Maleates and Fumarates

Diester derivatives of maleic and fumaric acid (see Chapter 3) are not easily polymerized. However, they do yield soft, tacky thermoplastics with free-radical generating initiators such as BPO. Diethyl fumarate, for example, polymerizes to an 89% yield of poly (ethyl succinate) when heated in the presence of 2% BPO for 7 Liquid-phase (neat) reaction at high pressure (5000 psi) improves the yield.Polymers of higher softening point and higher molecular weight may be prepared by emulsion-polymerization techniques. 

The fumarates polymerize much more readily than the maleates, since the transition state involving maleates is less resonance stabilized due to noncoplanarity of the carboxyl groups. Derivatives of dialkyl maleates and fumarates have also received attention as copolymerizable surfactants. Significant attention has been given to the polymerization properties of alkyl allyl maleates, diallyl maleates, and 

Information on maleate and fumarate ester copolymerizations may be found in Chapters 9 and 10 and various review articles. The glass 

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Esterification. Both mono- and dialkyl maleates and fumarates are obtained on treatment of maleic anhydride or its isomeric acids with alcohols or alkoxides (25). An extensive review is available (59). Alkyl fumarates (18) often are made from isomeri2ation of the corresponding maleate (19) (60). 

Hydroformylation. Esters of maleate and fumarate are treated with carbon monoxide and hydrogen in the presence of appropriate catalysts to give formyl derivatives. Dimethyl fumarate [624-49-7] is hydroformylated in 1 1 CO/H2 at 100°C and 11.6 MPa pressure with a cobalt [7440-48-4] catalyst to give an 83% yield of dimethyl formylsuccinate [58026-12-3] product (72). 

This Michael-type addition is catalyzed by lanthanum(3+) [16096-89-2] (80). Ethylene glycol [107-21-1] reacts with maleate under similar conditions (81). A wide range of nucleophilic reagents add to the maleate and fumarate frameworks including alcohols, ammonia, amines, sulfinic acids, thioureas, Grignard reagents, Michael reagents, and alkali cyanides (25). 

Oxidation. Maleic and fumaric acids are oxidized in aqueous solution by ozone [10028-15-6] (qv) (85). Products of the reaction include glyoxyhc acid [298-12-4], oxalic acid [144-62-7], and formic acid [64-18-6], Catalytic oxidation of aqueous maleic acid occurs with hydrogen peroxide [7722-84-1] in the presence of sodium tungstate(VI) [13472-45-2] (86) and sodium molybdate(VI) [7631-95-0] (87). Both catalyst systems avoid formation of tartaric acid [133-37-9] and produce i j -epoxysuccinic acid [16533-72-5] at pH values above 5. The reaction of maleic anhydride and hydrogen peroxide in an inert solvent (methylene chloride [75-09-2]) gives permaleic acid [4565-24-6], HOOC—CH=CH—CO H (88) which is useful in Baeyer-ViUiger reactions. Both maleate and fumarate [142-42-7] are hydroxylated to tartaric acid using an osmium tetroxide [20816-12-0]/io 2LX.e [15454-31 -6] catalyst system (89). 

Whilst vinyl acetate is reluctant to copolymerise it is in fact usually used today in copolymers. Two of particular interest to the plastics industry are ethylene-vinyl acetate (Chapter 11) and vinyl chloride-vinyl acetate copolymers (Chapter 12). In surface coatings internal plasticisation to bring the Tg to below ambient temperatures and thus facilitate film forming is achieved by the use of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and dialkyl maleates and fumarates. 

The possibility of recycling the catalyst was also studied. In order to decrease the amount of ethyl maleate and fumarate, the addition rate of ethyl diazoacetate was reduced and the reaction temperature was kept low during the addition. Furthermore, the catalyst concentration was reduced by doubling the volume of ionic liquid. Under these conditions the catalyst was reused seven times, although both the yield and the enantioselectivity decrease from the fourth reuse on (entry 6 in Table 6). 

