Aniline

Aniline
Aniline
Are common
Traditional names	Aminobenzene; Aniline; Benzoamine; Phenylamine
Chem. formula	C 6 H 5 N H 2
Physical properties
condition	colorless or yellowish liquid
Molar mass	93.1265 ± 0.0055 g / mol
Density	1,0217 g / cm³
Surface tension	43.3 N / m
Dynamic viscosity	3.71 Pa · s
Ionization energy
The speed of sound in matter	1659 m / s
Thermal properties
T. melt.	−6.3 ° C
T. bale.	184.13 ° C
T. aux.	and
T. svpl.	562 ° C
Etc. blast
Cr. pace.	425.65 ° C
Cr. pressure	5.134 MPa
Steam pressure
Chemical properties
Solubility in water	3.6 g / 100 ml
Solubility in cyclohexane	66.7 (30.8 ° C)
Dielectric penetration.	6.89
Optical properties
Refractive index	1,5863
Structure
Dipole moment	1.53 D
Classification
Reg. CAS number	62-53-3
PubChem
Reg. EINECS number	200-539-3
Smiles
Inchi
RTECS
Chebi	and
UN number
ChemSpider
Security
LD 50	250 mg / kg (cats, intragastrically),; 460 mg / kg (mouse, intragastric)
Toxicity	moderately toxic to small mammals, highly toxic to humans, is hematotoxin (causes hemolysis).;
NFPA 704	0 3 0

Aniline (aminobenzene, phenylamine) is an organic compound with the formula C ₆ H ₅ N H ₂ , the simplest aromatic amine . It is a colorless oily liquid with a characteristic odor, slightly denser than water and poorly soluble in it, well soluble in organic solvents. It rapidly oxidizes in air and acquires a red-brown color. Toxic. The name "aniline" comes from the name of one of the plants containing indigo - Indigofera anil (the modern international name for the plant is Indigofera suffruticosa ).

History

Aniline was first obtained in 1826 by distillation of indigo with lime by the German chemist Otto Unferdorben ( German: Otto Unverdorben ), which gave it the name "crystallin".

In 1834, Friedlieb Ferdinand Runge discovered aniline in coal tar and called it “cyanol”.

In 1840, Julius Fritzsche obtained aniline by heating indigo with a solution of K O H and called it “aniline”.

In 1842, Nikolai Zinin received aniline by the reduction of nitrobenzene with the action of ( N H ₄ ) ₂ S and called it "benzidam".

In 1843, August Wilhelm Hoffmann established the identity of all these compounds.

The industrial production of aniline-based mauvein violet dye began in 1856 .

Getting

In industry, aniline is obtained in two stages. At the first stage, benzene is nitrated with a mixture of concentrated nitric and sulfuric acids at a temperature of 50-60 ° C; as a result, nitrobenzene is formed. At the second stage, nitrobenzene is hydrogenated at a temperature of 200-300 ° C in the presence of catalysts :

{\mathsf {C_{6}H_{5}NO_{2}+3H_{2}\rightarrow C_{6}H_{5}NH_{2}+2H_{2}O}}

{\ displaystyle {\ mathsf {C_ {6} H_ {5} NO_ {2} + 3H_ {2} \ rightarrow C_ {6} H_ {5} NH_ {2} + 2H_ {2} O}}}

The first reduction of nitrobenzene was carried out using iron:

{\mathsf {4C_{6}H_{5}NO_{2}+9Fe+4H_{2}O\rightarrow 4C_{6}H_{5}NH_{2}+3Fe_{3}O_{4}}}

{\ displaystyle {\ mathsf {4C_ {6} H_ {5} NO_ {2} + 9Fe + 4H_ {2} O \ rightarrow 4C_ {6} H_ {5} NH_ {2} + 3Fe_ {3} O_ {4} }}}

Another way to obtain aniline is to restore nitro compounds - the Zinin reaction :

{\mathsf {C_{6}H_{5}NO_{2}+3(NH_{4})_{2}S\rightarrow C_{6}H_{5}NH_{2}+6NH_{3}+3S+2H_{2}O}}

{\ displaystyle {\ mathsf {C_ {6} H_ {5} NO_ {2} +3 (NH_ {4}) _ {2} S \ rightarrow C_ {6} H_ {5} NH_ {2} + 6NH_ {3 } + 3S + 2H_ {2} O}}}

Also, in aniline, nitrobenzene is reduced by zinc in the presence of an excess of hydrochloric acid.

