What Is Dihydroxyacetone?
Dihydroxyacetone is a white powder with a sweet taste and characteristic odor. Its chemical formula is C3H6O3, molecular weight 90.08, and its CAS number is 96-26-4. Dihydroxyacetone is also known as 1,3-dihydroxypropan-2-one (IUPAC name), DHA, and glycerone.
It was first discovered as a skin coloring agent by a German chemist in the 1920s, when its use in an X-ray irradiation experiment caused the skin surface to turn brown when spilled. Dihydroxyacetone is a 3-carbon ketose, and together with glyceraldehyde is the smallest monosaccharide. It is the simplest ketose without a chiral center and is the only monosaccharide that is not optically active.
Uses of Dihydroxyacetone
One use of dihydroxyacetone is in winemaking. The acetic acid bacteria acetobacter aceti and gluconobacter oxydans both utilize the ketone formation of glycerol in forming dihydroxyacetone. This formation is most likely responsible for the sweet, ethereal characteristics of the wine’s aroma. Dihydroxyacetone is said to influence the antimicrobial activity of wine because of its ability to bind to sulfur dioxide.
Other uses include an active ingredient in tanning skin care products. Common commercial products using dihydroxyacetone range from 3-5%, while professional products contain anywhere from 5-20%. They are available for coloring levels ranging from light to dark, and products with lower concentrations are easy to use for beginners.
However, multiple coats may be required to produce the desired color. Artificial tanning takes 2-4 hours to begin to appear on the skin surface, and the color darkens over a period of 24-72 hours, depending on the type of formulation.
Characteristics of Dihydroxyacetone
Dihydroxyacetone has a melting point of 82°C, a boiling point of 188°C, and a vapor pressure of 5.8 x 10-6 kPa/25°C. It has high solubility in water, but is somewhat insoluble in alcohols such as ethanol and insoluble in acetone.
Dihydroxyacetone normally forms a dimer, but in aqueous solution it changes to a monomer and becomes slightly acidic with a pH of 4 to 6. When it adheres to the skin, it reacts with amino acid residues of keratin, a protein on the skin surface, and turns yellow or brown. The pigment of the coloring component varies depending on the amino acid residue that reacts, but is collectively called melanoidin.
Other Information on Dihydroxyacetone
1. Dihydroxyacetone Manufacturing Process
Dihydroxyacetone can be synthesized by the gentle oxidation of glycerol with the structural isomer glyceraldehyde, using hydrogen peroxide and ferrous salts as catalysts. It can also be synthesized from glycerol in high yield and selectively at room temperature, also using cationic palladium catalysts with oxygen, air, or benzoquinone acting as co-oxidants.
2. Precautions for Handling and Storage
Precautions for handling and storage are as follows:
- Keep container tightly closed and store in a cool, dark place out of direct sunlight.
- Keep away from flames and high temperatures, as decomposition produces carbon monoxide and carbon dioxide.
- Take precautions when there is a possibility of contact with oxidizing agents, which are hazardous interchangeable materials.
- Take precautions to prevent dust dispersal.
- Use only outdoors or in well-ventilated areas.
- Wear protective gloves, protective glasses, protective clothing, and protective masks when using.
- Wash hands thoroughly after handling.
- In case of skin contact, wash with soap and water.
- In case of eye contact, rinse cautiously with water for several minutes.