Abstract: A biologically absorbable polyhydroxycarboxylic acid in which a content of water-soluble acid components is not more than 0.07 mol/kg in terms of monobasic acids, and which has a weight average molecular weight of 4,000 to 100,000 and contains neither a catalyst nor an organic solvent, and a production method thereof.

Abstract: A biologically absorbable polyhydroxycarboxylic acid in which a content of water-soluble acid components is not more than 0.07 mol/kg in terms of monobasic acids, and which has a weight average molecular weight of 4,000 to 100,000 and contains neither a catalyst nor an organic solvent, and a production method thereof.

Abstract: The ring opening polymerization of p-dioxanone is started in a liquid phase under stirring at a temperature of 85 to 105° C. after adding 0.002 to 0.005 mol percent of stannous 2-ethylhexanoate forming a white crystal at a temperature of 0° C. as a catalyst and 0.01 to 0.1 mol percent of initiator. Stirring is stopped when a stirring load has increased by 10 to 100 percent over an initial load, while the temperature is lowered to a range of 65 to 85° C., to continue the polymerization in a solid phase to produce poly(p-dioxanone). The polymer is used to make a monofilament having a knot tensile strength of at least 30,000 psi and a strength retention of at least 58 percent after four weeks of immersion in a physiological saline solution at 37° C. The monofilament provides an absorbable surgical suture which is highly resistant to hydrolysis and very useful for stitching a wound or incision which requires a long time for healing.

Abstract: A purified salt of &bgr;-hydroxyethoxy acetic acid of formula (1) having a fusion peak-top temperature detected by differential scanning calorimetry (DSC) and a purified 2-p-dioxanone of formula (2) derived from the purified salt of &bgr;-hydroxyethoxy acetic acid of formula (1). (wherein in formula (1), n=1-2, and if n=1, M is Na and/or K, and, if n=2, M is Ca and/or Mg.

Abstract: A purified salt of &bgr;-hydroxyethoxy acetic acid of formula (1) having a fusion peak-top temperature detected by differential scanning calorimetry (DSC) and a purified 2-p-dioxanone of formula (2) derived from the purified salt of &bgr;-hydroxyethoxy acetic acid of formula (1).

Abstract: A random-block copolymer having appropriate hydrolyzability, excellent flexibility and excellent mechanical strength, a monofilament thereof, and a process for producing the copolymer. The random-block copolymer comprises from 5 to 50 mol % of a random copolymer segment containing from 20 to 80 mol % of a lactide unit (A) and from 80 to 20 mol % of a caprolactone unit (B), and from 95 to 50 mol % of a block copolymer segment containing a glycolide unit (C).

Abstract: A herbicidal composition is here disclosed which exerts an excellent herbicidal activity and which is harmless to paddy rice.A 1-[1-methyl-1-(substituted phenyl)ethyl]-4,5-dimethyl-3-(substituted phenyl)-3-pyrroline-2-one derivative represented by the formula (I) ##STR1## (wherein X is a chlorine atom, fluorine atom or bromine atom; Y is a hydrogen atom, fluorine atom, chlorine atom or methoxy group; Z is a hydrogen atom, fluorine atom, bromine atom or chlorine atom; and Q is a hydrogen atom or fluorine atom)is a novel compound, and the herbicidal composition containing this compound as a herbicidally active ingredient has the strong activity and high selectivity as the herbicidal composition for paddy fields.

Abstract: A 3-azabicyclo[3.1.0]hexane-2-one derivative represented by the following formula (I), and a herbicidal composition containing the same as a herbicidally active ingredient: ##STR1## (wherein X is a halogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms or a haloalkyl group having 1 to 3 carbon atoms; Y is a halogen atom or an alkyl group having 1 to 3 carbon atoms; R.sub.1 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R.sub.2 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; m is an integer of 0 to 3; n is an integer of 0 to 2; and when m is 2 or 3, the groups represented by X may be identical or different, and when n is 2, the groups represented by Y may be identical or different).

Abstract: p-Aminophenyl acetate is isomerized to p-acetylaminophenol in the presence of an acid such as acetic acid or phosphoric acid.

Abstract: A process for producing a p-hydroxyneophyl m-phenoxybenzyl ether represented by the general formula (II) ##STR1## (X.sub.1 and X.sub.2 are independently a hydrogen atom or a halogen atom) by subjecting a corresponding p-alkoxyneophyl m-phenoxybenzyl ether represented by the general formula (I) ##STR2## (R represents a lower alkyl group, and X.sub.1 and X.sub.2 have the same definitions as above) to ether cleavage, in which process the ether cleavage reaction is effected in an aprotic polar solvent, using a lower alkoxide of an alkali metal or an alkaline earth metal or using a metal hydroxide in the presence of a lower alcohol.

Abstract: A higher yield of the difluorohalomethoxybenzene produced by the reaction of a metal phenolate with dibromodifluoromethane or bromochlorodifluoromethane can be obtained by conducting the addition of a metal alcoholate or a metal hydride as a reaction initiator to a solution or a suspension of an aprotic polar solvent containing the metal phenolate and dibromodifluoromethane or bromochlorodifluoromethane.