89-20-3Relevant articles and documents
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Hayashi,Furusawa
, (1951)
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Preparation method for biphenyltetracarboxylic dianhydride mixture
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Paragraph 0030; 0031, (2016/10/09)
The invention relates to a preparation method for a biphenyltetracarboxylic dianhydride mixture. The preparation method comprises the following steps: with phthalic acid as a starting raw material, carrying out an electrophilic substitution reaction so as to produce a phthalic acid derivative; then subjecting the derivative to esterification so as to produce phthalate; further catalyzing phthalate and carrying out a coupling reaction so as to produce a biphenyl tetraformate mixture; and finally, successively carrying out saponification and acidification so as to produce the product biphenyltetracarboxylic dianhydride mixture. The method provided by the invention uses cheap and easily phthalic acid as the starting raw material and is a novel low-cost easily-operatable environment-friendly production method for biphenyltetracarboxylic dianhydride; moreover, isomeric compounds of all the biphenyltetracarboxylic dianhydride are synthesized at one time in the invention, so efficiency is improved and the cost is reduced.
METHOD OF PURIFYING DIANHYDRIDES, THE DIANHYDRIDES FORMED THEREBY, AND POLYETHERIMIDES FORMED THEREFROM
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Page/Page column 39-40, (2009/10/22)
A method for purifying an oxydiphthalic anhydride comprises diluting a first mixture comprising an oxydiphthalic anhydride, a solvent, a catalyst, and an inorganic salt with a solvent, to provide a second mixture having a solids content of 10 to 30 percent based on total weight of the second mixture; filtering and washing the solids of the second mixture at a temperature below the crystallization point temperature of the oxydiphthalic anhydride to provide a third mixture; hydrolyzing the third mixture by adding water and a water-soluble acid to form a fourth mixture; heating the fourth mixture; then cooling to provide a solid-liquid mixture, optionally decanting a portion of the liquid, re diluting the remaining solid-liquid mixture, then filtering to provide a solid component; washing the solid component with water to provide a fifth mixture of oxydiphthalic tetra acid and water; ring closing the oxydiphthalic tetra acid to provide oxydiphthalic anhydride, and filtering the oxydiphthalic anhydride.
2,4-DIAMINOQUINAZOLINES FOR SPINAL MUSCULAR ATROPHY
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Page/Page column 63, (2010/02/15)
2,4-Diaminoquinazolines of formulae I-IV and VI (I, II, III, IV and VI) are useful for treating spinal muscular atrophy (SMA).