| The common name of ethanol is ethyl alcohol, | | | | order to make it unfit for consumption. The |
| grain alcohol or drinking alcohol is a volatile, | | | | products so obtained are tagged with the term |
| flammable and colourless liquid, powerful | | | | denatured alcohol. Absolute alcohol contains very |
| psychoactive drug and is one of the oldest known | | | | low water content not fir for human consumption. |
| recreational drugs. It is the commonly known | | | | It may contain toxic benzene if ethanol is obtained |
| alcohol used in thermometers and alcoholic | | | | by azeotropic distillation. It is used as a solvent in |
| beverages. Also used in the preparation of spirits. | | | | the laboratory and industries. Spectroscopic |
| It is a straight chain alcohol sharing the molecular | | | | ethanol has a low absorbance in ultraviolet and |
| formula C2H5OH and empirical formula C2H6O. It | | | | visible region so ideal foe ultraviolet and visible |
| can also be written alternatively as CH3-CH2-OH | | | | spectroscopy. |
| where the carbon of a methyl group is attached | | | | Rectified spirit is an azeotropic mixture with 4% |
| to another carbon of methyl group which in turn | | | | water content is used instead of anhydrous |
| is attached to a hydroxyl group. Ethanol is also | | | | ethanol for various purposes. Ethanol shares the |
| written as Et-OH. | | | | category of primary alcohol as the carbon atom |
| Fermentation of sugars into ethanol is one of the | | | | which is attached to the hydroxyl group is also |
| oldest known organic reactions known to humans | | | | attached to two hydrogen atoms in order to |
| so far. Consumption of ethanol as a beverage has | | | | complete the valency. This hydroxyl group is |
| been known since ancient times and in the | | | | mainly responsible for its chemical as well as |
| modern scenario it is produced from the | | | | physical properties. In presence of acid catalysts |
| by-products of petroleum refining. Ethanol has a | | | | ethanol reacts with carboxylic acids to produce |
| widespread use for humans like it is a component | | | | esters. This reaction is carried out industrially and |
| of solvents, medicines, scents, falvourings and fuel. | | | | water removal is very necessary from the ester |
| Ethanol has been a part of alcoholic beverage | | | | thus, obtained. Esters again react with acid or |
| since 9000 years ago and was consumed by the | | | | base and produce ethanol and carboxylic acid. This |
| natives of China. Distillation of ethanol was known | | | | reaction is known as saponification as it is used in |
| to early Greeks and Arabs who produced the | | | | preparation of soaps. Ethanol can also form esters |
| distilled wine with the trade name School of | | | | with inorganic acids. Strong acid desiccants cause |
| Salerno in the 12th century. First absolute alcohol | | | | dehydration of alcohol resulting in the production |
| was produced by Raymond Lull. First synthetic | | | | of diethyl ether and byproducts. If the |
| ethanol was produced by Henry Hennel of Great | | | | temperature of dehydration exceeds up to |
| Britain and S.G. Sérullas of France in 1826. | | | | 160°C then ethylene is obtained as a main |
| Michael Faraday produced ethanol in 1828 by acid | | | | product. Complete combustion of ethanol |
| catalyzed hydration of ethylene in the similar | | | | produces carbon dioxide and water. |
| manner as it is produced today for commercial | | | | Ethanol is a neutral molecule with a pH of nearly |
| production. | | | | 7.00. It can be completely converted into ethoxide |
| Ethanol is a volatile, colourless liquid with a strong | | | | ion by reacting it with a strong base like sodium. |
| characteristic odour and burns with a smokeless | | | | Ethanol also reacts with halogens to produce ethyl |
| flame not visible in the normal light. Its physical | | | | halides but this reaction requires zinc chloride as a |
| properties are generally based on its hydroxyl | | | | catalyst. The reaction of halogens with ethanol in |
| group and its short carbon chain. The hydroxyl | | | | the presence of base results in the formation of |
| group participates in hydrogen bonding making it | | | | haloforms and this reaction is called as haloform |
| more viscous and volatile in comparison to other | | | | reaction. Ethanol can be oxidized to acetaldehyde |
| polar organic compounds of similar molecular | | | | and further oxidized to acetic acid depending upon |
