Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Aniline

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Aniline, also phenylamine, colorless liquid, slightly soluble in water and soluble in organic solvents. It was first prepared in 1826 as one of the products obtained by heating indigo to a high temperature. The word aniline is derived from the specific name, anil, of the indigo plant, which in turn is derived from the Sanskrit word nila (“blue” or “indigo”).

In 1856 the British chemist Sir William Henry Perkin, while attempting to synthesize quinine, treated impure aniline with potassium dichromate and obtained a violet substance that could be used as a dye. Perkin named this material mauve and set up a factory to manufacture it. The enterprise was highly successful, and in a short time other synthetic dyestuffs, prepared from aniline or from other derivatives of coal tar, were competing with natural dyes.

Aniline is most readily prepared for commercial use by the reduction of nitrobenzene by iron and hydrochloric acid. It is also prepared commercially by the action of ammonia under high pressure on chlorobenzene in the presence of a catalyst. The raw material in both cases is made from benzene. The commercial product is known as aniline oil.

Currently, the principal use of aniline is in making an important class of plastics called polyurethanes. It also has important uses in making dyes, drugs (for example, sulfanilamide), explosives, and many other synthetic chemicals.

Aniline melts at -6.2° C (20.8° F) and boils at 184.3° C (363.8° F).