Sulfenate anions as organocatalysts for benzylic chloromethyl coupling polymerization via C=C bond formation

Abstract

Organocatalytic polymerization reactions have a number of advantages over their metal-catalyzed counterparts, including environmental friendliness, ease of catalyst synthesis and storage, and alternative reaction pathways. Here we introduce an organocatalytic polymerization method called benzylic chloromethyl-coupling polymerization (BCCP). BCCP is catalyzed by organocatalysts not previously employed in polymerization processes (sulfenate anions), which are generated from bench-stable sulfoxide precatalysts. The sulfenate anion promotes an umpolung polycondensation via step-growth propagation cycles involving sulfoxide intermediates. BCCP represents an example of an organocatalyst that links monomers by C=C double bond formation and offers transition metal-free access to a wide variety of polymers that cannot be synthesized by traditional precursor routes.

Cyclopentyl Methyl Ether: An Elective Ecofriendly Ethereal Solvent in Classical and Modern Organic Chemistry

“…Finally, the above‐described procedure has successfully been applied to the coupling polymerization of compounds bearing two chloromethyl substituents on the same or on different linked aromatic rings, as depicted in Scheme . Such a benzylic chloromethyl coupling polymerization links the monomers by C=C bond formation, always employing CPME (or MTBE) as the preferred solvent …”

Selenenate Anions (PhSeO−) as Organocatalyst: Synthesis of trans‐Stilbenes and a PPV Derivative

“…Previous work [26] from our laboratories demonstrated that sulfenate anions (ArSO À ) can catalyze polymerization of bis-benzylic chlorides yielding PPVs with high yields and low dispersity (Đ ), but required heating at 80°C. We expected selenenate anions could provide PPV derivatives under milder conditions.…”

“…We recently introduced the first sulfenate anion catalysts for the dehydrohalogen coupling of benzyl chlorides to make stilbenes [2] and the cross-coupling of benzyl chlorides with benzaldehydes under basic conditions to give diaryl acetylenes. [4] Recently, there has been significant interest and substantial progress in development of organocatalysts based on the heavier chalcogenide, selenium. This class of catalysts enabled the introduction of benzylic chloromethyl coupling polymerizations (BCCP), which is useful for the synthesis of poly(stilbenes).…”

“…The latter reaction represents the first catalytic method for the generation of all three bonds of the alkyne from precursors which do not contain triple bonds. This class of catalysts enabled the introduction of benzylic chloromethyl coupling polymerizations (BCCP), which is useful for the synthesis of poly(stilbenes) …”

Spiers Memorial Lecture : Carbon nanostructures by macromolecular design – from branched polyphenylenes to nanographenes and graphene nanoribbons

“…Cases can also be found, for example, in the synthesis of poly(phenylene vinylene)s or their nitrogen-incorporating analogues, where the coupling process directly furnishes double bonds. 135,136 The synthesis of GNRs is more complex, both conceptually and experimentally, since the growth of the polymer requires the formation of multiple bonds in sequential processes. Referring, again, to NG synthesis as a test case, one would have to first synthesize polyarylenes (e.g., with naphthalene or anthracene units) or polyphenylenes with additional oligophenylene side arms as precursor polymers.…”