| weight. It is a versatile solvent, miscible with | | | | the conditions and reagents. Oxidation of ethanol |
| water and other organic solvents like acetic acid, | | | | has no industrial significance but in human body |
| acetone, benzene, carbon tetrachloride etc. It is | | | | the oxidation of ethanol is carried out by the |
| also miscible with light aliphatic hydrocarbons like | | | | enzyme liver alcohol dehyrogenase. The oxidation |
| pentane and hexane. The miscibility of ethanol is | | | | byproduct of ethanol is acetic acid which has a |
| limited with alkanes up to undecane. The | | | | nutritive value for humans as it acts as a |
| ethanol-water mixture has a very less volume in | | | | precursor to acetyl-CoA and the acetyl group is |
| comparison to the volume of individual | | | | used for energy production during the |
| components. Mixing of ethanol with water is a | | | | biosynthesis of metabolites. |
| exothermic change resulting in the liberation of | | | | Ethanol is generally used as a motor fuel and fuel |
| 777 J/mol of energy at 298K. | | | | additive on large scale. Brazil has the largest |
| Pure ethanol is hygroscopic and readily absorbs | | | | industry for producing ethanol to be used as a |
| water from air and this is due to hydrogen | | | | fuel. Gasoline sold in Brazil contains 25% of |
| bonding. The polar nature of the hydroxyl group in | | | | anhydrous ethanol. Hydrous ethanol has got its |
| ethanol is responsible for dissolving many ionic | | | | use in greater proportion as a fuel in majority of |
| compounds like sodium and potassium hydroxides, | | | | cars being sold in the modern era. The |
| magnesium chloride, sodium bromide, sodium and | | | | combustion of ethanol in an internal engine yields |
| potassium chlorides are slightly soluble in ethanol. | | | | many products of incomplete combustion as |
| One end ethanol carries non-polar end so it also | | | | produced by gasoline including larger quantity of |
| dissolves non-polar substances like the essential | | | | formaldehyde and other compounds of |
| oils, flavouring agents and medicinal agents. The | | | | acetaldehyde. These byproducts show strong |
| addition of some percent of ethanol to water | | | | photochemical activity resulting in the production |
| reduces the surface tension of water considerably | | | | of ozone. The world production of ethanol was 51 |
| explaining the tears of wine property. When wine | | | | gigaliters in 2006 and Brazil and US topped in |
| is poured in a glass the ethanol evaporates | | | | ethanol production. More than 20% of the Brazilian |
| forming a layer of foam over the glass. As the | | | | cars utilize 100% ethanol as a fuel as their engine |
| ethanol content of wine decrease the surface | | | | is specially designed for using ethanol as a fuel |
| tension of wine increases. The ethanol water | | | | along with the flex engines. Flex fuel engines in |
| mixture with ethanol content of 50% is | | | | Brazil are able to work with ethanol, gasoline or |
| flammable. The refractive index of ethanol is | | | | with the mixture of both. Brazil utilizes sugarcane |
| more than that of water and is 1.36242. | | | | crop for the production of ethanol and the |
| Ethanol is produced both by the hydration of | | | | bagasse left after ethanol production is utilized for |
| ethylene as a petrochemical as well as by the | | | | the production of electricity. |
| fermentation of sugars by yeast and this process | | | | The United States industries are largely dependent |
| of production is a biological process. The | | | | on corn for the commercial production of ethanol. |
| production of ethanol by these two processes is | | | | One major problem with ethanol is that it cannot |
| equally depending upon the need of market. The | | | | be efficiently shipped through the pipelines as it is |
| production of ethanol as an industrial solvent by | | | | easily miscible with water. Ethanol is the major |
| hydration of ethylene is a chemical reaction | | | | psychoactive constituent of alcoholic beverages |
| occurring in the presence of catalyst. Phosphoric | | | | with strong depressing effect on the central |
| acid is used as a catalyst in this reaction which is | | | | nervous system. It has a complex mode of action |
| first adsorbed on the silica gel. The Shell Oil | | | | on different parts of brain and is a strong agonist |
| Company used phosphoric acid for commercial | | | | to the GABA receptors. Gamma-hydroxybutyric |
