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Sodium iodide

Basic information Outline Related chemical reaction Drug properties and Applications X-ray contrast agent Precaution and Taboo Solubility in water (g / 100ml) Chemical Properties Production method Safety Related Supplier

Sodium iodide Basic information

Product Name:
Sodium iodide
Mol File:

Sodium iodide Chemical Properties

Melting point:
661 °C(lit.)
Boiling point:
1300 °C
vapor density 
>1 (vs air)
vapor pressure 
1 hPa (767 °C)
refractive index 
Flash point:
storage temp. 
Store at RT.
water: soluble(lit.)
Specific Gravity
6-9 (50g/l, H2O, 20℃)
Water Solubility 
184 g/100 mL (25 ºC)
CAS DataBase Reference
7681-82-5(CAS DataBase Reference)
NIST Chemistry Reference
Sodium iodide(7681-82-5)
EPA Substance Registry System
Sodium iodide (7681-82-5)

Safety Information

Hazard Codes 
Risk Statements 
Safety Statements 
UN 3077 9 / PGIII
WGK Germany 
HS Code 
Hazardous Substances Data
7681-82-5(Hazardous Substances Data)
MLD i.v. in rats: 1.3 g/kg, Loeser, Konwiser, J. Lab. Clin. Med. 15, 35 (1929)



Sodium iodide Usage And Synthesis


Sodium iodide is a white solid obtained through the reaction between sodium carbonate with hydroiodic acid and further evaporation of the solution. There are anhydrous, dihydrate and pentahydrate compound. It is the raw material for the manufacturing of iodine, for being used in medicine and photography. The acidic solution of sodium iodide, due to the generation of hydroiodic acid, displays reductive capability.
Anhydrous compound has its chemical formula be NaI and the molecular weight of 149.89. It is colorless cubic crystal or white granular substance with salty taste and slightly bitter. It has a melting point of 651 ℃, boiling point of 1304 ℃, the relative density of 3.665 (4 ℃), 3.607 (25 ℃) and the refractive index of 1.7745. It is easily soluble in water (0 ℃: 159.7,20 ℃: 179.3,25 ℃: 184, 30 ℃: 190, 40 ℃: 205,50 ℃: 227,60 ℃: 257,80 ℃: 296,100 ℃:302) , ethanol (25 ℃:43.3), methanol (10 ℃:65.0,25 ℃: 78.0,40 ℃: 80.7,60 ℃:79,4), acetone (20 ℃:30.0, 80 ℃:21.8), ammonia and pyridine. It is also soluble in glycerol. It has strong hygroscopicity with gradually absorbing moisture in the air to reach the moisture content being 5%. It can turn to brown color due to release of iodine upon oxidation by air. The aqueous solution was slightly alkaline and also has the same change. You can supply a slight amount of alkaline to maintain its stability. The pH of the aqueous solution is 8-9.5. It should be stored sealed and free of light.
Its crystal is dihydrate sodium iodide with the chemical formula being NaI • 2H2O and the molecular weight being 185.92. It is colorless crystal with deliquescence and is easily soluble in water, ethanol and glycerol. It will loss crystal water at temperature above 65 ℃. Its melting point is 752 ℃. It has reduction capability. In air or aqueous solution, it is easily oxidized by oxygen in the air with its iodine being precipitated out and turning black color. It should be stored sealed and free of light.
The transition temperature of pentahydrate, dihydrate and anhydrous is as below: NaI • 5H2O---(-13.5 ℃)---NaI • 2H2O---(65 ℃)---NaI
Sodium iodide can be used as determination agent and measurement of palladium, platinum and thallium, etc through trace analysis measurement. The co-solvent of iodine (sodium iodide can form complex with iodine in an aqueous solution and can increase the iodine solubility), it can also be used as the raw materials of pharmaceuticals, photographic emulsion and single crystal.

