Anhydrides conversions

A pilot-scale rsactor that can produce 50 kg of GBL per one batch was designed. The reactor size was calculated on the basis of maleic anhydride conversion of 100% and GBL yield of 50%. By assuming the saturate liquid densily of reactant and product at the reaction conditions of 250 C and 70 atm undo- the condition of no solvent, the daisity and specific... 

As the loading of STA on the catalyst support is decreased, incomplete anhydride conversion is observed and significant hydrolysis of the anhydride to form iso-butyric acid is observed (Table 2). Use of silica supported phosphoric acid results in lower ketone yields and significant hydrolysis of the iso-butyric anhydride. Blank reactions (catalyst and anhydride, 90°C, 30 min) indicates that hydrolysis of anhydride is observed in the presence of these catalysts and may result from either dehydroxylation of the silica support or residual water in the catalyst, ffowever this reaction is slow (42%STA/silica, 44% conversion and 70%P[3PO4/silica, 86% conversion respectively). 

The activity of 42%STA/silica catalysts for the acylation of related aromatic reactants with iso-butyric anhydride was investigated. In the presence of anisole and veratrole, 100% anhydride conversion was observed, leading to the expected para-acylation products. No reaction was observed in the presence of chlorobenzene and other deactivated aromatic systems. 

For the copolymerization of epoxides with cyclic anhydrides and curing of epoxy resins, Lewis bases such as tertiary amines are most frequently used as initiators. In this case, terminal epoxides react with cyclic anhydrides at equimolar ratios. The time dependence of the consumption of epoxide and anhydride is almost the same for curing 35-36> and for model copolymerizations 39,40,45). The reaction is specific 39,40) to at least 99 %. In contrast, the copolymerization with non-terminal epoxides does not exhibit this high specificity, probably because of steric hindrances. The copolymerization of vinylcyclohexene oxide or cyclohexene oxide is specific only to 75-80 % and internal epoxides such as alkylepoxy stearates react with anhydrides only to 60-65 %. On the other hand, in the reaction of epoxy resins with maleic anhydride the consumption of anhydride is faster 65the products are discoloured and the gel is formed at a low anhydride conversion 39). Fischer 39) assumes that the other resonance form of maleic anhydride is involved in the reaction according to Eq. (33). 

As shown in Figure 4.5, it is well known that cis-A is the Diels-Alder adduct of 1,3-butadiene and maleic anhydride. Conversion of A to meso-B followed by its oxidation gave ( )-C. This was reduced to furnish ( )-74.22 This synthesis, however, was not efficient enough to give a sufficient amount of ( )-74. Its overall yield was only 4.6% based on A. 

The resulting chiral auxiliary 56 was acylated with Lrans-croIonic anhydride. Conversion with 1,3-dipoles and cleavage from the support with NaBH4 afforded the corresponding isoxazolines and isoxazolidines in 12-62% yield with an endo exo ratio of up to 9 1 and enantiomeric excesses up to 89% (Scheme 12.22). 

The catalyst system for the modem methyl acetate carbonylation process involves rhodium chloride trihydrate [13569-65-8]y methyl iodide [74-88-4], chromium metal powder, and an alumina support or a nickel carbonyl complex with triphenylphosphine, methyl iodide, and chromium hexacarbonyl (34). The use of nitrogen-heterocyclic complexes and rhodium chloride is disclosed in one European patent (35). In another, the alumina catalyst support is treated with an organosilicon compound having either a terminal organophosphine or similar ligands and rhodium or a similar noble metal (36). Such a catalyst enabled methyl acetate carbonylation at 200°C under about 20 MPa (2900 psi) carbon monoxide, with a space-time yield of 140 g anhydride per g rhodium per hour. Conversion was 42.8% with 97.5% selectivity. A homogeneous catalyst system for methyl acetate carbonylation has also been disclosed (37). A description of another synthesis is given where anhydride conversion is about 30%, with 95% selectivity. The reaction occurs at 445 K under 11 MPa partial pressure of carbon monoxide (37). A process based on a montmorillonite support with nickel chloride coordinated with imidazole has been developed (38). Other related processes for carbonylation to yield anhydride are also available (39,40). 

Anil formation from nitroso compound and 2,4,6-trinitrotoluene, 293 Anhydride, conversion to thioacid with HjS, 276... 

As one might expect, the addition of carbanions to the ylide (34) results in addition to the iminium bond. Similarly, this bond is reduced to form the diazetidinone (35), which displays some interesting chemistry, such as ring-expansion to an oxadiazine upon treatment with acetic anhydride.Conversion of the ylide into 3-oxo-1,2-diazetidinium tosylate (36) is achieved by using toluene-p-sulphonic acid. Treating the tosylate with a 1,3-dicarbonyl compound provides a novel route to pyrazoles. ... 

In a model reaction, the soUd catalyst named UDCaT-5 gives a 62% propionic anhydride conversion and 67% 4-methylacetophenone selectivity by performing the reaction at 180°C for 3h [78],... 

Hexahydrophthalic anhydride, conversion to N-carboxyanhydride, 225 Hexakis (methoxyl methyl) melamine, MA reactions, 515 Hexamethyl benzene MA CTC, 210, 243 MA photochemical reaction, 180... 

Figure 9.9 Effect of radial Peclet number on overall yield of anhydride, conversion = 99%. (Carberry and White 1969 reprinted with permission from Industrial and Engineering Chemistry. Copyright by American Chemical Society.)...

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