Naphthalene
Introduction
Naphthalene is a polycyclic aromatic hydrocarbon (PAH) that is most commonly recognized for its use in mothballs. It is a white, volatile solid that is derived from coal tar, but it can also be produced from petroleum or by the carbonization of plant material.
History
Naphthalene was first discovered in 1819 by English chemist and inventor Sir John Kidd. He isolated it from coal tar, a by-product of the production of coke and coal gas. The name 'naphthalene' comes from the Persian word 'naft', meaning 'naphtha', and the suffix '-ene', which is used in organic chemistry to denote substances that contain a double bond.
Chemical Structure
The chemical structure of naphthalene is composed of two fused benzene rings, making it the simplest example of a class of hydrocarbons called polycyclic aromatic hydrocarbons. The molecular formula of naphthalene is C10H8. It has 10 carbon atoms and 8 hydrogen atoms. The carbon atoms are arranged in a hexagonal lattice, with each carbon atom bonded to two other carbon atoms and one hydrogen atom.
Production
Naphthalene is primarily produced from coal tar, a by-product of the coking process used to produce steel. It can also be produced from petroleum or by the carbonization of plant material. The production process involves the distillation of coal tar, followed by crystallization and sublimation to purify the naphthalene.
Uses
Naphthalene has a wide range of uses. It is most commonly known for its use in mothballs, where it acts as a fumigant to kill moths and other insects. It is also used in the production of certain types of plastic, as a dye intermediate, and as a synthetic tanning agent. In addition, naphthalene is used in the production of phthalic anhydride, which is used to make plastics, dyes, and pharmaceuticals.
Health Effects
Exposure to naphthalene can have various health effects. Short-term exposure can cause headache, nausea, vomiting, and confusion. Long-term exposure can lead to cataracts, damage to the liver and kidneys, and in severe cases, can cause a condition called hemolytic anemia, which is a disorder that results in the destruction of red blood cells.
Environmental Impact
Naphthalene is a persistent organic pollutant, meaning it does not readily break down in the environment. It can contaminate soil and water and can be harmful to wildlife. It is also a greenhouse gas, contributing to global warming.