Hexanitroethane

• HNE
• 1,1,1,2,2,2 - hexanitroethane

Colorless crystals

Fixed

1.85 g · cm -3 ( 20 ° C)

135.5 ° C

Template: Infobox chemical / molecular formula search available

Hexanitroethane is an aliphatic nitro compound. In the molecule, all six possible substituent positions are replaced by a nitro group. Highly nitrated compound as it acts as a strong oxidizing agent and is an explosive.

Representation and extraction

A first preparation was described in 1914 by William Will. This is achieved by the reaction of the potassium salt of tetra nitroethane with nitric acid.

The potassium salt of the tetra- nitro ethane can be obtained in a synthetic sequence, starting from the Tribromnitromethan. In the first step, a dimerization takes place to Tetrabromdinitroethan.

In the second step, a nucleophilic substitution with potassium nitrite to Dibromtetranitroethan.

The Tetra nitroethane salt arises by further reaction with potassium cyanide.

A practicable for industrial production synthesis starts from furfural, which is brominated in the first stage ring opening oxidation of mucobromic acid (2,3- Dibrommalealdehydsäure ). Alternatively, furan-2 -carboxylic acid used as starting material. In the following step, the mucobromic acid at temperatures below room temperature briefly reacted with potassium nitrite to the dipotassium salt of the 2,3,3- Trinitropropioaldehyds. The target compound is obtained by nitration of the salt with nitric acid and sulfuric acid at -60 ° C.

Properties

Hexanitroethane can occur in two polymorphic crystal forms. At a temperature below 18 ° C before the crystalline form II. At the transition point at 18 ° C the formation of crystal Form I is carried out with an enthalpy of transition of 12.4 kJ mol -1. The crystal form I then melts at 135.5 ° C.

Hexanitroethane is a potentially dangerous substance within the meaning of the Explosives Act. Important explosion indicators are:

• Heat of explosion: 3020 kJ · kg -1 (H2O ( g)).
• Detonation velocity: 4950 m · s-1 at a density of 0.91 g · cm -3
• Normal gas volume: 678 l · kg -1.
• Specific energy: 813 kJ · kg -1
• Deflagration: 175 ° C
• Lead block expansion: 24.5 cm3 · g -1
• Impact Sensitivity: 10 N · m
• Friction sensitivity: 235 N

The thermal decomposition was detected in the solid and in solution starting at 60 ° C. The decomposition proceeds as a first order reaction. The reaction rate is significantly higher as in the solids in solution. For the decomposition of the solid, the following equation can be formulated.

The decomposition in solution in the first step tetranitro ethylene is formed, which on its Diels -Alder adducts such as can be detected with anthracene or cyclopentadiene.

In the reaction in alcohols under reflux for an addition to the intermediately formed tetranitro ethylene takes place. The Dinitroalkoxyalkylstruktur formed is not stable and forms by rearrangement of the nitro group to nitrite and elimination of nitrogen oxides to the corresponding esters of Dinitroessigsäure.

The Dinitroessigsäureester dimerized during storage slow the corresponding 3,4- bis-( alkoxycarbonyl) -2- furazan oxide. At higher temperatures the Dinitroessigsäureester can saponified to dinitromethane and decarboxylated.

Use

Hexanitroethane can be used in propellants as oxygen- equalizing addition.