Maleic anhydride, reaction with

Maleic anhydride condenses with 2-aminothiazole-4-carboxylic acid giving the raaleimide 107 (269) another report claims, however, that the reaction of 2-amino-4-methylthiazole with this anhydride gives the N-substituted maleamic acid (108) (Scheme 73) (270). 

Additive Polyimides. Rhc ne-Poulenc s Kin el molding compound and Kerimid impregnating resin (115), Mitsubishi s BT Resins (116), and Toshiba s Imidaloy Resin (117) are based on bismaleimide (4) technology. Maleic anhydride reacts with a diamine to produce a diimide oligomer (7). Eurther reaction with additional diamine (Michael addition) yields polyaminohismaleimide prepolymer with terminal maleic anhydride double bonds. Cure is achieved by free-radical polymerization through the terminal double bonds. 

Corrosion inhibiting compositions for metals subjected to highly acidic environments may be produced by reacting in a condensation reaction a styrene/ maleic anhydride copolymer with a polyamine to produce a polyimidoamine inhibitor [1568]. These inhibitors exhibit film-forming and film-persistency characteristics. Some relevant polyamines are listed in Table 6-2. 

We have previously (13) reported a rapid two step synthesis of 4-(pyrrolidino)pyridine copolymers via the reaction of commercially available maleic anhydride copolymers with 4-aminopyridine followed by reduction with LiAlH, yielding polymers with a high degree of functionalization. 

Complex vanadium-phosphorus-oxide catalysts are the most successful industrial catalysts for the selective oxidation of /i-butane to maleic anhydride (MA) with uses in tetrahydrofurans (THE) and polyurethane intermediates. A schematic diagram of the reaction is shown in figure 3.21(a). These catalysts have been studied extensively (e.g. Centi et al 1993, Bordes 1987). In the selective catalysation of a-butane to MA, the best active phase in the V-P-0 system is identified as the vanadyl pyrophosphate, (VO)2P207 (hereafter... 

The presence of a comonomer has, in certain cases, 9 marked influence on polymerization rate. For example, the mastication of natural rubber in the presence of maleic anhydride, even with small concentrations of the latter, about 5%, leads to accelerated polymerization of styrene monomer (11) either because of its high reactivity in the propagation step of heterochain copolymerization and/or because of a hardening effect. This reaction is discussed later. 

It was concluded that most probably maleic anhydride combines with the primary macroradicals (Scheme 4). Secondary radicals may be found by reaction with unsaturated groups of the rubber to add more monomers units along the chain and to produce a network. 

Substituted 2-vinylindoles yield the di- and tetra-hydrocarbazoles with JV-methyl-maleimide and maleic anhydride, and with DMAD, respectively (81UP30500, 82CJC419) and the expected cycloadducts are obtained from the reaction of 4-(2-indolyl)-l,2,5,6-tetrahy-dropyridines with iV-phenylmaleimide and with acrylonitrile (68HCA264). Both l-(l-methyl-... 

Oxidation of benzene to maleic anhydride 613-723 V205/Ti02, v2o5/ai2o3 Selectivity for maleic anhydride increases with the thickness of V2Os layers on the support Reaction rate is proportional to the density of surface V=0 65... 

However, Diels-Alder reactions are well known to be exceptional, with maleic anhydride reacting with cyelopentadiene by way of an endo transition structure 2.110 to give what is called the endo adduct 2.111 as the major product. The exo adduct 2.112 is a very minor product, unless the mixture is heated for a long time, when reversal of the Diels-Alder reaction and readdition establish the thermodynamic equilibrium in its favour. The endo adduct is evidently the product of kinetic control, and the preference for it is called Alder s rule. 

From the stereochemical structure of the adduct it can be inferred that the initial ortho photocycloaddition occurs with exo stereochemistry, whereas the subsequent Diels-Alder reaction of the ortho adduct with a second molecule of maleic anhydride proceeds with endo stereochemistry. 

In a classic Diels-Alder reaction, cyclopentadiene 24 combines with maleic anhydride 2 with complete stereospecificity to give either 25 or 26 so the two Hs on 2 remain cis to each other in both 25 and 26. These are called endo- and exo- adducts. This refers to the relationship between the alkene on the diene side and the carbonyl groups from the dienophile. These are much closer in the entio-adduct 25. The result is easy to see when both reagents are cyclic. 

Maleic anhydride reacts with cyclopenta-1,3-diene in a Diels-Alder reaction. Since there is a plane of symmetry, the reaction can lead to two achiral compounds, which are diastereomers of each other, containing an endo- or exo-oriented dicarboxylic anhydride group. These differ in absolute and relative configuration at the bond shared by both rings. Under normal conditions the Diels-Alder reaction proceeds stereospecifically to yield preferentially the endo product. Note that in the tricyclic product no trans fusion in the ring system is possible as a consequence of the reaction mechanism. Subsequent reduction of the products therefore affords two diols, which are also diastereomers of each other. These may be separated by chromatography on an achiral stationary phase. 

Heterocycle (427) gives naphthyridone (128) (69% yield) in a Vilsmeier reaction <83IJC(B)916>. Compound (428) and alkyne (429) yield product (430) (75% yield) in acetonitrile at 110°C and product (431) (58% yield) in toluene at 110°C <87CB1427>. Maleic anhydride reacts with enamine (432 R1 = Me, Et R2 = H, Me) giving pyranopyridtriones (433) (9-27% yield) <80S698>, and a mechanism has been proposed for this transformation. 

Attack at the heteroatoms was observed in the reactions of (1) and (2) with dimethyl acetylenedicarboxylate and with benzyne (78JCS(P1)1006). Compound (2) behaves as a heterodiene toward the acetylene ester, producing the quinoxaline (25) and selenium. The diester (25) was obtained only in trace amounts from (1). These reactions, and the failure of (1) and (2) to react with maleic anhydride, contrast with the behavior of naphtho[2,3-c] [l,2,5]thiadiazole which reacts with maleic anhydride across the center ring (64TL3815). 

Air and n-butane are introduced into a fluid-bed, catalytic reactor (1). The fluid-bed reactor provides a uniform temperature profile for optimum catalyst performance. Reaction gases are cooled and filtered to remove small entrained catalyst particles and then routed to the recovery section. Reactor effluent is contacted with water in a scrubber (2), where essentially 100% of the reactor-made maleic anhydride is recovered as maleic acid. The process has the capability of co-producing maleic anhydride (MAH) with the addition of the appropriate purification equipment. Scrubber overhead gases are sent to an incinerator for safe disposal. 

Inversely, vinylogous Mannich bases give the adducts 334 by reaction with dieno-philes such as maleic anhydride or with a vinyl group of their deamination product, thus... 

The addition of water to the reaction feed was investigated [136]. This led to two significant effects being noted. The selectivity to maleic anhydride increased (with increased yields of acetic and acrylic acids). There was also an increase in the surface area of the catalysts activated with the n-butane/water/air feed compared to the dry activated catalyst Arnold and Sundaresan excluded the possibility of the water vapor acting as a diluent by performing experiments with an n-butane/N2/air feed. Instead they proposed that water is adsorbed onto the surface, blocking sites that are responsible for over-oxidation of the products. 

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