28.
    发明专利
    未知

    公开(公告)号:BRPI0507293A

    公开(公告)日:2007-07-03

    申请号:BRPI0507293

    申请日:2005-02-02

    Applicant: BASF AG

    Abstract: The present invention provides a process for preparing dinitrotoluene, comprising the steps of a) reacting toluene with nitric acid in the presence of sulphuric acid to give mononitrotoluene, b) separating the reaction product from step a) into an organic phase comprising mononitrotoluene and an aqueous phase comprising sulfuric acid, c) reacting the organic phase comprising mononitrotoluene with nitric acid in the presence of sulphuric acid to give dinitrotoluene, d) separating the reaction product from step c) into an organic phase comprising dinitrotoluene and an aqueous phase comprising sulfuric acid, wherein the reaction product from step a) has a content of toluene of from 3.0 to 8% by weight, based on the organic phase, and a content of nitric acid of from 0.1 to 1.2% by weight, based on the aqueous phase, and the phase separation in step b) is effected in such a way that further reaction of the toluene with the nitric acid is prevented.

    30.
    发明专利
    未知

    公开(公告)号:AT335721T

    公开(公告)日:2006-09-15

    申请号:AT03785813

    申请日:2003-12-13

    Applicant: BASF AG

    Abstract: The invention relates to a process for preparing isocyanates by reaction of amines with phosgene in the presence of inert organic solvents in a reactor and subsequent work-up of the reaction mixture leaving the reactor, wherein the solvent is separated off in a two-stage or multistage, preferably two-stage, distillation process in which the solvent is separated off at a pressure of 0.1-15 bar in a first apparatus and at 1-900 mbar in a second apparatus or further apparatuses, with the heat of condensation of the solvent vapor from the first apparatus being used for partial or complete vaporization of solvent in the second apparatus.

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