THE CHEMISTRY OF ALPHA-HALO AND ALPHA-NITRO ESTERS: THE REACTION OF SODIUM DIETHYL METHYLMALONATE WITH DIETHYL-2-BROMO-2-METHYLMALONATE, DIETHYL-2-CHLORO-2-METHYLMALONATE, DIETHYL-2-FLUORO-2-METHYLMALONATE, AND DIETHYL-2-METHYL-2-NITROMALONATE

Chapter I. On being exposed to the light of two ordinary 20 Watt fluorescent lamps sodium diethyl methylmalonate reacts with diethyl-2-methyl-2-nitromalonate to give 1,1,3,3-tetracarbethoxybutane in 78% isolated yield. This reaction, which requires light, is inhibited by 5 mol% of m-dinitrobenzene and 10 mol% of di-t-butylnitroxide. Clearly, it is a chain reaction. A mechanism is proposed which invokes the intermediacy of radical anions and free radicals. Chapter II. Under the influence of two ordinary 20 Watt fluorescent lamps sodium diethyl methylmalonate reacts with diethyl-2-bromo-2-methylmalonate, diethyl-2-chloro-2-methylmalonate, and diethyl-2-fluoro-2-methylmalonate. A mixture of 2,2,3,3-tetracarbethoxybutane and 1,1,3,3-tetracarbethoxybutane is produced. When the fluoromalonic ester is employed, the 1,1,3,3-tetraester is the only product. In contrast, little or no 1,1,3,3-tetracarbethoxybutane is formed in the dark from the bromomalonic and chloromalonic esters; 2,2,3,3-tetracarbethoxybutane is the major product. In the dark the fluoromalonic ester gives neither the 1,1,3,3-tetraester nor the 2,2,3,3-tetraester. Catalytic amounts of di-t-butylnitroxide and dinirobenzene retard the formation of the 1,1,3,3-tetraester but do not slow down the formation of the 2,2,3,3-tetraester from the bromomalonic and chloromalonic esters. The use of ultraviolet light increases the rate of reaction and increases the proportion of 1,1,3,3-tetracarbethoxybutane relative to 2,2,3,3-tetracarbethoxybutane from the bromomalonic and chloromalonic esters. A stoichiometric amount of di-t-butylnitroxide retards the formation of the 1,1,3,3-tetraester and slows the reaction rate of the chloromalonic ester in ultraviolet light. This, and other evidence, strongly supports the radical anion-free radical chain mechanism proposed for the formation of 1,1,3,3-tetracarbethoxybutane. On the other hand, 2,2,3,3-tetracarbethoxybutane is thought to form by an ionic, non-chain process. Treatment of diethyl-2-bromo-2-methylmalonate or diethyl-2-chloro-2-methylmalonate with sodium naphthalide gives diethyl methylmalonate. In sharp contrast, the reaction of diethyl-2-fluoro-2-methylmalonate with sodium naphthalide gives 1,1,4,4-tetracarbethoxybutane. . . . (Author\u27s abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UM