M-Diethynylbenzene

Oxidative coupling of diacetylenes yields another unusual class of polymers. From m-diethynylbenzene, for example, is obtained a high-molecular weight polymer that can be cast into a tough, flexible film. 

The novel [6.6]metacyclophane 40 was prepared by coupling 31 with 1-alkynes as a key reaction. The shortest way to 40 is the coupling of m-diethynylbenzene (41)... 

Treatment of m-diethynylbenzene with a copper catalyst and dioxygen gave a poly(phenylene butadismylene) (315). Use of Cu-incorporated mesoporous materials as the oxidative polymerization catalyst for l,4-dieth5mylbenzene produced highly conjugated poly(l,4-phenylene-l,4-butadi5mylene) (316). 

This poljunerization can be applied to a wide range of condensations between diethynyldiphenylsilane and aromatic halides including p3rridine and thiophene derivatives (13) (84). It was reported that dehydrogenative coupling of phenylsi-lane with m-diethynylbenzene in the presence of MgO to provide poly(silylene-m-diethynylenephenylene) (14) (eq. 14) (85,86). 

Oxydi-p-phenylene)bis 2,4,5-triphenylcyclopentadienone) polymers with m-diethynylbenzene, 116 with p-diethynyl benzene, 105... 

Ando and co-workers have reported the synthesis of a silyl-carborane hybrid diethynylbenzene-silylene polymer (108) (Fig. 66) possessing high thermal stability.136 The polymer contained Si and —C=C— group in the main chain and m-carborane and vinyl groups in the side chain. The 5% weight-loss temperature of the cured polymer in air was over 1000°C as determined by thermogravimetric analysis. 

Well-controlled polymerization of substituted acetylenes was also reported. A tetracoordinate organorhodium complex induces the stereospecific living polymerization of phenylacetylene.600 The polymerization proceeds via a 2-1 -insertion mechanism to provide stereoregular poly(phenylacetylene) with m-transoidal backbone structure. Rh complexes were also used in the same process in supercritical C02601 and in the polymerization of terminal alkyl- and arylacetylenes.602 Single-component transition-metal catalysts based on Ni acetylides603 and Pd acet-ylides604 were used in the polymerization of p-diethynylbenzene. 

The polymerization reactions of bistetracyclone monomers XXIa-e with both m- and p-diethynylbenzene (XVII and XVIII) produced a series of polymers (XXII, Reaction 15) containing short blocks of phenylene units connected by methylene chains. High molecular weight polymers were obtained (Table II), and a range of physical properties was observed. 

The Diels-Alder reaction has been used to form many polymeric materials. One such material, for instance, forms from a reaction of diethynylbenzene with cyclopentadienone [194—196]. The products, phenylated polyphenylenes, reach molecular weights of M up to 40,000 ... 

Lin, V. S. Y. Radu, D. R. Han, M.-K. Deng, W. Kuroki, S. Shanks, B. H. Pruski, M., Oxidative polymerization of 1,4-diethynylbenzene into highly conjugated poly(phenylene butadiynylene) within the channels of surface-functionahzed mesoporous sihca and alumina materials. Journal of the American Chemical Society 124, (31), 9040-9041, 2002. 

Sonogashira reactions involving 1,4-diethynylbenzene (PSN-1) and 4,4 diethynylbiphenyl (PSN-2) give rise to BET surface areas of 846 m g and 1042 respectively.Alkyne-coupled polyhedral oligomeric silses-... 

The utilization of pendant groups to promote solubility in common organic solvents was first demonstrated with the aromatic polyphenylenes. Polymers prepared by the oxidation of benzene or dehydrogenation of polycyclohexadiene are crystalline materials and insoluble. Phenylated polyphenylenes obtained from the Diels-Alder polymerization of bistetracyclones with m- or p- diethynylbenzene are amorphous materials and are soluble in toluene. The pendant phenyl groups serve to decrease crystallinity and promote solubility. 

Ichitani, M. Yonezawa, K. Okada, K. Sugimoto, T. 1999. Silyl-carborane hybridized diethynylbenzene-si-lylene polymers. Polym. 7., 31 908—12. 

The effect on the Bergman cycloaromatization of sulfur-containing substituents in the acetylene branch was studied for simple models, such as butyl-2-(triisopropylsilylethynyl)phenylethynylsulfide 3.922 (Scheme 3.133) [411]. The starting sulfide 3.922 was synthesized by treatment of the mono-trisopropylsilyl-protected orf o-diethynylbenzene 3.921 with butyllithium excess followed by the addition of sulfur dichloride [411]. Cyclization of compound 3.922 (benzene, 200°C, 6 M of 1,4-cyclohexadiene) gave butyl-2-naphthylsulfide 3.923 in 53% yield. Comparison of the parameters of this reaction with the cyclization of ortho-diethynylbenzene showed that the presence of the sulfur atom increases the cyclization barrier although the yield from compound 3.922 is much less than that from ort/ o-diethynylbenzene. These studies are consistent... 

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