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Aniline is an
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
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 Commodity chemicals (or bulk commodities or bulk chemicals) are a group of chemicals that are made on a very large scale to satisfy global markets. The average prices of commodity chemicals are regularly published in the chemical trade magazines an ...
, as well as a versatile starting material for fine chemical synthesis. Its main use is in the manufacture of precursors to polyurethane, dyes, and other industrial chemicals. Like most volatile amines, it has the odor of rotten
fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
. It ignites readily, burning with a smoky flame characteristic of aromatic compounds. It is toxic to humans. Relative to benzene, it is electron-rich. It thus participates more rapidly in electrophilic aromatic substitution reactions. Likewise, it is also prone to
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
: while freshly purified aniline is an almost colorless oil, exposure to air results in gradual darkening to yellow or red, due to the formation of strongly colored, oxidized impurities. Aniline can be diazotized to give a diazonium salt, which can then undergo various nucleophilic substitution reactions. “Aniline” is ultimately from Portuguese ''anil'' which means "the indigo shrub", with suffix ''-ine'' indicating "derived substance". Like other amines, aniline is both a base (p''K''aH = 4.6) and a nucleophile, although less so than structurally similar aliphatic amines. Because an early source of the benzene from which they are derived was
coal tar Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat pso ...
, aniline dyes are also called coal tar dyes.


Structure


Aryl-N distances

In aniline, the C−N bond length is 1.41 Å, compared to 1.47 Å for cyclohexylamine, indicating partial π-bonding between N and C. The C(aryl)-NH2 distance in anilines is highly sensitive to substituent effects. This distance is 1.34 Å in 2,4,6-trinitroaniline vs 1.44 Å in
3-methylaniline There are three isomers of toluidine, which are organic compounds. These isomers are ''o''-toluidine, ''m''-toluidine, and ''p''-toluidine, with the prefixed letter abbreviating, respectively, ''ortho''; ''meta''; and ''para''. All three are aryl ...
.


Pyramidalization

The amine in anilines is a slightly pyramidalized molecule, with hybridization of the nitrogen somewhere between sp3 and sp2. The nitrogen is described as having high p character. The amino group in aniline is flatter (i.e., it is a "shallower pyramid") than that in an aliphatic amine, owing to conjugation of the lone pair with the
aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used ...
substituent. The observed geometry reflects a compromise between two competing factors: 1) stabilization of the N lone pair in an orbital with significant s character favors pyramidalization (orbitals with s character are lower in energy), while 2) delocalization of the N lone pair into the aryl ring favors planarity (a lone pair in a pure p orbital gives the best overlap with the orbitals of the benzene ring π system). Consistent with these factors, substituted anilines with electron donating groups are more pyramidalized, while those with electron withdrawing groups are more planar. In the parent aniline, the lone pair is approximately 12% s character, corresponding to sp7.3 hybridization. (For comparison, alkylamines generally have lone pairs in orbitals that are close to sp3.) The pyramidalization angle between the C–N bond and the bisector of the H–N–H angle is 142.5°. For comparison, in more strongly pyramidal methylamine, this value is ~125°, while that of formamide has an angle of 180°.


Production

Industrial aniline production involves two steps. First,
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 ...
is nitrated with a concentrated mixture of
nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...
and
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
at 50 to 60 °C to yield nitrobenzene. The nitrobenzene is then hydrogenated (typically at 200–300 °C) in the presence of metal
catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
s: : The reduction of nitrobenzene to aniline was first performed by
Nikolay Zinin Nikolay Nikolaevich Zinin (russian: link=no, Никола́й Никола́евич Зи́нин; 25 August 1812, in Shusha – 18 February 1880, in Saint Petersburg) was a Russian organic chemist. Life He studied at the University of Kazan where ...
in 1842, using inorganic sulfide as a reductant ( Zinin reaction). The reduction of nitrobenzene to aniline was also performed as part of reductions by Antoine Béchamp in 1854, using iron as the reductant (
Bechamp reduction The Béchamp reduction (or Béchamp process) is a chemical reaction that converts aromatic nitro compounds to their corresponding anilines using iron as the reductant.. : This reaction was once a major route to aniline, but catalytic hydrogena ...
). Aniline can alternatively be prepared from ammonia and
phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it r ...
derived from the
cumene process The cumene process (cumene-phenol process, Hock process) is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It w ...
. In commerce, three brands of aniline are distinguished: aniline oil for blue, which is pure aniline; aniline oil for red, a mixture of equimolecular quantities of aniline and ortho- and para-toluidines; and aniline oil for safranine, which contains aniline and ortho- toluidine and is obtained from the distillate (échappés) of the fuchsine fusion.


