Methanol (also called methyl alcohol, wood alcohol, and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic alcohol, with the chemical formula CH3OH (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a light, volatile, colorless and flammable liquid with a distinctive alcoholic odor similar to that of ethanol (potable alcohol), but is more acutely toxic than the latter. Methanol acquired the name wood alcohol because it was once produced through destructive distillation of wood. Today, methanol is mainly produced industrially by hydrogenation of carbon monoxide. Methanol consists of a methyl group linked to a polar hydroxyl group. With more than 20 million tons produced annually, it is used as a precursor to other commodity chemicals, including formaldehyde, acetic acid, methyl tert-butyl ether, methyl benzoate, anisole, peroxyacids, as well as a host of more specialized chemicals.
Occurrence Small amounts of methanol are present in normal, healthy human individuals. One study found a mean of 4.5 ppm in the exhaled breath of test subjects. The mean endogenous methanol in humans of 0.45 g/d may be metabolized from pectin found in fruit; one kilogram of apple produces up to 1.4 g of pectin (0.6 g of methanol.) Methanol is produced by anaerobic bacteria and phytoplankton.
Interstellar medium Methanol is also found in abundant quantities in star-forming regions of space and is used in astronomy as a marker for such regions. It is detected through its spectral emission lines. In 2006, astronomers using the MERLIN array of radio telescopes at Jodrell Bank Observatory discovered a large cloud of methanol in space 0.463 terametres (288 million miles) across. In 2016, astronomers detected methanol in a planet-forming disc around the young star TW Hydrae using the Atacama Large Millimeter Array radio telescope.
History In their embalming process, the ancient Egyptians used a mixture of substances, including methanol, which they obtained from the pyrolysis of wood. Pure methanol, however, was first isolated in 1661 by Robert Boyle, when he produced it via the distillation of buxus (boxwood). It later became known as "pyroxylic spirit". In 1834, the French chemists Jean-Baptiste Dumas and Eugene Peligot determined its elemental composition. They also introduced the word "methylène" to organic chemistry, forming it from Greek methy = "alcoholic liquid" + hȳlē = "forest, wood, timber, material". "Methylène" designated a "radical" that was about 14% hydrogen by weight and contained one carbon atom. This would be CH2, but at the time carbon was thought to have an atomic weight only six times that of hydrogen, so they gave the formula as CH. They then called wood alcohol (l'esprit de bois) "bihydrate de méthylène" (bihydrate because they thought the formula was C4H8O4 or (CH)4(H2O)2). The term "methyl" was derived in about 1840 by back-formation from "methylene", and was then applied to describe "methyl alcohol". This was shortened to "methanol" in 1892 by the International Conference on Chemical Nomenclature. The suffix -yl, which, in organic chemistry, forms names of carbon groups, is from the word methyl. French chemist Paul Sabatier presented the first process that could be used to produce methanol synthetically in 1905. This process suggested that carbon dioxide and hydrogen could be reacted to produce methanol. German chemists Alwin Mittasch and Mathias Pier, working for Badische-Anilin & Soda-Fabrik (BASF), developed a means to convert synthesis gas (a mixture of carbon monoxide, carbon dioxide, and hydrogen) into methanol and received a patent. According to Bozzano and Manenti, BASF's process was first utilized in Leuna, Germany in 1923. Operating conditions consisted of "high" temperatures (between 300 and 400 °C) and pressures (between 250 and 350 atm) with a zinc/chromium oxide catalyst. US patent 1,569,775 was applied for on 4 September 1924 and issued on 12 January 1926 to BASF; the process used a chromium and manganese oxide catalyst with extremely vigorous conditions: pressures ranging from 50 to 220 atm, and temperatures up to 450 °C. Modern methanol production has been made more efficient through use of catalysts (commonly copper) capable of operating at lower pressures. The modern low pressure methanol (LPM) process was developed by ICI in the late 1960s with the technology patent long since expired. During World War II, methanol was used as a fuel in several German military rocket designs, under the name M-Stoff, and in a roughly 50/50 mixture with hydrazine, known as C-Stoff. The Luftwaffe used 50/50 methanol-water solution MW 50 injected in the inlet manifold for anti-detonation in supercharged aircraft engines. The use of methanol as a motor fuel received attention during the oil crises of the 1970s. By the mid-1990s, over 20,000 methanol flexible fuel vehicles (FFVs) capable of operating on methanol or gasoline were introduced in the US. In addition, low levels of methanol were blended in gasoline fuels sold in Europe during much of the 1980s and early-1990s. Automakers stopped building methanol FFVs by the late-1990s, switching their attention to ethanol-fueled vehicles. While the methanol FFV program was a technical success, rising methanol pricing in the mid- to late-1990s during a period of slumping gasoline pump prices diminished interest in methanol fuels. In the early 1970s, a process was developed by Mobil for producing gasoline fuel from methanol. Between the 1960s and 1980s methanol emerged as a precursor to the feedstock chemicals acetic acid and acetic anhydride. These processes include the Monsanto acetic acid synthesis, Cativa process, and Tennessee Eastman acetic anhydride process.
Applications
Production of formaldehyde, acetic acid, methyl tert-butyl ether Methanol is primarily converted to formaldehyde, which is widely used in many areas, especially polymers. The conversion entails oxidation:
2 CH3OH + O2 → 2 CH2O + 2 H2O Acetic acid can be produced from methanol.
Methanol and isobutene are combined to give methyl tert-butyl ether (MTBE). MTBE is a major octane booster in gasoline.
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