Ethers, aryl acetylene terminated

Many engineering thermoplastics (e.g., polysulfone, polycarbonate, etc.) have limited utility in applications that require exposure to chemical environments. Environmental stress cracking [13] occurs when a stressed polymer is exposed to solvents. Poly(aryl ether phenylquin-oxalines) [27] and poly(aryl ether benzoxazoles) [60] show poor resistance to environmental stress cracking in the presence of acetone, chloroform, etc. This is expected because these structures are amorphous, and there is no crystallinity or liquid crystalline type structure to give solvent resistance. Thus, these materials may have limited utility in processes or applications that require multiple solvent coatings or exposures, whereas acetylene terminated polyaryl ethers [13] exhibit excellent processability, high adhesive properties, and good resistance to hydraulic fluid. 

SYNTHESIS AND PROPERTIES OF ACETYLENE TERMINATED ARYL-ETHER OLIGOMERS... 

The objective of this work is to synthesize a series of acetylene terminated aryl-ether systems for the purpose of correlating their thermal and thermal mechanical properties with molecular structure. 

A series of acetylene-terminated, aryl-ether thermoset systems were prepared by an Ullmann ether synthesis involving the condensation of various salts of aromatic bis—diols with m—dibromobenzene. The bromo end-capped oligomers were converted to the acetylene-terminated systems by the catalytically-induced, bromo-displacement reaction with 2-methyl-3-but3m-2-ol, followed by base hydrolysis. 

J. Cross couplings of aryl or alkenyl halides with TMSA proceeds in the presence of a Pd catalyst and Cul, followed by treatment with dilute aqueous KOH [54a] or K2CO3 in MeOH or a source of fluorine, such as KF, KF-crown ether, TASF, or Bu4NF to give terminal acetylenes [43a]. 

The substrate can be prepared by standard etherification reaction of a phenol derivative with a propargylic halide [lb]. Further carbon-carbon bond forming reactions of the terminal acetylenic carbon via metal acetylide provides a variety of substituted propargyl aryl ethers. Direct preparation using substituted propargyl ether is also possible. 

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