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US 10,294,198 B2Granted
Method for producing xylylene diisocyanates in the gaseous phase
AssigneeCovestro Deutschland AG
InventorsReinhard Halpaap, Ralph Weber, Josef Sanders, Frank Richter, Elsa Karoline Schadlich, Armin Schymura, Martin Ehrig, Sebastian Hoch, Robert Maleika
Life of this patent
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Abstract
The invention relates to a method for producing the isomers 1,3- and/or 1,4-xylylene diisocyanates by reacting the corresponding 1,3- and/or 1,4-xylylene diamines with phosgene in the gaseous phase.
Claims12
A method for producing 1,3- and/or 1,4-xylylene diisocyanate (XDI) by phosgenation of 1,3- and/or 1,4-xylylenediamine (XDA) with phosgene in the gas phase in a reactor connected to a vaporizer circuit, the method comprising:
- vaporizing xylylenediamine/xylylenediamines in a vaporizer in the vaporizer circuit, optionally with addition of stabilizers and/or an inert gas, at a pressure of <1000 mbar, with a mean residence time in the vaporizer circuit of 5 to 90 minutes and at a temperature in a pumping circuit connected to the vaporizer circuit of 40 to 190° C., wherein the temperature is maintained by cooling in a first heat exchanger in the pumping circuit,
- heating XDA vapors a further 10-100° K. above the vaporization temperature of the XDA at prevailing pressure in a second heat exchanger in the pumping circuit, and
- reacting the vapors from the second heat exchanger connected to the reactor with phosgene by gas-phase phosgenation in the reactor.
Dependencies are inferred from the claim text.