Related chemical reaction

Sodium iodide can react with chlorine or bromine, both generating elemental iodine, and can generate sodium halide at the same time.
1. 2NaI + Cl2 = 2NaCl + I2
2. 2NaI + Br2 = 2NaBr + I2
Sodium iodide can react with acid and generate the sodium salt of the corresponding acid as well as generating hydrogen iodide, hydrogen iodide or elemental iodine at the same time.
3. NaI + H3PO4 = NaH2PO4 + HI
4. 2NaI + H3PO4 = NaH2PO4 + 2HI
5. 3NaI + H3PO4 = Na3PO4 + 3HI
6. NaI + H3Sb4 = NaH2SbO4 (white) + HI
7. NaI + H2SO4 (conc.) = NaHSO4 + HI
8. 2NaI + 3H2SO4 (conc.) = 2NaHSO4 + I2 + SO2 + 2H2O
9. NaI + HCl = NaCl + HI
Sodium iodide can react with hypochlorite, generating sodium chloride, sodium hydroxide and elemental iodine.
10. 2NaI + HOCl = NaCl + NaOH + I2
Sodium iodide, upon reaction with the following salts or oxides can generate different sodium salt.
11. NaI + 6Ce (SO4) 2 + 3H2O = NaIO3 + 3Ce2 (SO4) 3 + 3H2SO4
12. 2NaI + 4Ce (SO4) 2 + 2HCl = Na2SO4 + 2Ce2 (SO4) 2 + 2ICl + H2SO4
13. NaI + 3NaIO4 = 4NaIO3
14. 2NaI + 3NaIO4 + 3H2O = NaIO3 + 2Na2H3IO6 + I2
15. 2NaI + 2CO2 + H2O2 = 2NaHCO3 + I2
16. 2NaI + MnO2 + 3H2SO4 = 2NaHSO4 + MnSO4 + I2 + 2H2O

Drug properties and Applications

It can be used for cystography, retrograde urography, cholangiography via T-tube and fistula angiography of other parts.
Urography: 6.25% 100ml. Cystography: 6.25% 150ml. Retrograde pyelography: 12.5% ​​5~7ml. T-tube cholangiography: 12.5% ​​10~30ml. Fistula angiography: determine the injection site and dose according the state of the illness.
This information is edited by Xiongfeng Dai from Chemicalbook.

X-ray contrast agent

The Toxicity is relative large. It can’t subject to intravenous injection. Patients of liver, renal insufficiency and iodine allergies should be hanged. Iodine allergy test should be done before administration.

Precaution and Taboo

X-ray contrast agent is a drug which can take the properties of easily penetrating or not easily penetrating of X-ray as contrast so that the checked part can be developed. The current clinically used contrast agents are divided into two categories including negative contrast agent (its developing density is lower than human soft tissue) and positive contrast agent (developing density is higher than human soft tissue). Negative contrast agents include air, carbon dioxide and oxygen. Positive contrast agents, except barium sulfate, are almost all organic iodide and iodine compounds. Sodium iodide was first used in the urinary system angiography. The iodine-carbon bond of the organic iodine compound is quite stable and is not easily to form iodide with almost no physiological effects on the human body. X-ray contrast agent, after absorption and appropriate concentration in certain organs or tissues, reaching a certain concentration, can absorb X-ray for radiography. They can be divided into two categories including water-soluble and oil-soluble. According to different chemical types, the former can be divided into phthalocyanine, organic acids, sulfonic acids and pyridine ketones; the latter is mainly iodized oil. Ideal contrast agent should have the following requirements: clear developing; non-toxic, no adverse reactions; easily absorbed and excreted; stable physical and chemical properties and can be subject to long-term storage without corrosion; easy to use; easy for manufacturing and inexpensive.

Solubility in water (g / 100ml)

Solubility (grams) per 100 ml of water at different temperatures (℃):
159g/0 ℃; 167g/10 ℃; 178g/20 ℃; 191g/30 ℃; 205g/40 ℃
257g/60 ℃; 295g/80 ℃; 302g/100 ℃

Chemical Properties

It is colorless cubic crystal or white crystalline powder. It is odorless with salty taste bitter. It is easily soluble in water, soluble in methanol, ethanol, acetone, glycerol, liquid ammonia and liquid sulfur dioxide. The aqueous solution was slightly alkaline.

