Acetylenes dithiophene

The roots of Arctium lappa (edible burdock, Gobo), which are used for food in Japan, are especially rich in both aliphatic acetylenes and acetylenic dithiophenes (Figure 5.6 and Table 5.1). Most of the aliphatic acetylenes isolated from A. lappa (17, 23-28, 35-38) are widely distributed in Asteraceae, whereas the dithiophenes (58-69) isolated from this species are not very common as only a few have been isolated from other plant species... 

Fraction 4 (P.E./CHjClj, 1 1) was a bright red solution the T1 NMR spectrum of which indicated a mixture of two acetylenic constituents (A and B) which were separated by preparative TLC on 1 mm silica gel plates. The red band (A), when left in soln for 15 hr at r.t., lost its color. The Tl NMR spectrum of the decolored soln was identical with the spectrum of compound B. Comparison of the physical data (1H NMR and MS) of the two compounds with the spectral data reported for the dithiophene (A) (10) and the thiophene (B)... 

Figure 28.3. Structural formulas of several electron-conducting polymers (a) frans-poly(acetylene), (b) cw-poly(acetylene), (c) poly(p-phenylene), (d) polyanUine (PAni), (e) poly(n-methylaniline) (PNMA), (f) polypyrrole (PPy), (g) polythiophene (PTh), (i) poly(3,4-ethylenedioxythiophene) (PEDOT), (j) poly(3-(4-fluorophenyl)thiophene) (PFPT), (k) poly(cyclopenta[2,l-b 3,4-dithiophen-4-one]) (PcDT), and (m) Mg polyporphine.

The detail preparation method is described elsewhere [71]. In brief, before adding quinone solution, the reaction mixmre of n-butyllithium and acetylene in THF solution was kept at 0 °C under argon atmosphere and stirred for a day until room temperature. The reaction mixmre was quenched by HCl and further stanous chloride dehydrate in acetic acid was added to obtained the product. The yield of obtained product 2, 6-dioctyl-4,8-bis(trimethylsilylethynyl)-benzo[l,2-b 4,5-b ] dithiophene as a white colour solid was 32 %. 

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