摘要:
Novel polyimides substituted by a substituent having an alkyl or fluoroalkyl group and having reduced water absorption; a process for producing these novel polyimides; and novel acid dianhydrides to be used in the production thereof. A polyimide containing a structure represented by the following general formula (I): wherein X1 represents a tetravalent organic group having a substituent —R1AR2 (wherein A represents a divalent linkage group; R1 represents a single bond or a C1-3 alkylene group; and R2 represents a C1-25 alkyl group or a fluoroalkyl group); and Y represents a divalent organic group.
摘要翻译:由具有烷基或氟烷基的取代基取代并具有降低的吸水性的新型聚酰亚胺; 一种生产这些新型聚酰亚胺的方法; 一种含有下述通式(I)表示的结构的聚酰亚胺:其中X 1表示具有取代基-R 1的四价有机基团AR 2(( 其中A表示二价连接基团; R 1表示单键或C 1-3亚烷基; R 2表示C 1-25烷基或氟代烷基)。 Y表示二价有机基团。
摘要:
In a process for preparing phthalic anhydride by passing a gas stream comprising o-xylene, oxygen and sulfur dioxide at elevated temperature over a catalyst comprising heavy metals, the content of N-acyl compounds in the gas stream is restricted to less than 200 ppm, based on the weight of o-xylene.
摘要:
Disclosed is a method for preparing oxy-diphthalic anhydrides, which comprises reacting a halo-phthalic anhydride represented by the formula (1): where Hal represents F, Cl, Br or I, with a carbonate salt selected from the group consisting of lithium carbonate, sodium carbonate, magnesium carbonate and calcium carbonate in a solvent to prepare oxy-diphthalic anhydrides represented by the formula (2):
摘要:
Disclosed is a method for removing impurities from products derived from oxidation of an ortho-dialkylaromatic compound which comprises at least one step selected from the group consisting of extraction of an aqueous solution comprising aromatic dicarboxylic acid product with an organic solvent and extraction of an organic solution comprising aromatic anhydride product with an aqueous bicarbonate solution for a time period insufficient to allow hydrolysis of anhydride to acid.
摘要:
This invention concerns compounds for inhibiting intracellular signal transduction, especially intracellular signal transduction mediate by one or more molecular interactions involving a phosphotyrosine-containing protein. This invention also relates to pharmaceutic compositions containing the compounds and prophylactic and therapeutic methods involving pharmaceutical and veterinary administration of the compounds. The compounds are of formula (1) as defined herein.
摘要:
On-spec phthalic anhydride is prepared by distillative purification of crude phthalic anhydride by a process in which crude phthalic anhydride is fed to a distillation column which is operated at reduced pressure, the low boilers are removed at the top or in the vicinity of the top of the distillation column and the on-spec phthalic anhydride is removed from the column via a side take-off.
摘要:
This invention relates to the vapor-phase oxidation of hydrocarbons by passing a gaseous mixture comprising of a molecular oxygen-containing gas and hydrocarbons which may contain substituents to a fixed bed of catalyst and provides a process for vapor-phase oxidation to be effected by passing a gaseous mixture of raw materials to a fixed bed of catalyst in which the void ratio of the catalyst layers increases by stages in one step or more from upstream downward in the flow of the gaseous mixture of raw materials. For example, the process can oxidize in vapor phase such hydrocarbons as naphthalene, xylene, benzene, toluene, durene, butene, acenaphthene, anthracene, indene and their derivatives in high yields with high productivity. Moreover, the process can prepare phthalic anhydride in high yields with high productivity by the vapor-phase oxidation of naphthalene or ortho-xylene.
摘要:
A process for preparing phthalic anhydride by gas-phase oxidation of xylene, naphthalene or mixtures thereof over two different fixed-bed catalysts arranged in zones in a shell-and-tube reactor which is thermostated by means of a heat transfer medium is carried out so that the maximum temperature in the second catalyst zone in the flow direction is at least 52° C. lower than the maximum temperature in the first catalyst zone. The process of the present invention makes it possible to prepare phthalic anhydride in high yields under conditions relevant to industrial practice.
摘要:
Oxydiphthalic anhydrides such as 4-oxydiphthalic anhydride are prepared by the reaction of a halophthalic anhydride with an alkali metal carbonate such as potassium carbonate in the presence of a catalyst system comprising an alkali metal bicarbonate such as potassium bicarbonate and a phase transfer catalyst, preferably a tetraarylphosphonium halide.
摘要:
A process to isolate dianhydride from an exchange reaction comprises extracting a bisimide/anhydride exchange reaction aqueous phase with an organic solution comprising an exchange catalyst at a first temperature and pressure to form an extracted aqueous phase comprising water, exchange catalyst and a dianhydride precursor; removing water from the extracted aqueous phase at a second temperature and pressure to form a molten phase, wherein the second pressure is less than the first pressure; removing water and exchange catalyst from the molten phase at a third temperature and pressure to form an isolation mixture; and converting the dianhydride precursor in the isolation mixture to dianhydride at a fourth temperature and pressure, wherein the fourth temperature is greater than the second and third temperatures and the fourth pressure is less than the second and third pressures.