${\mathsf {Zn+2HCl\rightarrow ZnCl_{2}+H_{2}\uparrow }}$ ${\ displaystyle {\ mathsf {Zn + 2HCl \ rightarrow ZnCl_ {2} + H_ {2} \ uparrow}}}$ ;

${\mathsf {C_{6}H_{5}NO_{2}+3H_{2}\rightarrow C_{6}H_{5}NH_{2}+2H_{2}O}}$ ${\ displaystyle {\ mathsf {C_ {6} H_ {5} NO_ {2} + 3H_ {2} \ rightarrow C_ {6} H_ {5} NH_ {2} + 2H_ {2} O}}}$ ;

And this excess binds the resulting aniline into a salt called phenylammonium chloride (aniline hydrochloride):

${\mathsf {C_{6}H_{5}NH_{2}+HCl\rightarrow [C_{6}H_{5}NH_{3}]^{+}Cl^{-}}}$ ${\ displaystyle {\ mathsf {C_ {6} H_ {5} NH_ {2} + HCl \ rightarrow [C_ {6} H_ {5} NH_ {3}] ^ {+} Cl ^ {-}}}}$ ;

This salt is easily soluble in the water formed in this process and can be crystallized from it,

In addition, after treatment with alkali, phenylammonium chloride gives aniline:

${\mathsf {[C_{6}H_{5}NH_{3}]^{+}Cl^{-}+Na^{+}OH^{-}{\xrightarrow[{}]{NaOH,\ -NaCl}}\ C_{6}H_{5}NH2+NaCl+H_{2}O}}$ ${\ displaystyle {\ mathsf {[C_ {6} H_ {5} NH_ {3}] ^ {+} Cl ^ {-} + Na ^ {+} OH ^ {-} {\ xrightarrow [{}] {NaOH , \ -NaCl}} \ C_ {6} H_ {5} NH2 + NaCl + H_ {2} O}}}$

Chemical Properties

Aniline is characterized by reactions both in the amino group and in the aromatic ring. The features of these reactions are due to the mutual influence of atoms. On the one hand, the benzene ring weakens the basic properties of the amino group compared to aliphatic amines and even ammonia. On the other hand, under the influence of the amino group, the benzene ring becomes more active in substitution reactions than benzene. It is well halogenated, nitrated and sulfonated. For example, aniline reacts vigorously with bromine water to form 2,4,6-tribromaniline (white precipitate). With HNO ₂ gives diazocompounds.

Oxidation

Unlike aliphatic amines, aromatic amines are easily oxidized. An example is the reaction of a chromium mixture with aniline; as a result, the dye “black aniline” is formed .

The classical oxidation reaction of aniline with potassium dichromate in an acidic environment is often used as a qualitative reaction to aniline:

{\mathsf {6C_{6}H_{5}NH_{2}+4K_{2}Cr_{2}O_{7}+19H_{2}SO_{4}\rightarrow }}

{\ displaystyle {\ mathsf {6C_ {6} H_ {5} NH_ {2} + 4K_ {2} Cr_ {2} O_ {7} + 19H_ {2} SO_ {4} \ rightarrow}}}

{\mathsf {6C_{6}H_{4}O_{2}+4K_{2}SO_{4}+4Cr_{2}(SO_{4})_{3}+3(NH_{4})_{2}SO_{4}+16H_{2}O}}

{\ displaystyle {\ mathsf {6C_ {6} H_ {4} O_ {2} + 4K_ {2} SO_ {4} + 4Cr_ {2} (SO_ {4}) _ {3} +3 (NH_ {4} ) _ {2} SO_ {4} + 16H_ {2} O}}}

In this case, the analytical effect is the appearance of the color of the solution from dark blue to black. As with most aniline oxidation reactions, the products are various quinones .

Another qualitative reaction to aniline, which is very sensitive, is the oxidation of aniline with bleach , in which violet staining appears ^[2] .

Electrophilic Substitution Reactions

The amino group, being a substituent of the first kind , has a strong activating effect on the benzene ring, due to which aniline molecules can be oxidized during nitration. To prevent oxidation, the amino group is “protected” by acylation before nitration.

