Monoethyl succinate

4-Ethoxy-4-oxobutanoic acid is a fatty acid ester and a hemisuccinate.

Heating compound I succinic anhydride (100g, 1mol) and ethanol (200 ml) are added to a reaction flask, 80-82 C reflux reaction 3 hours, the reaction is complete; concentrated the ethyl alcohol is mellow to obtain compound II (121g, yield: 83%).General procedure: Succinic anhydride was refluxed in an excess of the respective alcoholunder anhydrous conditions and the remaining alcohol was removedunder reduced pressure. Chloroform was added to precipitateremaining succinic acid, which was subsequently removed by filtration.The succinic acid mono ester was dried in vacuo and was used withoutfurther purificationGeneral procedure: Succinic anhydride was refluxed in an excess of the respective alcohol under anhydrous conditions and the remaining alcohol was removed under reduced pressure. Chloroform was added to precipitate succinic acid which was subsequently removed by filtration. The succinic acid mono ester was dried in vacuo and was used without further purification. xEthanol (8 mL, 0.14 mol, 3 eq), succinic anhydride (5.027 g, 0.05 mmol), 1 h at 100 C. Yield 4.945 g (67%) colorless liquid. 1H NMR (CDCl3): delta = 4.19 (q, 2H, H5, 3JH, H = 7.1 Hz), 2.72-2.70 (m, 2H, H2/H3), 2.66-2.63 (m, 2H, H2/3), 1.28 (t, 3H, H6, 3JH, H = 7.1 Hz) ppm.A solution of dihydro-furan2, 5-dione (20 g, 20 mmol) in ethanol (100 mL) was allowed to stir at 80 C over a period of 16h. The resulting reaction mixture was directly concentrated under reduced pressure. The residue was diluted with DCM (600 mL) and washed with saturated sodium bicarbonate solution (300 mL). The aqueous layer was separated from organic, acidified with 1 .5N HC1 (pH = 2) and extracted with DCM (300 x 2 mL), dried over Na2SO4 and concentrated under reduced pressure to obtain product 140-1 as a colorless liquid 11.5 g (39.3%).A solution of dihydro-furan-2, 5- dione (20 g, 20 mmol) in ethanol (100 mL) was allowed to stir at 80 C over a period of 16 h. The resulting reaction mixture was directly concentrated under reduced pressure. The residue was diluted with DCM (600 mL) and washed with saturated sodium bicarbonate solution (300 mL). The aqueous layer was separated from organic, acidified with 1.5N HC1 (pH = 2) and extracted with DCM (300 x 2 mL), dried over Na2S04 and concentrated under reduced pressure to obtain product L-l as a colorless liquid 11.5 g (39.3%General procedure: A mixture of succinic anhydride (1.0 eq) and dry alcohol (1 eq) in toluene (4 mL) was heated at reflux 2.5 h. The toluene was removed under reduced pressure and the residue was taken up in water, and the solution was extracted with dichloromethane, dried (MgSO4), and evaporated to afford monoalkylsuccinic acid. A solution of monoalkyl succinic acid (1.2 eq) and thionyl chloride (1.4 eq) in benzene (5 mL) was refluxed for 3 h. Subsequently, the majority of the SOCl2 and benzene were removed by distillation. The mixture was cooled down to room temperature and dried under a vacuum to give a crude chlorocarbony-alkyl ester. A solution of chlorocarbonyl-alkyl ester in dichloromethane (5 mL) was added to a round flask containing 14 (1 eq) by cannula, and subsequently added pyridine (1.4 eq). The resulting solution was stirred at room temperature overnight, and quenched by adding water. The solution was extracted with ethyl acetate, dried (MgSO4), and evaporated to give a residue which was purified by column chromatography (Al2O3), eluting by ethyl acetate /hexane (1:15) to provide 25-43.A mixture of succinic anhydride (1.0 eq) and dry alcohol (carbon number is from 2 to 20) (1 eq) in 4 mL toluene was heated at reflux 2.5 hours. The toluene was removed under reduced pressure and the residue was taken up in water, and the solution was extracted with dichloromethane, dried over MgSO4, and evaporated to obtain monoalkylsuccinic acid (carbon number is from 2 to 20).In the preparation of the coalescing agent COA- 1, 1.0 mole succinic anhydride and5.0 moles ethanol were added into round bottom flask and refluxed at 80 C for 24 hours. Then, the excess ethanol of the reaction was distilled out and obtained product was extracted with the mixed solvent comprising dichioromethane and water. Then, dichloromethane layer was evaporated to obtain monoethyl succinate of the further reactions.Succinic anhydride (1.0 g, 10 mmol) was placed in a 10 mL round bottom flask.Ethanol (3.5 mL, 60 mmol) was used as a solvent and heated to reflux for 4 hours.Excess ethanol is removed by distillation under reduced pressure.A pale yellow oil is obtained as monoethyl succinate (1.4 g, 96%).This product was directly subjected to the next reaction without isolation.In a round-bottomed flask, 5 g of succinic anhydride and 8 ml of absolute ethanol were added, and the mixture was heated under reflux at 90 C for 3 h to recover excess ethanol to obtain a pale yellow oily substance, namely monoethyl succinate (6.5 g, 89%). The product was directly reacted without isolation.In a round-bottomed flask, 1 g of aloe-emodin and 6 g of the above monoethyl succinate were added, and 0.1 ml of sulfuric acid was slowly added dropwise, and the reaction was performed at 100 C. for 2 hours using a heating mantle.The product was dissolved in 15 ml of dichloromethane and sonicated for 5 min, then the insoluble matter was removed by suction filtration.The dichloride solution was extracted 4 times with 60 ml of a 2.5% sodium bicarbonate solution, and extracted twice with 30 mL of pure water, and the dichloromethane layer was taken.The dichloromethane was recovered to obtain a crude aloe-emodin succinyl ethyl ester.Separation by column chromatography, silica gel column chromatography with dichloromethane: ethyl acetate = 6: 1 as eluent, take the first large color band (can be analyzed by thin layer plate), and recover the solvent.Petroleum ether cleaning: Five times the volume of petroleum ether was added to the above product for cleaning and suction filtration. The filter cake was washed twice with petroleum ether to obtain pure aloe-emodin succinyl ethyl ester as a yellow powder (0.5922 g, 42.3%).

Molecular Weight:146.14
XLogP3:0.5
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:5
Exact Mass:146.05790880
Monoisotopic Mass:146.05790880
Topological Polar Surface Area:63.6
Heavy Atom Count:10
Complexity:130
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes