Process for the production of monoisocyanate
AssigneeBayer Aktiengesellschaft
InventorsHartmut Knofel, Klaus Konig
Life of this patent
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Abstract
This invention relates to an improved process for the production of aliphatic relatively low boiling monoisocyanates from the corresponding carbamic acid chlorides, comprising adding an at least equivalent quantity, based on the hydrogen chloride bound in the carbamic acid chloride, of a relatively high boiling organic monoisocyanate or polyisocyanate whose boiling point is higher than the boiling point of the relatively low boiling monoisocyanate to be produced, to the carbamic acid chloride, optionally dissolved in inert organic solvents and then distilling off the relatively low boiling monoisocyanate by heating and/or applying a vacuum, or by means of an inert gas stream.
Claims11
A process for the preparation of relatively low boiling monoisocyanates of the formula:
- R--NCO
- from the corresponding carbamic acid chlorides corresponding to the following general formula:
- R--NH--COCl
- in which R represents an aliphatic hydrocarbon radical having from 1 to 5 carbon atoms;
- comprising adding an at least equivalent quantity, based on the hydrogen chloride bound in the carbamic acid chloride, of relatively high boiling organic monoisocyanate or polyisocyanate whose boiling point is higher than the boiling point of the relatively low boiling monoisocyanate to be produced, to the carbamic acid chlorides, optionally dissolved in inert organic solvents, and distilling off the relatively low boiling monoisocyanate from the thus-obtained mixture, optionally together with the solvent.
A process for the preparation of alkyl isocyanates of the formula:
- R--NCO
- by dehydrochlorinating the corresponding carbamic acid chlorides of the formula:
- R--NH--COCl
- wherein R is alkyl of 1 to 5 carbon atoms;
- comprising reacting the carbamic acid chlorides with a high-boiling organic monoisocyanate or diisocyanate whose boiling point is higher than the boiling point of the alkyl isocyanate to be produced and above the decomposition point of its corresponding carbamic acid chloride, and removing the resulting alkyl isocyanate from the reaction mixture.
Dependencies are inferred from the claim text.