Related aniline derivatives

Many analogues of aniline are known where the phenyl group is further substituted. These include toluidines, xylidines, chloroanilines, aminobenzoic acids,
nitroaniline The term nitroaniline in chemistry refers to a derivative of aniline (C6H5NH2) containing a nitro group (—NO2) There are three simple nitroanilines of formula C6H4(NH2)(NO2) which differ only in the position of the nitro group: * 2-Nitroaniline ...
s, and many others. They often are prepared by nitration of the substituted aromatic compounds followed by reduction. For example, this approach is used to convert
toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) ...
into toluidines and chlorobenzene into 4-chloroaniline. Alternatively, using Buchwald-Hartwig coupling or Ullmann reaction approaches, aryl halides can be aminated with aqueous or gaseous ammonia.


Reactions

The chemistry of aniline is rich because the compound has been cheaply available for many years. Below are some classes of its reactions.


Oxidation

The oxidation of aniline has been heavily investigated, and can result in reactions localized at nitrogen or more commonly results in the formation of new C-N bonds. In alkaline solution, azobenzene results, whereas
arsenic acid Arsenic acid or trihydrogen arsenate is the chemical compound with the formula . More descriptively written as , this colorless acid is the arsenic analogue of phosphoric acid. Arsenate and phosphate salts behave very similarly. Arsenic acid as su ...
produces the violet-coloring matter violaniline. Chromic acid converts it into quinone, whereas chlorates, in the presence of certain metallic salts (especially of vanadium), give aniline black. Hydrochloric acid and potassium chlorate give chloranil. Potassium permanganate in neutral solution oxidizes it to nitrobenzene; in alkaline solution to azobenzene, ammonia, and oxalic acid; in acid solution to aniline black. Hypochlorous acid gives 4-aminophenol and para-amino diphenylamine. Oxidation with persulfate affords a variety of
polyaniline Polyaniline (PANI) is a conducting polymer and organic semiconductor of the semi-flexible rod polymer family. The compound has been of interest since the 1980s because of its electrical conductivity and mechanical properties. Polyaniline is one o ...
s. These polymers exhibit rich redox and acid-base properties.


Electrophilic reactions at ortho- and para- positions

Like
phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it r ...
s, aniline derivatives are highly susceptible to electrophilic substitution reactions. Its high reactivity reflects that it is an enamine, which enhances the electron-donating ability of the ring. For example, reaction of aniline with
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
at 180 °C produces
sulfanilic acid Sulfanilic acid (4-aminobenzenesulfonic acid) is an organic compound with the formula H3NC6H4SO3. It is an off-white solid. It is a zwitterion, which explains its high melting point. It is a common building block in organic chemistry."Sulphan ...
, . If bromine water is added to aniline, the bromine water is decolourised and a white precipitate of 2,4,6-tribromoaniline is formed. To generate the mono-substituted product, a protection with acetyl chloride is required: The reaction to form
4-bromoaniline 4-Bromoaniline is a compound where an aniline molecule is substituted with a bromine atom on the ''para'' position. Commercially available, this compound may be used as a building block, e.g. in the preparation of p-bromobiphenyl Biphenyl (als ...
is to protect the amine with acetyl chloride, then hydrolyse back to reform aniline. The largest scale industrial reaction of aniline involves its alkylation with
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
. An idealized equation is shown: :2 C6H5NH2 + CH2O -> CH2(C6H4NH2)2 + H2O The resulting diamine is the precursor to
4,4'-MDI Methylene diphenyl diisocyanate (MDI) is an aromatic diisocyanate. Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. The 4,4′ isomer is most widely used, and i ...
and related diisocyanates.


Reactions at nitrogen


Basicity

Aniline is a weak base. Aromatic amines such as aniline are, in general, much weaker bases than
aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated, like hexane ...
amines. Aniline reacts with strong acids to form the anilinium (or phenylammonium) ion (). Traditionally, the weak basicity of aniline is attributed to a combination of inductive effect from the more electronegative sp2 carbon and resonance effects, as the lone pair on the nitrogen is partially delocalized into the pi system of the benzene ring. (see the picture below): Missing in such an analysis is consideration of solvation. Aniline is, for example, more basic than ammonia in the gas phase, but ten thousand times less so in aqueous solution.


