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Turpentine (also called spirit of turpentine, oil of turpentine, and wood turpentine) is a fluid obtained by the distillation of resin obtained from live trees, mainly pines. It is mainly used as a solvent and as a source of materials for organic synthesis.
Turpentine is composed of terpenes, mainly the monoterpenes alpha-pinene and beta-pinene with lesser amounts of carene, camphene, dipentene, and terpinolene. It is sometimes colloquially known as turps.
The word turpentine derives (via French and Latin) from the Greek word τερεβινθίνη terebinthine, the name of a species of tree, the terebinth tree. Mineral turpentine or other petroleum distillates are used to replace turpentine, but they are very different chemically.
One of the earliest sources was the terebinth or turpentine tree (Pistacia terebinthus), a Mediterranean tree related to the pistachio. Important pines for turpentine production include: maritime pine (Pinus pinaster), Aleppo pine (Pinus halepensis), Masson's pine (Pinus massoniana), Sumatran pine (Pinus merkusii), longleaf pine (Pinus palustris), loblolly pine (Pinus taeda) and ponderosa pine (Pinus ponderosa). Jeffrey pine, which resembles ponderosa pine, produces a resin that, when distilled, yields almost pure n-heptane, a volatile hydrocarbon which is highly flammable: therefore it cannot be used to make turpentine.
Canada balsam, also called Canada turpentine or balsam of fir, is a turpentine which is made from the oleoresin of the balsam fir. Venice turpentine is produced from the western larch Larix occidentalis.
In order to tap into the sap producing layers of the tree, turpentiners used a combination of hacks to remove the pine bark. Once debarked, pine trees secrete oleoresin onto the surface of the wound as a protective measure to seal the opening, resist exposure to micro-organisms and insects and prevent vital sap loss. Turpentiners wounded trees in V-shaped streaks down the length of the trunks so as to channel the oleoresin into containers. It was then collected and processed into spirits of turpentine. Oleoresin yield may be increased by as much as 40% by applying paraquat herbicides to the exposed wood.
The V-shaped cuts are called "catfaces" for their resemblance to a cat’s whiskers. These marks on a pine tree signify it was used to collect resin for turpentine production.
Crude oleoresin collected from wounded trees may be evaporated by steam distillation in a copper still. Molten rosin remains in the still bottoms after turpentine has been evaporated and recovered from a condenser. Turpentine may alternatively be condensed from destructive distillation of pine wood.
Oleoresin may also be extracted from shredded pine stumps, roots, and slash using the light end of the heavy naphtha fraction (boiling between 90°C and 115°C) from a crude oil refinery. Multi-stage counter-current extraction is commonly used so fresh naphtha first contacts wood leached in previous stages and naphtha laden with turpentine from previous stages contacts fresh wood before vacuum distillation to recover naphtha from the turpentine. Leached wood is steamed for additional naphtha recovery prior to burning for energy recovery.
When producing chemical wood pulp from pines or other coniferous trees, sulfate turpentine may be condensed from the gas generated in Kraft process pulp digesters. The average yield of crude sulfate turpentine is 5–10 kg/t pulp. Unless burned at the mill for energy production, sulfate turpentine may require additional treatment measures to remove traces of sulfur compounds.
The two primary uses of turpentine in industry are as a solvent and as a source of materials for organic synthesis. As a solvent, turpentine is used for thinning oil-based paints, for producing varnishes, and as a raw material for the chemical industry. Its industrial use as a solvent in industrialized nations has largely been replaced by the much cheaper turpentine substitutes distilled from crude oil. Turpentine has long been used as a solvent, mixed with beeswax or with carnauba wax, to make fine furniture wax for use as a protective coating over oiled wood finishes (e.g., lemon oil).
Turpentine is also used as a source of raw materials in the synthesis of fragrant chemical compounds. Commercially used camphor, linalool, alpha-terpineol, and geraniol are all usually produced from alpha-pinene and beta-pinene, which are two of the chief chemical components of turpentine. These pinenes are separated and purified by distillation. The mixture of diterpenes and triterpenes that is left as residue after turpentine distillation is sold as rosin.
Turpentine and petroleum distillates such as coal oil and kerosene have been used medicinally since ancient times, as topical and sometimes internal home remedies. Topically it has been used for abrasions and wounds, as a treatment for lice, and when mixed with animal fat it has been used as a chest rub, or inhaler for nasal and throat ailments. Many modern chest rubs, such as the Vicks variety, still contain turpentine in their formulations.
Taken internally it was used as treatment for intestinal parasites because of its alleged antiseptic and diuretic properties, and a general cure-all as in Hamlin's Wizard Oil. Sugar, molasses or honey were sometimes used to mask the taste. Internal administration of these toxic products is no longer common today.
Turpentine is also added to many cleaning and sanitary products due to its antiseptic properties and its "clean scent". In early 19th-century America, turpentine was sometimes burned in lamps as a cheap alternative to whale oil. It was most commonly used for outdoor lighting, due to its strong odour. A blend of ethanol and turpentine added as an illuminant called burning fluid was also important for several decades. In 1946, Soichiro Honda used turpentine as a fuel for the first Honda motorcycles as gasoline was almost totally unavailable following World War II.
Turpentine was a common additive in cheap gin until the 20th century and gave it its characteristic juniper berry flavour without the need for pricier distillations with aromatic spices and berries.
As an organic solvent, its vapour can irritate the skin and eyes, damage the lungs and respiratory system, as well as the central nervous system when inhaled, and cause renal failure when ingested, among other things. Being combustible, it also poses a fire hazard. Due to the fact that turpentine can cause spasms of the airways particularly in people with asthma and whooping cough, it can contribute to a worsening of breathing issues in persons with these diseases if inhaled.
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