Direct synthesis of poly(p-phenyleneethynylene)s from calcium carbide

Abstract

An efficient method for the preparation of poly(p-phenyleneethynylene)s (PPEs) from direct coupling reactions between aryl diiodides and inexpensive chemical feedstock calcium carbide is developed.

Calcium Carbide: A Unique Reagent for Organic Synthesis and Nanotechnology

“…It is important to mention examples in which calcium carbide was directly used as an acetylene source to synthesize symmetric diaryl ethynes (Scheme A, B) . As expected, the involvement of para ‐diiodobenzenes in a similar reaction (Scheme C) gave rise to polymerization products …”

“…[45] As expected, the involvement of para-diiodobenzenes in as imilarr eaction (Scheme 10 C) gave rise to polymerization products. [46] Bis-trialkyl-or bis-triarylstannylacetylenes are also promising synthons that can be produced from the ultrasound-promoted reaction of calcium carbidea nd an appropriate bis-trialkyl-or bis-triarylstannyl halide. [47] The synthesis of mononuclear triazoles is another important field of acetylene chemistry,b ecause only al imited numbero f methodsf or the preparation of these structures are known.…”

An Atom‐Economic Approach for Vinylation of Indoles and Phenols Using Calcium Carbide as Acetylene Surrogate

“…This may be attributed to calcium carbide deactivation via hydrolysis enabled by atmospheric moisture; the product, calcium hydroxide, coats the calcium carbide presumably limiting its availability for reaction. A lower yield of N-vinyl indole was obtained when dried DMSO was used in place of the undried DMSO ( With the optimized reaction conditions now in hand, we next expanded the scope of this transformation by subjecting a variety of indole derivatives (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) to the reaction under the optimized conditions ( Table 2). Representative results are reported in Table 2.…”

“…Key features of this reaction include the use of calcium carbide as a safe and inexpensive slow released acetylene source for N-and O-vinylation under simple reaction conditions without the need for metal catalyst or halogenated substrates. ene) species (PPEs), [6] polyenynes, [7] propargylamine, [8] enaminones, [9] and acetylenic alcohols. [10] Recently, calcium carbide was used as an electrophilic precursor in a vinylation reaction to produce vinylic derivatives such as O-vinyloximes, which could further cyclize into 2-arylpyrroles.…”

Synthesis of highly pure poly(aryleneethnylene)s using palladium supported on calcium carbonate as an eco‐friendly heterogeneous catalyst

“…Typically, PAEs are prepared by polycondensation between aryl halide and alkyne through Sonogashira coupling reaction involving the construction of a CC bond via Pd/Cu catalyzed sp 2 –sp coupling reaction (Scheme ) . Homogeneous Pd catalysts such as PdCl 2 (PPh 3 ) 2 and Pd(PPh 3 ) 4 are typically employed for the polymerization.…”