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Properties of substance:

ethyl chloroformate

Group of substances:

organic

Empirical formula (Hill's system for organic substances):

C3H5ClO2

Structural formula as text:

ClCOOC2H5

Molar/atomic mass: 108.524

Boiling point (°C):

92.5-92.6

Synthesis 1:

Reference: Adams R., Kamm O., Marvel C.S. Organic Chemical Reagents / University of Illinois bulletin. - 23 June 1919. - Vol. XVI, No. 43 pp. 42-43


C2H5OH + COCl2 → C2H5OCOCl + HCl

In a 3 L. flask fitted with a reflux condenser and a tube through which the phosgene may be passed are placed 736 g. (16 mols) of absolute alcohol. This is cooled to 0° and the phosgene passed in until the weight of the alcohol and flask has increased by 1090 g. (11 mols). During this operation, the temperature must be kept down below 10° or else a considerable by-product of diethyl carbonate results. Moreover, the low temperature causes the hydrochloric acid which is evolved in the reaction to remain in solution in the alcohol so that a fairly accurate weight of the phosgene which has entered can be obtained. The mixture, after the phosgene has been passed in, is allowed to stand for 30 min. below 10° in order to be certain that the phosgene has completely reacted and is then allowed to warm up to room temperature. The reaction mixture is now washed twice with an equal volume of ice water in order to remove the slight excess of alcohol, the chlorocarbonic ester dried over calcium chloride and distilled. The yield of pure product, boiling 93—96°, amounts to 1070 g. (90% theory). From a large tank of phosgene, the required amount of phosgene may be passed into the alcohol in the course of about 7 hrs. It is probable that with a lower temperature, the phosgene could be passed in even more rapidly.

If the directions are carefully followed, no phosgene is present when the reaction mixture is ready to be washed with water; it is advisable, however, to run this part of the experiment also under the hood. If the reaction mixture is not allowed to warm up to room temperature before getting out the pure chlorocarbonic ester, there is generally some phosgene unchanged. During this rise in temperature a little diethyl carbonate is formed which remains as the high boiling fraction in the final distillation. After all the phosgene has been passed in, the reaction mixture must not be allowed to stand too long or else certain amounts of diethyl carbonate are produced. In one run for example, the reaction mixture stood at room temperature over night after two-thirds of the phosgene had been added. The next morning, the other third was introduced and then the product was worked up in the usual way. It was found that between 20% and 30% of the total yield consisted of diethyl carbonate.

If the temperature is kept as low as 10° during the entrance of the phosgene and then purification of the chlorocarbonic ester within a short time is carried out only very small amounts of diethyl carbonate are produced. The amount of alcohol used in proportion to the phosgene is such that it will hold in solution readily practically all the hydrochloric acid developed in the reaction. If more phosgene is added, hydrochloric acid begins to be evolved and the total weight of the flask no longer indicates the amount of phosgene added. On a large scale where the tank of phosgene can be weighed before and after the experiment in order to get the amount used, only a slight excess of alcohol would undoubtedly be necessary.

Reactions of synthesis:

  1. [Ref.1]
    COCl2 + C2H5OH + C6H5NHCH3 → C6H5NHCH3 * HCl + C2H5OCOCl

Reactions:

  1. Yeild 47%. [Ref.1]
    C2H5OC(O)Cl + AgClO4 → C2H5OClO3 + AgCl + CO2
  2. [Ref.1aster]
    C2H5OCOCl + 2NH3 → C2H5OCONH2 + NH4Cl

Standard molar enthalpy (heat) of formation ΔfH0 (298.15 K, kJ/mol):

-505.3 (l)

Standard molar enthalpy (heat) of formation ΔfH0 (298.15 K, kJ/mol):

-462.9 (g)

References:

  1. CRC Handbook of Chemistry and Physics. - 90ed. - CRC Press, 2010. - pp. 5-23
  2. Свойства органических соединений: Справочник. - Под ред. Потехина А.А. - Л.: Химия, 1984. - pp. 358-359 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru