-
Categories
-
Pharmaceutical Intermediates
-
Active Pharmaceutical Ingredients
-
Food Additives
- Industrial Coatings
- Agrochemicals
- Dyes and Pigments
- Surfactant
- Flavors and Fragrances
- Chemical Reagents
- Catalyst and Auxiliary
- Natural Products
- Inorganic Chemistry
-
Organic Chemistry
-
Biochemical Engineering
- Analytical Chemistry
- Cosmetic Ingredient
-
Pharmaceutical Intermediates
Promotion
ECHEMI Mall
Wholesale
Weekly Price
Exhibition
News
-
Trade Service
Halogens mainly exist in the form of X - in nature , so the preparation of halogen elements can be done by oxidizing halide ions
.
1.
Preparation of F2
Fluorine is highly oxidizing.
Generally, it is not used chemical method to oxidize F - to prepare F 2 , but electrolysis method is used to prepare F 2
.
Generally, elemental fluorine is prepared by electrolyzing a mixture of HF and KF
2KHF 2 =2KF+F 2 +H 2
The anode of the electrolytic cell gets F 2 , and the cathode gets H 2
.
The two gases produced by electrolysis must be strictly separated and exported in time to prevent explosion
In 1986, chemist K.
Christe successfully synthesized elemental fluorine chemically
.
He uses KMnO 4 , HF, KF, HO 2 , and SbCl 5 as raw materials to prepare K 2 MnF 6 and SbF 5 first
KaMnF 6 and SbF 5 are then used to prepare MnF 4
.
MnF 4 is unstable and decomposes to obtain F 2
In the laboratory, heating and decomposing fluorine-containing compounds are often used to produce elemental fluorine, such as
BrF 5 =BrF 3 +F 2
This actually releases the stored fluorine
.
2.
Preparation of Cl 2
Industrial preparation of Cl 2 is mainly electrolysis of saturated brine
.
When electrolytically molten chloride is used to prepare active metal, chlorine gas with higher purity can also be obtained
.
For example, electrolysis of molten MgCI2 2 can be Mg and CI 2
MgC1 2 =Mg+Cl 2
Manganese dioxide and concentrated hydrochloric acid are commonly used in laboratories to prepare a small amount of chlorine under heating conditions
.
The easiest way is to oxidize concentrated hydrochloric acid with potassium permanganate
.
The advantage is that no heating is required, but the disadvantage is that the reaction is difficult to control and the price is relatively high
2KMnO .
4 + 16HCI (conc.
) = 2KCI 2MnCl + 2 + 5Cl 2 + 8H 2 O
3.
Preparation of Br 2
Under acidic conditions, the concentrated seawater is oxidized with Cl 2 to generate elemental bromine
.
Cl 2 + 2Br - = Br 2 + 2Cl -
The generated Br 2 is blown out with air and absorbed with Na 2 CO 3 solution
.
3Br 2 + 3Na 2 CO.
'S .
3 = 5NaBr + NaBrO3 .
3 + 3CO 2
Acidification of the absorption liquid will release the elemental bromine
.
5HBr+HBrO 3 = 3Br 2 +3H 2 O
In the laboratory, elemental bromine is prepared by oxidizing bromide under acidic conditions with an oxidizing agent
.
4.
2 Preparation
The content of iodine in seawater is low, but it is enriched in seaweed plants
.
Under acidic conditions, the seaweed ash can be leached with water to dissolve the I -in it , and then oxidized to produce elemental iodine
.
2I - + of MnO 2 + 4H + = the I 2 + Mn 2+ + 2H 2 O
After evaporation, concentration, filtration, sublimation and sublimation, relatively pure elemental iodine is obtained
.
The concentrated NalO 3 solution is reduced with NaHSO 3 to obtain elemental iodine
.
2IO .
3 - + 5HSO .
3 - = the I 2 + 3HSO .
4 - + 2SO .
4 2- + H 2 O
The method of preparing a small amount of elemental iodine in the laboratory is similar to that of preparing elemental bromine
.
