1,2-Propanediol

1,2-Propanediol, also known as Propylene glycol, is a colorless, odorless, viscous, highly hygroscopic liquid with a faintly sweet taste. It is miscible with water, ethanol, ether, chloroform, acetone and other organic solvents. The solubility to hydrocarbons and chlorinated hydrocarbons is small, but it is strong than ethylene glycol. 1,2-Propanediol contains an asymmetrical carbon atom, so it exists in two optically active forms (dextrorotatory and sinistrorotatory isomers). And the commercial 1,2-propanediol is a racemic mixture.

Preparation: 1,2-Propanediol can be obtaine by epoxypropane. It includes direct hydration and indirect hydration. The direct hydration is the reaction of epoxypropane and water at 150-160 °C and 0.78-0 .98 MPa. After evaporation and distillation, 1,2-propanediol is obtained. The indirect hydration is the reaction of epoxypropane and water in the presence of catalyst sulfuric acid. In addition, 1,2-propanediol also can be produced by direct catalytic oxidation from propylene. The catalyst is anhydrous tertiary butanol.

Uses: 1,2-Propanediol is an important raw material in unsaturated polyester, epoxy resins, polyurethane resins, plasticizers and surfactants. The amount occupies about 45% of total consumption. This unsaturated polyester is largely used for surface coatings and reinforced plastics. Because of good viscosity and moisture absorption, and non-toxic, 1,2-Propanediol is widely used as a hygroscopic agent, antifreeze, lubricants and solvents in the food, pharmaceutical and cosmetics industries. In the food industry, 1,2-propanediol and fatty acid reacts to produce propylene glycol ester of fatty acid, which is mainly used as food emulsifier. It is also used as solvent for spices, seasonings and food coloring. What's more, 1,2-propanediol is used as a humidifying agent of tobacco, mildew preventive, fruit ripening preservatives, film-forming coatings additives, antifreeze and heat transfer media, etc. It is often used as a substitute for ethanol and glycerol. In pharmaceutical industry, 1,2-propanediol is commonly used as solvent in the manufacture of various types of ointment, softener, excipients, preservatives, vitamins, penicillin, etc. As 1,2-propanediol has good solubility with various spices, it is also used as solvent of cosmetic and softeners, etc.

Safty: The 1,2-propanediol is low toxicity. So the acute oral toxicity is very low, and large quantities are required to cause perceptible health damage in humans. In the human body, 1,2-propanediol is metabolized into pyruvic acid (a normal part of the glucose-metabolism process, readily converted to energy), lactic acid (a normal acid generally abundant during digestion), acetic acid (handled by ethanol-metabolism), and propionaldehyde.

Other properties: (1)# of Rule of 5 Violations: 0; (2)ACD/BCF (pH 5.5): 1; (3)ACD/BCF (pH 7.4): 1; (4)ACD/KOC (pH 5.5): 6.738; (5)ACD/KOC (pH 7.4): 6.738; (6)#H bond acceptors: 2; (7)#H bond donors: 2; (8)#Freely Rotating Bonds: 3; (9)Polar Surface Area: 40.46 Å²; (10)Index of Refraction: 1.43; (11)Molar Refractivity: 18.976 cm³; (12)Molar Volume: 73.444 cm³; (13)Polarizability: 7.523×10^-24 cm³; (14)Surface Tension: 38.004 dyne/cm; (15)Density: 1.036 g/cm³; (16)Flash Point: 107.222 °C; (17)Enthalpy of Vaporization: 49.011 kJ/mol; (18)Boiling Point: 184.848 °C at 760 mmHg; (19)Vapour Pressure: 0.204 mmHg at 25°C.

Structure Descriptors:
1. Smiles:C([C@@H](C)O)O
2. InChI:InChI=1/C3H8O2/c1-3(5)2-4/h3-5H,2H2,1H3 

Toxicity: