is Z ppm/KON
then the amount of~ maanesitam ethoxide required to neutralise the acid 20 in the sample = 1 14.44 x Y x Z x 1 x 10''' /56.11 To this amount 11711St he added the amount of magnesium ethoxitle needed to oatalyse the reaction e8 O.:~S% w/w.J
A nitru~,en top covey was setpplied to the flask an d the mixture with ma~~netic stirrin:~ heated to 80°C. The reaction was monitored by CyC.
anti samples 25 withdrawn at dif3erent decrees of~cc~nversion.
The samples rwere p unified by usin~~ the following procedure.
An edtral volume of~saturat~d brine was added to the sample in the separating funnel and the. mixture shaken for 5 minutes. The mixture separated into two phases. an upper organic pD~ase and a lower aqueous phase. The lower 30 aqueous phase was decamed and the procedure repeated until the the aqueous layer pH decreased m 7~ 0.~ . Tc~ the upper organic phase was added I% w/w activated carbon and the mixture wa' heated td 100°C'. ti,a~ I hr at I
3 ;.3 la ( l rnn~i-Ig) on a rotateny evaporator. The material was then allowed to tool to room temperature and filtered tht-c~taf;h x cake of dried ['elite"' filter aid. It was found 3~ that it was possible to obtain conv~rsiuns of~the maieate starting material to the allyloxysuccinate in excess of 97% by this method.
2. Testin>= of reactive dllllellts I11 pMlllt formulations A good reactive diluent must meet a range of criteria including low odour and toxicity, low viscosity and the ability to "cut" the viscosity of the paint to facilitate application on the surface to be coated therewith. Furthermore, the diluent should not have a markedly adverse effect on the properties of the paint film such as drying speed, hardness, degree of wrinkling, durability and tendency to yellowing. The reactive diluents described above have therefore been tested in paint applications using both clear and pigmented paints. The diluents have been 1 D compared with paints formulated using white spirit, a conventional thinner.
2.1 Llnpi~tnented "Clenrcoat" Formulations 2.1. f Materials Used:
Unpigmented ("clearcoat") paint formulations were prepared using a high solids alkyd resin SETALO EPL O 1 / 1 / l 4 (ex AKZO NOBEL, and described in "Polymers Paint and C'.olour Journal, 1992, 182, pp. 372). In addition to the diluent, Siccatol0 9;~ drier (ex Af<ZO NOBEL) and methyl ethyl ketone-oxime (herea.tLer "MEI<-oxime") anti-skinning agent were used. Where used, the white spirit was Exxon type 100. The nominal propouions of the above materials in the paint formulations were:
2o TABLE 2 Materials Parts by wei ht ReS111 -~- Diluent 100.0 Siccatol 9 3~

MEI<-oxime 0. 5 Note that, fbr white spirit te~nnulations only, the proportions of drier and at7tlSk11111111g agent were calculated on the basis of the resin only. Thus, the concentration of these components in the paint was lower than for other diluents.
2.1.2 Method of Pr~paratiol~ of C'Iearcoat Formulationw Alkyd resin and diluent (2-(2,7-octadienoxy)-di-2,7-octadienyl succinate) were mixed in glass jars for 2 hours (eg using a Luckham multi-mix roller bed) in the proportions required to achieve a viscosity (measured via the 3o ICI cone and plate method using a viscometer supplied by Research Equipment (London) Limited) of G8 ~ 3 Pa s (6.8 ~ 0.3 poise). Typically SUBSTITUTE SHEET (RULE 26) this resulted IIl a 111txt11I'e WhICIl Was Ca. 8S% w/w resin. If further additions of diluent or resin were reduired to adjust the viscosity to 68 ~ 3 Pa s (6.8 ~ 0.3 poise), a filrther hour of llllx111g was allowed. The required quantity of drier was added and, after mixing ( 1 hour}, the required amount of anti-skinning agent was added. After final mixing for at least 30 minutes, the viscosity of the mixture was measured to ensure that the viscosity was between 61 and G9 Pa s (6.1 and 6.9 poise).
The mixture {"formulation") was then divided into two jars so as to leave ca. 10-I S% v/v headspace of air in the sealed jars. One of the jars was 1 o stored at 2 3°C in darkness for 7 days before paint applications tests were performed. The second jar was stored ("aged") at 35°C in daylight for days before applications tests were performed.
3. Test Procedntres Used for Cteurcoat T'ot-tnulatiotts:
3.1 Apt>tlication ofJ~~~1i11f film:
Thin films were applied to cleaned glass test plates using Sheen cube or draw-bar applicators with a nominal 75ym gap width.
3.2 Viscosity me.lsurelneltts and results:
The viscosity of each diluent was measured at 23°C using a suspended Ievel viscometer. Densities of the diluents were taken as an average of three readings made at 2S°('. L1S(11~ density bottles with a nominal 10 cm3 capacity, calibrated with water.
TABLE 3 : Viscosity of reactive diluents Dituent Viscosity (tn Pa.s AKZR {Exam ale S3) 18 3.3 1D1-yill~ Perforln.>Ince:
IJI'y111~ pel'fC)1'nlallCe VJaS lneaSllred USIIIg films applied to 30 cm x 2.5 cm glass str fps at7d BI< drying recorders. The BK recorders were enclosed in a Fisons contrc}Iled temperature and humidity cabinet so that the drying experiment could be lzerte~rmed at 10°C'. and at 70% relative humidity.
Sample pertbrmance was assessed on the basis of the second stage of-dlying (dust drying time, TZ).
SUBSTITUTE SHEET (RULE 26l SAMPLES
PREPARED
BI' THE
ABOVE
PROCESS
USING
MAGNESIUM

