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Ethanol has been used by humans since prehistory as the intoxicating ingredient in alcoholic beverages. Dried residues on 9000-year-old pottery found in northern China imply the use of alcoholic beverages even among Neolithic peoples. Its isolation as a relatively pure compound was first achieved by Islamic alchemists who developed the art of distillation during the Abbasid caliphate, the most notable of whom was Al-Razi. The writings attributed to Jabir Ibn Hayyan (Geber) (721-815) mention the flammable vapors of boiled wine. Al-Kindi (801-873) unambiguously described the distillation of wine. Distillation of ethanol from water yields a product that is at most 96% ethanol, because ethanol forms an azeotrope with water. Absolute ethanol was first obtained in 1796 by Johann Tobias Lowitz, by filtering distilled ethanol through charcoal.
Ethanol also known as Ethyl Alcohol is not a new fuel. In the 1850s, ethanol was a major lighting fuel. During the Civil War, a liquor tax was placed on ethanol to raise money for the war. The tax increased the price of ethanol so much that it could no longer compete with other fuels such as kerosene in lighting devices. Ethanol production declined sharply because of this tax and production levels did not begin to recover until the tax was repealed in 1906.
In 1908, Henry Ford designed his Model T to run on a mixture of gasoline and alcohol, calling it the fuel of the future. In 1919, when Prohibition began, ethanol was banned because it was considered liquor. It could only be sold when it was mixed with petroleum. With the end of Prohibition in 1933, ethanol was used as a fuel again. Ethanol use increased temporarily during World War II when oil and other resources were scarce.
During the 1930s, more than 2,000 service stations in the Midwest sold ethanol made from corn, but the ethanol industry closed down in the ’40s with the coming of low-priced petroleum. During World War I and II in both the United States and in Europe, alcohol fuels
supplemented supplies of oil-based fuels. During World War II, the government even commandeered whiskey distilleries for alcohol fuel production. In recent history, public interest in alcohol as a transportation fuel has changed with periods of war and the fluctuating supply and price of oil. The oil crisis in the 1970s raised the price of oil and gas and gave birth to the gasohol era, when gasoline was extended with the addition of 10 percent ethanol. (Gasohol is not considered an alternative fuel.) When gasoline became more plentiful, ethanol was blended with gasoline to increase the octane rating, and the name gasohol was replaced with names reflecting the increased octane. Unleaded plus or super unleaded are two examples of names used today.
In the 1850s nearly 90 million gallons of ethanol were produced every year in the US. At that time it was used as a fuel for lamps. It could also be consumed as an alcoholic beverage. In 1862 the Union Congress put a $2 per gallon excise tax on alcoholic beverages to help finance the Civil War. The tax made ethanol too expensive to use for lighting, so people started using kerosene and methanol instead.
Ethanol has been used by humans since prehistory as the intoxicating ingredient in alcoholic beverages. Dried residues on 9000-year-old pottery found in northern China imply the use of alcoholic beverages even among Neolithic peoples. Its isolation as a relatively pure compound was first achieved by Islamic alchemists who developed the art of distillation during the Abbasid caliphate, the most notable of whom was Al-Razi. The writings attributed to Jabir Ibn Hayyan (Geber) (721-815) mention the flammable vapors of boiled wine. Al-Kindi (801-873) unambiguously described the distillation of wine. Distillation of ethanol from water yields a product that is at most 96% ethanol, because ethanol forms an azeotrope with water. Absolute ethanol was first obtained in 1796 by Johann Tobias Lowitz, by filtering distilled ethanol through charcoal.
