Carbonic acid diethyl ester
|Surname||Carbonic acid diethyl ester|
|Molecular formula||C 5 H 10 O 3|
colorless liquid with an ethereal odor
|External identifiers / databases|
|Molar mass||118.13 g mol −1|
0.9764 g cm −3
−43 ° C
125.8 ° C
11 h Pa (20 ° C)
1.384 (20 ° C)
|As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C|
Presentation and extraction
Diethyl carbonate is a colorless and low-viscosity liquid that boils at 126 ° C under normal pressure. According to Antoine, the vapor pressure function results from log 10 (P) = A− (B / (T + C)) (P in bar, T in K) with A = 4.77616, B = 1721.904 and C = −37.959 in the temperature range from 263 to 399 K. The critical temperature is 296 ° C, the critical pressure is 34.6 bar. The heat capacity at 21 ° C is 210.9 J mol −1 K −1 or 1.78 J g −1 K −1 .
At higher temperatures, carbonic acid diethyl ester breaks down to carbon dioxide , ethanol and ethene . The decomposition reaction proceeds according to a first-order time law . With an activation energy of 195 kJ mol −1 and an Arrhenius factor of 1.15 10 13 s −1 , the half-lives of the decomposition are 95 h at 270 ° C, 5 h at 310 ° C, and 23 at 360 ° C min.
Carbonic acid diethyl ester forms flammable vapor-air mixtures. The compound has a flash point below 25 ° C. The explosion range is between 1.4% by volume (69 g / m 3 ) as the lower explosion limit (LEL) and 11.7% by volume (570 g / m 3 ) as the upper explosion limit (UEL). The limit gap width was determined to be 0.83 mm. This results in an assignment to explosion group IIB. The ignition temperature is 445 ° C. The substance therefore falls into temperature class T2.
Carbonic acid diethyl ester is used as a solvent for cellulose nitrate and ether, synthetic and natural resins. It is also used in organic syntheses, for example in carboethoxylation , and in the synthesis of heterocycles .
It is also produced when phosgene is “defused” . This arises from the decomposition of chloroform under the influence of oxygen and the influence of light in addition to hydrochloric acid . By adding ethanol , the chloroform can be made "phosgene-proof", because the phosgene reacts immediately with the alcohol to form harmless diethyl carbonate.
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