Production method

Eight iron iodide method: based on the mass ratio of iodine method: iron = 3.3: 1, first add the washed iron powder to the reactor; then add water with the mass ratio of the added water amount over iron being 7: 1. Successively add iodine tablet. Owing to the large amount of heating generated during the reaction between iodine and iron, we should use chilled water to cool outside of the reactor to a temperature below 65 ℃. After addition of iodine tablet, the solution turns dark red-brown. When the solution exhibits light green, add the second batch of iodine; after further removal of the iron powder by filtration, add iodine for reaction to generate eight iron iodide. Sodium bicarbonate solution was added to the vessel, add slowly with stirring of eight iron iodide for reaction and there will be carbon dioxide gas released at this time. The reaction solution was allowed to stand; the supernatant was aspirated and concentrated by evaporation to 70~72 ° Bé, filter upon hot, cool and crystallize, centrifuge, separate, and dry to obtain the finished product of sodium iodide.
Fe + I2 → FeI2
3FeI2 + I2 → Fe3I8
Fe3I8 + 8NaHCO3 → 8NaI + Fe3O4 + 4H2O + 8CO2 ↑
Reduction method of iron powder: take 100% to 103% the theoretical amount of caustic soda, add water into 10% solution and heat in the reactor to 60~80 ℃. Add quantitatively of iodine with several times, maintain the temperature of 80~90 ℃ and react upon stirring for about 1h with the reaction liquid being brown and the Ph range of 6 to 7 while there is white crystals of sodium iodide being precipitated out. The reaction solution was cooled to below 30 ℃. Add 2 times the theoretical amount of iron powder to reduce the sodium iodate to sodium iodide. At the beginning, the reaction is relative fierce. When the reaction is eased, heat to boiling and continue the stirring for reaction of 1~2h, then use 10% caustic soda solution for adjustment the Ph to 8; boil for 30min, after cooling, standing for filtration; evaporate and concentrate the colorless filtrate so that the crystal is precipitated out; further filter upon hot, dry to obtain the finished product of sodium iodide.
3I2 + 6NaOH → 5NaI + NaIO3 + 3H2O
NaIO3 + 3Fe + 3H2O → NaI + 3Fe (OH) 2

Chemical Properties

White or almost white, crystalline powder or colourless crystals, hygroscopic.

Chemical Properties

Sodium iodide, white solid, soluble, formed by reaction of sodium carbonate or hydroxide and hydriodic acid, and then evaporating. Used in photography, in medicine and as a source of iodide.

Physical properties

Physical Properties White crystalline deliquescent powder or granules; saline and slight bitter taste; absorbs moisture from air; slowly turns brown on exposure to air due to iodine evolved; density 3.67g/cm3; melts at 660°C; vaporizes at 1,304°C; vapor pressure 1 torr at 767°C and 5 torr at 857°C; very soluble in water, 178.7 g/100 mL at 20°C and 294 g/100 mL at 70°C; soluble in ethanol and acetone.


Used as iodometric reagent


ChEBI: A metal iodide salt with a Na(+) counterion.


Sodium iodide is prepared by adding hydriodic acid or an acidic iodide solution to a solution of sodium hydroxide or sodium carbonate, followed by evaporation and crystallization: NaOH + HI → NaI + H2O
The solution is filtered to remove any impurities prior to its evaporation and crystallization.


sodium iodide: A white crystallinesolid, NaI, very soluble in water andsoluble in both ethanol and ethanoicacid. It is known in both the anhydrousform (cubic; r.d. 3.67; m.p.661°C; b.p. 1304°C) and as the dihydrate(monoclinic; r.d. 2.45). It is preparedby the reaction of hydrogeniodide with sodium carbonate orsodium hydroxide in solution. Likepotassium iodide, sodium iodide inaqueous solution dissolves iodine toform a brown solution containingthe I3- ion. It finds applications inphotography and is also used in medicineas an expectorant and in the administrationof radioactive iodine for studies of thyroid function and fortreatment of diseases of the thyroid.

Safety Profile

Moderately toxic by ingestion, intravenous, and intraperitoneal routes. Human teratogenic effects by ingestion: developmental abnormalities of the endocrine system. Human reproductive effects by ingestion: effects on newborn, including postnatal measurements. A skin and eye irritant. Reacts violently with BrF3, HClO4, oxidants. When heated to decomposition it emits toxic fumes of Iand Na2O. See also IODIDES.

Purification Methods

Crystallise NaI from water/ethanol solution and dry it for 12hours under vacuum, at 70o. Alternatively, dissolve it in acetone, filter it and cool it to -20o; the resulting yellow crystals are filtered off and heated in a vacuum oven at 70o for 6hours to remove acetone. The NaI is then crystallised from very dilute NaOH, dried under vacuum, and stored in a vacuum desiccator [Verdin Trans Faraday Soc 57 484 1961].


Sodium iodide SupplierMore

Jiangsu zhenri Chemical Co., Ltd Gold
400-628-6299 0510-85686299-
Shanghai Aladdin Bio-Chem Technology Co.,LTD Gold
400-620-6333 021-20337333-801
Shandong Ono Chemical Co., Ltd. Gold
0539-6362799(To 20)
Henan Wanxiang Technology & Trade Co., Ltd. Gold
13949088811 0371-56669001-
Shanghai Kangtuo Chemical Co., Ltd. Gold
Basic information Outline Related chemical reaction Drug properties and Applications X-ray contrast agent Precaution and Taboo Solubility in water (g / 100ml) Chemical Properties Production method Safety Related Supplier