Maleic anhydride yields

The reactions of primary amines and maleic anhydride yield amic acids that can be dehydrated to imides, polyimides (qv), or isoimides depending on the reaction conditions (35—37). However, these products require multistep processes. Pathways with favorable economics are difficult to achieve. Amines and pyridines decompose maleic anhydride, often ia a violent reaction. Carbon dioxide [124-38-9] is a typical end product for this exothermic reaction (38). 

Under the present reaction conditions, we observed the formation of succinic anhydride almost simultaneously together with the formation of GBL. The hydrogaiation of maleic anhydride yields succinic anhydride, and the subsequent hydrogenation of succinic anhydride produces GBL. The rate of hydrogenation of maleic anhydride to succinic anhydride was very fast compare to that of succinic anhydride to GBL. When the reaction was CEuried out wifliout solvent, tetrahydrofiiran was not producal. The above results indicate that the Pd-Mo-Ni/SiOz catalyst under our experimental conditions played an important role for the selective formation of GBL. Therefore, it is inferred that the catalyst composition may influence the route by which tetrahydrofiiran was formed, probably due to the different absorption mechanism of maleic anhydride, succinic anhydride, and GBL. 

The unusual annulation of a substituted phenyl ring through [4 + 2] cycloaddition of vinyl compound 59 with dimethyl acetylenedicarboxylate (DMAD) as dienophile affords indolo benzazepine 60 in 53% yield, while a similar reaction with N-methyl-maleimide or maleic anhydride yields tetracyclic 61a,b in 53-87% yield (Scheme 12 (2003T6659)). 

A special case of asymmetric enantiomer-differentiating polymerization is the isoselective copolymerization of optically active 3-methyl-1-pentene with racemic 3,7-dimethyl-1-octene by TiCl4 and diisobutylzinc [Ciardelli et al., 1969]. The copolymer is optically active with respect to both comonomer units as the incorporated optically active 3-methyl-l-pentene directs the preferential entry of only one enantiomer of the racemic monomer. The directing effect of a chiral center in one monomer unit on the second monomer, referred to as asymmetric induction, is also observed in radical and ionic copolymerizations. The radical copolymerization of optically active a-methylbenzyl methacrylate with maleic anhydride yields a copolymer that is optically active even after hydrolytic cleavage of the optically active a-methylbenzyl group from the polymer [Kurokawa and Minoura, 1979]. Similar results were obtained in the copolymerizations of mono- and di-/-menthyl fumarate and (—)-3-(P-styryloxy)menthane with styrene [Kurokawa et al., 1982],... 

Bryce-Smith and Gilbert have shown that toluene, t-butylbenzene, chlorobenzene, o- andp-xylene, and biphenyl all undergo photoaddition to maleic anhydride, yielding 1 2 adducts [33], All the substituents decrease the rate of formation of adducts. Benzonitrile, nitrobenzene, phenol, methyl benzoate, durene, hexamethylbenzene, naphthalene, and biphenylene fail to undergo the addition of these, benzonitrile, nitrobenzene, methyl benzoate, and biphenylene do not form charge-transfer complexes. Bradshaw [34] found that various alkylben-zenes give 1 2 adducts with maleic anhydride upon photosensitization with acetophenone. 

Ortho photocycloadditions of benzene derivatives to maleic anhydride have been tabulated in Table 1. Only the structures of the primary ortho adducts are given, but these are not the isolated adducts They always undergo endo [2 + 4] cycloaddition with maleic anhydride, yielding 1 2 adducts. An interesting feature to be seen from Table 1 is that substituents on the benzene (alkyl, phenyl, or halogen) always turn up at the position most remote from the site of addition. In view of the different nature of these substituents, it seems that steric rather than electronic factors are responsible for this regioselectivity. 

Calculated and experimental maleic anhydride yields for the three fluid bed reactors involved in the scale-up of the Mitsubishi process are shown together in Figure 7. The yield value for the 45 cm dia. reactor was used to determine the reaction rate constant k, but the calculations for the 15 cm dia. bed and for the laboratory reactor with 4 cm diameter were performed without any parameter fitting. The calculation for the 15 cm bed is surprisingly close to the measurement whereas there is some deviation between theory and experiment on the laboratory scale the reason of which ist not quite clear. It should be noted however that in the laboratory reactor 1-butene was used as feed while on the pilot scale C -fractions of the naphtha cracker i.e. mixtures of various hydrocarbons were used. 

The interactions of a-olefins or styrene with sulfur dioxide (16) or a-olefins (24, 58, 78), frans-stilbene (64), styrene (1,63), p-dioxene (52), 2,2-dimethyl-l,3-dioxole (17), or alkyl vinyl ethers (1, 63) with maleic anhydride yield charge transfer complexes which are stable and generally readily detectable either visually or by their ultraviolet absorption spectra. However, under the influence of a sufficiently energetic attack in the form of heat or free radicals, the diradical complexes open, and alternating copolymers are formed. 

Much more work has involved N-protected 1,2-dihydropyridines thus, DielsAlder reactions between dihydropyridine 533 and many acrylic acid esters or dimethyl maleate have been described, though variable yields of endo 543 and exo 544 2-azabicyclo[2.2.2]octene products are obtained. The reaction with maleic anhydride yielded only the endo product 545 <2003T7555>. Chiral catalysts have been developed to allow the enantioselective DielsAlder reactions of 1,2-dihydropyridines <2002T8299>. 