Nitrogen Reactions

With nitrous acid forms a diazonium cation, for example:

${\mathsf {C_{6}H_{5}NH_{2}+NaNO_{2}+2HCl\rightarrow C_{6}H_{5}N_{2}^{+}Cl^{-}+NaCl+2H_{2}O}}$ ${\ displaystyle {\ mathsf {C_ {6} H_ {5} NH_ {2} + NaNO_ {2} + 2HCl \ rightarrow C_ {6} H_ {5} N_ {2} ^ {+} Cl ^ {-} + NaCl + 2H_ {2} O}}}$

This reaction can be used to produce phenol if diluted sulfuric is used instead of hydrochloric acid:

${\mathsf {2C_{6}H_{5}NH_{2}+2NaNO_{2}+2H_{2}SO_{4}\rightarrow (C_{6}H_{5}N_{2}^{+})_{2}SO4^{2-}+Na_{2}SO_{4}+4H_{2}O\rightarrow 2C_{6}H_{5}OH+2N_{2}\uparrow +Na_{2}SO_{4}+H_{2}SO_{4}+2H_{2}O}}$ ${\ displaystyle {\ mathsf {2C_ {6} H_ {5} NH_ {2} + 2NaNO_ {2} + 2H_ {2} SO_ {4} \ rightarrow (C_ {6} H_ {5} N_ {2} ^ { +}) _ {2} SO4 ^ {2 -} + Na_ {2} SO_ {4} + 4H_ {2} O \ rightarrow 2C_ {6} H_ {5} OH + 2N_ {2} \ uparrow + Na_ {2 } SO_ {4} + H_ {2} SO_ {4} + 2H_ {2} O}}}$

Where, first, the same diazonium salt is formed, which, when heated in a dilute aqueous solution, hydrolyzes and decomposes to phenol, and molecular nitrogen is released.

Due to the instability of nitrous acid, it is often replaced with alkali metal nitrite in an acidic environment. Diazonium salts are used for the Sandmeyer reaction .

Other reactions

Hydrogenation of aniline in the presence of a nickel catalyst gives cyclohexylamine .

Aniline interacts with hydrochloric acid to form phenylammonium chloride ^[3] :

{\mathsf {C_{6}H_{5}NH_{2}+HCl\rightarrow [C_{6}H_{5}NH_{3}]Cl}}

{\ displaystyle {\ mathsf {C_ {6} H_ {5} NH_ {2} + HCl \ rightarrow [C_ {6} H_ {5} NH_ {3}] Cl}}}

Aniline interacts with bromine and even bromine water with the formation of 2,4,6-tribromaniline ^[4] :

{\mathsf {C_{6}H_{5}NH_{2}+3Br_{2}\rightarrow C_{6}H_{2}Br_{3}NH_{2}+3HBr}}

{\ displaystyle {\ mathsf {C_ {6} H_ {5} NH_ {2} + 3Br_ {2} \ rightarrow C_ {6} H_ {2} Br_ {3} NH_ {2} + 3HBr}}}

Production and Application

Initially, aniline was obtained by reduction of nitrobenzene with molecular hydrogen; the practical yield of aniline did not exceed 15%. During the interaction of concentrated hydrochloric acid with iron, atomic hydrogen was released , which was more chemically active than molecular hydrogen . The Zinin reaction is a more efficient method for producing aniline. Nitrobenzene was poured into the reaction mass, which is reduced to aniline.

As of 2002, in the world the bulk of the aniline produced is used to produce methyldiisocyanates , which are then used to produce polyurethanes . Aniline is also used in the production of artificial rubbers , herbicides and dyes (purple dye movein ) ^[5] .

In Russia, it is mainly used as an intermediate in the production of dyes , explosives and medicines ( sulfa drugs ), but due to the expected increase in the production of polyurethanes , a significant change in the picture is possible in the medium term.

Toxic Properties

Aniline is poisonous. It has a negative effect on the central nervous system . Blood poison, causes oxygen starvation of the body due to the formation of methemoglobin in the blood, hemolysis and degenerative changes in red blood cells .

Aniline enters the body when breathing, in the form of vapors, as well as through the skin and mucous membranes. Absorption through the skin is enhanced by heating the air or drinking alcohol.

With mild aniline poisoning, weakness, dizziness, headache, blueness of the lips, auricles and nails are observed. With moderate poisoning, nausea, vomiting, sometimes a staggering gait, increased heart rate are also observed. Severe cases of poisoning are extremely rare.

In chronic aniline poisoning (anilism), toxic hepatitis occurs, as well as neuropsychiatric disturbances, sleep disturbance, memory loss, etc.

