A Diels-Alder reaction happens between 9-Anthracenemethanol (208.26 g/mol) and N-Methylmaleimide (111.10 g/mol).
I'm using 0.069 g 9-Anthracenemethanol (0.033 mol) and 0.11g N-Methylemaleimide (0.0009 mol, limiting reagent).
Since DA reactions have 100% atom economy, the product has the molar mass of both products combined, 319.36 g/mol.
Multiplying that by the moles of limiting reagent, we get 0.28 g product. However, the mass of both starting materials combined (0.069g + 0.110g) together is not even 0.28g. What am I doing wrong?