ETHO~IDE
& TEST
DATA

Solvent Fresh ged Description Drying Tying Times imes hrs hrs Solvent-IDi-octadienyi maleate prepared 1 1.88 13.86 with 0.1% MSA

and treated with magnesium ethoxide (7% succinate, reaction interru 9.26 13.09 ~ted Solvent-I treated fiu~ther with magnesium ethoxide (58% succinate) 7.6 9.53 Solvent-Dioctadienyl maleate prepared with 2 0. 1% dibutyl tin oxide 10.47 13.56 Solvent-2 treated with magnesium ethoxide (75% + succinate) 6.83 9.7 The above process was repeated with the product from Example I using the enhancement method (b) which achieved an allyloxy succinate yield of 97%.
The corresponding dt_ytllg times were as Ibllows:
Fresh A~~ed S.6 hours s.4 hours SUBSTITUTE SHEET (RULE 26)

Claims (16)

CLAIMS:

1. A process for producing a 2-substituted succinate ester of the formula (I), said process comprising, reacting:
(a) a dicarboxylic compound selected from the group consisting of maleic acid, maleic anhydride, fumaric acid and a dialkyl ester of maleic or fumaric acid with an alcohol R'O[CHR".cndot.CH2O]x H, wherein x is 0 or an integer from 1-6, in the presence of a catalyst to form a hydrocarbyl ester or, when x = 1-6, a hydrocarbyloxy alkylene ester of maleic and/or fumaric acid; and (b) the ester from step (a) with an alkaline earth metal alkoxide in the presence of a further amount of the alcohol to form the 2-substituted succinate ester of formula (I):

wherein:
R' = R and is an unsaturated hydrocarbyl or allylically unsaturated hydrocarbyloxy alkylene group having at least 5 carbon atoms, R" is H or an alkyl or an alkylene group having 1 to 2 carbon atoms, and each of a and b is the same or different and has a value of 0 or is an integer from 1-6.

2. A process according to claim 1, wherein R' is derived from the reactant alcohol R'O[CHR".cndot.CH2O]x H, wherein x is 0 or an integer from 1-6, which is used for making the succinate ester.

3. A process according to claim 1, wherein the reactant alcohol is an allylic alcohol.

4. A process according to claim 3, wherein the allylic alcohol is selected from the group consisting of 2-ethyl-hex-2-en-1-ol, 2-octen-1-ol, 1-octen-3-ol, 2,7-octadienol, 2-ethyl allyl alcohol, hept-3-en-2-ol, 4-methyl pent-3-en-2-ol, 4-t-butoxy but-2-en-1-ol, 4-n-butoxy but-2-en-1-ol, cinnamyl alcohol and isophorol.

5. A process according to any one of claims 1 to 4, wherein the 2-succinate ester of the formula (I) is prepared by reacting in the first stage (a) the reactant alcohol with maleic acid or anhydride and/or fumaric acid or an ester thereof in the presence of a catalyst.

6. A process according to claim 5, wherein the catalyst used is selected from the group consisting of zinc acetate, dibutyl tin oxide, stannous oxalate, para-toluene sulphonic acid and phosphoric acid.

7. A process according to any one of claims 1 to 6, wherein the reaction for making a succinate ester of formula (I) is carried out at a temperature below 120°C.

8. A process according to any one of claims 1 to 7, wherein the ester product from the step (a) is then further reacted in a step (b) with a further amount of the reactant alcohol in the presence of an alkaline earth metal alkoxide catalyst at a temperature below 120°C and at a pressure in the range from atmospheric to 50 Kpa to enhance the amount of the desired 2-succinate ester in the product from step (a) at the expense of the maleates and fumarates in said product.

9. A process according to any one of claims 1 to 8, wherein the alkaline earth metal alkoxide is magnesium alkoxide.

10. A process according to any one of claims 1, 2 and 5 to 9 when not dependent on claim 3 or 4, wherein reaction of 2-ethyl hexenol with maleic acid or anhydride followed by reaction of the product with magnesium alkoxide of 2-ethylhexenol as catalyst gives rise to a product which comprises 2-(2-ethyl hexenoxy)-di[2-(2-ethyl hexenyl)]
succinate.

11. 2-(2-ethyl hexenony)-di[2-(2-ethyl hexenyl)]
succinate.

12. A process according to any one of claims 1 to 3 and 5 to 9 when not dependent on claim 4, wherein reaction of octadienoxy ethanol with maleic acid or anhydride followed by the reaction of the product with the magnesium alkoxide of octadienoxy ethanol as catalyst gives rise to a product comprising di-2-(octadienoxy)ethyl-2-(2-octadienoxy) ethoxy succinate.

13. Di-[(2-octadienoxy)ethyl]-2-[(2-octadienoxy) ethoxy] succinate.

14. A paint or coating formulation based on an alkyd resin and comprising 2-octadienoxy di-octadienyl succinate as a reactive diluent in a paint or coating.

15. A paint or coating formulation based on an alkyd resin according to claim 14, wherein said formulation further comprises one or more of butylated hydroxy-toluene (2,6-butoxy-4-methyl phenol) and 2,4,6-tert-butyl phenol to inhibit haze and/or peroxidation.

16. An emulsion paint comprising vinyl acetate and a comonomer selected from one or more of the ether esters prepared by a process according to any one of claims 1 to 10 and 12.