Methylene diphenyl diisocyanate (MDI) is used to make polyurethane consumer products such as sealants, adhesives, and foams. When MDI is cured with methanol, the construction of methylene diphenyl dicarbamate (MDC) occurs. Residual MDI can be present in consumer products. This is a concern due to the possible toxicity MDI could have to humans. Usually the commercial synthesis of MDI results in a mixture of three different isomers (2,2’ MDI, 2,4’ MDI, and 4,4’ MDI). Of these three isomers 2,2’ MDI is produced in the smallest amount ,&lt; 5%. Here a direct route for the synthesis of 2, 2’ MDC is reported. MDC was synthesized in three steps. First a Suzuki reaction between 2-nitrobenzyl bromide and 2-nitrophenyl boronic acid was completed to install a methylene linkage. This dinitrated product was then hydrogenated to produce 2,2’ methylene diphenyl aniline (MDA). The diamine was then converted to a carbamate upon addition of methyl chloroformate. A deuterated version of 2, 2’ MDC was also synthesized using this three step route. Both deuterated and nondeuterated 2, 2’ MDC standards were used to develop methods for quantifying amounts of residual MDI/MDC in consumer products.

Synthesis of a deuterated isotopically labeled 2,2' MDI derivative

2019 Spring National Meeting

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