Hydrazoic acid

Structural formula
	Mesomeric boundary structures of hydrazoic acid
General
Surname	Hydrazoic acid
other names	Azoimide; Hydrogen azide;
Molecular formula	HN 3
Brief description	colorless, volatile, explosive liquid with a pungent odor
External identifiers / databases
EC number	231-965-8
ECHA InfoCard	100,029,059
PubChem	24530
Wikidata	Q408925
properties
Molar mass	43.03 g mol −1
Physical state	liquid
density	1.09 g cm −3 (25 ° C)
Melting point	−80 ° C
boiling point	35.7 ° C
Vapor pressure	523 h Pa (20 ° C)
pK s value	4.6 (in H 2 O); 7.9 (in DMSO );
solubility	Infinitely miscible with water, soluble in ethanol and diethyl ether
safety instructions
H and P phrases	H: 200-319-335-370
	P: 201-202-260-261-264-270-271-280-281-304 + 340-305 + 351 + 338-307 + 311-312 321-337 + 313-372-374-380-401-403 + 233-405-501
MAK	DFG / Switzerland: 0.1 ml m −3 or 0.18 mg m −3
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Hydrazoic acid is an unstable, extremely explosive, irritating, pungent smelling liquid to the mucous membranes. The azide ion N ₃^- has a linear structure and is isoelectronic with carbon dioxide . The salts of hydrazoic acid are called azides . Because of the instability of the acid, azides are not synthesized from hydrazoic acid but from sodium azide . Hydrazoic acid is obtained by reacting sulfuric acid with sodium azide.

Extraction and presentation

By reacting nitrous acid with excess hydrazine in aqueous nitric acid or perchloric acid at an H ⁺ concentration of over 0.2 mol / l:

{\ displaystyle \ mathrm {N_ {2} H_ {5} ^ {+} + HNO_ {2} \ longrightarrow HN_ {3} + H_ {2} O + H_ {3} O ^ {+}}}

Some of the hydrazoic acid goes through the reaction

{\ displaystyle \ mathrm {HN_ {3} + HNO_ {2} \ longrightarrow N_ {2} + N_ {2} O + H_ {2} O}}

lost.

By oxidizing hydrazine with aqueous 10% nitric acid at about 40 ° C with a yield of about 35%:

{\ displaystyle \ mathrm {17 \ N_ {2} H_ {4} +16 \ ENT_ {3} \ longrightarrow}}

{\ displaystyle \ mathrm {4 \ HN_ {3} +4 \ NH_ {4} NO_ {3} +4 \ N_ {2} O + 11 \ N_ {2} +32 \ H_ {2} O}}

By electrolysis of a saturated solution of hydrazinium sulfate in 20% sulfuric acid at 0 ° C and a high anodic current density.

By reacting sodium amide with sodium nitrate in liquid ammonia at 100 ° C under pressure:

{\ displaystyle \ mathrm {2 \ NaNH_ {2} + NaNO_ {3} \ longrightarrow \}}

{\ displaystyle \ mathrm {\ NaN_ {3} +2 \ NaOH + H_ {2} O}}

The method of neutralizing sodium azide solution with sulfuric acid and distilling it leads to uncontrolled explosions. Günther and Meyer therefore recommend starting the production of pure hydrazoic acid from pure sodium azide and stearic acid .

properties

Hydrazoic acid is a colorless, mobile and highly explosive liquid. The connection is particularly explosive due to shock , friction , fire and other sources of ignition. Anhydrous hydrazoic acid explodes when heated and when exposed to slight vibration. Concentrated solutions must not be heated, poured into a splash, or put on hard with the container. Dilute aqueous solutions up to 20% HN ₃ are not explosive. Polyethylene , glass , stainless steel , aluminum and titanium are suitable as container material .

