Acetylenes extended

Acetylene-Extended Tetrathiafulvalenes in Cross-Conjugated Systems... 

Figure 8.24 (a) Acetylene-extended DT[n]radialene series, (b) Synthesis of 77. 

Cross-Conjugated Systems in Acetylene-Extended Radiaannulene Frameworks... 

To extend the study of the apparent decomposition recombination reaction, and specifically to determine if the carbon atoms exchange with other atoms in other acetylene molecules, tests using carbon isotopes were conducted. A mixture of 50% regular acetylene, C2H2, and 50% heavy acetylene. 

Polymerization by Gycloaddition. Bisimides and oligoimides capped with reactive unsaturations such as maleimide, acetylene, and xylylene groups, can be chain-extended by a cycloaddition reaction with proper bisdienes. 

Soon after the 1946 report by Woodward on the condensation of thioglycolic acid and a,P-unsaturated esters in the presence of base to produce structures like 2-carbomethoxy-3-ketotetrahydrothiophene 4, Fiesselmann extended this reaction to a,p-acetylenic esters for the direct preparation of 3-hydroxy-2-thiophenecarboxyIic acid derivatives. ... 

The use of the Hammett equation has also been extended to several new types of applications. Since these are not germane to the subject matter of the present chapter, we wiU simply mention work on applications to ethylenic and acetylenic compounds the various applications to physical properties, such as infrared frequencies and intensities, ultraviolet spectra, polarographic half-wave potentials, dipole moments,NMR and NQR spectra,and solubility data and applications to preparative data and biological activity. 

Intramolecular addition of the amide group to the triple bond in pyrazoles is more difficult, and results in closure of the 5-lactam rather than the y-lactam ring. The reaction time of the 4-phenylethynylpyrazole-3-carboxylic acid amide under the same conditions is extended to 42 h (Scheme 129) (Table XXVII). The cyclization of l-methyl-4-phenylethynyl-l//-pyrazole-3-carboxylic acid amide, in which the acetylene substituent is located in the 7r-electron-rich position of the heterocycle, is the only one complete after 107 h (Scheme 130) (90IZV2089). 

Organocopper chemistry is still rapidly expanding its syntlietic scope. Hie scope of carbocupration, previously limited to acetylenes, has recently been extended to olefins [33-36]. 1,6-, 1,8-, 1,10-, and 1,12-Addition and 1,5-Su2" substitution reac-... 

Extended tetrathiafulvalenes with acetylenic cores are interesting compounds because of their redox and chromophoric properties. Such molecules are both interesting from materials and supramolecular chemistry perspectives. A tetraethynylethene-extended tetrathiafulvalene, for instance, was prepared using a microwave-promoted Sonogashira reaction [72]. Coup-... 

In this contribution, in order to illustrate tlie importance of shake-up bands for extended systems, we simulate and compare on correlated grounds the ionization spectra of polyethylene and poly acetylene, the most simplest systems one can consider to represent insulating or semi-conducting polymers. Conclusions for the infinite stereoregular chains are drawn by exU apolation of the trends observed with the first terms of the related n-alkane or acene series, CnH2n+2 and CnHn+2. respectively, with n=2, 4, 6 and 8. Our simulations are also compared to X-ray photoionization spectra (7) recorded on gas phase samples of ethylene, butadiene and hexatriene, which provide a clear experimental manisfestation of the construction of correlation bands (8-12). 

Many of the Lewis structures in Chapter 9 and elsewhere in this book represent molecules that contain double bonds and triple bonds. From simple molecules such as ethylene and acetylene to complex biochemical compounds such as chlorophyll and plastoquinone, multiple bonds are abundant in chemistry. Double bonds and triple bonds can be described by extending the orbital overlap model of bonding. We begin with ethylene, a simple hydrocarbon with the formula C2 H4. 

Acetylene terminated polyimide prepolymers have many advantages over conventional polyimides in the areas of processing and solvent resistance. In addition, the presence of the isoimide structure further extends the the utility of these systems by modification of the solubility properties and glass transition temperature. 

In extending the synthetic utility of Cp2Ti(CO)(PEt3) (41) as a convenient source of Cp2Ti(CO), Rausch and co-workers reacted 41 with various acetylenes and thus obtained the corresponding titanocene mono-carbonyl-rj2-acetylene complexes in good yields (50,96). These complexes... 

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