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Introduction |
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Carbon compounds are of two types: inorganic and organic. The compounds that have a mineral origin fall under the category of inorganic compounds. The compounds having plant or animal origin are classified as organic compounds. Lavoisier showed that nearly all compounds of plant origin are composed of carbon, hydrogen and oxygen. While those of animal origin also had other substances like nitrogen, sulphur or phosphorus. In spite of the fact that organic compounds were originally derived from living sources, today, most of these compounds can be synthesized. |
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Functional Groups Containing Oxygen |
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The functional group is an atom, or a group of atoms which can replace one or more hydrogen/s in a hydrocarbon. This group when present in organic compounds defines the characteristic physical and chemical properties of that particular family of organic compounds. Thus a functional group is the site of chemical reaction in an organic compound. |
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Alcohols |
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The hydroxy derivatives of aliphatic hydrocarbons (compounds having their carbon atoms in chains and not in the form of rings) are called alcohols. When one, two or more hydrogen atoms of a hydrocarbon are replaced by a corresponding number of hydroxyl groups (-OH), alcohols can be obtained.
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Ethyl alcohol or Ethanol |
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Ethyl alcohol is the most important member of the alcohol series and is otherwise known as alcohol, spirit of wine and grain alcohol. It can be prepared by any one of the general methods of preparation of primary alcohol. |
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Manufacture of Ethanol by Fermentation |
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Ethanol can be manufactured by the fermentation of: (i) Molasses. (ii) Starch. |
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Some Important Forms of Alcohol |
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Absolute alcohol or anhydrous alcohol (100% alcohol) is prepared by adding a little benzene to the rectified spirit followed by distillation. |
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Properties of Ethanol |
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Ethanol, being a monohydric alcohol exhibits the properties particular of that series. Monohydric alcohols can be considered as derivatives of alkanes obtained by replacing one hydrogen atom by a hydroxyl group. Similarly, they can be considered as derivatives of water obtained by replacing one hydrogen atom by an alkyl group. For this reason ethanol exhibits the properties of both ethane and water. |
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Uses of Ethanol |
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* Paints and varnishes
* Alcoholic beverages
* Transparent soaps |
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Analytical Tests for Ethanol |
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Ethanol can be identified by the fruity odour it emits when heated gently with sodium acetate and concentrated sulphuric acid. This is due to the formation of ethyl acetate. |
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Aldehydes and Ketones |
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Aldehydes and ketones are hydrocarbon derivatives that contain the carbonyl group as shown below
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Formaldehyde (Methanal) |
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Preparation
By passing methanol vapors over heated copper at 570K.
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Properties of Formaldehyde |
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Reaction with Ammonia
Formaldehyde reacts with ammonia to give hexamethylene tetramine (urotropine) that is used in disinfecting the urinary canal.
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Uses of Formaldehyde |
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Reactant in the manufacture of formaldehyde resins like bakelite and galalith by catalytic condensation with phenol or casein (milk protein). The resin can be moulded while hot into different shapes under pressure. |
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Propanone (Acetone) |
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By Dehydrogenation of Propan-2-ol
Acetone is prepared by dehydrogenation of propan-2-ol using heated copper.
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Carboxylic Acids |
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Organic compounds that contain one or more carboxyl groups, (-COOH) have acidic properties and are known as carboxylic acids. The word carboxyl rightly represents this functional group in the sense that it is a combination of the carbonyl group and the hydroxyl group as shown below:
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Acetic Acid |
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Acetic acid is one of the commonest organic acids and has been known for quite a long time in the form of vinegar. It is also present free in a number of fruit juices. In the combined state it occurs in many oils and essential oils. |
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Properties of Acetic Acid |
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Acetic acid is a colorless, corrosive liquid with a pungent smell at ordinary temperatures. But below 290K, it solidifies to an icy mass called glacial acetic acid. It boils at 391K and its specific gravity is 1.08 at 273K. It is miscible with water, alcohol and ether in all ratios. It is a good solvent for phosphorus, sulphur, iodine and inorganic compounds. |
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Uses of Acetic Acid |
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Manufacture of rubber from latex and casein from milk. It is used for coagulation |
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Carbon Compounds as Polymers |
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Polymerization is the process of formation of large molecules or macromolecules with high molecular weight from small molecules. 'Poly' means many and 'meros' means parts in Greek. The simple compounds from which these macromolecules are made are called monomers. When two monomers combine, a dimer is got. The compound is known as a trimer and a tetramer when three and four monomers combine with each other. Many monomers combine together to form a high molecular weight substance called polymer. |
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Nylon |
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Nylon is a synthetic polyamide fiber. It is the first manmade fiber. It was synthesized in the year 1935. In the year 1939, sixty four million pairs of nylon stockings were sold in the market vouching for the popularity of nylon. The name nylon comes from the fact that it was synthesized in New York and London at the same time. |
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Polyester |
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Polyester is the general name given to all polymers that contain multiple ester [-R-CO-O] groups as monomers. Terylene is an example of polyester. This synthetic fibre was first developed in England. |
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Polyethylene or Polythene |
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Polythene is formed by the addition polymerization of multiple monomers of ethylene or ethene. When liquid ethylene is polymerized at high temperature and pressure, a resin of polyethylene is obtained. It can be melted spun or moulded as desired. Note that in addition polymerization there is no elimination of simple molecules like water or methanol.
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Natural Rubber |
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Natural rubber is an excellent example of a natural polymer and an elastomer in particular. Elastomers are substances that can be readily stretched. They retract rapidly to their original form when released. Natural rubber is also called plantation rubber. |
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Synthetic Rubber - Neoprene |
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Synthetic or artificial rubbers are also polymers. They are not natural rubbers and are superior to natural rubber. |
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Synthetic Rubber - Thiokol |
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Another important synthetic rubber is thiokol. It is a polymer of ethylene polysulphide. It can be prepared by the condensation of 1,2-dichloroethane with sodium polysulphide.
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Soaps and Detergents |
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Soaps are sodium or potassium salts of higher fatty acids (are organic acids that have more than 16 carbon atoms in their molecules) like stearic, palmitic and oleic acids. The sodium soaps are called hard soaps and the potassium soaps are known as soft soaps. Soaps are obtained from oils and fats. For example tristearin is got from beef and mutton tallow, tripalmitin from palm oil and triolein from lard (pig fat), olive oil and cottonseed oil. In India, soap is commonly got from coconut, groundnut, til and mahua oils. |
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Synthetic Detergents |
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They possess the desirable properties of ordinary soaps and can be used with hard water and in acidic solutions as well. Synthetic detergents are sodium salts of a long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates. Their calcium or magnesium salts are soluble in water. |
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Conclusion |
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Currently, 106 elements are known to the human kind. The number of carbon compounds alone is much more than the number of compounds of all remaining 105 elements put together. The number of carbon compounds known to man is around 600,000 whereas the number of the compounds of all the remaining compounds is just about 300,000. Since the number of organic compounds is so high, and since their properties are totally different from the inorganic compounds, they are studied as a separate branch of chemistry. Most of the compounds that we come across in our day-to-day life are organic in nature. The role of organic compounds in human life is a revelation as more and more compounds are discovered by the day. |
