Sodium ethoxide reaction with diethyl succinate

Diethyl succinate, reaction with sodium ethoxide, 46, 25... 

The condensation of aldehydes and ketones with succinic esters in the presence of sodium ethoxide is known as the Stobbe condensation. The reaction with sodium ethoxide is comparatively slow and a httlo reduction of the ketonic compound to the carbinol usually occurs a shorter reaction time and a better yield is generally obtained with the more powerful condensing agent potassium ieri.-butoxide or with sodium hydride. Thus benzophenone condenses with diethyl succinate in the presence of potassium [Pg.919]

Sodium azide, reaction with l butyl chloroacetate, 46, 47 reaction with diazomum salt from o amino-f> -ni trobiphcny L, 46, 86 Sodium chlorodifluoroacetate, 47, SO reaction with tnphenylphosphme and benzaldehyde, 47, SO Sodium ethoxide, 46, 2S reaction with diethyl succinate, 46,2S Sodium formate as reducing agent in preparation of palladium catalyst, 46, 90... 

Dicarbethoxy-l,4-cyclohexanedione has been prepared by the self-condensation of diethyl succinate by use of sodium or sodixim ethoxide catalyst (with or without a solvent) and by reaction of ethyl 4-bromo-3-ketobutanoate or ethyl 4-chloro-3-ketobutanoate with sodium ethoxide in ethanol. 

In the Stobbe condensation side reactions encountered by the use of other reagents are considerable—e.g., in the condensation of benzophenone and diethyl succinate with sodium ethoxide and ether, a significant amount of benzhydrol is always obtained (16). The condensation of benzophenone with diethyl succinate, using sodium hydride dispersions, was completed rapidly and gave an excellent yield (95.7%) of )3-carbethoxy-7, 7 -biphenylvinyl acetic acid. 

I. 2,5-Dicarbethoxy-1,4-cyclohexanedione (7) A 500-ml, three-necked, round-bottom flask is fitted with a condenser (drying tube) and arranged for magnetic stirring. A solution of sodium ethoxide is prepared in the flask by the addition of sodium (9.2 g, 0.4 g-atom) in small pieces to 90 ml of absolute ethanol. The mixture is heated at reflux for 3 hours (oil bath) to complete the reaction. Diethyl succinate (34.8 g, 0.2 mole) is added to the hot solution in one portion exothermic ) and the mixture is refluxed for 24 hours. (A pink precipitate forms and persists during the reflux.)... 

Sodium ethoxide, 46, 2S reaction with diethyl succinate, 46,25... 

A. Z,5-DicaThelhoxy-l,4-cyclohexanedione. A solution of sodium ethoxide is prepared by adding small pieces of sodium (92 g., 4 g. atoms) as rapidly as possible to 900 ml. of commercial absolute ethanol contained in a 3-1., three-necked, round-bottomed flask equipped with two stoppers and a reflux condenser fitted with a drying tube packed with calcium chloride and soda lime. The reaction is completed by heating the mixture under reflux for 3-4 hours (Note 1). To the hot solution is added diethyl succinate (348.4 g., 2 moles) (Note 2) in one portion Caution Exothermic reaction), and the mixture is heated under reflux by maintaining the original bath temperature for 24 hours. A thick pink-colored precipitate is formed almost immediately and remains throughout the reaction. 

CH2,CH2,C02Et. From the latter the three-carbon unit of diethyl succinate may be recognised, and the Stobbe condensation is a suitable illustration of this process. Thus the reaction of aldehydes or ketones with succinic esters in the presence of potassium t-butoxide (or with sodium hydride) gives alkylidene-succinic acid esters (25). The reaction is somewhat slower in the case of the less basic sodium ethoxide. 

Potassium ethoxide was prepared from 1.95 g potassium and 9.2 mL absolute ethanol in 150 mL anhydrous ether. To this mixture 14.6 g diethyl oxalate was added. After 15 min, a solution of 13.5 g ethyl (3Lmethoxy-2-biphenylyl)-acetate in 50 mL dry ether was added, and the mixture was refluxed for 51 h. The reaction mixture was cooled and extracted with 5% sodium hydroxide solution. The aqueous layer was saturated with carbon dioxide, and the precipitated oil was taken up in ether. Evaporation of the ether solution afforded 10.6 g crude diethyl Q -keto-Q -(3-methoxy-2-biphenylyl)-succinate, which was used in subsequent experiments without purification. From the alkali-insoluble fraction, 4.2 g ethyl (3 -methoxy-2-biphenylyl)-acetate was recovered. 

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