Method for converting monoisocyanates to ureas

Patent metadata

Field	Value
Publication number	US-12091377-B2
Application number	US-201917295120-A
Country	US
Kind code	B2
Filing date	Oct 31, 2019
Priority date	Dec 7, 2018
Publication date	Sep 17, 2024
Grant date	Sep 17, 2024

Abstract

Organic isocyanates are converted to ureas by heating in the presence of certain cobalt, magnesium, chromium and lanthanide series organometallic catalysts. The process requires no water or other reactants. The process is particularly useful for removing small quantities of monoisocyanates from a solvent stream recovered from a polyisocyanate manufacturing process. The urea compounds in some instances can be recycled back into the polyisocyanate manufacturing process and reacted with polyisocyanate compounds to form biurets.

First claim

What is claimed is:

1. A method for converting an organic isocyanate comprising one or more isocyanates, wherein at least one of the one or more isocyanates is a substituted or unsubstituted phenyl isocyanate, to one or more urea compounds in the presence of a non-polar organic solvent, comprising reacting a solution of the organic isocyanate in a liquid nonpolar organic solvent in the presence of at least 0.025 wt.-% of a organometallic catalyst, based on the weight of the organic isocyanate, wherein the organometallic catalyst is selected from the group consisting of bis(cyclopentadienyl) Cr(II), bis(methylcyclopentadienyl) Cr(II) and compounds having at least one metal ion bonded to at least one organic ligand and the metal ion is selected from one or more of Co(II), Mg(II), Y(III), Cr(III) and a lanthanide series metal ion in the 3+ oxidation state, to convert at least a portion of the organic isocyanate to the one or more urea compounds.

2. The method of claim 1 wherein the metal ion is Co(II) or Mg(II).

3. The method of claim 2 wherein at least one organic ligand is an arene ligand.

4. The method of claim 3 wherein the arene ligand is cyclopentadienyl or methylcyclopentadienyl.

5. The method of claim 1 wherein the organometallic catalyst is one or more of bis(cyclopentadienyl) Co(II), bis(cyclopentadienyl) Mg(II), bis(cyclopentadienyl) Cr(II), tris(cyclopentadienyl) Gd(III), tris(cyclopentadienyl) Y(III), tris(cyclopentadienyl) La(III), bis(methylcyclopentadienyl) Co (II), bis(methylcyclopentadienyl) Mg(II), bis(methylcyclopentadienyl) Cr(II), tris (methylcyclopentadienyl) Gd(III), tris(methylcyclopentadienyl) Y(III), tris(methylcyclopentadienyl) La(III), a tris(cyclopentadienyl) lanthanide series metal and a tris(methylcyclopentadienyl) lanthanide series metal.

6. The method of claim 2 wherein at least one organic ligand is a β-diketone.

7. The method of claim 6 wherein the organometallic catalyst is one or more of Co(II) acetylacetonate and bis(2,4-pentanedionato) Mg(II).

8. The method of claim 1 wherein the organic isocyanate includes unsubstituted phenyl isocyanate.

9. The method of claim 1 further comprising a step of producing a process stream in an isocyanate manufacturing process by separating a process solvent from a polyisocyanate product produced in a step of reacting a polyamine with phosgene in solution in the process solvent, and the solution of the organic isocyanate in a liquid nonpolar organic solvent is or includes the process stream.

10. The method of claim 9 wherein the polyamine is MDA and/or PMDA.

11. The method of claim 10 further comprising a step of recycling at least a portion of the one or more urea compounds into the isocyanate manufacturing process and reacting the recycled one or more urea compounds with a polyisocyanate to form one or more biuret compounds.

12. The method of claim 11 further comprising reacting the recycled one or more urea compounds with a polyisocyanate to form one or more biuret compounds during the step of separating the polyisocyanate produce from the process solvent.

13. The method of claim 1 further comprising the step of separating at least a portion of the one or more nonpolar organic solvents from the one or more urea compounds.

14. An MDI and/or polymeric MDI manufacturing process, comprising the steps of:
a) reacting aniline with formaldehyde to produce a mixture of methylene dianiline (MDA), one or more polymethylene polyanilines having at least three aniline groups (PMDA) and unreacted aniline in a solvent;
b) distilling aniline from the mixture produced in step a) to produce a process stream containing the MDA, PMDA and residual aniline;
c) phosgenating the process stream from step b) in a non-polar solvent to form an isocyanate process stream containing the non-polar solvent, MDI, one or more polymethylene polyphenylisocyanates that have at least three phenyl isocyanate groups (PMDI) and phenyl isocyanate;
d) separating MDI and PMDI from the isocyanate process stream obtained in step c) by distillation to produce a solvent stream containing the non-polar solvent, 0.2 to 10 weight percent phenyl isocyanate based on the weight of the solvent stream and up to 5 weight percent, based on the weight of the solvent stream, of MDI and/or PMDI;
e) reacting the solvent stream obtained in step d) in the presence of at least 0.025 wt.-% of an organometallic catalyst, based on the weight of the phenyl isocyanate, wherein the organometallic catalyst is selected from the group consisting of bis(cyclopentadienyl) Cr(II), bis(methylcyclopentadienyl) Cr(II) and compounds having at least one metal ion bonded to at least one organic ligand and the metal ion is selected from one or more of Co(II), Mg(II), Y(III), Cr(III) and a lanthanide series metal ion in the 3+ oxidation state, to convert at least a portion of the phenyl isocyanate to 1,3-diphenylurea and optionally aniline, and optionally to thermally deactivate the organometallic catalyst; and
f) recycling 1,3-diphenylurea and optionally non-polar solvent and optionally residues from the thermal deactivation of the catalyst, from step e) directly or indirectly into step d), whereby at least a portion of the 1,3-diphenylurea reacts with at least a portion of the MDI and/or PMDI to form biuret compounds.

Assignees

• Dow Global Technologies Llc
• Dow Portugal Produtos Quimicos Soc Unipessoal Lda

Inventors

• Hefner Jr Robert E
• Braun Helge
• Costa Armenio
• Cramm Brian

Classifications

• C07C273/1809

  with formation of the N-C(O)-N moiety · CPC title

• C07C273/1872 Primary

  Preparation of compounds comprising a -N-C(O)-N-C(O)-N- moiety · CPC title

• B01J2531/845

  Cobalt · CPC title

• B01J2531/22

  Magnesium · CPC title

• B01J31/2295

  Cyclic compounds, e.g. cyclopentadienyls · CPC title