Diphenyl diacetylene

The reaction direction remains the same for methyldiacetylene and diphenyl-diacetylene (120°C, 20 h, yield 85.8%) (71AKZ743), the cyclization products being 1,3,5-trisubstituted pyrazoles 20 and 21. 

In some cases, chemical substituents can bring about unusual monotropic liquid crystalline phases which only exist upon heating or cooling. The diphenyl-diacetylenes are examples in this category [22]. Early theoretical connections between molecular electronic structure and orientational order... 

By the same process it is possible to prepare diphenyl-diacetylene from the copper derivative of plienyl-acetylene ... 

Diphenyl-diacetylene is the parent hydi ocarhon of indigo blue, and the dye itself can be prepared by means of tliis reaction, starting with o-nitro-phenyl-propiolic acid. By loss of carbon dioxide the acid becomes o-nitro-phenyl-acetylene, the copper derivative of which passes to di-ortho-nitrophenyl-diacety-lene ... 

Its formation from diphenyl-diacetylene shows that the carbon atoms are placed in the following manner —... 

Diacetylene monomers with aromatic groups directly bonded to the triple bonds typically do not undergo extensive conversion to polymer (64). More extensive conversions appear to take place in fluorine-substituted diphenyl diacetylenes (65), and this may be an important new vector in PDA research. 

Y. Arakawa, S. Nakajima, R. Ishige, M. Uchimura, S. Kang, G. Konishi, J. Watanabe, Synthesis of diphenyl-diacetylene-based nematic liquid crystals and their high birefringence properties, J. Mater. Chem. 22 (2012) 8394. 

Teyssie and Koen-Girabi) have reported that 1,4-diphenyl-diacetylene can be polymerized through one acetylene bond, XXXIV, and then treated thermally or chemically to give material which has been postulated to be partially cyclized, XXXV 85). 

Polydiacetylenes. Dimethanol-diacetylene (H0CH2C=C-C=CCH OH) (DMDA) was used as received from Farehan Chemical Co. Diphenyl urethane-diacetylene -NH-COO-(CH2) -C=C-C=C-(CH2) -OOC-NH- < ) (TCDU) wasused as received from Allied Chemical Co. Both monomers were successfully deposited as epitaxial films on various alkali halides from vapor and solution phases. The following conditions were used for these crystallizations vapor phase DMDA = 40 C at 10 torr, vapor phase TCDU = 150 C at 10 torr, solution (1 wt % in toluene) phase DMDA = 70 C for 30 minutes, solution (.4 wt % in ethyl acetate) phase TCDU = 30 C for 5 minutes. 

Polyacetylenes26 27 exhibit a number of fine-structure bands. Diacetylenes show medium intensity bands (e 100-350) in the 210-250 mp region. Tri- and tetra- and higher acetylenes, however, exhibit very high intensity bands (e > 100,000) at lower wavelengths (200-280 mp) in addition to the medium intensity bands (240-390 mp). Absorption spectra of diphenyl-poiyacetylenes have been reported27 (see references 37 and 38 for naturally occurring acetylenic compounds). 

---