AbstractThe course of the Diels‐Alder reaction of N‐(2,4,6‐tri‐bromophenyl)maleimide (I) with 2‐methyl‐1,3‐butadiene (Ip) and of N‐(2,4,6‐trichlorophenyl)maleimide (II) with Ip, 2‐chloro‐1,3‐butadiene (Cp), and butadiene (Bt) in CHCl3was investigated. For the I‐Ip addition, the reaction order was determined with respect to both components, and the activation energy was calculated. The Diels‐Alder adducts thus obtained were characterized by elementary analysis, by1H‐ and13C‐NMR spectra, specific volume contractions, melting points, solubilities, and polymerization abilities. Copolymers of I and II with Ip, Cp, Bt, and 2‐methylpropene (Ib) were prepared, and their composition was determined. The copolymerization and Diels‐Alder addition of I‐Ip and II‐Ip occurring in parallel were investigated, and the participation of these two proces