Sodium iodide is commonly used to treat and prevent iodine deficiency.
Sodium iodide is used in polymerase chain reactions, and also (as an acetone solution) in the Finkelstein reaction, for conversion of an alkyl chloride into an alkyl iodide. This relies on the insolubility of sodium chloride in acetone to drive the reaction.
R-Cl + NaI R-I + NaCl
Sodium iodide doped with thallium, NaI(Tl), when subjected to ionizing radiation, emit photons (i.e., scintillate) and are used in scintillation detectors, traditionally in nuclear medicine, geophysics, nuclear physics, and environmental measurements. NaI(Tl) is the most widely used scintillation material and has the highest light yield of the commonly used scintillators. The crystals are usually coupled with a photomultiplier tube, in a hermetically sealed assembly, as sodium iodide is hygroscopic. Fine-tuning of some parameters (i.e., radiation hardness, afterglow, transparency) can be achieved by varying the conditions of the crystal growth. Crystals with a higher level of doping are used in X-ray detectors with high spectrometric quality. Sodium iodide can be used both as single crystals and as polycrystals for this purpose.
The radioactive iodide salt of sodium, Na131I, is used for the treatment of thyroid cancer and hyperthyroidism.
Solubility data
Solubility of NaI in various solvents
(g NaI / 100g of solvent at 25C)
H2O
184
Liquid ammonia
162
Liquid sulfur dioxide
15
Methanol
62.5 - 83.0
Formic acid
61.8
Acetonitrile
24.9
Acetone
28.0
Formamide
57 - 85
Acetamide
32.3
Dimethylformamide
3.7 - 6.4
References
^ The Free Dictionary: sodium iodide 131I
^ Burgess, J. "Metal Ions in Solution" (Ellis Horwood, New York, 1978) ISBN 0-85312-027-7
See also
Gamma spectroscopy
Scintillation counter
Teratology
External links
International Chemical Safety Card 1009 - Sodium Iodide (Anhydrous)
Material Safety Data Sheet (MSDS) - Safety data for sodium iodide
Sodium Iodide Consumer Information
Surveillance and Measurement (SAM) Model 940 Radioactive Isotope Identification Device
