FUMARIC ANHYDRIDE

Alternatively, acid-based polyanhydrides such as poly(fumaric anhydrides) and poly(maleic anhydrides) have raised interest because of the capacity of anhydrides to progressively hydrolyse in the presence of physiological fluids, leading to the production of high amounts of carboxylic groups on the surface of the dosage form, which have been shown to enhance bioadhesiveness of the matrix, thus increasing its residence time at the mucosal surfaces. 

Unsaturated Poly (fumaric anhydride) Poly (4,4 -stilbene dicarboxylic acid anhydride) Homopolymers are crystalline and insoluble in organic solvents, copolymers with aliphatic acids renders it less crystalline and soluble in chlorinated hydrocarbons. 

Biodegradable copolymers of fumaric anhydride and isophthalic anhydride were synthesised by the melt condensation polymerisation of purified prepolymer mixtures and formulated into microspheres loaded with theophylline and diltiazem hydrochloride using a solvent extraction procedure. The important parameters of the microencapsulation process were identified and in vitro... 

Colourless prisms m.p. 130 C. Manufactured by treating maleic anhydride with water. It is converted to the anhydride by heating at By prolonged heating at 150 "C or by heating with water under pressure at 200 C, it is converted to the isomeric (trans) fumaric acid. Reduced by hydrogen to succinic acid. Oxidized by alkaline solutions of potassium permanganate to mesotartaric acid. When heated with solutions of sodium hydroxide at 100 C, sodium( )-malate is formed. Used in the preparation of ( )-malic acid and in some polymer formulations. 

Both acids 3deld succinic acid, m.p. 185°, upon catalytic reduction (see Section 111,150), thus establishing their structures. Maleic and fumaric acids are examples of compounds exhibiting cis-trans isomerism (or geometric isomerism). Maleic acid has the cm structure since inter alia it readily 3delds the anhydride (compare Section 111,93). Fumaric acid possesses the trans structure it does not form an anhydride, but when heated to a high temperature gives maleic anhydride. 

Donor substituents on the vinyl group further enhance reactivity towards electrophilic dienophiles. Equations 8.6 and 8.7 illustrate the use of such functionalized vinylpyrroles in indole synthesis[2,3]. In both of these examples, the use of acetyleneic dienophiles leads to fully aromatic products. Evidently this must occur as the result of oxidation by atmospheric oxygen. With vinylpyrrole 8.6A, adducts were also isolated from dienophiles such as methyl acrylate, dimethyl maleate, dimethyl fumarate, acrolein, acrylonitrile, maleic anhydride, W-methylmaleimide and naphthoquinone. These tetrahydroindole adducts could be aromatized with DDQ, although the overall yields were modest[3]. 

Unsaturated Polyesters. Unsaturated polyesters are produced by reaction between two types of dibasic acids, one of which is unsaturated, and an alcohol to produce an ester. Double bonds in the body of the unsaturated dibasic acid are obtained by using maleic anhydride or fumaric acid. 

TALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15)... 

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