Acylation

Aniline reacts with acyl chlorides such as acetyl chloride to give
amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it i ...
s. The amides formed from aniline are sometimes called anilides, for example is acetanilide. At high temperatures aniline and carboxylic acids react to give the anilides.


''N''-Alkylation

''N''-Methylation of aniline with methanol at elevated temperatures over
acid catalysts In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...
gives ''N''-methylaniline and ''N'',''N''-dimethylaniline: :C6H5NH2 + 2 CH3OH -> C6H5N(CH3)2 + 2H2O ''N''-Methylaniline and ''N'',''N''-dimethylaniline are colorless liquids with boiling points of 193–195 °C and 192 °C, respectively. These derivatives are of importance in the color industry. Aniline combines directly with alkyl iodides to form secondary and tertiary amines.


Carbon disulfide derivatives

Boiled with carbon disulfide, it gives sulfocarbanilide (diphenyl thiourea) (), which may be decomposed into phenyl
isothiocyanate In organic chemistry, isothiocyanate is the functional group , formed by substituting the oxygen in the isocyanate group with a sulfur. Many natural isothiocyanates from plants are produced by enzymatic conversion of metabolites called glu ...
(), and triphenyl guanidine ().


Diazotization

Aniline and its ring-substituted derivatives react with nitrous acid to form diazonium salts. Through these intermediates, the amine group can be converted to a
hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydrox ...
(), nitrile (), or halide group (, where X is a halogen) via Sandmeyer reactions. This diazonium salt can also be reacted with and phenol to produce a dye known as benzeneazophenol, in a process called '' coupling''. The reaction of converting primary aromatic amine into diazonium salt is called diazotisation. In this reaction primary aromatic amine reacts with sodium nitrile and with 2 moles of HCl which is known as Ice cold mixture because the temperature use to be 0.5 °C and it forms benzene diazonium salt as major product and water and sodium chloride.


Other reactions

It reacts with nitrobenzene to produce
phenazine Phenazine is an organic compound with the formula (C6H4)2N2. It is a dibenzo annulated pyrazine, and the parent substance of many dyestuffs, such as the toluylene red, indulines, and safranines (and the closely related eurhodines). Phenazine c ...
in the Wohl-Aue reaction. Hydrogenation gives
cyclohexylamine Cyclohexylamine is an organic compound, belonging to the aliphatic amine class. It is a colorless liquid, although, like many amines, samples are often colored due to contaminants. It has a fishy odor and is miscible with water. Like other amine ...
. Being a standard reagent in laboratories, aniline is used for many niche reactions. Its acetate is used in the aniline acetate test for carbohydrates, identifying pentoses by conversion to furfural. It is used to stain neural RNA blue in the
Nissl stain Franz Alexander Nissl (9 September 1860, in Frankenthal – 11 August 1919, in Munich) was a German psychiatrist and medical researcher. He was a noted neuropathologist. Early life Nissl was born in Frankenthal to Theodor Nissl and Maria Haas. ...
.


Uses

Aniline is predominantly used for the preparation of methylenedianiline and related compounds by condensation with formaldehyde. The diamines are condensed with phosgene to give methylene diphenyl diisocyanate, a precursor to urethane polymers. : Other uses include rubber processing chemicals (9%), herbicides (2%), and dyes and pigments (2%). As additives to rubber, aniline derivatives such as phenylenediamines and diphenylamine, are antioxidants. Illustrative of the drugs prepared from aniline is paracetamol (acetaminophen, Tylenol). The principal use of aniline in the dye industry is as a precursor to
indigo Indigo is a deep color close to the color wheel blue (a primary color in the RGB color space), as well as to some variants of ultramarine, based on the ancient dye of the same name. The word "indigo" comes from the Latin word ''indicum'', ...
, the blue of blue jeans.


