Showing papers by "Yoshiharu Kimura published in 1983"

Stereoselective micellar catalysis. Part 4. Catalytic hydrolyses of enantiomeric esters by dipeptide derivatives containing a histidyl residue

Abstract: The rate constants for hydrolyses of the enantiomers of various amino acid p-nitrophenyl esters catalysed by optically active dipeptide catalysts containing a histidyl residue have been determined at pH 7.30, 0.02M-phosphate buffer, and 25°C in the presence of cetyltrimethylammonium bromide micelles. The dipeptide catalysts demonstrate greater stereoselectivity than simple optically active catalysts. The structural effects of catalysts and substrates are examined by investigation of the rate constants and stereoselectivities. The role of their hydrophobicity and their stereoselective reaction mechanism are discussed.

Catalysis of enantiomeric ester hydrolysis by N‐decanoyl‐L‐histidine in polymer domains

Abstract: Catalytic hydrolysis of enantiomeric substrates by N-decanoyl-L-histidine was studied at pH 7.30, 0.02M phosphate buffer, and 25°C in the presence of quaternized polymers. The rate of reaction is remarkably accelerated in the presence of polyethylenimine derivatives, but the observed stereoselectivity depends on the structure of the substrates.

Polyalkylene terephthalate composition and preparing same

Abstract: PURPOSE:To prepare the titled compsn. with improved antistatic properties, by molding a mixt. of polyethyleneoxydiglycolic acid (alkali metal salt) and polyalkylene terephthalate. CONSTITUTION:0.05-5wt% polyethyleneoxydiglycolic acid (alkali metal salt) of formula (wherein n is 4-300), average MW 300-10,000, is mixed with polyalkylene terephthalate (e.g., polyethylene terephthalate). The mixt. is molded at 260-280 deg.C in fiber, film, or hollow body, and then, if necessary, stretched. EFFECT:No discoloration during melt-molding, exceedingly low cut-off in spinning, no decrease in strength of fiber, and capable of preventing poor bite of pellets into a spinning machine.