Abstract: Disclosed are novel N-oxyl compounds of the following formula (1). wherein n is an integer of 1 to 18; R1 and R2 are each hydrogen or methyl, but at least one of them is hydrogen; R3, R4, R5 and R6 are each a straight-chain or branched alkyl group; and R7 is hydrogen or (meth)acryloyl. When these compounds are added to vinyl monomers such as &agr;,&bgr;-unsaturated carboxylic acids and esters thereof, they exhibit a satisfactory polymerization-inhibiting effect even at low contents and even at elevated temperatures.

Abstract: A distillation process is used to separate methanol from a mixture of methanol with methyl acrylate or methyl methacrylate, as well as from a mixture of methanol and water with methyl acrylate or methyl methacrylate with the use of an azeotropic solvent, which forms an azeotropic mixture with methanol. In distilling such a mixture by the use of a distillation column:(1) part of the condensate of vapors distilled over from the top of the distillation column top is returned to the top of the column;(2) the remaining condensate is separated into two layers;(3) the upper layer essentially composed of an azeotropic solvent from the two separated layers is fed to an intermediate portion of the distillation column;(4) the lower layer essentially composed of methanol from the above two separated layers is withdrawn from the distillation system; and(5) methyl acrylate or methyl methacrylate, or else, methyl acrylate or methyl methacrylate and water, are recovered from the bottom of the column.

Abstract: Glycidyl methacrylate is produced by the reaction of an alkali metal salt of methacrylic acid with epichlorohydrin in the presence of a quaternary ammonium salt and a polymerization inhibitor in a reaction system where the water content is adjusted to 500 to 2000 ppm. Glycidyl methacrylate is purified by the method of the present invention, wherein the reaction mixture obtained by the above method is washed with a dilute aqueous solution of sodium hydroxide and heated under a reduced pressure to remove unchanged epichlorohydrin by distillation, after which steam is blown into the reaction system under the conditions of reduced pressure and heating to distill away the remaining epichlorohydrin together with glycidyl methacrylate as the first distillate fraction, followed by ceasing the steam blow and carrying out distillation under the conditions of reduced pressure and heating to obtain glycidyl methacrylate as the main distillate fraction.