Anhydrous oxalic acid and ethanol were esterified in the presence of toluene to produce crude diethyl oxalate. The crude ester is distilled into finished product. Raw material consumption quota: 985kg / T oxalic acid, 744kg / T ethanol (95%) and 73.4kg/t toluene. Another preparation method is to add ethanol, benzene and oxalic acid into the reactor, heat it to 68 ℃, azeotrope reflux dehydration, and take no water out as the end point of the reaction, then recover benzene to obtain crude diethyl oxalate, distill under reduced pressure, and collect 103 ℃ / 6kpa fraction to diethyl oxalate. It is purified by washing with dilute sodium carbonate solution, drying anhydrous potassium carbonate or sodium sulfate and vacuum distillation.
Another preparation method is to add 45g (0.5mol) of anhydrous oxalic acid ① (2), 81g (1.76mol) of anhydrous ethanol, 200ml of benzene and 10ml of concentrated sulfuric acid into the reaction bottle equipped with agitator and water separator. It is heated under stirring and refluxed at 68 ~ 70 ℃ for azeotropic dehydration. After the water is basically evaporated, ethanol and benzene are evaporated. Wash with water after cooling, wash with saturated sodium bicarbonate solution, wash with water, and dry with anhydrous sodium sulfate. Diethyl oxalate (57g) was obtained by atmospheric distillation and collecting the fraction at 182 ~ 184 ℃, with a yield of 78%. ① dehydrate oxalic acid with anhydrous chloroform water until it crystallizes as follows: steam it with anhydrous oxalic acid and inject it into the powder containing carbon. Filter by suction, dry and store in dryer for standby. Anhydrous oxalic acid can also be prepared by drying directly in an oven. In this experiment, a corresponding amount of oxalic acid containing crystal water can also be used, but the reaction time is longer.
Diethyl oxalate is used to prepare active pharmaceutical ingredients (API), plastics and dyestuff intermediates. It is also used as a solvent for cellulose esters, ethers, resins, perfumes and lacquers for electronics. It is involved in the transesterification reaction with phenol to get dipheny oxalate. It is also involved in the Claisen condensation ketosteroids to prepare glyoxalyl derivatives. Further, it is used to prepare sym-1,4-diphenyl-1,4-dihydro-1,2,4,5-polytetrazine. In addition to this, it is utilized in the microemulsion synthesis of zinc oxide nanoparticles.
manufacture of phenobarbital, ethylbenzyl malonate, triethylamine, and similar chemicals, plastics, dyestuff intermediates. Solvent for cellulose esters, perfumes.
Diethyl oxalate has the general properties of esters. It absorbs moisture in the air and decomposes slowly. It reacts with ammonia to form amide compounds and condenses with acetone to ethyl pyruvate. It is mainly used in the pharmaceutical industry. It is an intermediate of azathioprine, peripheral sulfanilamide, carboxyphenyllipase penicillin, ethoxybenzylpenicillin, chloroquine lactate, thiabendazole, sulfamethoxazole and other drugs. It can be used as an intermediate of plastics, dyes and other products, and as a solvent of cellulose and spices.
Diethyl acetate is often used as the substrate of nucleophilic reagent α,γ- Dicarbonyl esters, ketone compounds, synthesis of heterocyclic compounds, etc. synthesis α,γ- Dicarbonyl esters can be formed by nucleophilic substitution reaction between ketones and diethyl oxalate under alkaline conditions α,γ- Dicarbonyl ester (formula 1). The dicarbonyl ester often exists in enol structure and can be used to synthesize heterocyclic compounds (formula 2)
Diethyl oxalate is produced via esterification of ethanol and
oxalic acid. It is a preferred solvent for cellulose acetate and
nitrate.
A colorless liquid. Flash point 168°F. Slightly denser than water and insoluble in water. Hence sinks in water. May irritate skin and mucous membranes; may be mildly toxic by ingestion; may emit irritating fumes in a fire. Vapors are much heavier than air. Used as a solvent for plastics and in the manufacture of perfumes and pharmaceuticals.
Diethyl oxalate is an ester. Esters react with acids to liberate heat along with alcohols and acids. Strong oxidizing acids may cause a vigorous reaction that is sufficiently exothermic to ignite the reaction products. Heat is also generated by the interaction of esters with caustic solutions. Flammable hydrogen is generated by mixing esters with alkali metals and hydrides
Toxic by ingestion, strong irritant to skin
and mucous membranes.
TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Contact with molten substance may cause severe burns to skin and eyes. Reaction with water or moist air will release toxic, corrosive or flammable gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
Combustible material: may burn but does not ignite readily. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapors may travel to source of ignition and flash back. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.
Poison by ingestion.
Flammable liquid when exposed to heat or
flame; can react with oxidzing materials. To
fight fire, use foam, CO2, dry chemical.
When heated to decomposition it emits
acrid smoke and fumes. See also
OXALATES and ESTERS.
