Sodium azide

Phototransformation in water

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Study type:

not specified

Principles of method if other than guideline:

no data

GLP compliance:

not specified

Radiolabelling:

not specified

Analytical method:

not specified

Light source:

not specified

Light spectrum: wavelength in nm:

ca. 214 - ca. 254

Reference substance:

not specified

Dark controls:

not specified

Quantum yield (for direct photolysis):

1

Transformation products:

yes

No.:

#1

No.:

#2

Validity criteria fulfilled:

not specified

Conclusions:

Sodium azide readily hydrolyzes in aqueous media to hydrazoic acid (HN3).
Photolysis of aqueous HN3 at 214 nm or 254 nm obeys the following stoichiometry with a quantum yield of 1.00 ± 0.05 for all N-containing species:
HN3 + H2O → N2 + NH2OH
Ammonia, N2H4, NOx and H2 were not detected.

Executive summary:

Sodium azide readily hydrolyses in aqueous media to hydrazoic acid (HN3).

Photolysis of aqueous HN3 at 214 nm or 254 nm obeys the following stoichiometry with a quantum yield of 1.00 ± 0.05 for all N-containing species: HN3+ H2O → N2+ NH2OH

Ammonia, N2H4, NOx and H2 were not detected.

 

Reference 2

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Review article which does not give sufficient information on experimental details; no reference is given with respect to phototransformation, thus documentation is insufficient.

GLP compliance:

not specified

Details on results:

Sodium azide is stable in water in the absence of light but appears to be susceptible to photodecomposition by solar radiation. Photolysis of sodium azide may result in metal nitrides initially, with the eventual formation of the free metal and nitrogen gas.

Validity criteria fulfilled:

not applicable

Conclusions:

Sodium azide is stable in water in the absence of light but appears to be susceptible to photodecomposition by solar radiation. Photolysis of sodium azide may result in metal nitrides initially, with the eventual formation of the free metal and nitrogen gas.

Executive summary:

Sodium azide is stable in water in the absence of light but appears to be susceptible to photodecomposition by solar radiation. Photolysis of sodium azide may result in metal nitrides initially, with the eventual formation of the free metal and nitrogen gas.

Description of key information

Two secondary sources on sodium azide are available that discuss the photo transformation of sodium azide in water. Both of these studies suggest that Sodium azide is likely to undergo transformation in water when exposed to light. Numerous reaction products are suggested, including nitrogen gas, metal nitrides and hydroxylamine. However, Betterton (2003) refers to experiments performed at 214 and 254 nm, i.e. in far ultraviolet range, which is outside the wavelength band of interest for aqueous photolysis. The U.S. EPA hazard information profile (1977) does not give any information about the study design or sources, but states that Sodium azide is stable in water in the absence of light. It appears to be susceptible to photodecomposition by solar radiation. Photolysis of sodium azide may result in metal nitrides initially, with the eventual formation of the free metal and nitrogen gas.

In conclusion, direct photo transformation of sodium azide in water can be considered to be insignificant.