Solid 1,3-butadiynes

The acetone is removed by evaporation with a rotary evaporator, and the residue is dissolved in petroleum ether (bp 30-40°C, 150 mL) (Note 9) and shaken in a separatory funnel with 3 M aqueous hydrochloric acid (150 mL). The phases are separated and the aqueous phase is washed with petroleum ether (bp 30-40°C, 3 x 150 mL). The combined organic layers are washed with saturated aqueous sodium chloride (50 mL), dried (NagSO ), and evaporated to dryness with a rotary evaporator. The solid residue is dissolved in hot methanol (400 mL) to which has been added 3 M aqueous hydrochloric acid (4 mL). The solution may be filtered at "this stage if it is necessary to remove colored Insoluble Impurities. Water is then added dropwise until recrystallized material is permanently present. The solution is allowed to cool, finally in ice, and crystalline bis(trimethylsilyl)butadiyne (BTMSBD) is collected. The material is washed with a small portion of ice-cold methanol-water (50 50 v/v 50 mL), and dried in the air to give bis(trimethylsilyl)-butadiyne (31-35 g, 68-76%), mp 111-112°C (lit.2,3 107-108°C) (Note 10). A further 3-5 g (6-10%) of the product is obtained from the mother liquors (Notes 11 and 12). ... 

X-Ray structures of bis(thiophenes) and bis[benzo(7)thiophenes] have been determined. In compounds 1,4-bis-(2-thienyl)butadiyne 34a, both the thiophene rings are disordered. Thus the position of sulfur and carbon atoms in thiophene rings, adjacent to the diacetylenic backbone, are interchangeable but with unequal occupations. The thiophene rings are planar and the dihedral angle between them is 65.6°. The diacetylene chains are inclined to the shortest axis, that is, the -axis, by 40.5°, and the perpendicular distance between the adjacent chains is 3.823 A, as against the respective values of 45° and 3.4 < Aj < 4.0 A, required for solid-state polymerization. 

To a solution of copper chloride (2.4 mg, 0.024 mmol) in DMF (1.5 ml) was added l-chloro-2-phenylacetylene (50 mg, 0.37 mmol) at r.t. To the mixture was added trimethyl(4-methoxyphenylethynyl)silane (50 mg, 0.25 mmol). The reaction mixture was stirred for 48 h at 80 °C, quenched with 3 M HCl, and extracted with diethyl ether (25 ml x 2). The combined ethereal layer was washed with aqueous NaHCOj solution, then with brine and dried over MgS04. Filtration and evaporation provided a brown oil. Purification by column chromatography (Si02, hexane dichloromethane = 10 1) gave l-(4-methoxyphenyl)-4-phenyl-1,3-butadiyne (36 mg, 65% yield) as a colorless solid. 

In recent years interest in these materials has grown mainly for physical reasons. The layer perovskites are looked at as model compounds for the study of magnetic properties in two-dimensional systems (J2) and as models for the study of structural phase transitions in lipid bilayer-type arrays ( ). The use of layer perovskites as a matrix for organic solid state reactions represents a fairly new research topic. First experiments were carried out studying the photolysis of butadiyne (diacetylene) derivatives (li-ZSl) For a corresponding study of the butadiene derivatives the compounds listed in Table I were synthesized. 

Hydrazine hydrate reacts with 1,3-butadiyne moieties in competition with the carbonyl groups. Therefore, tosylhydrazine is employed for the selective reaction with the latter. The sodium salts of the resulting tosylhydrazones are heated to give the diazo compounds 16,18, and 20 [8, 10]. As some of the 1,3-butadiyne derivatives in Table 11-2 undergo spontaneous polymerization in the solid state (see Section 11.4.1), they have to be kept in solution. 1,3-butadiyne units are also known to react with diazo groups [11] and therefore the diazo compounds such as 16, 18, and 20 must be kept refrigerated. 

Natural Spins Detected during the Solid-State Polymerization of 1,3-Butadiynes... 

Scheme 11-4 Topochemically controlled solid-state polymerization pattern of 1,3-butadiynes.

Butadiyne derivatives are known to undergo a solid-state 1,4-addition of the unsaturated units according to... 

Polymerization has been attempted b conventional free radical, cationic and anionic initiators. Reactivity was observed, but a well defined polymer structure was not characterized. Butadiyne has been reported to fonj condensation copol3r-mers b nucleophilic addition of diamines or heterocyclic compounds. From its structure as the simplest diacetylene, it would be expected to figure prominently in solid state diacetylene polymerizations (Eq. 1). In one instance Wegner does... 

Figure 8.7 Solid state polymerization scheme of butadiyne to PDA.

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