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EC number: 219-799-4
CAS number: 2536-05-2
Generally, diisocyanates are known to hydrolyze readily in water to yield a carbamic acid intermediate, which decarboxylates to produce CO2 and an amine; the latter immediately reacts with more diisocyanate to yield a di-substituted urea as primary reaction product [Ullmann’s Encyclopedia of Industrial Chemistry]. Because the MDI substances are di-isocyanates, a nearly improbable and simultaneous hydrolysis of both isocyanate groups is necessary to form the diamine (e.g., Methylenedianiline; MDA), a minor hydrolysis product. The kinetically- and probability-favored urea formation reactions of this nature result in formation of polyurea solids which have high molecular weight, and are insoluble and non-reactive in the environment. Furthermore, and to a much lesser degree, also Mono-ureas of MDI (both NCO- and Amino-ended) are formed. This reaction dominates the environmental fate of diisocyanates, and therefore also impacts the hazardous properties of these substances as tested in the laboratory, and as observed in the environment. Approximated amounts in which the hydrolysis products of the MDI category members are occurring are:
Mono-urea of MDI (both NCO- and Amino-ended); Methylenedianiline (MDA)
Details on the behavior of the substances of the methylenediphenyl diisocyanate (MDI) category in the aquatic environment are described in the Category Justification Document included in Section 13. Consequently, separate PBT assessments are provided for the following, relevant hydrolysis products:
2. Mono-ureas of MDI (both NCO- and Amino-ended)
3. Methylenedianiline (MDA)
No such assessment is performed for CO2, which is a naturally occurring gas. A PBT assessment is not required for those type of substances under Regulation (EC) No 1907/2006 (REACH).
As demonstrated by the individual assessments of the hydrolysis products of the MDI category provided in the subsections under the PBT section, none of these reaction products is considered a PBT / vPvB substance. Therefore, also the substances of the MDI category are not PBT / vPvB.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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