FUNDAMENTAL PRINCIPLES OF ORGANIC CHEMISTRY 2022
EARLIER DEFINITION OF ORGANIC COMPOUNDS
Over 200 years ago, compounds were classified according to their properties and origin. Thus, organic compounds were defined as
The compounds obtained from living organisms were called Organic Compounds.
Due to this definition, it was believed that a vital force present in living organisms is involved in the preparation of organic compounds and therefore, these compounds could not be prepared in the laboratory from inorganic materials. This theory was called Vital Force Theory.
MODERN DEFINITION OF ORGANIC COMPOUNDS
All organic compounds contain Carbon as an essential part and also Hydrogen. Moreover, it was found that forces in organic compounds were the same as in inorganic compounds. So, the modem definition of organic compounds is
The compounds containing Carbon and Hydrogen and their derivatives are called organic compounds.
The branch of chemistry that deals with the study of compounds of Carbon and Hydrogen and their derivatives are called organic chemistry.
In 1828, a German Scientist, Fredrick Wohler, prepared the first organic compound in the laboratory. He prepared urea from ammonium cyanate by the following reaction.
NH4CNO ⇌ NH₂CONH₂
Urea is an organic compound present in the waste of mammals while NH4CNO is an inorganic compound of mineral origin.
IMPORTANCE OF WOHLER’S EXPERIMENT
• Due to the concept of vital force, nobody tried to prepare organic compounds in the laboratory.
• By preparing urea in the laboratory, Wohler proved that no vital force is involved in the preparation of organic A compounds and these can be prepared in the laboratory, from simple inorganic compounds.
• After the work of Wohler, many scientists started preparing organic compounds in the laboratories. They prepared a large number of organic compounds.
• By now, millions & millions of organic compounds have been prepared in the laboratory. our daily life. All this progress is due to
• These organic compounds have a wide range of applications Wholer’s work, opened a new way of science, by disproving the vital force theory.
ELEMENTS IN ORGANIC COMPOUNDS
All organic compounds contain Carbon.
Most organic compounds also contain Hydrogen.
Besides Carbon & Hydrogen, the following elements are also found in organic compounds N, S, halogens, P, etc.
However, some compounds having carbon are not included in organic compounds due to historical reasons. e.g. CO, CO, HCO3–, Carbides, etc.
SOME FEATURES OF ORGANIC COMPOUNDS
PECULIAR NATURE OF CARBON
The self-linking ability of carbon is called catenation.
Carbon can link with other carbon and for long chains and rings. Due to the property of catenation carbon forms millions of compounds.
Carbon also forms stable and multiple bonds with other atoms oxygen, nitrogen Sulphur, etc. Thus it forms compounds of various sizes, shapes, and structures.
NON-IONIC NATURE OF ORGANIC COMPOUNDS
Organic compounds are generally covalent compounds, therefore, they do not give ionic reactions.
SIMILARITY IN BEHAVIOUR
Organic compounds have close similarities. Therefore, organic compounds have been divided into a few homologous series e.g. alcohols, hydrocarbons, etc.
The members of the homologous series show almost similar behavior.
Thus the study of all organic compounds is not necessary. Only a study of a few homologous series tells the behavior of all organic compounds.
COMPLEXITY OF ORGANIC COMPOUNDS
Many organic molecules are large and have complex structures eg starch has the formula ( C₂H₂O₂ ), where it may be several thousand.
Similarly, proteins are complex molecules. Their molecular mass range from a few thousand to millions.
Many organic compounds with different structures have the same molecular formula. This phenomenon is called isomerism. It is a very common phenomenon in organic compounds.
RATES OF ORGANIC REACTIONS
Organic reactions are generally very slow. Thus yields are also low. It is due to the molecular nature of organic compounds.
Most organic compounds are insoluble in water. These generally dissolve in non-polar organic solvents eg benzene, petroleum ether, etc.
IMPORTANCE OF ORGANIC CHEMISTRY
Organic chemistry is very important in our life.
Almost all the chemical reactions, taking place in living organisms are organic. They involve organic molecules such as enzymes, carbohydrates, proteins, lipids, vitamins, nucleic acids, etc.
Food is also mainly composed of organic compounds e.g. protein, carbohydrates, fats, etc.
Organic compounds are also present in medicines, clothing, etc.
Many other important things have been synthesized. e.g. plastics, synthetic rubber, medicines preservatives, paints, varnishes, textile fibers, fertilizers, pesticides, detergents cosmetics, dyes, etc. These synthetic compounds prevent the shortage of natural products.