Abstract:
The invention relates to a novel method for the nitration of organic compounds, preferably of aromatics and heteroaromatics, using known and novel types of nitration reagents.
Abstract:
The family of dyes of the invention are fluoresceins and rhodols that are directly substituted on one or more aromatic carbons by fluorine. These fluorine-substituted fluorescent dyes possess greater photostability and have lower sensitivity to pH changes in the physiological range of 6-8 than do non-fluorinated dyes, exhibit less quenching when conjugated to a substance, and possess additional advantages. The dyes of the invention are useful as detectable tracers and for preparing conjugates of organic and inorganic substances.
Abstract:
4, 6-Dinitroresorcinol is prepared by reacting resorcinol with concentrated nitric acid that is substantially free of suboxides of nitric acid. It has been found that greater than 60 percent yields of the desired product can be obtained when the concentration of aqueous nitric acid used is between 80 and 93 weight percent, and the concentration of suboxides is less than 2 weight percent based on the weight of nitric acid.
Abstract:
The invention relates to a new nitration system, comprising dinitrogen pentoxide dissolved in liquid sulphur dioxide. The invention also relates to a process for nitrating aromatic compounds, where the nitration agent used is dinitrogen pentoxide dissolved in sulphur dioxide. This process is particularly favourable for nitration of aromatics that are unstable under acidic conditions. Further, this process has given very good results when nitrating aromatics that hardly have been possible to nitrate by using known nitration systems reported in the literature.
Abstract:
Described herein is a continuous process for the production of dinitrotoluene characterized by the following steps: (a) reacting toluene with dilute nitric acid to produce a product mixture containing mononitrotoluene, water and unreacted nitric acid; (b) then separating the mononitrotoluene from the mixture; (c) then reacting the mononitrotoluene recovered from step (b) with concentrated nitric acid to produce a product mixture containing dinitrotoluene, water and unreacted nitric acid; (d) then separating a portion of the nitric acid from the mixture for recycle to step (c); (e) then adding water to the mixture of water, unreacted nitric acid and dinitrotoluene; (f) then separating the dinitrotoluene from the mixture by crystallization; (g) then recycling the remaining dilute nitric acid from step (f) to step (a).
Abstract:
High purity 4,6-dinitro-1,3-benzenediol is prepared by (a) contacting a 1,2,3-trihalobenzene with a nitrating agent and an acid under reaction conditions such that a 1,2,3-trihalo-4,6-dinitrobenzene is produced, (b) contacting the 1,2,3-trihalo-4,6-dinitrobenzene prepared in (a) with an alkanol and a base under reaction conditions such that a 4,6-dinitro-2-halo-1,3-benzenediol is produced, and (c) contacting the 4,6-dinitro-2-halo-1,3-benzenediol prepared in (b) with a hydrogenating agent in the presence of a solvent and a catalyst under reaction conditions such that a 4,6-diamino-1,3-benzenediol is produced. This 4,6-diamino-1,3-benzenediol is useful in the preparation of high molecular weight polybenzoxazoles.