INVESTIGADORES
GARAY raul Oscar
artículos
Título:
Para-Xylylenes and Analogues by Base-induced Elimination from 1,4-bis-(Dialkylsulfoniomethyl)arene Salts in Poly(1,4-Arylene vinylene) Synthesis by the Wessling Soluble Precursor Method
Autor/es:
F. DENTON; A. SARKER; P.M. LAHTI; R. O. GARAY; F. E. KARASZ
Revista:
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
Editorial:
JOHN WILEY & SONS INC
Referencias:
Lugar: New York; Año: 1992 vol. 30 p. 2233 - 2240
ISSN:
0887-624X
Resumen:
para-Xylylenes are generated by treatment of various
1,4-bis(dialkylsulfoniomethyl)arene dihalides with base in water, methanol, and
aqueous acetonitrile, as shown by UV-Vis spectroscopy. This procedure allows
the monitoring of the transient xylylene monomers that yield polyelectrolyte
precursor polymers for poly(arylene vinylene)s, formed by variations of the
chemistry developed originally by Wessling and co-workers. Alkoxy, alkyl, and
halogen ring substituents on the sulfonium salt precursors do not greatly
affect the ability to generate and observe the growth and decay of steady-state
concentrations of the para-xylylene intermediates. Use of strong
resonance-acceptor substituents?such as cyano or nitro?on the ring reduces
production of a strong para-xylylene absorption, possibly due to
reluctance of the ylides initially formed from the bis-sulfonium salts to
eliminate to the xylylenes. By variation of UV-Vis conditions, it was found
that use of 20% aqueous acetonitrile rather than water allowed formation of low
to modest molecular weight polyelectrolytes in cyano-substituted cases (Mw
= 8000?37,000). Use of UV-Vis test experiments should be useful for screening
of bis sulfonium salt precursors that may be expected to give high molecular
weight polyelectrolytes?in cases where para-xylylene formation is
easy?as well as for finding reaction conditions that will optimize polymer
formation.