4797. Hydrogen Iodide

Nomenclature

CAS number: 10034-85-2
Anhydrous hydriodic acid.
HI; mol wt 127.91.
H 0.79%, I 99.21%.

Description and references

Prepd by catalytic union of the elements: Caley, Burford, Inorg. Synth. 1, 159 (1939); Powell, Campbell, J. Am. Chem. Soc. 69, 1227 (1947). May also be prepd by treating concd hydriodic acid solns with P2O5: Schmeisser in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 286-289. Lab prepn: Hoffman, Inorg. Synth. 7, 180 (1963). Purification: A. Klemenc, Die Behandlung und Reindarstellung von Gasen (Vienna, 2nd ed., 1948) p 239; Irving, Wilson, Chem. Ind. (London) 1964, 653. Reviews of prepn and properties of HI and other hydrogen halides: Hills in Mellor's vol. II, suppl. 1 (originally published as suppl. II, part 1) 857-869 (1956); Downs, Adams, in Comprehensive Inorganic Chemistry vol. 2, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 1280-1329.

Properties

Colorless, acrid, non-flammable gas. Fumes in moist air. Decomposed by light. mp 50.8°. bp760 35.1°; bp2 atm 18.9°; bp5 atm 7.3°; bp10 atm 32.0°; bp60 atm 127.5°. d0 5.66; d25 5.23 g/l. Crit temp 151.0°, crit press. 82.0 atm. Sp heat (25°) 0.0545 cal/g/°C. Poisonous. Extremely sol in water. Soly (g/100 g H2O): 234 (10°); 900 (0°). Soly in organic solvents: Gerrard, Chem. Ind. (London) 1969, 295; Ahmed et al., J. Appl. Chem. 20, 109 (1970). Forms an azeotrope with water, see Hydriodic Acid. Reacts with the lower aliphatic alcohols forming the corresponding iodo compds. Forms a colorless liquid at atm pressure when cooled with dry ice and ether or similar cooling mixture. Attacks natural rubber.

Caution

Strong irritant.

Use

Manuf of hydriodic acid, organic iodo compds, to remove iodine from iodo compds.