Centralite (

empirical formula In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, would simply be SO, as is the ...

: C₁₇H₂₀N₂O) is a

gunshot residue Gunshot residue (GSR), also known as cartridge discharge residue (CDR), gunfire residue (GFR), or firearm discharge residue (FDR), consists of all of the particles that are expelled from the muzzle of a gun following the discharge of a bullet. It ...

also known as ethyl centralite. Its

IUPAC name In chemical nomenclature, a preferred IUPAC name (PIN) is a unique name, assigned to a chemical substance and preferred among the possible names generated by IUPAC nomenclature. The "preferred IUPAC nomenclature" provides a set of rules for choo ...

is 1,3-diethyl-1,3-diphenylurea. Ethyl centralite is insoluble in

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

, but is soluble in

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscibl ...

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

and

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

. It is mainly used as a burning rate moderator and stabilizer for

smokeless powder Finnish smokeless powderSmokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to gunpowder ("black powder"). The combustion products are mainly gaseous, compared t ...

, and also a

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticiz ...

for

celluloid Celluloids are a class of materials produced by mixing nitrocellulose and camphor, often with added dyes and other agents. Once much more common for its use as photographic film before the advent of safer methods, celluloid's common contemporary ...

Naming

Synonyms

Bis(''N''-ethyl-''N''-phenyl)urea; Carbamite; Centralit; Centralite; Centralite1; Centralite 1; Centralite-1; Centralite I; ''N'',''N''′-Diethylcarbanilide; Diethyldiphenylharnstoff; ''N'',''N''′-Diethyl-''N''′-diphenyl-L-harnstoff; 1,3-Diethyl-1,3-diphenylharnstoff; Diethyldiphenylurea; 1,3-Diethyldiphenylurea; 1,3-Diethyl-1,3-diphenylurea; ''s''-Diethyldiphenylurea; ''sym''-Diethyldiphenylurea; ''N'',''N''′-Diphenyl-''N'',''N''′-diethylharnstoff; ''N'',''N''′-Diphenyl-''N'',''N''′-diethylurea; Ethylcentralit; Ethylcentralite; Ethyl centralite; USAF EK-1047; Zentralit. The term "Centralite" was originally applied to dimethyldiphenylurea developed about 1906 at the German Central War Laboratory ''Zentralstelle für wissenschaftlich-technische Untersuchungen'' in Neubabelsberg as a deterrent coating for

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. Its reaction history is considerably more complicated than that of

diphenylurea 1,3-Diphenylurea is a phenylurea-type compound with the formula (PhNH)2CO (Ph = C6H5). It is a colorless solid that is prepared by transamidation of urea with aniline. DPU is a cytokinin Cytokinins (CK) are a class of plant hormones that pr ...

. Ending up with nitrated

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...

s, the methyl analog centralite-2 or sym-dimethyldiphenylurea is also known and is used somewhat abroad. The centralite are considered to be somewhat less effective as stabilizers than 2-nitrodiphenylamine, but they are also quite good

s. When found in propellants they are frequently used at higher fractions than the diphenylamines to take advantage of their plasticizing properties.

References

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External links

Fine Chemicals & Intermediates : Ethyl Centralite
Ureas Plasticizers