Synthesis of phosgene

Preparation of phosgene

In the laboratory, phosgene may be easily prepared by treating chloroform with chromic acid mixture (Ber., 1869, 2, 547). However, phosgene prepared by this method is impure and contains chloroform and chlorine.

Preparation of phosgene by treating chloroform with chromic acid mixture

Preparation of phosgene by treating chloroform with chromic acid mixture

Preparation of phosgene from oleum and carbon tetrachloride

More convenient phosgene could be prepared by reaction of CCl4 and oleum.

Preparation of phosgene by reaction of CCl4 and oleum

Preparation of phosgene by reaction of CCl4 and oleum

100 ml of carbon tetrachloride are placed in a flask connected with the dropping funnel containing 120 ml oleum (80% free sulfur trioxide), thermometer and a reflux condenser.

A glass apparatus for the preparation of phosgene by reaction of carbon tetrachloride with oleum

A glass apparatus for the preparation of phosgene by reaction of carbon tetrachloride with oleum

The flask reaction flask is gently heated while oleum is allowed to enter drop by drop from the dropping funnel. The phosgene formed in the reaction flask is purified by passing through the concentrated sulfuric acid. Further phosgene is liquefied by passing through condensation receivers, externally cooled with a freezing mixture of  calcium chloride and ice. After addition of all the oleum reaction flask is heated for about 5 minutes. Phosgene prepared by this method has carbon tetrachloride and sulfuryl chloride impurities.

The war gases chemistry and analysis, by M. Sartory, 59-62, 1939

Preparation of phosgene from 100% sulfuric acid and carbon tetrachloride

Preparation of phosgene from 100% sulfuric acid and carbon tetrachloride

Preparation of phosgene from 100% sulfuric acid and carbon tetrachloride

The apparatus consists of a flask with a short reflux condenser; a dropping funnel and delivery tube leading to an empty wash bottle are fitted into the top of the condenser. The wash bottle is connected to a Buchner flask, which acts as a receiver. 100% sulfuric acid, to which 2 % by weight of ignited kieselguhr has been added, is placed in the flask, meanwhile, carbon tetrachloride is introduced into the dropping funnel and dry toluene into the receiver. The sulfuric acid is heated to 120-130° C in an oil bath and the carbon tetrachloride is allowed to drop in slowly. The resulting phosgene is absorbed in the toluene, whilst the hydrogen chloride passes on.

A text book of practical organic chemistry, by A. I. Vogel, 198, 1974

Preparation of phosgene from chlorine and carbon monoxide

Phosgene also could be prepared  directly reacting carbon monoxide and chlorine in presence of catalyst (activated carbon).

Preparation of phosgene from chlorine and carbon monoxide

Preparation of phosgene from chlorine and carbon monoxide

For the preparation of phosgene the equipment is prepared as shown below.

A glass apparatus for the preparation of phosgene by reacting chlorine and carbon monoxide

A glass apparatus for the preparation of phosgene by reacting chlorine and carbon monoxide

To a wide-mouthed glass flask which is properly closed with the inlet tubes for chlorine and carbon monoxide and outlet connected with condenser filled with granules of activated carbon. The other end of the condenser is connected to the externally cooled receivers for the liquefying of phosgene with a freezing mixture of ice and calcium chloride.

Separately carbon monoxide and chlorine is passed through a washing bottles containing sulfuric acid, and introduced into the wide-mouthed glass flask where the gases mixes. The chlorine is passed in at the rate of five or six bubbles a second and the carbon monoxide at eight or nine bubbles a second. The reaction takes place in the condenser where charcoal becomes heated as the two gases pass through the charcoal.  The condenser should be well cooled with cold water. Obtained phosgene is liquefied by passing through condensation receivers, externally cooled with a freezing mixture of calcium chloride and ice.

The war gases chemistry and analysis, by M. Sartory, 59-62, 1939

IUPAC Name

carbonyl dichloride

InChI

InChI=1S/CCl2O/c2-1(3)4

InChI Key

YGYAWVDWMABLBF-UHFFFAOYSA-N

Canonical SMILES

C(=O)(Cl)Cl

MeSH Synonyms

Phosgene

Depositor-Supplied Synonyms

PHOSGENE, Carbonic dichloride, Carbonyl dichloride, Carbonyl chloride, Carbon oxychloride, Phosgen, Chloroformyl chloride, Carbonic chloride, Carbon dichloride oxide, Carbonylchlorid, Fosgeen, Fosgen, Dichloroformaldehyde, Fosgene, Carbonic acid dichloride, Combat gas, Carbone (oxychlorure de), Phosgene solution, RCRA waste number P095, Fosgeen [Dutch], Fosgen [Polish], Koolstofoxychloride, Phosgen [German], Fosgene [Italian], 75-44-5, NCI-C60219, Carbonylchlorid [German], Carbonio (ossicloruro di), RCRA waste no. P095, Koolstofoxychloride [Dutch], UN 1076, HSDB 796, Cartridge for Phosgene Generation, dichloromethanone, YGYAWVDWMABLBF-UHFFFAOYSA-N, Carbone (oxychlorure de) [French], EINECS 200-870-3, Carbonio (ossicloruro di) [Italian], UN1076, UNII-117K140075, BRN 1098367, Triphosgene, Cartridge for Phosgene Generation, chloroketone, dichloroketone, carbonylchloride, chloro ketone, dichloromethane one, AC1L1MDO, AC1Q3GYF, 79372_ALDRICH, 79380_ALDRICH, 519758_ALDRICH, 519782_ALDRICH, 681776_ALDRICH, SCHEMBL4685827, 79372_FLUKA, 79380_FLUKA, CHEBI:29365, CTK2H7567, Phosgene [UN1076] [Poison gas], Phosgene [UN1076] [Poison gas], AKOS015915019, AN-23855, LS-105937, FT-0654575, Cartridge for Phosgene Generation, Starter Kit, 4-03-00-00031 (Beilstein Handbook Reference), I14-7264, 117K140075, Triphosgene, Cartridge for Phosgene Generation, Starter Kit

Removed Synonyms

COCl2, CID6371, D010705, CG, 2602-42-8

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