A method for producing an aromatic dianhydride includes reacting an aromatic diimide with a substituted or unsubstituted phthalic anhydride in an aqueous medium in the presence of an amine exchange catalyst to provide an aqueous reaction mixture including an N-substituted phthalimide, an aromatic tetraacid salt, and at least one of an aromatic triacid salt and an aromatic imide diacid salt. The method further includes removing the phthalimide from the aqueous reaction mixture by extracting the aqueous reaction mixture with an organic solvent using a single packed extraction column. The aromatic tetraacid salt is converted to the corresponding aromatic dianhydride. Aromatic dianhydrides prepared according to the method are also described.

A method for producing an aromatic dianhydride includes reacting an aromatic diimide with a substituted or unsubstituted phthalic anhydride in an aqueous medium in the presence of an amine exchange catalyst to provide an aqueous reaction mixture including an N-substituted phthalimide, an aromatic tetraacid salt, and at least one of an aromatic triacid salt and an aromatic imide diacid salt. The method further includes removing the phthalimide from the aqueous reaction mixture by extracting the aqueous reaction mixture with an organic solvent using a single packed extraction column. The aromatic tetraacid salt is converted to the corresponding aromatic dianhydride. Aromatic dianhydrides prepared according to the method are also described.

The invention is directed to a process for the ring-opening of a cycloadduct obtainable from a reaction of a furanic compound and a diene, said process comprising contacting the cycloadduct with an acidic mixture comprising sulfuric acid and an activating agent to obtain a ring-opened product. The present invention is particularly directed a continuous process.

The invention is directed to a process for the ring-opening of a cycloadduct obtainable from a reaction of a furanic compound and a diene, said process comprising contacting the cycloadduct with an acidic mixture comprising sulfuric acid and an activating agent to obtain a ring-opened product. The present invention is particularly directed a continuous process.

The present invention provides a halo-de-carboxylation process for the preparation of organic chlorides, organic bromides and mixtures thereof, from their corresponding carboxylic acids, using a chlorinating agent selected from trichloroisocyanuric acid (TCCA), dichloroisocyanuric acid (DCCA), or combination thereof, and a brominating agent.

The present invention provides a halo-de-carboxylation process for the preparation of organic chlorides, organic bromides and mixtures thereof, from their corresponding carboxylic acids, using a chlorinating agent selected from trichloroisocyanuric acid (TCCA), dichloroisocyanuric acid (DCCA), or combination thereof, and a brominating agent.

Gracilin A congeners and methods for their use as immunosuppressive and neuroprotective agents.

Gracilin A congeners and methods for their use as immunosuppressive and neuroprotective agents.

A polymer being a product of reactants including a diamine and a monomer represented by Chemical Formula 1:

##STR00001##

wherein, in Chemical Formula 1, R.sup.1, R.sup.2, o, p, L.sup.1, A.sup.1, R.sup.a, m, and n are the same as defined in the detailed description.

A polymer being a product of reactants including a diamine and a monomer represented by Chemical Formula 1:

##STR00001##

wherein, in Chemical Formula 1, R.sup.1, R.sup.2, o, p, L.sup.1, A.sup.1, R.sup.a, m, and n are the same as defined in the detailed description.