Synthesis of chlorine

Preparation of elemental chlorine

Classically elemental chlorine could be prepared by treating hydrochloric acid with an oxidizing agents (manganese dioxide, potassium permanganate, potassium chromate). Chlorine prepared from potassium permanganate always contains appreciable amounts of oxygen.

Preparation of chlorine

Preparation of chlorine

One-third of a flask is filled with manganese dioxide. Manganese dioxide is treated with a quantity of concentrated hydrochloric acid which is just sufficient to cover it. On gentle heating the mixture, a regular current of chlorine is generated; this is passed through two wash bottles containing water and concentrated sulfuric acid respectively. The water retains any hydrochloric acid which is carried along with the gas, and the sulfuric acid dries it.

Preparation of chlorine

Preparation of chlorine

By slightly modified method chlorine gas could be prepared without using hydrochloric acid. In order to prepare the elemental chlorine the sodium chloride is treated with manganese dioxide and sodium bisulfate.

Preparation of chlorine by reacting sodium chloride with manganese dioxide and sodium bisulfate

Preparation of chlorine by reacting sodium chloride with manganese dioxide and sodium bisulfate

A blender is charged with 38 grams of manganese dioxide, followed by 100 grams of sodium chloride; thereafter, the mixture is blended on high speed for about 30 minutes. 233 grams of sodium bisulfate monohydrate are added, and then the blending is continued for about 10 to 15 minutes. The obtained mixture is placed into an apparatus as illustrated bellow, and then the mixture is heated to 70° C. During the heating chlorine gas will be steadily evolved. This procedure will produce about 30 grams of chlorine gas.

A glass apparatus for the preparation of chlorine

A glass apparatus for the preparation of chlorine

Kings Chem Guide Third Edition, by Jared Ledgard, 170, 2014.

Alternatively, chlorine is prepared by mixing 180 g of sodium chloride (common salt) in lumps with 150 g of finely pulverized manganese dioxide, free from calcium carbonate.

Preparation of chlorine from sodium chloride, manganese dioxide and sulfuric acid

Preparation of chlorine from sodium chloride, manganese dioxide and sulfuric acid

The mixture is placed in a flask and treated with a completely cooled mixture of 450 g of concentrated sulfuric acid and 210 g of water. The reaction flask is occasionally shaken and in a short time a uniform and continuous evolution of chlorine is obtained. The current of chlorine can be regulated by the application of a gentle heat.

A very regular current of chlorine can also be obtained from finely pulverized potassium dichromate and crude concentrated hydrochloric acid by heating the mixture on the water bath. To 1 liter of hydrochloric acid, 180-200 g of pulverized potassium dichromate are used. Potassium dichromate oxidizes hydrochloric acid, yielding chlorine free from carbon dioxide.

Preparation of chlorine from potassium dichromate and concentrated hydrochloric acid

Preparation of chlorine from potassium dichromate and concentrated hydrochloric acid

Chlorine can be prepared in a Kipps apparatus from pieces of bleaching powder and hydrochloric acid.

Laboratory manual of inorganic preparations, by H. T. Vulte, 10-27, 1895

For complete purification, chlorine washed with concentrated sulfuric acid is condensed into a receiver (preferably calibrated) cooled in ether/carbon dioxide, and a regular stream of chlorine is produced by placing the receiver in a bath of ice and water. A safety flask should be placed between the reaction flask and the chlorine supply. The following are suitable solvents for chlorine: carbon tetrachloride (8.5% of Cl2), chloroform (20% of Cl2), acetic acid (11.6g of Cl2 per 100 ml), dimethylformamide, halobenzenes, and hexachlorobutadiene.

IUPAC Name

molecular chlorine

InChI

InChI=1S/Cl2/c1-2

InChI Key

KZBUYRJDOAKODT-UHFFFAOYSA-N

Canonical SMILES

ClCl

MeSH Synonyms

Chlorine

Depositor-Supplied Synonyms

CHLORINE, Molecular chlorine, Bertholite, dichlorine, Chloor, Cloro, Chlorine gas, Chlorine mol., Chlore [French], Cloro [Italian], Chloor [Dutch], Chlor [German], Caswell No. 179, Bertholite /warfare gas/, 7782-50-5, UN 1017, Chlorinated water (chlorine), CCRIS 2280, HSDB 206, UNII-4R7X1O2820, KZBUYRJDOAKODT-UHFFFAOYSA-N, EINECS 231-959-5, UN1017, EPA Pesticide Chemical Code 020501, CL2, 81859-29-2, dichlorane, Chlorine mol, Chlorinated water, AC1L2NHV, AC1Q3VDB, 295132_ALDRICH, CHEBI:29310, CTK5E9151, Chlorine [UN1017] [Poison gas], Chlorine [UN1017] [Poison gas], AKOS015915796, 4R7X1O2820, LS-2438, FT-0693134, 3B4-2170, I14-52713, 22537-15-1

Removed Synonyms

Dichloran, Chlore, Chlor, Diatomic chlorine, Dichloran (flame retardant), CID24526, D002713

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