Substituted ethylenes in which substituents occur on both carbon atoms (with the exception of the fluoroethylenes) usually are not prone to polymerize, although some of them, such as the maleates and fumar-ates, copolymerize readily with other monomers. The further fact that, with rare exceptions, the monomers unite through the addition of the substituted carbon atom of one unit to the unsubstituted carbon atom of the next permits representation of nearly all vinyl addition polymers by the general structural formula... 

An important competing process with significant practical consequences is the catalytic dimerization of diazoacetate to form maleate and fumarate esters. Most catalysts suffer from this side reaction, leading to the use of the alkene as solvent in order to accelerate the productive pathway and the slow addition of diazo compound in order to minimize dimerization. Since this problem is generally shared across most catalyst architectures, it will be mentioned in discussions of individual asymmetric catalyst systems only in those instances where these precautions prove to be unnecessary. 

In contrast with olefins, alkoxy-alkoxycarbonylation of alkynes to give /J-alkoxyacrylic esters is not a common reaction, and has occasionally been observed as a side reaction of the main reaction pathway leading to maleates and fumarates [77,80]. However, with suitably functionalized alkynes bearing a coordinating group (such as o ,a -disubstituted propargylic acetates) it may become the major reaction course (Scheme 15) [88]. 

Similar experiments have been performed with fumaric and maleic acids (trans and cis l,4-but-2-enedicarboxylic acid). Identical observations were made - at the beginning of the reaction, a broad Bragg reflection centered at 10.0 A is seen to grow in to the patterns. This corresponds to the second stage intercalates of maleate and fumarate. Upon continued addition of the dicarboxylates, a phase at 12.9 A appears. This is the maleate intercalate basal... 

The carbon dioxide anion-radical was used for one-electron reductions of nitrobenzene diazo-nium cations, nitrobenzene itself, quinones, aliphatic nitro compounds, acetaldehyde, acetone and other carbonyl compounds, maleimide, riboflavin, and certain dyes (Morkovnik and Okhlobystin 1979). The double bonds in maleate and fumarate are reduced by CO2. The reduced products, on being protonated, give rise to succinate (Schutz and Meyerstein 2006). The carbon dioxide anion-radical reduces organic complexes of Co and Ru into appropriate complexes of the metals(II) (Morkovnik and Okhlobystin 1979). In particular, after the electron transfer from this anion radical to the pentammino-p-nitrobenzoato-cobalt(III) complex, the Co(III) complex with thep-nitrophenyl anion-radical fragment is initially formed. The intermediate complex transforms into the final Co(II) complex with the p-nitrobenzoate ligand. 

This enzyme [EC 5.2.1.1] catalyzes the interconversion of maleate and fumarate. 

A plausible reaction mechanism for this reaction was proposed by the authors. The Cu(i) carbene 182 generated from ethyl diazoacetate and the chiral Gu(i) complex can either react with another molecule of ethyl diazoacetate to form a mixture of diethyl maleate and fumarate 183, or with the imine lone pair to form a Gu(i)-complexed azomethine ylide... 

The formation of carbanions, according to Scheme 6, has been much studied but has proved to be of little preparative use. The benzyl anion, generated from benzyl-dimethylsulphonium tosylate, reacted with acrylonitrile but the addition product was formed in only low yield Similarly the reactive ylid formed by deprotonation of trimethylsulphonium salts has been cathodically generated and trapped by several aldehydes and ketones as well as ethyl maleate and fumarate examples are given in Scheme 7. For the best case (benzophenone), the epoxide was formed in 40%... 

Cyclopropanation.2 This metal carbonyl cluster is an effective catalyst for cyclo-propanation of alkenes with ethyl diazoacetate. Minor by-products are diethyl maleate and fumarate, but products of allylic C -H insertion are not formed. The yield of the cyclopropane can be increased if the ethyl diazoacetate is added slowly over a period of 6 hours to the olefin and catalyst. Under these conditions yields of eyclopropanes are 85 -90%. 

