Spontaneous reactions of 1-(2,2-dimethyl-1,3-dioxane-4,6-dione-5-ylidene)-4-(dicyanomethylene)-2,5-cyclohexadiene (QM 1) with p-methoxystyrene (MeOSt) were investigated in chloroform at room temperature at different monomer feed ratios. Reaction products obtained as hexane-insoluble and hexanesoluble fractions were characterized by elemental analysis and IR, 1 H NMR, and 13 C NMR spectroscopies. The hexane-insoluble products were to be copolymers of 7-(4-methoxyphenyl)-8,8-dicyanoquinodimethane (QM 2) with small amounts (3-6 mol %) of the QM 1, and the reaction product in the hexane-soluble fractions was to be the one-to-one adduct (Cycloadduct) of methylene Meldrum's acid (MM) with MeOSt. It was found that in the spontaneous reaction of the QM 1 with MeOSt a side reaction involving a metathesis process took place to form new two products, QM 2 and MM, and the former polymerized and the latter underwent the cycloaddition reaction with MeOSt. The formation of the Cycloadduct was also confirmed by a model reaction using 1-[(6-hydroxy-2,2-dimethyl-4-oxo-4H-1,3-dioxin-5-yl)-methyl]pyridinium hydroxide as a precursor of the MM and MeOSt. To identify the reactive intermediate, the spontaneous reactions of the QM 1 with MeOSt were carried out in the presence of 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) and methanol. No products trapped by TEMPO were obtained, but in the case of methanol the one-to-one-to-one adduct (Adduct) of the QM 1, MeOSt, and methanol was isolated. It was concluded, therefore, that the spontaneous reaction of the QM 1 with MeOSt might proceed via a zwitterionic tetramethylene intermediate.

The spontaneous reactions of 1‐(2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione‐5‐ylidene)‐4‐(dicyanomethylene)‐2,5‐cyclohexadiene (QM‐1) with a vinyl ether, butyl vinyl ether (BVE), and a cyclic ketene acetal, 2‐methylene‐1,3‐dioxepane (MDOP), were investigated. The reaction of QM‐1 with BVE produced a terpolymer composed of QM‐1, 7‐butoxy‐8,8‐dicyanoquinodimethane, and BVE units as a hexane‐insoluble product and a one‐to‐one adduct of methylene Meldrum's acid and BVE as a hexane‐soluble product. The spontaneous reaction of QM‐1 with BVE produced, in the presence of 2,2,6,6‐tetramethylpiperidine‐1‐oxy (TEMPO), a terpolymer carrying TEMPO units in the chain ends, and in the presence of methanol, a one‐to‐one‐to‐one adduct of QM‐1, BVE, and methanol was isolated. The spontaneous reaction with bulkier, electron‐donating MDOP produced a low‐molecular‐weight alternating cooligomer of QM‐1 with MDOP. The spontaneous polymerization was proposed to proceed via a zwitterionic intermediate taking two forms, gauche and trans, depending on the bulkiness of the comonomer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3800–3811, 2004