History

Aniline was first isolated in 1826 by Otto Unverdorben by
destructive distillation Destruction may refer to: Concepts * Destruktion, a term from the philosophy of Martin Heidegger * Destructive narcissism, a pathological form of narcissism * Self-destructive behaviour, a widely used phrase that ''conceptualises'' certain kind ...
of
indigo Indigo is a deep color close to the color wheel blue (a primary color in the RGB color space), as well as to some variants of ultramarine, based on the ancient dye of the same name. The word "indigo" comes from the Latin word ''indicum'', ...
. He called it ''Crystallin''. In 1834, Friedlieb Runge isolated a substance from
coal tar Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat pso ...
that turned a beautiful blue color when treated with chloride of lime. He named it ''kyanol'' or ''cyanol''. In 1840,
Carl Julius Fritzsche Carl Julius Fritzsche (17 October 1808 in Neustadt – 8 June 1871) was a German pharmacist and chemist. He was a nephew of pharmacist Friedrich Adolph August Struve (1781–1840). After five years spent working at his uncle's pharmacy in ...
(1808–1871) treated indigo with
caustic potash Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exploi ...
and obtained an oil that he named ''aniline'', after an indigo-yielding plant, anil (''
Indigofera suffruticosa ''Indigofera suffruticosa'', commonly known as Guatemalan indigo, small-leaved indigo (Sierra Leone), West Indian indigo, wild indigo, and anil, is a flowering plant in the pea family, Fabaceae. ''Anil'' is native to the subtropical and tropical ...
''). In 1842, Nikolay Nikolaevich Zinin reduced nitrobenzene and obtained a base that he named ''benzidam''. In 1843, August Wilhelm von Hofmann showed that these were all the same substance, known thereafter as ''phenylamine'' or ''aniline''.


Synthetic dye industry

In 1856, while trying to synthesise quinine, von Hofmann's student
William Henry Perkin Sir William Henry Perkin (12 March 1838 – 14 July 1907) was a British chemist and entrepreneur best known for his serendipitous discovery of the first commercial synthetic organic dye, mauveine, made from aniline. Though he failed in trying ...
discovered
mauveine Mauveine, also known as aniline purple and Perkin's mauve, was one of the first synthetic dyes. It was discovered serendipitously by William Henry Perkin in 1856 while he was attempting to synthesise the phytochemical quinine for the treatment of ...
and went into industry producing the first commercial
synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic ...
dye. Other aniline dyes followed, such as fuchsin, safranin, and induline. At the time of mauveine's discovery, aniline was expensive. Soon thereafter, applying a method reported in 1854 by Antoine Béchamp, it was prepared "by the ton". The Béchamp reduction enabled the evolution of a massive dye industry in Germany. Today, the name of BASF, originally ''Badische Anilin- und Soda-Fabrik'' (English: Baden Aniline and Soda Factory), now the largest chemical supplier, echoes the legacy of the synthetic dye industry, built via aniline dyes and extended via the related azo dyes. The first azo dye was aniline yellow.


Developments in medicine

In the late 19th century, derivatives of aniline such as acetanilide and phenacetin emerged as analgesic drugs, with their cardiac-suppressive
side effects In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequenc ...
often countered with
caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class. It is mainly recreational drug use, used recreationally as a Nootropic, cognitive enhancer, increasing alertness and attentional perfor ...
. During the first decade of the 20th century, while trying to modify synthetic dyes to treat African sleeping sickness, Paul Ehrlich – who had coined the term ''
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemother ...
'' for his '' magic bullet'' approach to medicine – failed and switched to modifying Béchamp's
atoxyl Arsanilic acid, also known as aminophenyl arsenic acid or aminophenyl arsonic acid, is an organoarsenic compound, an amino derivative of phenylarsonic acid whose amine group is in the 4-position. A crystalline powder introduced medically in the l ...
, the first organic
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
al drug, and serendipitously obtained a treatment for
syphilis Syphilis () is a sexually transmitted infection caused by the bacterium '' Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, a ...
salvarsan – the first successful chemotherapy agent. Salvarsan's targeted microorganism, not yet recognized as a bacterium, was still thought to be a parasite, and medical bacteriologists, believing that bacteria were not susceptible to the chemotherapeutic approach, overlooked Alexander Fleming's report in 1928 on the effects of penicillin.D J Th Wagener, ''The History of Oncology'' (Houten: Springer, 2009)
pp 150–1
In 1932, Bayer sought medical applications of its dyes. Gerhard Domagk identified as an antibacterial a red azo dye, introduced in 1935 as the first antibacterial drug, prontosil, soon found at
Pasteur Institute The Pasteur Institute (french: Institut Pasteur) is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who invented pasteurization and vacc ...
to be a prodrug degraded ''
in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and p ...
'' into sulfanilamide – a colorless intermediate for many, highly colorfast azo dyes – already with an expired patent, synthesized in 1908 in Vienna by the researcher Paul Gelmo for his doctoral research. By the 1940s, over 500 related
sulfa drug Sulfonamide is a functional group (a part of a molecule) that is the basis of several groups of drugs, which are called sulphonamides, sulfa drugs or sulpha drugs. The original antibacterial sulfonamides are synthetic (nonantibiotic) antimi ...
s were produced. Medications in high demand during
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
(1939–45), these first ''miracle drugs'', chemotherapy of wide effectiveness, propelled the American pharmaceutics industry. In 1939, at Oxford University, seeking an alternative to sulfa drugs, Howard Florey developed Fleming's penicillin into the first systemic antibiotic drug,
penicillin G Benzylpenicillin, also known as penicillin G (PenG) or BENPEN, and in military slang "Peanut Butter Shot" is an antibiotic used to treat a number of bacterial infections. This includes pneumonia, strep throat, syphilis, necrotizing enterocol ...
. ( Gramicidin, developed by René Dubos at Rockefeller Institute in 1939, was the first antibiotic, yet its toxicity restricted it to topical use.) After World War II,
Cornelius P. Rhoads Cornelius Packard "Dusty" Rhoads (June 9, 1898 – August 13, 1959) was an American pathologist, oncologist, and hospital administrator who was involved in a racist scandal and subsequent whitewashing in the 1930s. Beginning in 1940, he served a ...
introduced the chemotherapeutic approach to cancer treatment.


