General Introduction:
Organic compounds are vital for sustaining life on earth. We ourselves are composed largely of organic molecules and we depend on organic compounds that occur in nature for our food, for our clothing, for many of our medicines and for our energy (natural gas, petroleum, etc). These organic molecules which make our life possible include molecules like proteins, enzymes, vitamins, lipids, carbohydrates, nucleic acids, etc. Our bodies are also regulated and defended by complex organic molecules. So, organic chemistry plays very vital role in our life.
Berzelius, a Swedish chemist proposed that the synthesis of these compounds within the plants and animals required some mysterious force. This force was called vital force and the theory was referred to as Vital Force Theory.
However, the vital force theory received a crippling blow in 1828 when Friedrich Wohler, a German chemist accidently obtained urea, (NH2)2C0, an organic compound found in the urine of mammals. In fact, Wohler tried to prepare ammonium cyanate, a substance with mineral origin, by heating ammonium sulphate and potassium cyanate. But under the reaction conditions, ammonium cyanate rearranged to urea, a compound which was of organic nature.
(NH4)2SO4 + KCNO ————→ NH4CNO + K2SO4
Ammonium sulphate Ammonium cyanate
NH4CNO ————→ (NH2)2CO
Urea (organic compound)
Organic chemistry is now defined as the chemistry of carbon compounds as all organic compounds contain carbon as their essential constituent. Thus, organic chemistry is the chemistry of compounds of carbon. The definition appears to be incomplete since there are many carbon compounds which are of inorganic nature. For example, carbon monoxide (CO), carbon dioxide (CO2), carbon disulphide (CS2), calcium carbonate (CaCO3) etc., are all inorganic compounds although all of them contain carbon in them.
Organic compounds may be regarded as hydrocarbons. i.e., compounds of carbon and hydrogen. A large number of organic compounds also contain elements like nitrogen, oxygen, sulphur, halogens, phosphorus etc. which are derived from hydrocarbons by replacing one or more hydrogen atoms in their molecules with these atoms. Thus, the modern definition of the organic chemistry is the chemistry of the hydrocarbons and their derivatives.