Anhydrides ring opening

Table 25 NHC catalyzed acid anhydride ring opening of aziridines...

Amplification. See Chirality amplification Anhydrides, ring opening, 331 Anionic polymerization methyl sorbate, 174 trityl acrylate, 181 Annelation, Robinson method, 336 Antibiotics, 8, 44, 80 Antibodies, 12... 

The isoxazolopyridinium salt (208), boiled briefly with acetic anhydride, ring opens and recloses to the pyrrolo[3,2-6]pyridine (209) which reacts further as shown (Scheme 66). The phenylhydrazone behaves similarly (78T1581). 

Amine Containing Molecule Glutaric Anhydride Ring Opening with Amide Bond Formation... 

The small exotherm at 117°C preceding the main exotherm at 154°C is dependent on the concentration of phthalic anhydride it appearing at higher concentrations of phthalic anhydride. A mixture of phthalic anhydride and imidazole catalyst with no epoxy resin present shows a broad, low exotherm starting at 125°C. This suggests that anhydride ring opening occurs as the first step in the process. 

N-Aryl-2,3-quinoxalinedicarboximides (54) are formed instead of the expected sydnones when 3-arylnitrosoamino-l-arylpyrrolidine-2,5-diones (53) are treated with acetic anhydride. Ring opening of the... 

Other Anhydrides.- Ring-opening polymerizations of 1,3-anhydro-... 

Anhydrides. Ring-opening poly(addition-condensation) of cyclic acid anhydrides with glycols proceeded through lipase catalysis (135). The polymerization of succinic anhydride with 1,8-octanediol proceeded using lipase PF catalyst at room temperatime to produce the polyester with M of 3x 10 . 

With anhydrides, the catalyst facilitates the anhydride ring opening ... 

It can be assumed that the first step is the formation of a carboxylic group after anhydride ring opening by water or adventitious hydroxyl groups, which, once introduced, can be regenerated by various means. 

Transesterification can occur either by alcoholysis or by acidolysis the latter is less important commercially. When acid anhydrides are used, they react in two steps first, the anhydride ring opening by a hydroxyl, giving a half ester of acid, followed by condensation of the acid group with another hydroxyl. The first reaction occurs at... 

Soluble unsaturated polyesters were synthesized from maleic anhydride and glycidol in dimethoxyethane. At 80 °C, an acid anhydride ring opening occurred and monomaleate ester was formed. In the second step, at 120 °C, the epoxy ring was opened by the COOH group (Fig. 5), formed in the first step [20]. 

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