Adipic anhydride

In an attempt to avoid the polymerization/depolymerization equilibrium that occurs during melt polycondensation, Albertsson and Lundmark (1988) also studied the irreversible reaction of adipic anhydride with ketene. However, they reported very little difference in molecular weights when two ketene syntheses were compared to melt polycondensation and ringopening polymerization using a zinc catalyst (Albertsson and Lundmark, 1988). 

Aluminum isopropoxide has proved to be a very effective initiator for the polymerization of lactones pPL, 6VL, eCL, DXO, and pBL and dilactones D,L- and L-LA, and GA. It is worth noting that cycHc carbonates, e.g., 2,2-dimethyltri-methylene carbonate (DTC) and cycHc anhydrides such as adipic anhydride (AA) have also been polymerized by aluminum trialkoxides with the unique possibility to control the molecular parameters of the polycarbonate (PDTC) and polyanhydrides (PAA). This is illustrated in Scheme 2 and the preferred reaction conditions are given in Table 3. 

Esterification Starch acetate - Esterification with acetic anhydride or vinyl acetate Acetylated distarch adipate - Esterification with acetic anhydride and adipic anhydride Starch sodium octenylsuccinate - Esterification by octenylsuccinic anhydride... 

Fig. 11. Release of drug from poly(trimethylene carbonate)-poly(adipic anhydride) (PT-MC-PAA) blends with different amounts of PAA ( ) 100%, ( ) 80%, (A) 50%, ( ) 20%, and( ) 0%...

Blending is yet another way of manipulating the polymer properties. PTMC degrades too slowly to be useful for most drug delivery applications. Blends were prepared in an attempt to enhance and control the drug delivery rate [121]. Films were prepared from PTMC and poly(adipic anhydride) (PAA), which were partially miscible and formed macroscopically homogeneous blends. The PAA was found to act as a plasticizer and facilitated the erosion of PTMC by increasing the porosity and hydration. PTMC-PAA blends offered sustained and controllable release of an incorporated therapeutic substance as shown in Fig. 11 [121]. 

Monostarch phosphate 1410 E1410 Vinyl acetate < 7.5% Adipic anhydride and acetic anhydride <0.12% Orthophosphoric acid or sodium or potassium Phosphate (reported as phosphorus) <0.4%... 

Adipic anhydride, not to exceed 0.12%, and acetic anhydride Not more than 2.5% of acetyl groups introduced into finished product... 

Poly (tri methyl Carbonate)-poly(adipic Anhydride) Blends... 

The influence of molecular structure on the degradation mechanism of degradable polymers of poly(tri-methylene carbonate), poly (trimethylene carbonate-co-caprolactone), and poly(adipic anhydride) was explored by Albertsson and Eklund [7]. Measuring the change of the mass and the molecular weight for the... 

Aliphatic polyanhydrides H2 X = A, Adipic anhydride (AA) X = S, Sebacic anhydride (SA)... 

Another variation of this process is the preparation of adipic acid from cyclic adipic anhydride... 

Dibenzoylbutane has been prepared by the action of aluminum chloride on a mixture of benzene and adipyl chloride or benzene and polymeric adipic anhydride. It has also been obtained as a by-product in the action of zinc and alcohol on a, /3-dibromopropiophenone. The melting points recorded are 102°, 105-106°, and ii2°. ... 

Fig. 13. Positive (A), negative (B) ion spectra of poiy(adipic anhydride) (from Ref [66] )...

Adipic anhydride according to Voerman968 this is obtained by heating adipic acid for 6-7 h with ten times its weight of thionyl chloride on a water-bath. 

The reaction of adipic anhydride with (a-ethoxycarbonylethylidene)triphenylphosphorane <87BCJ689> gives endo-enol -lactone, namely 6-(a-ethoxycarbonylethyl)hex-5-enolide in low yield accompanied by several ring-opening products. 

T. Fey, H. Keul, H. Hbcker, Interconversion of alternating poly(ester amide)s and cyclic ester amides from adipic anhydride and a, co-amino alcohols, Macromol. Chem. Phys. 204 (2003) 591-599. 

ROP offers an alternate approach to the synthesis of polyanhydrides used for medical applications. Albertsson and coworkers prepared adipic acid polyanhydride from cyclic adipic anhydride (oxepane-2,7-dione) using cationic (e.g., AICI3 and BFjTCjHj) ), anionic (e.g., CHjCOO K and NaH), and coordination-type inhibitors snch as stannous-2-ethylhexanoate and dibutyltin oxide [24,25]. ROP takes place in two steps (1) preparation of the cyclic monomer and (2) polymerization of the cyclic monomers [26]. 

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