| 摘要 |
1,206,377. Pyrrole free radicals. COMMISSARIAT A L'ENERGIE ATOMIQUE. 20 March, 1969 [4 April, 1968], No. 14662/69. Heading C2C. Free radicals of formula where R 1 , R 2 , R 3 and R 4 are the same or different C 1 -C 4 alkyl radicals, specifically 1- oxyl - 2,5 - ditertbutyl - 3,4 - diethoxycarbonyl pyrrole are prepared by dimerizing an alkyl alkoylacetate, e.g. by contacting with sodium and adding dropwise a solution of iodine in organic solvent or reacting with a second alkyl alkoylacetate to form a dialkyl-(α,#-dialkoyl) succinate; cyclizing with hydroxylamine hydrochloride and sodium acetate to 1-hydroxy-2,5- dialkyl - 3,4 - di - (alkoxycarbonyl) pyrrole; and oxidizing, e.g. with lead dioxide to the 1 - oxyl - 2,5 - dialkyl - 3,4 - di - (alkoxycarbonyl) pyrrole. The products are used as inhibitors of radical polymerization, monomer stabilizers, anti-oxidizing agent, photo-stabilizer and spin markers in biological molecules. |
