Extra Credit: Mercury

Mercury is an element that is found in air, water and soil. It has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If heated, it is a colorless, odorless gas. It also combines with other elements to form powders or crystals. Mercury is in many products. Metallic mercury is used in glass thermometers, silver dental fillings, and button batteries. Mercury salts may be used in skin creams and ointments. It's also used in many industries.

Mercury in the air settles into water. It can pass through the food chain and build up in fish, shellfish, and animals that eat fish. The nervous system is sensitive to all forms of mercury. Exposure to high levels can damage the brain and kidneys. Pregnant women can pass the mercury in their bodies to their babies.

http://www.nlm.nih.gov/medlineplus/mercury.html

Mercury was known to ancient Chinese and Hindus before 2000 BC and was found in tubes in Egyptian tombs dated from 1500 BC. It was used to forma amalgams of other metals around 500 BC. The Greeks used mercury in ointments and the Romans used it, unfortunately for those using it, in cosmetics. Mercury is one of the elements which has an alchemical symbol, (alchemy is an ancient pursuit concerned with, for instance, the transformation of other metals into gold). Named after the planet "Mercury" (the origin of the symbol Hg is the Latin word "hydrargyrum" meaning "liquid silver").

Mercury can be used to make thermometers, barometers and other scientific instruments. Mercury conducts electricity and is used to make silent, position dependent switches. Mercury vapor is used in streetlights, fluorescent lamps and advertising signs.

Mercury easily forms alloys with other metals, such as gold, silver, zinc and cadmium. These alloys are called amalgams. Amalgams are used to help extract gold from its ores, create dental fillings (in the case of silver) and help extend the life of dry cell batteries (in the case of zinc and cadmium). Mercury forms useful compounds with other elements. Mercuric chloride (HgCl2) is a very poisonous salt and was once used to disinfect wounds. Mercurous chloride (Hg2Cl2), also called calomel, is an antiseptic used to kill bacteria. Mercuric sulfide (HgS) is used to make a red paint pigment called vermilion. Mercuric oxide (HgO) is used to make mercury batteries.

Mercury is poisonous and can enter the body through the respiratory tract, the digestive tract or directly through the skin. It accumulates in the body, eventually causing severe illness or death. Mercury in the elemental (gaseous) form targets the brain, kidney, and lung. Divalent mercury forms in the kidney and methyl mercury targets the brain, and the fetal brain.

http://education.jlab.org/itselemental/ele080.html

Most people are not exposed to inorganic mercury but rather absorb methylmercury through the consumption of fish and shellfish. Methylmercury is easily absorbed in the digestive tract, where it forms a complex with the amino acid cysteine. This new complex resembles a large neutral amino acid found in the body, methionine, and can more easily gain entry into cells. As with inorganic mercury, once in the bloodstream, methylmercury will accumulate in the brain and cause damage to the central nervous system. Methylmercury is naturally removed from the body over time. Eventually, this methylmercury-cysteine complex is transported to the liver where it is secreted into bile, after which enzymes break the complex down into its amino acid and methylmercury parts. Some of this methylmercury then comes in contact with the bacteria in the intestine and is broken down into inorganic mercury and carbon. The inorganic mercury is poorly absorbed in the digestive tract and 90 percent is excreted in the feces. The rest of the methylmercury that does not interact with bacteria is reabsorbed by the body and goes through the process again. It takes about 30 to 40 hours for methylmercury to be distributed to the tissues of the body (Clarkson & Magos, 2006). This cycle is the reason it takes so long to rid the body of mercury and how it can accumulate in the blood. It can take up to a year for mercury levels to drop significantly

http://www.csa.com/discoveryguides/mercury/review4.php

Turpentine and Terpenoids

Terpenoids is a subclass of the prenyllipids (terpenes, preylquinones, and sterols), represent the oldest group of small molecular products synthesized by plants and are probably the most widespread the oldest group of small molecular products synthesized by plants and are probably the most widespread group of natural products.

Terpenoids can be described as modified terpenes, where methyl groups are moved or removed, or oxygen atoms added. Inversely, some authors use the term "terpenes" more broadly, to include the terpenoids

During the 19th century, chemical works on turpentine led to name "terpene" the hydrocarbons with the general formula C10H16 found in that complex plant product. These terpenes are frequently found in plant essential oils which contain the "Quinta essentia", the plant fragrance

They are universally present in small amounts in living organisms, where they play numerous vital roles in plant physiology as well as important functions in all cellular membranes. The various functions of terpene natural products in the natural world have been reviewed. On the other hand, they are also accumulated in many cases, and it is shown that the extraordinary variety they then display can be due to ecological factors playing an evolutionary role.

Terpenoids are extraordinarily diverse but they all originate through the condensation of the universal phosphorylated derivative of hemiterpene, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) giving geranyl pyrophosphate (GPP).

Terpenes history spans various civilizations. As they are largely found in essential oils, they were used in the Ancient Egypt for various religions aims. Camphor was introduced in Europe from the East by the Arabs around the 11th century.

The process of obtaining plant essential oils by fatty extraction was known by the early Middle Ages. In the 12th century, Arnaud de Villanosa described distillation of oils from rosemary and sage. He made an "oleum mirabile" from oils of turpentine and rosemary. It is noticeable that some 60 oils were described in the Nuremberg edition of "Dispensatorium valerii cordi" written in 1592.

Analyses of oils of turpentine were made in 1818 by JJ Houston de la Billardière. Dumas proposed in 1866 the name "terpene", derived from turpentine, instead of camphor for crystalline oxygenated substances extracted from essential oils. In 1887, Wallach O proposed that one isoprenic unit of 5 carbon atoms (C5H8) is always present in the molecule of terpenes (Justus Lieb Ann Chem 1887, 238, 78).

The structure of camphor was established by Bredt in 1893, that of pinene by Wagner in 1894 and that of citral by Tiemann in 1895. b-Carotene was isolated in 1837 by Wackenrodder from carrots, and its correct molecular form was determined in 1907 by Willstätter.

http://www.cyberlipid.org/simple/simp0004.htm

Terpene is any of a large and varied class of hydrocarbons, with the molecular formula (C5H8)n, that are produced by a wide variety of plants, such as conifers. Terpenes also are produced by some other living organisms, such as swallowtail butterflies, which emit terpenes from their osmeterium, and a fungus isolated from St. John's Wort. The term "terpene" at times is used broadly to also include the terpenoids, which are terpenes that have been chemically modified, such as through oxidation.

Terpenes are natural products derived from plants that have medicinal properties and biological activity. Terpenes may be found in cleaning products, rubefacients, aromatherapy, and various topical preparations. Terpenes may exist as hydrocarbons or have oxygen-containing compounds such as ketone or aldehyde groups (terpenoids).

http://emedicine.medscape.com/article/818675-overview