Sodium chlorite (NaClO2) is a white crystalline solid, being able to accelerate the burning of organic substances. It is used in paper manufacture, water purification bleaching wood pulp, textile, fats, and oils, as a disinfectant and in many other fields. In the organic synthesis, it can be frequently used for the oxidation of aldehydes to carboxylic acids. It can also be used to convert Alkyl furans to the 4-oxo-2-alkenoic acids. Moreover, the acidified sodium chlorite (mixture of sodium chlorite with acid such as citric acid) can be used for the sanitation of the hard surfaces as well as rinsing of many foods. In Army, it can be used to combating contaminants such as benigh microbes and food pathogens.
Crystallise the chlorite from hot water and store it in a cool place. It has also been crystallised from MeOH by counter-current extraction with liquid ammonia [Curti & Locchi Anal Chem 29 534 1957]. A major impurity is chloride ion which can be removed by recrystallisation from 0.001M NaOH. [Schmeisser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 312 1963.]
SODIUM CHLORITE SOLUTION is an oxidizing agent. Can react with acids to form spontaneously explosive chlorine dioxide gas (ClO2). Reacts with ammonia to produce ammonium chlorite, which is shock-sensitive. Finely divided metallic or organic substances in dry mixture with chlorites are highly flammable and may be ignited on friction (Lab. Gov. Chemist 1965). A mixture of organic matter and solid sodium chlorite can be extremely sensitive to heat, impact, or friction (Diox Process 1949). Sodium chlorite reacts very violently with organic materials containing divalent sulfur or with free sulfur (may ignite).
ChEBI: An inorganic sodium salt in which chlorite is the counterion.
LD50166mg/kg (rats, per os).
Chlorine dioxide can be produced in use and staying in the air containing 45mg/kg chlorine dioxide for several hours can lead to death for a groundhog. It is irritating to respiratory mucous and eyes.
TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
Air & Water Reactions
Soluble in water.
The industrial production includes hydrogen peroxide method and electrolysis method.
For hydrogen peroxide method, we dissolve sodium chlorate in water to obtain the solution containing 250 g/L sodium chlorate, add chlorine dioxide generator and then adjust sulfuric acid into 4mol/L H2SO4. Add the gas mixture containing sulfur dioxide and air mixture and 4mol/L H2S04 into the chlorine dioxide generator to react, pass the chlorine dioxide gas generated through 3 bubbling absorption towers in series and obtain the solution containing 140 ~ 160 g/L NaClO2 after the reaction with 27.5% hydrogen peroxide and 18% ~ 20% liquid caustic soda. The clear liquor after the precipitation is the liquid sodium chlorite product. Control the concentration of sodium chlorite solution between 350g/L and 400g/L by evaporation and concentration and then obtain the finished product of solid sodium chlorite after cooling crystallization, filtration and drying. As follows:
For electrolysis method, we dissolve sodium chlorate in mixed acid composed by water and sulfuric acid with 260g sodium chlorate in per milliliter, add the mixed acid into chlorine dioxide generator to react with the mixed gas made up of sulfur dioxide and air (containing 8% ~ 10% sulfur dioxide), take 15% chlorine dioxide gas generated into the cathode chamber of electrolytic bath and add brine and distilled the water continuously in the anode chamber to carry out electrolysis to generate the sodium chlorite solution containing about 20% sodium chlorite. We can obtain the finished product of solid sodium chlorite after removing the trace of free chlorine dioxide and spray-drying at 130℃, or by evaporation concentration, cooling crystallization, filtration and drying. As follows:
A colorless liquid consisting of sodium chlorite dissolved in water. Corrosive to skin and/or metals.
The sodium test (IT-28) is positive.
With the addition of dilute hydrochloric acid in the 5% sample liquid, yellow gas should be produced and the liquid becomes yellow-brown.
The litmus red test paper turns blue after soaking up with 5% sample liquid infiltration.
Sodium chlorite is a kind of efficient bleacher and bactericide. It is used for bleaching of pulp and various fibers such as cotton, linen, mulberry, reed, viscose fiber and so on. It can also bleach sugar, flour, starch, ointment, wax, oil, etc. It is also used for leather depilation, surface treatment of certain metals, water purification, sewage treatment, etc. It can also be used to purify trace amounts of nitric oxide in coke oven gas.
Weigh accurately 100 mg of the sample and dissolve it in water to make 250ml. Take 20ml of its solution in the iodine flask, add 12ml of 1mol/L of sulfuric acid and 25ml of potassium iodide test solution (TS-192), plug tightly at once, keep it in the dark for 5min and then add 0.5ml of starch test solution (TS-235). Use 0.1mol/L sodium thiosulfate solution to titrate and carry out the blank test at the same time. Per milliliter of 0.1mol/L sodium thiosulfate solution acts as 2.261mg sodium chlorite (NaClO2).
Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.