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US 5,315,034 AGranted
Procedure for the preparation of alkyl isocyanates
AssigneeEnichem Synthesis S.p.A.
InventorsFranco Mizia, Franco Rivetti, Ugo Romano
Life of this patent
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Abstract
Multistep process for the preparation of alkyl mono and diisocyanates consisting in reacting the corresponding aliphatic amine or diamine with dimethylcarbonate and, substantially, in partially vaporizing and converting the urethane thus formed in an evaporator to subsequently terminate the cracking in a II.degree. reactor, and finally subjecting the cracking product to fractional distillation at reduced pressure, recycling the unconverted part to the partial vaporization step.
Claims16
Procedure for the preparation of alkyl mono and diisocyanates having the formula:
- R--[NCO].sub.x
- wherein x represents an integer selected from 1 or 2, and R represents an alkyl radical with a number of carbon atoms of up to ten, either linear or branched, simple or having substituents selected from alkoxy groups, halogens or cycloalkyl radicals;
- or a cycloalkyl radical with a number of carbon atoms of between 5 and 7, again either simple or having substituents selected from those specified above, which includes the following operations:
- a) reaction of an amine having the formula
- R--[NH.sub.2 ].sub.x
- with dimethylcarbonate in the presence of a basic catalyst
- b) neutralization of the basic catalyst;
- c) removal of the alcohol formed and any excess of dimethylcarbonate;
- d) vaporization with partial cracking of the urethane obtained in step a);
- e) exhaustive cracking of the urethane obtained in step d);
- f) fractional distillation at reduced pressure of the cracking product obtained in step e).
8 more elements
Dependencies are inferred from the claim text.