| 摘要 |
The use of 0.001-1.0 wt. % p-phenylenediamine(I) and/or I derivs. (e.g., N-phenyl-N'-isopropyl-(II), N-N'-diphenyl-, or N,N'-di-β-naphthyl-p-phenylenediamine) polymn. inhibitors in methacrylic acid(III) or III esters contg. >=1% III permits purifn. of III or III esters by distn. in the presence of >= 0.01-5% air or O. Thus, 95:5 Me methacrylate III mixt. contg. 100 ppm of II was charged to a distn. column, and 0.1 vol.% air was introduced simultaneously. Continuous distn. was conducted at 90 mmHg in a 1-plate still, with temps. at the bottom and top of the column 60-80 and 40-50, resp., without polymer deposits in the still.
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