Chemical Properties
A colourless, oily liquid with an aromatic odour. It is miscible with ethanol, ether, acetone, and other common organic solvents, but only slightly soluble in water.
Uses
manufacture of phenobarbital, ethylbenzyl malonate, triethylamine, and similar chemicals, plastics, dyestuff intermediates. Solvent for cellulose esters, perfumes.
Uses
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.
Production Methods
Diethyl oxalate is produced via esterification of ethanol and
oxalic acid. It is a preferred solvent for cellulose acetate and
nitrate.
Application
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)
Preparation
Anhydrous oxalic acid and ethanol were esterified in the presence of toluene to produce crude diethyl oxalate. The crude ester was distilled to obtain the finished product. The raw material consumption per ton of product was: 985 kg of oxalic acid, 744 kg of ethanol (95%), and 73.4 kg of toluene.
Another preparation method was as follows: Ethanol, benzene, and oxalic acid were added into the reactor and heated to 68 °C for azeotropic reflux dehydration. The reaction endpoint was determined by the cessation of water separation. Benzene was then recovered to yield crude diethyl oxalate, which was distilled under reduced pressure, with the fraction collected at 103 °C / 6 kPa being diethyl oxalate. The product was purified by washing with a dilute sodium carbonate solution, drying over anhydrous potassium carbonate or sodium sulfate, and vacuum distillation.
Another preparation method involved adding 45 g (0.5 mol) of anhydrous oxalic acid ①, 81 g (1.76 mol) of anhydrous ethanol, 200 mL of benzene, and 10 mL of concentrated sulfuric acid into a reaction flask equipped with a stirrer and a water separator. The mixture was heated under stirring and refluxed at 68–70 °C for azeotropic dehydration. After most of the water had been evaporated, ethanol and benzene were removed by evaporation. The crude product was washed with water after cooling, then washed with a saturated sodium bicarbonate solution, followed by another water wash, and finally dried with anhydrous sodium sulfate. Diethyl oxalate (57 g) was obtained by atmospheric distillation, with the fraction collected at 182–184 °C, giving a yield of 78%.
① Preparation of anhydrous oxalic acid: Oxalic acid was dehydrated with anhydrous chloroform until crystallization occurred, as follows: The mixture was steamed with anhydrous oxalic acid and injected into a powder containing carbon. The product was filtered by suction, dried, and stored in a desiccator for later use. Anhydrous oxalic acid could also be prepared by drying directly in an oven. In this experiment, a corresponding amount of oxalic acid containing water of crystallization could also be used, but the reaction time was longer.
General Description
Ethyl oxalate appears as a colorless liquid. 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.
Air & Water Reactions
Insoluble in water.
Reactivity Profile
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
Hazard
Toxic by ingestion, strong irritant to skin
and mucous membranes.
Health Hazard
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.
Fire Hazard
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.
Safety Profile
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.
