Benzoyl peroxide, reaction with diethyl

Benzophenone, 46, 36 N-(2-Benzothiazolyl)urea, 46, 72 Benzoyl chloride, reaction with hydrogen fluoride, 46, 4 Benzoyl fluoride, 46, 3 Benzoylhydrazine, 46, 8S Benzoyl peroxide, reaction with diethyl ethylmalonate, 45, 37 2-Benzyl-2-carbomethoxycyclopenta-none, 45, 7... 

Benzoyl fluoride, 46,3 Benzoy lhydrazine, 46, 85 Benzoyl peroxide, as catalyst for reaction of chloroform with as,as 1,5 cyclooctadiene, 47, 11 reaction with diethyl ethylmalonate, 46, 37... 

To a 1-1., three-necked, round-bottomed flask is added 7.2 g. (0.15 mole) of a 50% dispersion of sodium hydride in mineral oil (Note 1). The sodium hydride is washed several times by decantation with dry ether and is then covered with 300 ml. of dry benzene (Note 2). The flask is equipped with dropping funnel, stirrer, and reflux condenser. Diethyl ethylmalonate (28.2 g., 0.15 mole) (Note 1) is added dropwise over a 5-minute period, and the reaction mixture is stirred for 2 hours until a clear solution forms. The solution is cooled in an ice bath, and 24.2 g. (0.1 mole) of benzoyl peroxide (Note 3) in 300 ml. of dry benzene is added dropwise over a 1-hour period with continuous stirring After another 30 minutes, a peroxide test (Note 4) is made to ensure that all the peroxide has reacted. 

A. Diethyl propionylsuccinate (1). A solution of 412 g. (2.4 mole) of diethyl maleate (Note 1), 278 g. (4.8 mole) of freshly distilled propionaldehyde (Note 2), and 1.2 g. (0.0048 mole) of benzoyl peroxide in a normal 2-1. Pyrex flask is heated under reflux while undergoing irradiation with an ultraviolet lamp (Note 3). The initial reflux temperature is 60°. After 2 hours another 1.2 g. (0.0048 mole) of benzoyl peroxide is added. Strong reflux and irradiation are maintained throughout the entire reaction period. After 18 hours total time, the internal pot temperature reaches 68°. At this point the last 1.2 g. (0.0048 mole) of benzoyl peroxide is added, and the reaction is continued for a total of 30 hours, at which time the pot temperature reaches 74.5°. The reflux condenser is then replaced by a distillation head. The excess propionaldehyde (119 g.) is distilled under atmospheric pressure, b.p. 48-49°. Succinate 1 is distilled under reduced pressure. The main fraction, b.p. 145-151.5° (15-16 mm), provides 417-449 g. (75-81%) of product having sufficient purity for use in the next step (Note 4). 

Tetrahydropyran-4-ones, for example diethyl 6-methyl-4-oxotetrahydropyran-3,3-dicar-boxylate (600), are brominated at C-3 (77JCS(Pl)l647). Chromanones are readily halogenated at C-3 (see above) when they are treated with phosphorus pentachloride, the reaction does not stop at monochlorination the carbonyl group is attacked and 3,4-dichloro-2//-chromene (601) is formed, an uncommon conversion of a chromanone into a chromene (79TL3901). Chroman yields 4- and 6-bromides when treated with NBS-benzoyl peroxide. 

Catalysis of benzylic bromination, see 1,3-Dibromo-5,5-dimethylhydantoin. Benzoyloxylation of malomc esters. Dibenzoyl peroxide reacts with the sodium derivative of diethyl ethylmalonate to give diethyl (O-benzoyl)ethyltartronate. This is a general reaction for /8-dicarbonyl compounds. 

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