Sodium azide

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

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

Principles of method if other than guideline:

no data

GLP compliance:

not specified

Radiolabelling:

not specified

Analytical monitoring:

not specified

Estimation method (if used):

no data

Positive controls:

not specified

Negative controls:

not specified

Transformation products:

yes

No.:

#1

No.:

#1

Methodological problems arise from the fact that aqueous sodium azide dissociates to N₃^- and under acidic conditions hydrazoic acid (HN₃) is formed, which is a volatile substance that partitions strongly to the gas phase.

Validity criteria fulfilled:

not applicable

Remarks:

Reference is a literature review, therefore validity criteria do not apply.

Conclusions:

Sodium azide (NaN3) forms hydrazoic acid (HN3) in aqueous solutions, particularly at acidic conditions. In contrast to the statement in Betterton (2003), this reaction does not constitute hydrolysis, but is a simple acid-base equilibrium. Hydrazoic acid is volatile and may evaporate to the gas phase.

Executive summary:

Sodium azide (NaN₃) forms hydrazoic acid (HN₃) in aqueous solutions, particularly at acidic conditions. In contrast to the statement in Betterton (2003), this reaction does not constitute hydrolysis, but is a simple acid-base equilibrium. Hydrazoic acid is volatile and may evaporate to the gas phase.

Reference 2

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Qualifier:

no guideline followed

GLP compliance:

no

Radiolabelling:

not specified

Analytical monitoring:

not specified

Transformation products:

yes

No.:

#1

No.:

#1

Validity criteria fulfilled:

not applicable

Remarks:

Reference is a literature review/handbook, therefore validity criteria do not apply.

Conclusions:

The azides, sodium azide (NaN3), potassium azide (KN3), and lead azide (PbN3) are water-soluble crystals that form hydrazoic acid (HN3) when dissolved in water, wich constitutes an acid-base equilibrium, but not hydrolysis.

Executive summary:

The azides, sodium azide (NaN₃), potassium azide (KN₃), and lead azide (PbN₃) are water-soluble crystals that form hydrazoic acid (HN₃) when dissolved in water, wich constitutes an acid-base equilibrium, but not hydrolysis.

Reference 3

Endpoint:

hydrolysis

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

NaN3 is an ionic solid that dissociates to its ionic compounds Na+ and N3-.

Description of key information

Sodium azide does not contain any hydrolysable chemical groups. Therefore, the substance cannot undergo hydrolysis. Two review papers on sodium azide are available that discuss the behaviour of sodium azide in water. Both of these studies suggest that sodium azide is highly soluble in water, and once dissolved will form hydrazoic acid, which is the corresponding acid in an acid-base equilibrium (which does not constitute hydrolysis).