Ethylene glycol

  • Ethylene glycol (EG)
  • Ethylene glycol / glycol
  • Monoethylene glycol / glycol
  • Ethanediol
  • 1,2- dihydroxy
  • 1,2- ethanediol
  • Ethane -1 ,2 -diol
  • Ethylene alcohol
  • Ethylenoxidhydrat
  • Glycol / glycol
  • Genantin
  • Glysantine

Colorless, viscous liquid with a sweet taste

Liquid

1.11 g · cm -3

-16 ° C.

197 ° C

5.3 Pa ( 20 ° C)

15.1 (25 ° C)

Miscible with water, ethanol and acetone

1.4318 (20 ° C)

Attention

10 ml · m- 3, 26 mg · m-3

-460.0 KJ / mol

Template: Infobox chemical / molecular formula search available

(Mono- ) ethylene glycol ( MEG) (common name: Glycol or glycol ) is the simplest divalent alcohol with a chemical name of ethane-1 ,2 -diol. It is the simplest vicinal diol ( Methandiol or formaldehyde hydrate is a gem- diol ).

The term glycols is further employed for two classes of diols, which are derived from ethylene glycol. Of a 1,2- diol such as 1,2- propanediol. On the other hand for α, ω - diols resulting from the condensation of ethylene glycol polyethylene glycols examples are diethylene glycol ( DEG), triethylene glycol (TEG).

Extraction and production

Ethylene glycol is produced from ethylene or ethylene oxide. OMEGA in the process mono- ethylene glycol is produced at a high selectivity ( > 99%) via the intermediate stage of the ethylene carbonate.

Properties

Ethylene glycol is a colorless, viscous liquid at room temperature. The melting point is -16 ° C. Under normal pressure, the compound boils at 197 ° C. The vapor pressure function is given by Antoine corresponding log10 (P) = A- ( B / ( T C)) (P in Torr, T in ° C) with A = 9.6, B = 3225 and C = 283 in the temperature range of 53 ° C to 198 ° C.

Ethylene glycol is above the flash point flammable vapor - air mixtures. The compound has a flash point at 111 ° C. The explosion range is between 3.2 vol - % (80 g/m3) as the lower explosive limit ( LEL) and 43 vol - % ( 1090 g/m3 ) and upper explosive limit (UEL ). The ignition temperature is 410 ° C. The fabric falls within the temperature class T2.

Ethylene glycol begins to decompose at 165 ° C and is thereby released, inter alia, glycol aldehyde, glyoxal, acetaldehyde, methane, formaldehyde, carbon monoxide and hydrogen.

Use

Large consumers of ethylene glycol are the manufacturers of polyester such as polyethylene terephthalate (PET), which together with terephthalic acid (PTA ) in a polycondensation polyester melt is produced.

Furthermore, ethylene glycol is used as an absorbent for the removal of water vapor from natural gas and refinery gas or circulation of gases Hydrorefining application.

In many academic research groups, ethylene glycol is used as the solvent and at the same time as reducing agents for the liquid-phase synthesis of one-dimensional metal nanostructures.

An important application is that of ethylene glycol as an antifreeze agent. Disadvantage is the lower specific heat capacity ( 50/50-Gemisch about 3.5 kJ / (kg · K) ) as compared to pure water ( 4.18 kJ / (kg · K) ); Thus, a larger volume flow of the glycol-water mixture is required to transport the same amount of heat as with pure water. In return, the boiling point of the mixture compared to pure water rises, at 50/50 to 108 ° C.

The use of ethylene glycol - water mixtures as heat transfer medium in the cooling or heating systems can continue - such as improper installation, operation and when using partially air-permeable plastic pipes - oxygen get into the liquid; so there is a risk of oxidation of ethylene glycol to carboxylic acids ( glycolic acid, formic acid, oxalic acid, etc.), which can corrode metallic components of the system and require the use of additional corrosion inhibitors, inhibitors and buffers.

Safety

Ethylene glycol is classified as harmful. The main routes of exposure are the digestive system and the skin, about the former can be expected of a very rapid and almost complete absorption. Ethylene glycol is irritating to mucous membranes, especially of the eye. At high doses it also is toxic to nerve tissue, it comes to cardiovascular and metabolic disorders and kidney damage.

Furthermore, the vapors of ethylene glycol are toxic, which can lead already at 20 ° C to toxic concentrations.

Toxicity

The minimum lethal dose for humans approximately 100 ml and 1.4 g / kg body weight are given. In some cases and with optimal medical therapy, the intake of about 1000 ml of ethylene glycol was survived.

Antidote

In cases of poisoning with fomepizole is, a competitive inhibitor of alcohol dehydrogenase, an antidote is available.

CAS registry number PubChem Dangerous Substances Directive (67/548/EEC) Vicinal (chemistry) geminal OMEGA process Antoine equation Flammability limit Glycolaldehyde CRC Handbook of Chemistry and Physics Integrated Authority File
8931
de