Diethylene glycol,  also known as 2,2'-oxybisethanol, is colorless, virtually odorless, viscous, hygroscopic liquid with a sweetish taste. It has a higher boiling point, viscosity and specific gravity compared to MEG. It is miscible with water, ethanol, ethylene glycol, acetone, chloroform, and furfural, but not miscible with ether, carbon tetrachloride, carbon disulfide, straight-chain aliphatic hydrocarbons, or aromatic hydrocarbons. Diethylene glycol is an important industrial solvent. It is utilized in the manufacture of unsaturated polyesters, plasticizer and some important resins. 

Diethylene glycol is one kind of glycols derived from oxirane. These glycols have the formula HOCH₂CH₂(OCH₂CH₂)_nOH are:
n = 0 ethylene glycol; MEG
n = 1 DEG
n = 2 triethylene glycol, TEG, or triglycol
n = 3 tetraethylene glycol
n = 4 pentaethylene glycol
n > 4 polyethylene glycol

Preparation: Diethylene glycol is produced as a by－product, along with triethylene glycol, in the manufacture of ethylene glycol from hydrolysis of ethylene oxide. The industry generally operates to maximize MEG production. Availability of DEG will depend on demand for derivatives of the primary product, ethylene glycol, rather than on DEG market requirements.

Uses: Diethylene glycol is used to produce unsaturated polyester resins, plasticizers, polyurethanes, rubber, fiberglass, oil viscosity improver, and so on. It is also used as antifreeze, gas dehydration, plasticizer, solvent, aromatics extraction agent, cigarette hygroscopic agent, textile lubricant and finishing agent, antidesiccant of paste and a variety of glue, etc. What's more, it is used as solvent for oil, resins, nitrocellulose, printing ink, dyes and other organic compounds. Although a dilute solution of diethylene glycol can also be used as a coolant, ethylene glycol is much more commonly used.

Safty: Firstly, diethylene glycol is irritant, and may cause inflammation to the skin or other mucous membranes. Then, it is harmful and may cause damage to health. Besides, it is toxic and may at low levels cause damage to health. And it could even cause heritable genetic damage. Therefore, if swallowed, seek medical advice immediately and show this container or label. Despite the discovery of diethylene glycol's toxicity in 1937 and its involvement in mass poisonings around the world, it also has caused many deaths in different countries. In China, it was also used as a component of cheap toothpaste and winemakers as an adulterant to create a "sweet" wine. Besides China, there also many countries has been damaged by diethylene glycol. Such as: 1937-The Massengill Incident (United States), 1969–South Africa, 1985-Spain, 1985-Wine Scandal, 1986–India, 1990-Nigeria, 1990-1992-Bangladesh, 1992-Argentina, 1995-1996-Haiti, 2006-China, 2006-Panama, 2007-Worldwide toothpaste incident, and 2008 - Nigeria.

Other properties: (1)ACD/BCF (pH 5.5): 1; (2)ACD/BCF (pH 7.4): 1; (3)ACD/KOC (pH 5.5): 3.58; (4)ACD/KOC (pH 7.4): 3.58; (5)#H bond acceptors: 3; (6)#H bond donors: 2; (7)#Freely Rotating Bonds: 6; (8)Polar Surface Area: 49.69; (9)Index of Refraction: 1.442; (10)Molar Refractivity: 25.39 cm³; (11)Molar Volume: 95.9 cm³; (12)Polarizability: 10.06 ×10^-24 cm³; (13)Surface Tension: 42.1 dyne/cm; (14)Density: 1.106 g/cm³; (15)Flash Point: 143.3 °C; (16)Enthalpy of Vaporization: 56.1 kJ/mol; (17)Boiling Point: 245.7 °C at 760 mmHg; (18)Vapour Pressure: 0.00469 mmHg at 25°C; (19)Exact Mass: 106.062994; (20)MonoIsotopic Mass: 106.062994; (21)Topological Polar Surface Area: 49.7; (22)Heavy Atom Count:7; (23)Formal Charge: 0; (24)Complexity: 26.1.

Structure Descriptors:
1. Smiles:O(CCO)CCO
2. InChI:InChI=1/C4H10O3/c5-1-3-7-4-2-6/h5-6H,1-4H2

Toxicity: