- Chemistry in everyday life – 04
- ALDEHYDES, KETONS AND CARBOXYLIC ACIDS
Chemistry in everyday life – 04
- It is obtained Commercially by Fermentation, the oldest method is from sugars. The sugar in molasses, sugarcane or fruits such as grapes is converted to glucose and fructose, (both of which have the formula
C6H12O6 in the presence of an ENZYME, INVERTASE. Glucose and fructose undergo fermentation in the presence of another enzyme, ZYMASE, which is found in yeast.
- IN WINE MAKING, GRAPES ARE THE SOURCE OF SUGARS AND YEAST. As grapes ripen, the quantity of sugar increases and yeast grows on the outer skin. When grapes are crushed, sugar and the enzyme come in contact and fermentation starts. Fermentation takes place in anaerobic conditions i.e., in absence of air.
Carbon dioxide is released during fermentation. The action of zymase is inhibited once the percentage of alcohol formed exceeds 14 per cent. If air gets into fermentation mixture, the oxygen of Air Oxidises Ethanol to Ethanoic Acid which in turn destroys the taste of ALCOHOLIC DRINKS.
- ETHANOL IS A COLOURLESS LIQUID with boiling point 351 K. It is used as a solvent in paint industry and in the preparation of a number of carbon compounds. The commercial alcohol is made unfit for drinking by mixing in it some COPPER SULPHATE (to give it a colour) and pyridine (a foul-smelling liquid). It is known as Denaturation of Alcohol.
- Ingestion of ethanol acts on the central nervous system. In moderate amounts, it affects judgment and lowers inhibitions. Higher concentrations cause nausea and loss of consciousness. Even at higher concentrations, it interferes with spontaneous respiration and can be fatal.
- Diethyl ether has been used widely as an inhalation anesthetic. But due to its slow effect and an unpleasant recovery period, it has been replaced, as an anesthetic, by other compounds.
9. ALDEHYDES, KETONS AND CARBOXYLIC ACIDS
- ALDEHYDES, KETONES AND CARBOXYLIC ACIDS are widespread in plants and animal kingdom. They play an important role in biochemical processes of life. They add fragrance and flavour to nature, for example, vanillin (from vanilla beans), SALICYLALDEHYDE (from meadow sweet) and CINNAMALDEHYDE (from cinnamon) have very pleasant fragrances.
- They are used in many food products and pharmaceuticals to add flavours. Some of these families are manufactured for use as solvents (i.e., acetone) and for preparing materials like ADHESIVES, PAINTS, RESINS, PERFUMES, PLASTICS, FABRICS, ETC.
- In chemical industry aldehydes and ketones are used as solvents, starting materials and reagents for the synthesis of other products. Formaldehyde is well known as formalin (40 per cent) solution used to PRESERVE BIOLOGICAL SPECIMENS AND TO PREPARE BAKELITE (a phenol-formaldehyde resin), urea-formaldehyde glues and other polymeric products.
- ACETALDEHYDE Is used primarily as a starting material in the manufacture of Acetic Acid, Ethyl Acetate, Vinyl Acetate, Polymers and Drugs. Benzaldehyde is used in perfumery and in dye industries. Acetone and ethyl methyl ketone are common industrial solvents. Many aldehydes and ketones, e.g., Butyraldehyde, Vanillin, Acetophenone, Camphor, etc. are well known for their odours and flavours.
- Methanoic Acid Is Used in Rubber, Textile, Dyeing, Leather and Electroplating Industries. Ethanoic acid is used as solvent and as vinegar in food industry. Hexanedioic Acid is used in the manufacture of nylon 6, 6. Esters of benzoic acid are used in perfumery. Sodium benzoate is used as a food preservative. Higher fatty acids are used for the manufacture of soaps and detergents.
- Amines constitute an important class of organic compounds derived by replacing one or more hydrogen atoms of ammonia molecule By Alkyl or Aryl Group. In nature, they occur among proteins, vitamins, alkaloids and hormones.
- SYNTHETIC EXAMPLES INCLUDE POLYMERS, DYESTUFFS AND DRUGS. Two biologically active compounds, namely adrenaline and ephedrine, both containing secondary ammo group, are used to increase blood pressure. Novocain, a synthetic amino compound, is used as an anesthetic in dentistry. Benadryl, A Well-Known Antihistaminic Drug also contains tertiary amino group.
- Quaternary Ammonium Salts are used as surfactants. Diazonium salts are intermediates in the preparation of a variety of aromatic compounds including dyes.