Rocket fuel

Some early American rockets, such as the Aerobee and WAC Corporal, used a mixture of aniline and furfuryl alcohol as a fuel, with
nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...
as an oxidizer. The combination is
hypergolic A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other. The two propellant components usually consist of a fuel and an oxidizer. T ...
, igniting on contact between fuel and oxidizer. It is also dense, and can be stored for extended periods. Aniline was later replaced by hydrazine.Brian Burnell. 2016. http://www.nuclear-weapons.info/cde.htm#Corporal SSM


Toxicology and testing

Aniline is toxic by inhalation of the vapour, ingestion, or percutaneous absorption.Muir, GD (ed.) 1971, ''Hazards in the Chemical Laboratory'', The Royal Institute of Chemistry, London. The
IARC IARC may refer to: * International Aerial Robotics Competition * International Age Rating Coalition * International Agency for Research on Cancer * International Arctic Research Center * Israel Amateur Radio Club The Israel Amateur Radio Club ...
lists it in Group 3 (''not classifiable as to its carcinogenicity to humans'') due to the limited and contradictory data available. The early manufacture of aniline resulted in increased incidents of bladder cancer, but these effects are now attributed to naphthylamines, not anilines. Aniline has been implicated as one possible cause of forest dieback.Krahl-Urban, B., Papke, H.E., Peters, K. (1988) ''Forest Decline: Cause-Effect Research in the United States of North America and Federal Republic of Germany''. Germany: Assessment Group for Biology, Ecology and Energy of the Julich Nuclear Research Center. Many methods exist for the detection of aniline.''Basic Analytical Toxicology'' (1995), R. J. Flanagan, S. S. Brown, F. A. de Wolff, R. A. Braithwaite, B. Widdop: World Health Organization


Oxidative DNA damage

Exposure of rats to aniline can elicit a response that is toxic to the
spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .
, including a
tumorigenic Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abnorm ...
response. Rats exposed to aniline in drinking water, showed a significant increase in oxidative DNA damage to the spleen, detected as a 2.8-fold increase in 8-hydroxy-2’-deoxyguanosine (8-OHdG) in their DNA. Although the
base excision repair Base excision repair (BER) is a cellular mechanism, studied in the fields of biochemistry and genetics, that repairs damaged DNA throughout the cell cycle. It is responsible primarily for removing small, non-helix-distorting base lesions from ...
pathway was also activated, its activity was not sufficient to prevent the accumulation of 8-OHdG. The accumulation of oxidative DNA damages in the spleen following exposure to aniline may increase mutagenic events that underlie tumorigenesis.


Notes


References

*


External links

*
International Chemical Safety Card 0011
* {{Authority control Dyes German inventions Hazardous air pollutants IARC Group 3 carcinogens Phenyl compounds