| production of ethanol in 1947. The reaction is | | | | acid (GHB) is also another agonist to the GABA |
| carried out at extremely high pressure steam of | | | | receptors. Ethanol is metabolized in human body |
| at about 300°C. In US the Union Carbide | | | | as an energy providing nutrient as it acts as a |
| Corporation also utilized this process for | | | | precursor for acetyl-CoA which is a common |
| commercial production of ethanol but at present | | | | intermediate in both glucose and fatty acid |
| only Lyondell Basell uses this process for | | | | metabolism. Alcoholic beverages vary widely in |
| commercial production. | | | | their alcoholic content. Most of the alcoholic |
| At present indirect hydration of ethylene is carried | | | | beverages are classified as fermented beverages |
| out by reacting it with concentrated sulphuric acid | | | | as they are produced by the action of yeast on |
| in order to generate ethyl sulphate which is later | | | | the sugary foodstuffs or distilled beverages which |
| on hydrolyzed to obtain ethanol and sulphuric acid | | | | include ethanol addition by distillation. The ethanol |
| again. Production of ethanol to be used in alcoholic | | | | content of an alcoholic beverage is measured in |
| beverages and industrial fuel is carried out by | | | | term of volume fraction of ethanol expressed as |
| fermentation only. There are certain strains of | | | | alcoholic proof units. |
| yeast which convert sugars into ethanol and | | | | Fermented beverages can be easily classified on |
| carbon dioxide. The process of yeast culture | | | | the basis of their key foodstuffs. Beers are made |
| under controlled environment to produce alcohol is | | | | from cereal gains or starchy materials while wines |
| called as fermentation. Ethanol can be produced | | | | and ciders are prepared from fruit juices and |
| by the cereal grains but first these are converted | | | | meads from honey. Different cultures and |
| into sugars. In brewing of the beer, the grains are | | | | different nations use different sorts of foodstuffs |
| first allowed to germinate or malt is used which | | | | for the preparation of alcoholic beverages. Distilled |
| produces the enzyme amylase. This amylase is | | | | beverages are prepared by distilling the |
| responsible for conversion of all the starch | | | | fermented beverages. The important categories |
| present in the malted grain into sugars. For | | | | of distilled beverages include whiskeys made from |
| production of ethanol as a fuel, starch is first | | | | fermented cereal grains, brandies obtained from |
| hydrolyzed into glucose by treating it with | | | | fermented fruit juices and rum obtained from |
| sulphuric acid. | | | | fermented molasses or sugarcane juice. Vodka |
| Cellulose can also be used as a source of sugar | | | | and similar neutral grain spirits can be obtained by |
| for ethanol fermentation. At present many | | | | distilling either potatoes or grains and the products |
| enzyme producing companies are trying to | | | | thus obtained lack the taste of key ingredient. |
| develop genetically modified fungi for the | | | | Many other alcoholic beverages are also prepared |
| production of cellulase, xylanase, and hemicellulase | | | | from fruits, herbs and spices in different parts of |
| enzymes. These enzymes will convert the starch | | | | the globe. In many beverages ethanol is |
| present in the agricultural residue into sugars which | | | | concentrated other than distillation like in Applejack |
| will be fermented later on for commercial | | | | which is obtained by freeze distillation and water is |
| production of ethanol. Ethanol can also be | | | | frozen out of the apple cider leaving an ethanol |
| produced from anaerobic bacterium Clostridium | | | | rich liquid. Ice beer is also freeze distilled with beer |
| ljungdahlii which is present in the chicken wastes | | | | as a base liquid. Fortified wines are prepared by |
| and used as a fuel. Production of ethanol from | | | | adding brandy to partially fermented wine. This |
| corn is under strong criticism. Ethanol can also be | | | | step kills the yeast and retains some sugar in the |
| produced from the closed loop ethanol plant | | | | grape juice as a result these wines are quite |
| where ethanol is produced from manure and the | | | | sweeter than other wines. |
| manure left after ethanol production is used for | | | | Alcoholic beverages are also used in cooking as |
