摘要:
A process for the production of mixtures of diphenylmethane diisocyanates and polyphenyl polymethylene polyisocyanates comprising the steps ofA. reacting aniline and an O-alkyl carbamate to form N-phenylurethanes;B. isolating the N-phenylurethanes;C. condensing, in the presence of an acid, the N-phenylurethanes with formaldehyde or bifunctional compounds having the formulaX--CH.sub.2 --X in which X stands for a RO--, RS-- or ROCO radical and R denotes an alkyl radical, to form mixtures of methylene bis(phenylurethanes) and polymethylene polyphenylurethanes;D. cleaving the mixtures of methylene bis(phenylurethanes) and polymethylene polyphenylurethanes at temperatures of 175.degree. C. to 600.degree. C.; andE. isolating the mixtures of diphenylmethane diisocyanates and polyphenyl polymethylene polyisocyanate resulting from step D.
摘要:
Organic isocyanates, preferably alkyl, mono-, di- and/or polyisocyanates or aryl-mono-, di- and/or polyisocyanates, are prepared by thermally cleaving the corresponding urethanes at temperatures of 175.degree. C. to 600.degree. C. in the presence of carbon, preferably in an agitated carbon bed or in a fluidized bed containing carbon.
摘要:
Hexamethylene 1,6-diisocyanate and/or isomeric aliphatic diisocyanates where alkylene is of 6 carbon atoms, preferably 2-methylpentamethylene 1,5-diisocyanate and/or 2-ethyltetramethylene 1,4-diisocyanate, are prepared by a process wherein the corresponding dialkylurethanes are vaporized, without decomposition, at from 220.degree. to 300.degree. C., advantageously under reduced pressure, the dialkylurethane vapors are subjected to thermal cleavage under reduced pressure, preferably from 0.1 to 200 mbar, and at above 300.degree. C., preferably from 310.degree. to 480.degree. C. The cleavage products are fractionally condensed with the product obtained in the first condensation stage consisting predominantly of the diisocyanates, while that obtained in the second condensation stage is the alcohol.
摘要:
N- and O-substituted carbamates are prepared by reacting urea with an aminopropanol at 140.degree. C. or above. The compounds obtained by the novel process are useful starting materials for the preparation of textile finishing agents, stabilizers, plasticizers, dyes and crop protection agents.
摘要:
A process for the preparation of an aryl mono-, di-, and/or polyurethane comprising the steps of A. reacting a primary aromatic mono-, di-, and/or polyamine with an O-alkyl carbamate in the presence of an alcohol at temperatures greater than 160.degree. C., andB. separating the ammonia and other by-products from the aryl mono-, di-, and/or polyurethane.The reaction is preferably carried out in the presence of urea. The aryl mono-, di-, and/or polyurethanes produced are valuable end and intermediate products. They can be transferred into the corresponding isocyanates which can then be used for the preparation of polyurethanes.
摘要:
Carbonates are prepared by reacting carbamic acid esters with alcohols at above 140.degree. C., the ammonia formed being stripped from the reaction mixture during the reaction by passing an inert gas or vapor therethrough.The carbonates obtainable by the process of the invention are valuable starting materials for the preparation of dyes, crop protection agents and plastics.
摘要:
The invention describes a process for the preparation of N,o-substituted mono- and/or polyurethanes of formulaR.sup.1 [--NHCOOR.sup.2 ].sub.n,in whichR.sup.1 is an aliphatic, cycloaliphatic, aromatic, araliphatic, or heterocyclic radical, which may be substituted,R.sup.2 is an aliphatic, cycloaliphatic, or araliphatic radical which may be substituted with alkoxy or polyoxyalkylene groups, andn is a whole number from 1 to 5,through the reaction of N-substituted allophanates and/or polyallophanates with alcohols R.sup.2 OH in the presence or absence of catalysts at temperatures of at least 160.degree. C., preferably from 165.degree. to 250.degree. C.
摘要:
This invention discloses a non-phosgene process for the preparation of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate by the reaction of the precursor diamine with urea and an aliphatic alcohol in the presence of a dialkyl carbonate and an alkyl carbonate. The intermediate diurethane is separated from starting materials and by-products and thermally cleaved to alcohol and diisocyanate which are separated by fractional condensation of the products from the vapor state. This process gives high yields of the desired diisocyanate and lends itself particularly to continuous processing.
摘要:
A process for the pyrolysis of mono-, di-, and polyurethanes to the corresponding mono-, di-, and polyisocyanates wherein the urethane to be cleaved is heated under pressure and sprayed through a nozzle into a pyrolysis chamber maintained at reduced pressure. The isocyanate and alcohol cleavage products are separated by fractional condensation.
摘要:
This invention pertains to a process for the preparation of an aromatic di- and/or polyisocyanate comprising the steps ofA. preparing an aromatic di- and/or polyurethane by1. reacting a primary aromatic di- and/or polyamine with an O-alkyl carbamate at temperatures greater than 100.degree. C.;2. separating the ammonia and other by-products from the aromatic di- and/or polyurethane;B. heating and the aromatic di- and/or polyurethane at temperatures of from 175.degree. C. to 600.degree. C.; andC. isolating the di- and/or polyisocyanate resulting from step B.