In case of aniline poisoning, it is necessary, first of all, to remove the victim from the poisoning site, and to wash with warm (but not hot!) Water. The use of antidotes ( methylene blue ), cardiovascular agents or inhalation of carbogen are also used . The victim needs to ensure peace.

The maximum permissible concentration of aniline in the air of the working zone is 3 mg / m ³ . In reservoirs (with their industrial pollution) - MPC 0.1 mg / l (100 mg / m ³ ) ^[6] .

Notes

↑ ¹ ² ³ ⁴ http://www.cdc.gov/niosh/npg/npgd0033.html
↑ Oxidation of aniline with a solution of bleach (neopr.) . A single collection of digital educational resources. Date of treatment August 14, 2017.
↑ Tsvetkov L.A. § 36. Amines // Organic chemistry. Textbook for grade 10. - 20th ed. - M .: Enlightenment , 1981. - S. 171-175.
↑ Gabrielyan O.S. § 16. Amines. Aniline // Chemistry. Grade 10. Basic level: textbook. for general education. institutions. - 4th ed. - M .: Bustard, 2008 .-- S. 116-121.
↑ Aniline ( inaccessible link) . www.the-innovation-group.com (February 19, 2002). - Aniline producers price capacity market demand consumption production growth uses outlook nd, The Chemical Market Reporter, Schnell Publishing Company. Date of treatment August 14, 2017. Archived February 19, 2002.
↑ Aniline // Angola - Barzas. - M .: Soviet Encyclopedia, 1970. - S. 32-33. - (The Great Soviet Encyclopedia : [in 30 vols.] / Ch. Ed. A. M. Prokhorov ; 1969-1978, vol. 2).

Literature

Artemenko A.I. Organic chemistry. - M .: "Higher School", 1987. - 430 p.

Links

Anilin // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.

[_3f726103e78b8728-1] ¹ ² ³ ⁴ http://www.cdc.gov/niosh/npg/npgd0033.html

[2] Oxidation of aniline with a solution of bleach (neopr.) . A single collection of digital educational resources. Date of treatment August 14, 2017.

[3] Tsvetkov L.A. § 36. Amines // Organic chemistry. Textbook for grade 10. - 20th ed. - M .: Enlightenment , 1981. - S. 171-175.

[4] Gabrielyan O.S. § 16. Amines. Aniline // Chemistry. Grade 10. Basic level: textbook. for general education. institutions. - 4th ed. - M .: Bustard, 2008 .-- S. 116-121.

[CPoA-5] Aniline ( inaccessible link) . www.the-innovation-group.com (February 19, 2002). - Aniline producers price capacity market demand consumption production growth uses outlook nd, The Chemical Market Reporter, Schnell Publishing Company. Date of treatment August 14, 2017. Archived February 19, 2002.

[6] Aniline // Angola - Barzas. - M .: Soviet Encyclopedia, 1970. - S. 32-33. - (The Great Soviet Encyclopedia : [in 30 vols.] / Ch. Ed. A. M. Prokhorov ; 1969-1978, vol. 2).

Aniline


Are common
Traditional names	Aminobenzene Aniline Benzoamine Phenylamine
Chem. formula	C ₆ H ₅ N H ₂
Physical properties
condition	colorless or yellowish liquid
Molar mass	93.1265 ± 0.0055 g / mol
Density	1,0217 g / cm³
Surface tension	43.3 N / m
Dynamic viscosity	3.71 Pa · s
Ionization energy
The speed of sound in matter	1659 m / s
Thermal properties
T. melt.	−6.3 ° C
T. bale.	184.13 ° C
T. aux.	and
T. svpl.	562 ° C
Etc. blast
Cr. pace.	425.65 ° C
Cr. pressure	5.134 MPa
Steam pressure
Chemical properties
Solubility in water	3.6 g / 100 ml
Solubility in cyclohexane	66.7 (30.8 ° C)
Dielectric penetration.	6.89
Optical properties
Refractive index	1,5863
Structure
Dipole moment	1.53 D
Classification
Reg. CAS number	62-53-3
PubChem
Reg. EINECS number	200-539-3
Smiles
Inchi
RTECS
Chebi	and
UN number
ChemSpider
Security
LD ₅₀	250 mg / kg (cats, intragastrically), 460 mg / kg (mouse, intragastric)
Toxicity	moderately toxic to small mammals, highly toxic to humans, is hematotoxin (causes hemolysis).
NFPA 704	0 3 0