Organic Compounds

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Organic Compounds

Ethanol (C2H5OH)

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colourless liquid. It is a potent psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs. In common usage, it is often referred to simply as alcohol or spirits. Ethanol chemical formula is C2H5OH. Ethanol is a covalent bond; covalent bonds are chemical bonds between two non-metals. They are also considered poor conductors of electricity.

Molecular formula: CH3CH2OH or C2H5OH

Production in Industry

There are two major industrial pathways to ethanol. Ethanol which is intended for industrial use is made by the first method, while ethanol intended for food use tends to be made by the second method.

Production by steaming ethene

Ethanol is manufactured by reacting ethene with steam. The reaction is reversible, and the formation of the ethanol is exothermic.

Only 5% of the ethene is converted into ethanol at each pass through the reactor. By removing the ethanol from the equilibrium mixture and recycling the ethene, it is possible to achieve an overall 95% conversion.

A flow scheme for the reaction above

The equation shows that the ethene and steam react 1:1. In order to get this ratio, you would have to use equal volumes of the two gases.

Because water is cheap, it would seem sensible to use an excess of steam in order to move the position of equilibrium to the right according to Le Chatelier's Principle. In practice, an excess of ethene is used. This is very surprising at first sight. Even if the reaction was one-way, you couldn't possibly convert all the ethene into ethanol. There isn't enough steam to react with it. The reason for this oddity lies with the nature of the catalyst. The catalyst is phosphoric (V) acid coated onto a solid silicon dioxide support. If you use too much steam, it dilutes the catalyst and can even wash it off the support, making it useless.

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Production by fermentation

A solution of sucrose, to which yeast is added, is heated. An enzyme, invertase, which is present in yeast, is added and this acts as a catalyst to convert the sucrose into glucose and fructose. The glucose, C6H12O6, and fructose, C6H12O6, formed are then converted into ethanol and carbon dioxide by another enzyme, zymase, which is also present in yeast. The fermentation process takes three days and is carried out at a temperature between 250C and 300C. The ethanol is then obtained by fractional distillation.

Sugar (glucose or fructose) → alcohol (ethanol) + carbon ...

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