Ethanol is a monohydric primary alcohol. It melts at -117.3°C and boils at 78.5°C. It is miscible (i.e., mixes without separation) with water in all proportions and is separated from water only with difficulty; ethanol that is completely free of water is called absolute ethanol. Ethanol forms a constant-boiling mixture, or azeotrope, with water that contains 95% ethanol and 5% water and that boils at 78.15°C; since the boiling point of this binary azeotrope is below that of pure ethanol, absolute ethanol cannot be obtained by simple distillation. However, if benzene is added to 95% ethanol, a ternary azeotrope of benzene, ethanol, and water, with boiling point 64.9°C, can form; since the proportion of water to ethanol in this azeotrope is greater than that in 95% ethanol, the water can be removed from 95% ethanol by adding benzene and distilling off this azeotrope. Because small amounts of benzene may remain, absolute ethanol prepared by this process is poisonous. Ethanol burns in air with a blue flame, forming carbon dioxide and water. It reacts with active metals to form the metal ethoxide and hydrogen, e.g., with sodium it forms sodium ethoxide. It reacts with certain acids to form esters, e.g., with acetic acid it forms ethyl acetate. It can be oxidized to form acetic acid and acetaldehyde. It can be dehydrated to form diethyl ether or, at higher temperatures, ethylene.
Combustion of Ethanol Ethanol burns with a pale blue, non luminous flame to form carbon dioxide and steam.
C2H5OH + 3O2 ==> 2CO2 + 3H2O
Ethanol
Oxidation of Ethanol
Ethanol is oxidised
* with acidified Potassium Dichromate, K2Cr2O7, or
* with acidified Sodium Dichromate, Na2Cr2O7, or
* with acidified potassium permanganate, KMnO4,
to form ethanal, (i.e. acetaldehyde).
[O]
C2H5OH ==> CH3CHO + H2O
Ethanol Ethanal
The ethanal is further oxidised to ethanoic acid (i.e. acetic acid) if the oxidising agent is in excess.
[O]
CH3CHO ==> CH3COOH
Ethanal Ethanoic Acid
The oxidising agent usually used for this reaction is a mixture of sodium dichromate or potassium dichromate and sulphuric acid which react together to provide oxygen atoms as follows.
Na2Cr2O7 + 4 H2SO4 ==> Na2SO4 + Cr2(SO4)3 + 4H2O + 3[O]
Dehydration of Ethanol
When ethanol is mixed with concentrated sulphuric acid with the acid in excess and heated to 170 degC, ethylene is formed. (One mole of ethanol loses one mole of water)
H2SO4
C2H5OH ==> C2H4 + H2O
170 degC
When ethanol is mixed with concentrated sulphuric acid with the alcohol in excess and heated to 140 degC, diethyl ether distils over (two moles of ethanol loses one mole of water).
H2SO4
2 C2H5OH ==> C2H5OC2H5 + H2O
140 deg
Reaction of Ethanol with Sodium
Sodium reacts with ethanol at room temp to liberate hydrogen. The hydrogen atom of the hydroxyl group is replaced by a sodium atom, forming sodium ethoxide.
C2H5OH + Na ==> C2H5ONa + (H2(
Apart from this reaction, ethanol and the other alcohols show no acidic properties.
Dehydrogenation of Ethanol
Ethanol can also be oxidised to ethanal (i.e. acetaldehyde) by passing its vapour over copper heated to 300 degC. Two atoms of hydrogen are eliminated from each molecule to form hydrogen gas and hence this process is termed dehydrogenation.
C2H5OH ==> CH3CHO + H2
Ethanol Ethanal
Esterification of Ethanol
Ethanol, C2H5OH, reacts with organic acids to form esters.
H(+)
C2H5OH + CH3COOH ==> CH3COOC2H5 + H2O
Ethanol Ethanoic Ethyl Water
Acid Acetate
Halogenation or Substitution of Ethanol with PCl5
Ethanol reacts with phosphorus pentachloride at room temperature to form hydrogen chloride, ethyl chloride (i.e. chloroethane) and phosphoryl chloride.
C2H5OH + PCl5 ==> C2H5Cl + POCl3 + HCl
Ethanol Phosphorus Ethyl Phosphorus Hydrogen
Pentachloride Chloride Pentachloride Chloride
Halogenation or Substitution of Ethanol with HCl
Ethanol reacts with hydrogen chloride to form ethyl chloride (i.e. chloroethane) and water. A dehydrating agent (e.g. zinc chloride) is used as a catalyst.