N ₃^- , the hydrazoic acid anion

The nitrogen atoms of hydrazoic acid are not arranged linearly because of the boundary structures that occur. The bond angle on the middle nitrogen atom is 173.3 °, the bond angle on the hydrogen atom is 108.8 °. In contrast, the azide ion (N ₃ ion) has a linear structure. The nitrogen-nitrogen bonds also have different lengths. The H – N bond length of gaseous hydrazoic acid is 101.5 pm.

use

Sodium azide, the sodium salt of hydrazoic acid, is a key ingredient in the synthesis of important nitrogen compounds.

Sodium azide is used as a preservative for milk test samples and in chemical synthesis for the introduction of azide groups (-N ₃ ) and for the preparation of triazoles .

A mixture of sodium azide, potassium perchlorate , iron (III) oxide, filler and binder serves as a propellant for airbags.

Some salts of hydrazoic acid, particularly lead azide and silver azide , are useful as initiating explosives .

Polyglycidyl azide (GAP, (C ₃ H ₅ N ₃ O) _n ) is a polymer that is used as a high-energy binder in solid rockets .

links

The salts of hydrazoic acid are similar in some properties to the chlorides . Silver azide and lead azide are colorless, sparingly soluble and highly explosive. Sodium azide (NaN ₃ ) is easily soluble in water (420 g / L), can be melted without decomposition and decomposes from 300 ° C in a controllable reaction into metallic sodium and nitrogen . Copper azide Cu (N ₃ ) ₂ is extremely explosive and often explodes when touched.

toxicology

Hydrazoic acid is very toxic, severely irritating to the mucous membranes and has an unbearable penetrating odor. When inhaling small amounts, there is initially a feeling of pressure in the nose.

The lethal dose is less than 5 mg per kg of body weight. Symptoms of poisoning are nausea, headache, dizziness, drop in blood pressure and a racing heart.

Individual evidence

^ Dale L. Perry, Sidney L. Phillips: Handbook of inorganic compounds. CRC Press, 1995, ISBN 978-0-8493-8671-8 , p. 193.
↑ ^a ^b ^c ^d ^e ^f Entry for CAS no. 7782-79-8 in the GESTIS substance database of the IFA , accessed on February 11, 2007 (JavaScript required)
↑ ^a ^b ^c Entry on hydrazoic acid. In: Römpp Online . Georg Thieme Verlag, accessed on October 25, 2018.
↑ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
↑ Boardwell pk _a table
↑ ^a ^b Roth / Weller: Hazardous chemical reactions , ecomed security, Hüthig Jehle Rehm publishing group, Landsberg / Lech, 34th supplement 8/2001.
^ ^A ^b GHS Classification Hydrogen azide Japanese Government: Ministry of Health, Labor and Welfare & Ministry of the Environment, accessed on November 12, 2015
↑ Swiss Accident Insurance Fund (Suva): Limits - Current List of MAK and BAT Values (Search for 7782-79-8 or hydrogen azide ), accessed on November 2, 2015.
^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 .
↑ G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 472-4, ISBN 0-12-126601-X .
^ ^A ^b A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 681.

[1] Dale L. Perry, Sidney L. Phillips: Handbook of inorganic compounds. CRC Press, 1995, ISBN 978-0-8493-8671-8 , p. 193.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f Entry for CAS no. 7782-79-8 in the GESTIS substance database of the IFA , accessed on February 11, 2007 (JavaScript required)

[Roempp-3] Entry on hydrazoic acid. In: Römpp Online . Georg Thieme Verlag, accessed on October 25, 2018.

[4] Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8

[5] Boardwell pk _a table

[Roth/Weller-6] Roth / Weller: Hazardous chemical reactions , ecomed security, Hüthig Jehle Rehm publishing group, Landsberg / Lech, 34th supplement 8/2001.

[GHS-7] A ^b GHS Classification Hydrogen azide Japanese Government: Ministry of Health, Labor and Welfare & Ministry of the Environment, accessed on November 12, 2015

[8] Swiss Accident Insurance Fund (Suva): Limits - Current List of MAK and BAT Values (Search for 7782-79-8 or hydrogen azide ), accessed on November 2, 2015.

[9] AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 .

[10] G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 472-4, ISBN 0-12-126601-X .

[Holle-11] A ^b A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 681.