The present invention refers to a process for preparing amines comprising reacting a compound of the formula R.sup.1COR.sup.2 comprising a carbonyl moiety with a amine compound of the formula HNR.sup.3R.sup.4 and carbon monoxide in the presence of a catalyst.

Monoisocyanate impurities are removed from a process stream obtained when solvent is separated from a polyisocyanate product. The monoisocyanates are reacted with amine compounds at specific molar ratios to produce ureas. The ureas can be discarded by burning, landfilling or otherwise. Alternatively the ureas can be recycled back into the polyisocyanate manufacturing process, where they are formed into biuret compounds that can remain with the polyisocyanate product.

Monoisocyanate impurities are removed from a process stream obtained when solvent is separated from a polyisocyanate product. The monoisocyanates are reacted with amine compounds at specific molar ratios to produce ureas. The ureas can be discarded by burning, landfilling or otherwise. Alternatively the ureas can be recycled back into the polyisocyanate manufacturing process, where they are formed into biuret compounds that can remain with the polyisocyanate product.

The invention relates to a method for the preparation of di- and polyamines of the diphenylmethane series, care being taken during the shutdown of the production process that an excess of aniline and respect to formalin is ensured.

The invention relates to a method for the preparation of di- and polyamines of the diphenylmethane series, care being taken during the shutdown of the production process that an excess of aniline and respect to formalin is ensured.

The invention relates to a method for the preparation of di- and polyamines of the diphenylmethane series, care being taken during the shutdown of the production process that an excess of aniline and respect to formalin is ensured.

The invention relates to a method for the preparation of di- and polyamines of the diphenylmethane series (MDA) from aniline and formaldehyde, care being taken during the start up that a sufficient excess of aniline with respect to formaldehyde is ensured, said excess amounting to at least 105% of the desired molar ratio of aniline to formaldehyde for the target recipe of the MDA to be produced.

The invention relates to a method for the preparation of di- and polyamines of the diphenylmethane series (MDA) from aniline and formaldehyde, care being taken during the start up that a sufficient excess of aniline with respect to formaldehyde is ensured, said excess amounting to at least 105% of the desired molar ratio of aniline to formaldehyde for the target recipe of the MDA to be produced.

The invention relates to a method for the preparation of di- and polyamines of the diphenylmethane series (MDA) from aniline and formaldehyde, care being taken during the start up that a sufficient excess of aniline with respect to formaldehyde is ensured, said excess amounting to at least 105% of the desired molar ratio of aniline to formaldehyde for the target recipe of the MDA to be produced.

The present application provides solvent-free methods for decarboxylation of amino acids via imine formation with a ketone, enone, enal, aldehyde co-reagent or combination thereof, under heated conditions, with optional recovery of the co-reagent and/or co-reagent byproduct.