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| PATENT EXAMPLES |
I. Synthesis of the monomers The following provides the preferred method of synthesis of these uniform aliphatic-aromatic polymers. Infared spectroscopy of the monomers and polymers was performed on a Perkin-Elmer 1430 spectrophotometer. Polymeric samples were film cast onto NaCl plates from a solution of the polymer in chloroform. Monomer and prepolymer samples were either pressed into KBr pellets or dispersed in nujol onto NaCl plates. The melting points of prepolymers were determined on a Fisher Johns melting point apparatus. The molecular weights of the polymers and prepolymers were estimated on a Perkin-Elmer GPC system consisting of the series 10 pump and the 3600 Data Station with The LKB 214-rapid spectral detector at 254 nm wavelength. Samples were eluted in chloroform through two PL Gel columns (Polymer Laboratories; 100 A and 1000 A pore sizes) in series at a flow rate of 1.5 ml/min. Molecular weights of polymers were determined relative to polystyrene standards (Polysciences; polyanhydrides with molecular weights from 500 to 1,500,000) using CHROM 2 and GPC 4 computer programs (Perkin-Elmer, Mass.). .sup.1 H-NMR spectra were obtained on a Varian 250 MHz spectrophotometer, using deuterated chloroform as a solvent and tetramethylsilane as an internal reference. UV measurements were performed on a Perkin-Elmer 553 UV/VIS spectrophotometer. The methyl p-carboxyphenoxyalkanoate monomers were prepared according to the method of Izard. Izard, C. F.; Kworek, X. I. J. Am. Chem. Soc. 1951, 73, 1861, (1951) as follows: Preparation of P-Carboxyphenoxyalkanoic acids Freshly cut sodium metal (5.98 g, 0.26 mole) was gradually introduced into 150 ml of dry methanol in a 1000 ml flask equipped with a stirrer, and a reflux condenser with a drying tube. Upon complete solution of the sodium, first, 39.56 g (0.26 mole) of methyl p-hydroxybenzoate in 100 ml of methanol and later 50.0 g (0.26 mole) of methyl 5-bromovalerate were added rapidly. The reaction was allowed to reflux for 78 hours. After 78 hours of refluxing precipitated material was removed by filtration. The diester was precipitated upon pouring the solution into an ice water mixture. A clear powdery white precipitate was obtained, and filtered from the remaining solution. The precipitate was dried overnight, and weighed to obtain 58.35 g (84% yield). Methyl p-carboxyphenoxyacetate (CPA), (85% yield), and methyl p-carboxyphenoxyoctanoate (CPO) (75% yield) were prepared similarly using methyl bromoacetate, and methyl 8-bromooctanoate, respectively. The data analysis of the esters is described in Table 1. The methyl esters were then hydrolyzed to the corresponding diacids as follows: 600 ml of 2 N NaOH solution is added to 58.35 g of methyl p-carboxyphenoxyvalerate in a 1000 ml flask equipped with a condenser and stirrer. The solution is allowed to reflux for 10 hours while stirring. The solution is allowed to cool to room temperature. The compound is then isolated by lowering the pH of the solution from 12 to less than 1 by adding concentrated sulfuric acid. The precipitate is filtered from solution and allowed to dry overnight (57.00 g, 93% yield). CPA and CPO were hydrolyzed to the diacid similarly. The data analysis is described in Table 1. |
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