ZnCl2
C2H5OH + HCl ==> C2H5Cl + H2O
Ethanol Ethyl
Chloride
Ethanol is produced both as a petrochemical, through the hydration of ethylene, and biologically, by fermenting sugars with yeast, which process is more economical is dependent upon the prevailing prices of petroleum and of grain feed stocks.
Ethanol for use as industrial feedstock is most often made from petrochemical feed stocks, typically by the acid-catalyzed hydration of ethylene, represented by the chemical equation
C2H4(g) + H2O(g) ? CH3CH2OH(l)
The catalyst is most commonly phosphoric acid, adsorbed onto a porous support such as diatomaceous earth or charcoal. This catalyst was first used for large-scale ethanol production by the Shell Oil Company in 1947. The reaction is carried out at with an excess of high pressure steam at 300 °C.
In an older process, first practiced on the industrial scale in 1930 by Union Carbide, but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentrated sulfuric acid to produce ethyl sulfate, which was then hydrolyzed to yield ethanol and regenerate the sulfuric acid:
Ethanol for use in alcoholic beverages, and the vast majority of ethanol for use as fuel, is produced by fermentation. When certain species of yeast, most importantly, Saccharomyces cerevisiae, metabolize sugar in the absence of oxygen, they produce ethanol and carbon dioxide. The chemical equation below summarizes the conversion:
C6H12O6 ? 2 CH3CH2OH + 2 CO2
The process of culturing yeast under conditions to produce alcohol is called as brewing. Ethanol’s toxicity to yeast limits the ethanol concentration obtainable by brewing. The most ethanol-tolerant strains of yeast can survive up to approximately 15% ethanol by volume.[16]
The fermentation process must exclude oxygen. If oxygen is present, yeast undergo aerobic respiration which produces carbon dioxide and water rather than ethanol. In order to produce ethanol from starchy materials such as cereal grains, the starch must first be converted into sugars. In brewing beer, this has traditionally been accomplished by allowing the grain to germinate, or malt, which produces the enzyme, amylase. When the malted grain is mashed, the amylase converts the remaining starches into sugars. For fuel ethanol, the hydrolysis of starch into glucose can be accomplished more rapidly by treatment with dilute sulfuric acid, fungally produced amylase, or some combination of the two.
– Fuel Grade Ethanol / Anhydrous or hydrous
– Biodiesel
– Extra Neutral Ethanol / Anhydrous or hydrous
– Industrial Grade Ethanol / Anhydrous or hydrous
– Crude Ethanol
Ethanol is used extensively as a solvent in the manufacture of varnishes and perfumes; As a preservative for biological specimens; In the preparation of essences and flavorings; In many medicines and drugs; as a disinfectant and in tinctures (e.g., tincture of iodine); in alcoholic beverages and as a fuel and gasoline additive.
Fuel
Many automobiles manufactured since 1998 have been equipped to enable them to run on either gasoline or E85, a mixture of 85% ethanol and 15% gasoline. E85, however, is not yet widely available (check with the manufacturer of your vehicle before using any ethanol in your vehicle).
Personal care products
* When the label says ‘ethyl alcohol”, there’s ethanol in hairspray, mouthwash, after shave lotion, cologne and perfume; also in deodorants, lotions, hand sanitizers, soaps and shampoos.
Pharmaceuticals
* As a prime carrier, found in medicines such as cough treatments, decongestants, iodine solution, and many others
* As a solvent, used for processing antibiotics, vaccines, tablets, pills, and vitamins
Cleaning products
* A bottle of household disinfectant spray can contain nearly 80 percent ethanol.
* Solvent in the manufacture of paints, lacquer, and explosives
* Raw material in the production of vinegar and yeast
* Chemical intermediate in chemical processing
* Food products like extracts, flavorings, and glazes
* Energy source in some liquid animal feed products
The distilling ethanol for human consumption has been going on for centuries. Pure beverage ethanol is manufactured in the form of grain neutral spirits, then sold in bulk to bottlers or other distillers. They blend it or package into familiar, name-brand products that use grain neutral spirits as the volume of the alcohol content