Olefinic dienophiles such as maleic anhydride and maleimide add to 4,6-dimethyl-2-pyrone to afford mono Diels-Alder adducts. These on irradiation afford, by a photo-decarboxylation, a diene which can be trapped by a dienophile to afford the products (311). - - Acetone-sensitized photoaddition of the oxazolones (312) to maleic and dimethyl maleic anhydride yields the adducts (313). - ... 

Through copolymerization there can be made materials with different properties than those of either homopolymer, and thus another dimension is added to the technology. Consider, for example, styrene. Polymerized alone, it gives a good electric insulator that is molded into parts for radios, television sets, and automobiles. Copolymerization with butadiene (30%) adds toughness with acrylonitrile (20-30%) increases resistance to impact and to hydrocarbons with maleic anhydride yields a material that, on hydrolysis, is water-soluble, and is used as a dispersant and sizing agent. The copolymer in which butadiene predominates (75% butadiene, 25% styrene) is an elastomer, and since World War II has been the principal rubber substitute manufactured in the United States. 

As is customary for redox reactions, the yield of the useful product (maleic anhydride) rises with (n-butane) conversion, while selectivity to maleic anhydride declines with conversion. Under the conditions studied, the highest maleic anhydride yield of 30.6%, at a conversion of 57.8%, was obtained at 500 °C, using a feed composition of 1 n-Cy 15 O2 / 84 N2, a contact time of 4.9 sec, and a WHSV of 0.04/hr. Under comparable conversion conditions we obtained with the most celebrated, n-butane to maleic anhydride catalyst (VO)2P207 [16], a maleic anhydride yield of 38.5%. 

Figure 2. Maleic anhydride yield vs n-butane conversion with NbTio75V(,25P30 2 as catalyst...

Toax - temperature of the maximum of maleic anhydride yield selectivity to maleic anhydride... 

The thermal reaction of a conjugated diene and maleic anhydride yields the cyclic Diels-Alder adduct. However, alternating copolymers are readily formed when the reaction is carried out in the presence of a free-radical precursor at a temperature where the catalyst half-life is one hour or less, or the catalyst addition time is less than one hour (2, 13). 

The radical catalyzed homopolymerization of the furan-maleic anhydride (F-MAH) Diels-Alder adduct yields a saturated homopoly-mer at temperatures below 60 C, and an unsaturated equimolar alternating copolymer at elevated temperatures, due to retrograde dissociation of the adduct (10, 11). The copolymerization of monomeric furan and maleic anhydride yields the same unsaturated alternating copolymer, independent of temperature (1C)). 

In contrast, the radical catalyzed homopolymerization of the cyclopentadiene-maleic anhydride (CPD-MAH) Diels-Alder adduct yields a saturated homopolymer at temperatures as high as 220 C, while retrograde dissociation occurs at even higher temperatures. Nevertheless, the copolymerization of monomeric cyclopentadiene and maleic anhydride yields a saturated 1 2 copolymer (12-15). 

A thermal ene-reaction of unsaturated fatty acids with maleic anhydride produces branched triacids. As an example, the Diels-Alder reaction of conjugated triene fatty acids, that is calendic acid and maleic anhydride, yields a branched triacid product with high regioselectivity and stereoselectivity (Fig. 3.13). 

The driving force for this decomposition is clearly the formation of Nj. The 2-cyanoprop-2-yl radicals can then abstract a hydrogen from a substrate and set off a radical chain reaction. For example, when heated with a small quantity of AIBN, styrene and maleic anhydride yield a copolymer with almost perfectly alternating monomer units ... 

A variety of electron-deficient olefins were shown to be effective dienophiles, giving the expected cycloaddition products (Table 7.9). Reaction ofthe o-xylylene species 2 with maleic anhydride yielded only the cis product, while cis olefins (e.g., dimethyl or diethyl maleate) yielded a mixture of cis and tram cycloaddition products. Tram esters (diethyl fumarate and methyl crotonate) yielded tram adducts however, fumaronitrile gave a mixture of cis and tram adducts. In a separate experiment, it was discovered that upon exposure to the activated nickel, dimethyl maleate was isomerized to dimethyl fumarate. The exact mechanism of the isomerization is at this point unexplained. Noncyclic cis olefins appear to give mixtures of cis and tram cycloadducts, while tram olefins may yield tram products or mixtures of cis and tram products. In cases where mixtures are produced, the tram isomer is the major adduct isomer with the ratio of cis tram isomers apparently being affected by the nature of the olefin. Thus, although the cycloaddition reaction itself is still not proven to be a concerted rather than a stepwise process, the mixture of cis and tram cycloadducts could arise from isomerization of the olefin prior to the cycloaddition process. 

Copolymerization of styrene with maleic anhydride yields alternating structures, probably due to the formation of charge transfer complexes [126,127]. Statistical copolymers... 

Shekari A., Patience G.S. and Bockrath R.E. (2010). Effect of feed nozzle configuration on n-butane to maleic anhydride yield From lab scale to commercial, Appl. Catal. A General, 376, pp. 83-90. 

Shekari A. and Patience G.S. (2010). Maleic anhydride yield during cychc n-butane/oxygen operation, Catal. Today, 157, pp. 334—338. 

Chlorination of molten maleic anhydride yields a,)3-dichlorosuccinic anhydride 55. Hydrolysis of the latter can yield the di-acid 56. The addition reaction is usually carried out under pressure. ... 

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