Triethyl orthoformate (TEOF)

Triethyl orthoformate is a multiple carboxylic acid ester. It represents a hypothetical triple ester of the virtually non-existent orthoformic acid that is actually obtained from the reaction of other compounds such as chloroform or hydrogen cyanide. The molecules of the substance are built around a central carbon atom. In addition to a connected hydrogen atom, this has bonds to three oxygen atoms, which are each connected to an ethyl group and form an ethoxy group with it. The compound can therefore also be referred to as triethoxymethane.

Triethyl orthoformate is in liquid form under normal conditions. The compound is colorless in appearance and has a pleasant, aromatic odor. The substance only reaches its boiling point when heated to 146 °C and withstands severe cooling before congealing to a solid at temperatures below -76 °C. Liquid triethyl orthoformate is lighter than water.

The substance is hygroscopic and attracts moisture, but is only slightly soluble in water. Instead, the compound gradually decomposes on contact with water. In contrast, triethyl orthoformate is readily soluble in many organic solvents such as diethyl ether and ethanol.

When stored as intended, triethyl orthoformate is chemically stable. It is particularly important to ensure that the substance is stored dry and airtight, as it can gradually decompose simply by absorbing humidity. Dangerous reactions and strong heat development can occur with acids and strong oxidizing agents.

Triethyl orthoformate is combustible and highly flammable. The vapors of the compound can form explosive vapor-air mixtures with the ambient air. When handling open containers of the substance, it should also be noted that the vapors are heavier than air and can therefore collect on the floor and spread unnoticed in the work rooms. In order to avoid dangerous remote ignitions, triethyl orthoformate must therefore be kept far away from potential sources of ignition such as electrostatically charged devices, devices that are heated to a high temperature, sparks and open flames. In addition to formic acid and ethanol, the combustion of the substance can produce harmful gases such as carbon dioxide and carbon monoxide.

Triethyl orthoformate is a mildly irritating substance that can cause redness and irritation of the skin and eyes upon direct contact. Wetted parts of the body should be cleaned immediately with water. If the symptoms persist, you should also seek medical help. If an eye comes into contact with the compound, it must be rinsed immediately under running water and then examined by an ophthalmologist to rule out impairment of vision.

Inhalation of vapors and aerosols of the substance can irritate the mucous membranes of the respiratory tract and lead to coughing and shortness of breath. In high concentrations, the vapors can also cause pulmonary edema. If triethyl orthoformate is swallowed, see a doctor immediately to have possible symptoms of poisoning evaluated and treated.

Triethyl orthoformate is considered to be slightly hazardous to water and should not be released into the environment to avoid damaging aquatic organisms. The competent authorities must be informed of the escape of larger quantities of the substance into the soil, water bodies or wastewater. As a highly flammable hazardous substance, triethyl orthoformate is subject to special transport regulations.