| fertilizing the crops. 75% of ethanol is produced | | | | they impart flavour and also dissolve some of the |
| by this process a good success. Alternative | | | | hydrophobic compounds which are insoluble in |
| methods for ethanol production are also in use | | | | water. Ethanol is a very important industrial |
| where ethanol is produced from waste materials | | | | ingredient which finds its use as base in production |
| like wood chips, sugarcane bagasse and switch | | | | of many chemicals like ethyl halides, ethyl esters, |
| grass. | | | | diethyl ether, acetic acid, ethyl amines and to a |
| The ethanol concentration is measured by two | | | | lesser extent butadiene. Ethanol is more |
| methods by the breweries and ethanol producing | | | | commonly used in medical wipes and in hand |
| plants. Infrared ethanol sensors are used for | | | | sanitizers as well as an antiseptic. It kills microbes |
| measuring the vibrational frequency of the | | | | by neutralizing their proteins, dissolving lipids and is |
| dissolved ethanol using CH band at 2900 cm-1. | | | | effective against most bacteria and fungi and |
| Calculation is done by the Beer Lambert Law. | | | | many viruses but ineffective against bacterial |
| Another method uses hydrometer which | | | | spores. |
| measures the alcohol content during fermentation | | | | Ethanol is also used as an antidote for poisoning |
| by detecting change in the specific gravity. | | | | many other toxic alcohols like methanol and |
| Hydration of ethylene and brewing produces | | | | ethylene glycol. It competes with other alcohols |
| mixture of ethanol and water which requires | | | | for the alcohol dehydrogenase enzyme and thus, |
| purification. Fractional distillation produces 95.6% | | | | prevents formation of toxic aldehyde and |
| concentrated ethanol by volume which is an | | | | carboxylic acid derivatives and declines the |
| azeotrope mixture having boiling point of 78.1°C | | | | tendency of glycol to form crystals in kidneys. |
| and cannot be further purified by distillation. | | | | Ethanol is miscible with water and so is an |
| Absolute ethanol can be obtained by desiccation | | | | effective purpose solvent. It finds use in paints, |
| using adsorbents like starch, corn grits or zeoloites | | | | tinctures, markers and personal care products like |
| which adsorb water and other methods include | | | | perfumes and deodorants. It is also used in vodka |
| azeotropic distillation and extractive distillation. | | | | sauce a popular flavouring agent for foods. Before |
| Most ethanol fuel refineries used an adsorbent for | | | | the development of modern medicines ethanol |
| obtaining pure and concentrated ethanol. Absolute | | | | was used as a medicine against depression and as |
| ethanol can also be obtained by distillation carried | | | | an anesthetic. Ethanol was also used as a fuel in |
| out with benzene and rectified spirit and in the | | | | the bipropellant rockets during the World War-II. |
| third fraction ethanol is obtained at 78.3°C. Some | | | | The removal of ethanol through the oxidation by |
| benzene is left in the alcohol so obtained and is | | | | alcohol dehydrogenase in the liver from human |
| not fit for consumption as benzene is carcinogenic. | | | | body is limited. Removal of large concentration of |
| Desiccation of glycerol also produces absolute | | | | ethanol from blood follows zero order kinetics. |
| alcohol and the alcohol so obtained is called as | | | | The blood alcohol concentration can be used for |
| spectroscopic alcohol because of the absence of | | | | modifying the biochemistry of methanol and |
| benzene in it so used as a solvent in | | | | ethylene glycol. Pure ethanol causes irritation on |
| spectroscopy. | | | | skin and the eyes. Nausea, vomiting and |
| The pure ethanol and alcoholic beverages are | | | | intoxication are the common symptoms of |
| highly taxed by the government of the country | | | | ingesting it. Long term effects can result in serious |
| but apart from consumption ethanol shares a | | | | liver damage. Ethanol is not a carcinogen but its |
| number of uses in human life. To remain free | | | | metabolites may act as carcinogens. |
| from the taxes bittering agents like denatonium | | | | We can summarize that ethanol is good as well as |
| benzoate and toxins such as methanol, naphtha, | | | | bad as it adds a flavour to our life. |
| and pyridine are added to absolute ethanol in | | | | |