Para-substituted phenylacetylenes

The gas-phase acidities of meta- and para-substituted phenylacetylenes and benzyl alcohols have been determined by measuring equilibrium constants of proton-transfer reactions using an FT-ICR spectrometer.151 The gas-phase acidities have been related linearly to those of benzoic acids with a slope of unity. 

On the basis of a small mesomeric effect in the copolymerization of para-substituted phenylacetylenes by WC16, it has been concluded that this polyermization is not conventional ionic, but a kind of coordination polymerization 85). 

Subsequently, Tang et al. studied the polymerization of phenylacetylene and of para-substituted phenylacetylenes with lipophilic and water-soluble catalysts [148]. 

SCHEME 7.4 The synthesis of a solid phase library of pentamers using ortho-, meta-, and para-substituted phenylacetylene monomers. 

While the reactions of PhCH2SH with para-substituted phenylacetylenes (Ar C=CH) in the presence of Tp Rh(PPh3)2 provided Markovnikov-type adducts... 

Fig. 6.2 Phenylacetylene macrocycle 1 (PAM) with pure para-substituted phenylenes and macrocycle 2 containing both para- and meta-substituted phenylenes. Additionally,...

Selective and Efficient Access to ortho, meta, and para Ring-Substituted Phenylacetylene Derivatives R-[C=C-C6H4] .-Y (Y=H, NO2, CN, I, NH2)... 

The intermediates react further to give (Alk,Ar)C=CNuCl. With thiolate nucleophiles (EtS and PhS ), Hal = Cl, Br, I, the mechanism is restricted to attack on the halogen (5), but attack on the carbon is also observed in the reaction of EtS and ArC CCl. The second-order rate constants in methanol-water mixtures for meta- and para-substituted l-bromo-2-phenylacetylenes correlate well with Hammett a constants p = IT5. A linear correlation was also observed between ogK and pX of the corresponding thiols. 

A new vinylrhodiiun complex (10) for the living polymerization of pheny-lacetylenes has been prepared, isolated, and fully characterized by x-ray analysis (174). Catalyst (10) polsrmerizes phenylacetylene and its para-substituted... 

Much work has been carried out on phenylacetylene and its derivatives631,648-674. Of particular interest are the ori/io-substituted phenyl derivatives because, unlike their met a and para isomers, they generally give living systems when initiated by MoOCl4/Bu4Sn/EtOH (1/1/1), allowing the preparation of block copolymers. This is the... 

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