Internal plasticizing demands a chemical relationship between the components which constitute the product. Therefore, good effects can be expected from copolymers of styrene and isobutylene, ethylene, or diolefins like butadiene or isoprene. Internal plasticizing of PVC can be effected by copolymerizing vinyl chloride with acrylates of higher alcohols or maleates and fumarates. The important ABS products are internal copolymers of butadiene, styrene, and acrylonitrile. The hardness of the unipolymers of styrene and acrylonitrile can be modified by butadiene which, as a unipolymer, gives soft, rubberlike products. As the copolymerization parameters of most monomers are known, it is relatively easy to choose the most suitable partner for the copolymerization. When the product of the r—values is l, there is an ideal copolymerization, because the relative reactivity of both monomers toward the radicals is the same. Styrene/butadiene, styrene/vinyl thiophene, and... 

Hydroformylation - [CARBON MONOXIDE] (Vol 5) - [OXO PROCESS] (Vol 17) -of allyl alcohol [ALLYL ALCOHOL AND MONOALLYL DERIVATIVES] (Vol 2) -catalysts for [CATALYSIS] (Vol 5) -C-19 dicarboxylic acids from [DICARBOXYLIC ACIDS] (Vol 8) -of ethylene [ETHYLENE] (Vol 9) -of ethylene [PROPYL ALCOHOLS - N-PROPYLALCOLHOL] (Vol 20) -of maleate and fumarate esters [MALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) -phosphine catalyst [PHOSPHORUS COMPOUNDS] (Vol 18) -platinum-group metal catalysts for [PLATINUM-GROUP METALS] (Vol 19) -rhodium catalysis [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19) -ruthenium cmpds or catalyst [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19) -use of coordination compounds [COORDINATION COMPOUNDS] (Vol 7)... 

The photochemical addition596 of DMAD to 3//-pyrrolizine (25) and to 3,3-dimethyl-3/f-pyrrolizine (26) gave low yields of adducts 27 and 28 from 25 the 8-maleate and fumarate derivatives (29 and 30) were also obtained. Thermolysis of 28 gave 31, whereas photolysis gave the... 

Likewise with the dienophile the maleate and fumarate esters 2.90 and 2,92 react with butadiene to give diastereoisomeric adducts 2.91 and 2.93, in which the substituents retain, as a consequence of the suprafacial nature of the developing overlap, the cis and trans relationships they had in the dienophiles. Diels-Alder reactions are much used in organic synthesis, not only because two new C-C bonds are made in one step, but also because the relative stereochemistry of up to four new stereogenic centres is predictable. 

The first report of the use of racemic sulfinyl maleates as dienophiles appeared in 1983 [85]. This paper described the synthesis of 2-phenylsulfmyl maleate and fumarate, but only the reaction of cyclopentadiene with the first ( )-87, a synthetic equivalent of dimethyl acetylenedicarboxylate, was studied. The reaction takes place at room temperature on silica gel and the stereochemistry of the adducts remained undetermined because the isolated product is the compound resulting from the pyrolytic sulfinyl elimination, which occurs spontaneously under the reaction conditions used (Scheme 46). 

The unperturbed dimensions of various condensation polymers obtained by the present method are listed in Table 10. A polyelectrolyte chain, sodium polyphosphate, has been included because theta-solvent results are available. The freely-rotating chain dimension (Lzyof of poly(dimethylsiloxane) in the table is due to Flory and his coworkers (705), that for the polyphosphate chains is taken directly from the paper of Strauss and Wineman 241 ), while most of the others have been calculated in the standard manner with the convenient and only negligibly incorrect assumption that all the aliphatic bond angles are tetrahedral. The free-rotation values for the maleate and fumarate polyesters are based on parameters consistent with those of Table 6 for diene polymers. 

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