Triacetin, is the

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

with the formula . It is classified as a

triglyceride A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and ''glyceride''). Triglycerides are the main constituents of body fat in humans and other vertebrates, as ...

, i.e., the triester of

glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

. It is a colorless, viscous, and odorless liquid with a high boiling point and a low melting point. It has a mild, sweet taste in concentrations lower than 500 ppm, but may appear bitter at higher concentrations. It is one of the glycerine acetate compounds.

Uses

Triacetin is a common

food additive Food additives are substances added to food to preserve Taste, flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), sal ...

, for instance as a

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

flavouring A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of the gus ...

s, and for its

humectant A humectant is a hygroscopic (water-absorbing) substance used to keep things moist. They are used in many products, including food, cosmetics, medicines and pesticides. When used as a food additive, a humectant has the effect of keeping moistur ...

function, with

E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

E1518 and Australian approval code A1518. It is used as an

excipient An excipient is a substance formulated alongside the active ingredient of a medication, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred ...

in pharmaceutical products, where it is used as a humectant, a

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticiz ...

, and as a solvent.

Potential uses

The plasticizing capabilities of triacetin have been utilized in the synthesis of a biodegradable phospholipid gel system for the dissemination of the cancer drug

paclitaxel Paclitaxel (PTX), sold under the brand name Taxol among others, is a chemotherapy medication used to treat a number of types of cancer. This includes ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical ca ...

(PTX). In the study, triacetin was combined with PTX, ethanol, a phospholipid and a medium chain triglyceride to form a gel-drug complex. This complex was then injected directly into the cancer cells of

glioma A glioma is a type of tumor that starts in the glial cells of the brain or the spine. Gliomas comprise about 30 percent of all brain tumors and central nervous system tumours, and 80 percent of all malignant brain tumours. Signs and symptoms ...

-bearing mice. The gel slowly degraded and facilitated sustained release of PTX into the targeted glioma cells. Triacetin can also be used as a

fuel additive Petrol additives increase petrol's octane rating or act as corrosion inhibitors or lubricants, thus allowing the use of higher compression ratios for greater efficiency and power. Types of additives include metal deactivators, corrosion inhib ...

as an

antiknock agent An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel's octane rating by raising the temperature and pressure at which auto-ignition occurs. The mixture known as gasoline or petrol, when used in high com ...

which can reduce

engine knocking In spark ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignit ...

gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...

, and to improve cold and

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

properties of

biodiesel Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat ( tallow), soybean oil, or some other vegetable oi ...

. It has been considered as a possible source of

food energy Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscular activity. Most animals derive most of their energy from aerobic respiration, namely combining the carbohy ...

in artificial food regeneration systems on long

space mission Spaceflight (or space flight) is an application of astronautics to fly spacecraft into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in o ...

s. It is believed to be safe to get over half of one's dietary energy from triacetin.

Synthesis

Triacetin was first prepared in 1854 by the French chemist

Marcellin Berthelot Pierre Eugène Marcellin Berthelot (; 25 October 1827 – 18 March 1907) was a French chemist and Republican politician noted for the ThomsenBerthelot principle of thermochemistry. He synthesized many organic compounds from inorganic substa ...

. Triacetin was prepared in the 19th century from

and

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main componen ...

. Its synthesis from

acetic anhydride Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH3CO)2O. Commonly abbreviated Ac2O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis. It is a co ...

and glycerol is simple and inexpensive. : 3 + 1 → 1 + 3 This synthesis has been conducted with

catalytic Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and al ...

and microwave irradiation to give a 99% yield of triacetin. It has also been conducted with a

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

(II)

Salen complex A metal salen complex is a coordination compound between a metal cation and a ligand derived from ''N'',''N''′-bis(salicylidene)ethylenediamine, commonly called salen. The classical example is salcomine, the complex with divalent cobalt , usual ...

catalyst supported by

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

and heated to 50 °C for 55 minutes to give a 99% yield of triacetin.

Safety

The

US Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

has approved it as Generally Recognized as Safe
GRAS
food additive and included it in the database according to the opinion from the Select Committee On GRAS Substances (SCOGS). :"''Triacetin and two types of acetooleins have been found to be without toxic effects in long-term feeding tests in rats at levels that were several orders of magnitude greater than those to which consumers are exposed. Three types of acetostearins have been found to be without toxic effects in long-term feeding tests in rats at levels up to 5 g per kg per day. This contrasts with an estimated human consumption of a fraction of a milligram per kg per day. It is recognized that at an even higher feeding level (10 g per kg per day) male rats developed testicular atrophy and female rats, uterine discoloration. However, such a level which would amount to 50 g or more for an infant and 600 g for an adult per day, is vastly higher than would be possible in the consumption of foods to which acetostearins are added for functional purposes.''" Triacetin is included in the SCOGS database since 1975. Triacetin was not toxic to animals in studies of exposure through repeated inhalation over a relatively short period.

References

{{Glycerides Acetate esters Triglycerides Plasticizers Antiknock agents Ester solvents Excipients E-number additives