The invention relates to a method for producing isocyanates by reacting the corresponding amines with phosgene in the gas phase, optionally in the presence of at least one inert medium. Said phosgene is guided into a reactor (21) through a first inlet and the amine is guided through a second inlet of an ejector (1). The first inlet and the second inlet join in a mixing area (17) in which the phosgene and the amine are mixed to form a reaction mixture. A diffuser (19) that is joined to the mixing area (17) increases the pressure and the temperature of the reaction mixture consisting of phosgene and amine.

Method for producing isocyanates

Process for preparing isocyanates by phosgenation of amines, wherein phosgene and amine are brought into contact in at least 2 mixing chambers connected in parallel.

Process for preparing isocyanates

The invention relates to a method for producing isocyanates by reacting primary amines with phosgene in the gaseous phase. Said method is characterized in that the reaction of amine and phosgene occurs in a reaction channel, the internal dimensions of which have a width/height ratio of at least 2/1.

Production of isocyanates in the gaseous phase

Preparing meta-toluene diisocyanate comprises reacting meta-toluenediamine with phosgene in the gas phase, where: the meta-toluenediamine and phosgene are separately added into a reactor, and a gaseous meta-toluenediamine is produced by evaporation in an evaporator; in the evaporator, the liquid meta-toluenediamine contains less than 0.5 wt.% of toluene diamine residues, less than 0.2 wt.% of ammonia and cycloaliphatic amines, and less than 20 ppm of heavy metals; and the meta-toluenediamine is partially evaporated in the evaporator, and 0.1 wt.% of meta-toluenediamine is not evaporated. Preparing m-toluene diisocyanate comprises reacting meta-toluene diamine with phosgene in the gas phase, where: the meta-toluenediamine and phosgene are separately added into a reactor, and a gaseous meta-toluene diamine is produced by evaporation in an evaporator; in the evaporator, the liquid meta-toluenediamine contains less than 0.5 wt.% of toluene diamine residues, less than 0.2 wt.% of ammonia and cycloaliphatic amines, and less than 20 ppm of heavy metals; the ratio between the quantity of liquid (kg) present in the evaporator and the gas stream (kg/h) leaving the evaporator is less than 2 hours; the meta-toluenediamine is partially evaporated in the evaporator, and at least 0.1 wt.% of meta-toluene diamine is not evaporated; the unevaporated amount of meta-toluenediamine is not added into the reactor; and the meta-toluenediamine is thermally treated at at least 100[deg] C for at least 15 minutes, before adding into the evaporator and then the resulting ammonia is separated.

Method for manufacturing isocyanates in the gaseous phase

The invention relates to a process for the production of uretdione polyisocyanates with improved storage stability and their use as a starting component for polyurethane plastics, in particular as a crosslinker component for the production of two-component polyurethane coating compositions.

Process for the preparation of uretdione polyisocyanates with improved monomer stability

Prepn. of aromatic cpds. substd. by at least two isocyanate gps., where at least one cpd. (A) (comprising at least two prim. amine functions and at least one aromatic residue) is contacted with phosgene - in the vapour phase, using a 0-100% (pref. 5-60) excess of phosgene relative to the number of moles of functional amine gps.. Pref. the cpd. (A) comprises at least two amine functions and at least one 6-14C (more pref. 6-10C) aromatic residue opt. substd. by one or more hydrocarbyl radicals chosen from 1-10C (more pref. 1-6C) alkyl, aryl, alkyl-aryl or aryl-alkyl. The cpd. corresps. to the formula H2N-R-NH2 (I); where R = aromatic gp. (opt. substd.) as described above. More specifically, A is chosen from toluene diamine, xylylene-diamine and phenylene-diamine (singly or mixed) with or without isomers.

Process for the preparation of aromatic polyisocyanate compounds in gas phase

The invention concerns a method for preparing a (poly)isocyanate composition with reduced viscosity comprising at least a dimeric isocyanate with uretidine-dione unit from initial monomeric isocyanates, characterised in that the initial reaction medium is heated, in the absence of a dimerization catalyst, to a temperature of not less than 50 °C and not more than 200 °C for a duration of not more than 24 hours.

Method for preparing (poly)isocyanate composition with reduced viscosity

A process for extraction of ferulic acid present in an aqueous phase, obtained by treatment of at least one plant material, and also containing polysaccharides, is described, said process comprising at least the following steps: 1) the treatment of said plant material followed by a solid/liquid separation to recover a solid phase and an aqueous liquid phase comprising the ferulic acid and said polysaccharides, 2) the treatment of said liquid phase to selectively separate, on the one hand, the polysaccharides and, on the other hand, the ferulic acid present in an aqueous fraction, 3) the concentration of said aqueous fraction containing the ferulic acid so as to recover a ferulic acid-concentrated stream, 4) the recovery of the ferulic acid in solid form.

Optimized process for extraction of ferulic acid with pretreatment

A low viscosity polyisocyanate composition containing at least one isocyanate dimer having a uretidinedione unit is prepared from a reaction medium containing at least one isocyanate monomer in which the isocyanate groups are borne by sp 3 carbon atoms. The reaction medium is heated, in the absence of a dimerization catalyst, to a temperature of at least 50° C. and not more than 200° C. for a period of not more than 24 hours.

Method for the preparation of low-viscosity (poly) isocyanates

The invention relates to a method for the purification of natural vanillin, comprising at least one step in which the natural vanillin is evaporated.

Denis Revelant

Papers

Process for the preparation of aromatic polyisocyanate compounds in gas phase

Method for preparing (poly)isocyanate composition with reduced viscosity

Optimized process for extraction of ferulic acid with pretreatment

Method for the preparation of low-viscosity (poly) isocyanates

Method for the purification of natural vanillin