Acetone - Structure, Uses and Properties of Acetone
Acetone, also known as dimethyl ketone and propanone is the simplest, smallest and most important of all the aliphatic (fat-derived) ketones. Pure acetone is a colourless, clear liquid. It is somewhat aromatic with a pleasant fruity odour and is a volatile, flammable liquid.
Acetone is a highly miscible liquid. It readily dissolves in substances like water, ethanol, ether etc. Its freezing point is −94.7 °C. Its boiling point is 56.05 °C, while its flash point is −20 °C. Its molecular formula is CH3COCH3. Its IUPAC name is Propan-2-one. Acetone can dissolve many fats and multiple resins as well as substances like cellulose acetate, nitrocellulose, and other cellulose ethers. Acetone naturally occurs in plants, trees, volcanic gases, forest fires, and as a product of the breakdown of body fat. It is also found in small quantities in normal urine and blood, while the concentration may be higher in diabetic patients. We can detect traces of it in vehicle exhaust, tobacco smoke, and landfill sites. It is found among the many products formed in the destructive distillation of materials like wood, sugar, and cellulose, etc.
History of acetone:
Acetone was first produced and used by alchemists during the late Middle Ages. The method of manufacture at that time was via the dry distillation of metal acetates, like lead acetates. It was also called ‘spirit of Saturn’ because it was primarily produced with lead acetate, which contains lead. Lead has the same symbol as the astrological symbol for the planet Saturn.
French chemist Jean-Baptise Dumas and German chemist Justus von Liebig determined the empirical formula for acetone in 1832. French chemist Antoine Bussy named acetone by adding the suffix -one to the stem of the corresponding acid, that is acetic acid in 1833. In 1852, an English chemist named Alexander William Williamson realized that acetone was nothing but methyl acetyl. French chemist Charles Fredric concurred with the findings of Williams in the following year. In 1861 Johann Josef Loschmidt presented the structure of acetone but he did not receive any attention at that time. German Chemist August Kekule published the modern structural formula for acetone in 1865. Chaim Weizmann developed the process for industrial production of acetone during World War I. This process is wildly used to this day and is known as Weizmann Process.
Ca (CH3COO)2 → CaO(s) + CO2(g) + (CH3)2CO
Production of acetone:
Acetone is mostly produced directly or indirectly from propylene. Roughly 83% of acetone is produced by the cumene process. Since this process requires phenol, acetone production is tied to phenol production. In the cumene process, benzene is treated with alkaline propylene to produce cumene, which is oxidized by air to produce phenol and acetone.
Other than this method, the direct oxidation of propylene (also known as the Wacker-Hoechst process) or the hydration of propylene to give propanol, which can be oxidized to acetone can also be used.
The United States has the highest production capacity of acetone, followed by Taiwan and China. The largest company which produces acetone is INEOS Phenol, owning 17% of the world’s capacity. It also owns the world’s largest production site, in Beveren, Belgium, which has the capacity to produce 420,000 tonnes each year.
Uses of acetone:
2) Chemical Intermediate
3) Laboratory Use
4) Medical and Cosmetic Uses
5) Other Domestic uses
Solvent – Acetone is a good usable solvent for many plastics and a few synthetic fibers. It is used to dissolve two-part epoxies and superglue before they harden. It is also used for thinning polyester resin and cleaning tools with it. It is used in paints and varnishes as a volatile component. It is useful in the preparation of metal before painting as a heavy-duty degreaser. It is used to remove rosin flux after high-reliability soldering applications, and thus prevent rusty bolt effect.
Acetone also functions as a solvent in the pharmaceutical industry and is used as a denaturant in denatured alcohols. Acetone is also present as an excipient in multiple pharmaceutical drugs.
Although it is somewhat flammable, acetone is used as a solvent during storage and transportation of acetylene, which cannot be pressurized as a pure compound. Hence acetylene is dissolved in acetone while being transported. One-third of the world's acetone is used as a solvent.
Chemical Intermediate – Acetone is used to synthesize compounds like methyl methacrylate. It involves a conversion of acetone to acetone cyanohydrin, followed by nitrite being hydrolyzed to an unsaturated amide, which is then esterified.
Synthesis of bisphenol A is another major use of acetone. Many polycarbonates, polyurethanes, and epoxy resins constitute bisphenol A. The synthesis of bisphenol A involves the condensation of phenol along with acetone.
(CH3)2CO + 2 C6H5OH → (CH3)2C(C6H4OH)2 + H2O
Another major use of acetone is in the production of solvents methyl isobutyl alcohol and methyl isobutyl ketone. These products arise through the process of aldol condensation and give diacetone alcohol.
2 (CH3)2CO → (CH3)2C(OH)CH2C(O)CH3
Laboratory use – Acetone functions as a polar aprotic solvent in a variety of organic reactions such as SN2 reactions in the laboratory. In the process of Jones oxidation, the use of acetone is critical. It does not form an azeotrope with water, which means it has a different boiling point than water when dissolved in it. Added to this its low cost and volatility, it is commonly used as a rinsing agent in laboratory glassware. Acetone can be cooled to a low temperature up to −78 °C by using dry ice, hence is used to conduct reactions at a lower temperature. Since acetone is fluorescent under ultraviolet light, its vapor is an ideal fluorescent tracer in fluid flow experiments. Acetone is also sometimes used as precipitator for proteins.
Medical and Cosmetic use – Acetone is widely used in many general medicines and cosmetic product. It is also a component listed as a food additive and used in nail polish remover and paints thinner. Dermatologist for acne treatments uses acetone to peel off dry skin.
Acetone is also used in chemical peeling treatments. Prior to chemexfoliation, acetone is used to clean the skin and remove excess fat.
Other domestic uses – Acetone is used in nail polish remover and paint thinners. Acetone is a component of superglue remover too. It also removes residue from glass and porcelain. It is also used by makeup artists to remove skin adhesives. Vapor polishing of printing artifacts on 3-D printed models applies acetone. This technique is called acetone vapor bath smoothing. Low-grade acetone is also sometimes used as a glassware rinsing agent for removing residue in academic laboratories before a final wash.
Extra-terrestrial Occurrence of Acetone:
On 30 July 2015, upon the first touchdown of Philae lander on the surface of comet 67P, scientists reported that measurements by COSAC and Ptolemy instruments revealed sixteen organic compounds on the surface of the comet. Four of these organic compounds were not seen on any other comet before this occasion. One of the four organic compounds happened to be acetone.