Centralite

Last updated
Centralite [1]
Centralite.svg
Names
Preferred IUPAC name
N,N′-Diethyl-N,N′-diphenylurea
Other names
Centralite 1
Carbamite
Ethyl centralite
N,N′-Diethylcarbanilide
Bis(N-ethyl-N-phenyl)urea
1,3-Diethyl-1,3-diphenylurea
sym-Diethyldiphenylurea
USAF EK-1047
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.001.496 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C17H20N2O/c1-3-18(15-11-7-5-8-12-15)17(20)19(4-2)16-13-9-6-10-14-16/h5-14H,3-4H2,1-2H3 X mark.svgN
    Key: PZIMIYVOZBTARW-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C17H20N2O/c1-3-18(15-11-7-5-8-12-15)17(20)19(4-2)16-13-9-6-10-14-16/h5-14H,3-4H2,1-2H3
    Key: PZIMIYVOZBTARW-UHFFFAOYAC
  • O=C(N(c1ccccc1)CC)N(c2ccccc2)CC
Properties
C17H20N2O
Molar mass 268.360 g·mol−1
AppearanceWhite to light grey crystalline powder
Density 0.8 g/cm3
Insoluble
Solubility in Acetone, ethanol and benzeneSoluble
−134.05·10−6 cm3/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Ethyl centralite is an organic compound. Its chemical name is 1,3-diethyl-1,3-diphenylurea. The molecular formula of ethyl centralite is C17H20N2O. This compound has important uses in industry and forensics. The structure of ethyl centralite includes two phenyl groups (aromatic rings) attached to a central urea group. There are also ethyl groups (–C₂H₅) bound to the nitrogen atoms of the urea. This structure gives ethyl centralite its special chemical properties. [2] Ethyl centralite is an important part of gunshot residue (GSR). When a gun is fired, the chemical reactions from the burning of the propellant leave behind tiny particles called gunshot residue. Ethyl centralite is one of the compounds found in GSR. It serves as an indicator in forensic investigations. Ethyl centralite helps determine if a firearm was recently fired. Ethyl centralite is widely used in various industries. Its main use is in the production of smokeless powder. In this use, it acts as a burning rate moderator and stabilizer. These functions are important for the controlled and consistent ignition of propellants. This is essential for the safety and effectiveness of ammunition. Ethyl centralite is also used as a plasticizer in the manufacturing of celluloid and enhances the flexibility and durability of the material. [2] [3]

Contents

History

In the 19th century chemists identified that nitrocellulose can destroy itself with the help of nitrogen oxides separating from it at storage, and tried to find bases which might capture those oxides. Urea has been used for stabilizing celluloid in the 19th century (and even in early American military powders), but like other water-soluble bases, it also attacks nitrocellulose, so German chemists substituted hydrogen atoms with nonpolar organic radicals to diminish this effect. [4]

Naming

The term "Centralite" was originally applied to dimethyldiphenylurea developed about 1906 at the German private military-industrial laboratory Zentralstelle für wissenschaftlich-technische Untersuchungen  [ de ] (Center for Scientific-Technical Research) in Neubabelsberg as a deterrent coating for smokeless powder in military rifle cartridges. Thereafter, all hydrocarbon-substituted symmetrical diphenyl urea compounds used as smokeless powder deterrents (or moderants) were called centralites after the laboratory. The preferred ethyl centralite became known as Centralite No. 1 and the original methyl centralite was identified as Centralite No. 2. Butyl centralite was also used as a celluloid plasticizer. [5] [6]

Comparison with analogs

Compared to diphenylurea, it has a far more convoluted reaction history. Finally, nitrated anilines are produced. Centralite-2, also known as sym-dimethyldiphenylurea, is a methyl analog that is moderately utilized overseas. Though they are likewise excellent plasticizers, centralites are thought to be a little less effective stabilizer than 2-nitrodiphenylamine. To benefit from their plasticizing qualities, they are commonly employed in propellants at higher fractions than diphenylamines.

Synthesis

Ethyl centralite is also known as 1,3-diethyl-1,3-diphenylurea. It is synthesized through a chemical reaction. This reaction involves the condensation of aniline (C₆H₅NH₂) with ethyl isocyanate (C₂H₅NCO). The reaction typically occurs under controlled conditions. In this reaction, aniline reacts with ethyl isocyanate. This forms ethyl centralite through the formation of urea linkages.

The general reaction can be represented as follows:

2 C6H5NH2 + 2 C2H5NCO → C6H5NHCONHC6H5(C2H5)2 + 2 CO2

In this reaction, aniline (C6H5NH2) serves as the aromatic amine and ethyl isocyanate (C2H5NCO) is the isocyanate compound that reacts with the amine groups.

The reaction produces ethyl centralite. It also produces carbon dioxide (CO₂) as a byproduct. The process is usually done in a solvent, such as an alcohol. The solvent helps dissolve the reactants. It also helps control the reaction temperature. After the reaction is finished, the ethyl centralite is purified. This is done through recrystallization or other purification methods. The goal is to obtain a pure product. [7] [8]

Applications

Smokeless powder

Forensic science

References

  1. CID 6828 from PubChem
  2. 1 2 "Ethyl centralite / Centralite I, CAS: 85-98-3 - Synthesia". organics.synthesia.eu. Retrieved 2023-11-02.
  3. "Typical Product Specifications & Properties - Ethyl Centralite" (PDF).
  4. "Explosives". Philadelphia, P. Blakiston. 1917.
  5. Davis, Tenney L. (1943). The Chemistry of Powder & Explosives (Angriff Press [1992] ed.). John Wiley & Sons Inc. pp. 317–320. ISBN   0-913022-00-4.
  6. Davis, William C. Jr. (1981). Handloading . National Rifle Association of America. p.  130. ISBN   0-935998-34-9.
  7. "The Preparation Method of Centralite-II".
  8. "Syntheses and Characterisations of Derivatives of Ethyl Centralite".
  9. "SHOOTERS WORLD RELOADING GUIDE" (PDF).
  10. 1 2 3 "Exploring the Versatile Applications and Synthesis of 1,3-Dimethyl-1,3-diphenylurea in Modern Chemistry".
  11. "A stabilizer of explosives: Centralite ll".