1-Naphthylamine is an aromatic amine

Amine

Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

. It can be prepared by reducing

Redox

Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 1-nitronaphthalene with iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 and hydrochloric acid

Hydrochloric acid

Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

 at about 70 °C, the reaction mixture being neutralized with milk of lime, and the naphthylamine steam

Steam

Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...

-distilled. It may also be prepared, in the form of its acetyl

Acetyl

In organic chemistry, acetyl is a functional group, the acyl with chemical formula COCH3. It is sometimes represented by the symbol Ac . The acetyl group contains a methyl group single-bonded to a carbonyl...

 derivative, by heating 1-naphthol

1-Naphthol

1-Naphthol, or α-naphthol, is a colorless crystalline solid with the formula C10H7OH. It is an isomer of 2-naphthol differing by the location of the hydroxyl group on naphthalene. The naphthols are naphthalene homologues of phenol, with the hydroxyl group being more reactive than in the phenols....

 with sodium acetate

Sodium acetate

Sodium acetate, CH3COONa, also abbreviated NaOAc, also sodium ethanoate, is the sodium salt of acetic acid. This colourless salt has a wide range of uses.-Industrial:...

, ammonium chloride

Ammonium chloride

Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride...

 and acetic acid

Acetic acid

Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

; by heating 1-naphthol with calcium chloride

Calcium chloride

Calcium chloride, CaCl2, is a salt of calcium and chlorine. It behaves as a typical ionic halide, and is solid at room temperature. Common applications include brine for refrigeration plants, ice and dust control on roads, and desiccation...

-ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 to 270 °C; and by heating pyromucic acid, aniline

Aniline

Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

, zinc chloride

Zinc chloride

Zinc chloride is the name of chemical compound with the formula ZnCl2 and its hydrates. Zinc chlorides, of which nine crystalline forms are known, are colorless or white, and are highly soluble in water. ZnCl2 itself is hygroscopic and even deliquescent. Samples should therefore be protected from...

 and lime

Lime (mineral)

Lime is a general term for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide. It is also the name for a single mineral of the CaO composition, occurring very rarely...

 to 300 °C. It crystallizes in colorless needles which melt at 50 °C. It possesses a disagreeable odor, sublime

Sublimation (physics)

Sublimation is the process of transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase...

s readily, and turns brown on exposure to air. Oxidizing agent

Oxidizing agent

An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...

s, such as ferric chloride, give a blue precipitate with solutions of its salt

Salt

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

s. Chromic acid

Chromic acid

The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixture for glass. Chromic acid may also refer to the...

 converts it into 1-naphthoquinone. Sodium

Sodium

Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

 in boiling amyl alcohol

Amyl alcohol

An amyl alcohol is any of 8 alcohols with the formula C5H11OH. A mixture of amyl alcohols can be obtained from fusel alcohol. Amyl alcohol is used as a solvent and in esterfication for example in the production of amyl acetate...

reduces it to aromatic tetrahydro-1-naphthylamine, a substance having the properties of an aromatic amine

Aromatic amine

An aromatic amine is an amine with an aromatic substituent - that is -NH2, -NH- or nitrogen group attached to an aromatic hydrocarbon, whose structure usually contains one or more benzene rings. Aniline is the simplest example....

, for it can be diazo

Diazo

Diazo refers to a type of organic compound called diazo compound that has two linked nitrogen atoms as a terminal functional group. The general formula is R2C=N2. The simplest example of a diazo compound is diazomethane...

tized and does not possess an ammoniacal smell. Since it does not form an addition product with bromine

Bromine

Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...

, reduction must have taken place in one of the nuclei only, and on account of the aromatic character of the compound it must be in that nucleus which does not contain the amino group. This tetrahydro compound yields adipic acid

Adipic acid

Adipic acid is the organic compound with the formula 42. From the industrial perspective, it is the most important dicarboxylic acid: About 2.5 billion kilograms of this white crystalline powder are produced annually, mainly as a precursor for the production of nylon...

, (C₆O₄H₁₀), when oxidized by potassium permanganate

Potassium permanganate

Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...

. The 1-naphthylamine sulfonic acid

Sulfonic acid

Sulfonic acid usually refers to a member of the class of organosulfur compounds with the general formula RS2–OH, where R is an alkyl or aryl. The formal part of acid, HS2–OH, are formally derivatives of the "parent" inorganic compound with the formula HSO2.-Preparation:Sulfonic acid is...

s are used for the preparation of azo dye

Dye

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

s, these dyes possessing the important property of dyeing unmordanted cotton

Cotton

Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....

. The most important is naphthionic acid, 1-amino-4-sulfonic acid, produced by heating 1-naphthylamine and sulfuric acid

Sulfuric acid

Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 to 170-180 °C with about 3% of crystallized oxalic acid

Oxalic acid

Oxalic acid is an organic compound with the formula H2C2O4. This colourless solid is a dicarboxylic acid. In terms of acid strength, it is about 3,000 times stronger than acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate , is a chelating agent for metal cations...

. It forms small needles, very sparingly soluble in water. With diazotized benzidine it
gives Congo red

Congo red

Congo red is the sodium salt of 3,3'-bis. It is a secondary diazo dye...

.