The main attention of ancient chemists and alchemists was focused on the compounds obtained from minerals i.e., non-living sources. Such compounds were known as Inorganic compounds. In eighteenth century, some progress was made in the investigation of substances such as sugar, gelatin, fats, oils etc., which were obtained from living organism like plants and animals. Lavoisier was the first to establish that the compounds derived from animal and vegetable sources have almost similar composition of elements. Nearly all of them were composed of carbon, hydrogen and oxygen elements. In view of the similarity of composition, the compounds obtained from living organisms i.e., animals and plants, were collectively called organic compounds. The study of organic compounds began to develop as a separate branch of chemistry known as organic chemistry.
In the early days, it was considered impossible to prepare organic compounds in the laboratory. Berzelius (1815) proposed that these compounds could only be produced by some mysterious force existing in living organisms. The laboratory synthesis of these compounds was not possible because of the absence of such a mysterious force. This simple generalisation was called vital force theory.
The vital force theory held its ground till 1828, when Friedrich Wohler, a German chemist succeeded in preparing an organic compound, Urea (NH2CONH2) from ammonium cyanate. In fact, he was trying to prepare ammonium cyanate by heating potassium cyanate and ammonium sulphate:
This accidental preparation of urea clearly indicated that no mysterious force was involved during the production of organic compounds. It also gave new direction to the chemists who started working for the preparation of other organic compounds. Later on, Kolbe (1845) synthesised acetic acid and Hennel synthesised ethyl alcohol. Synthesis of these compounds gave a death blow to vital force theory. At present, about 95 per cent of organic compounds have been synthesised in the laboratory.
DEFINIION OF ORGANIC CHEMISTRY
Investigations about the structures of organic compounds gave way to a more precise definition of organic chemistry.
It is the study of hydrocarbons (compounds of carbon and hydrogen elements) and other compounds regarded as derivatives of hydrocarbons.
It may be noted that some organic compounds may also contain elements like nitrogen, oxygen, sulphur, phosphorus, halogen, etc., besides carbon and hydrogen.
SOURCES OF ORGANIC COMPOUNDS
Organic compounds are very abundantly distributed in nature and are also prepared by synthetic methods. The important sources of these compounds along with some products are given in the flow sheet as follows: