Organic chemistry

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Organic chemistry developed with reasonable speed along with the other branches of chemistryuntil 1856. The preparation of mauve dye by Perkin (England) in that year and of fuchsin in Françein 1859 touched off explosive activity in the chemistry of coal tar and its components. Thus organicchemistry became commercially valuable and raced ahead in those parts of the subject not related toliving organisms. It was not until the period from about 1920 to 1940, when the science had advanced enough to allow better understanding of the molecules of life, that the emphasis began toswing back to the compounds of carbon derived from living systems.

Ten million organic compounds are known today. Vigorous research is going on to synthesize new compounds. Three hundred new compounds are coming up every day.

ORGANIC PRODUCTS AND INDUSTRIES

It is probably easier to make a list of what organic chemistry is not about than of what it is about.However, here is a partial list of products of organic chemical origin:

Paints and varmishes
Antibiotics and drugs
Dyes
Anesthetics
Vitamins, enzymes, and nucleic acids
Hormones and steroids
Synthetic polymers as fibers, sheets, articles,
elastics, and plastics
Perfumes and flavors
Proteins, fats, oils, and carbohydrates
Insecticides and herbicides

Industries based on technology derived from organic chemistry are many and varied. We list a few:

Agriculture and agricultural by-products
Petroleum refining
Coal tar products
Sugar refining
Pulp and paper
Pharmaceuticals
Polymers
Leather
Fermentation
Paints and varmishes

DEFINITION OF ORGANIC CHEMISTRY

Although the original meaning of the term organic chemistry no longer applies, it has been retained because of wide usage and also because so many of the substances involved in organic chemistry docome directly or indirectly from living matter. The modern definition may most simply be stated as :Organic chemistry is defined as the study of carbon compounds. However, there are several exceptions :

Carbon monoxide, CO
Carbon dioxide, CO2
Carbon disulfide, CS2
Carbonates, e.g., N2¿CO,
Bicarbonatės, e.g., NaHCO,
Cyanides, e.g., KCN
Thiocyanates, e.g., NaSCN
Cyanates, e.g., KOCN
Carbides, c.g., CaC2

These compounds are studied as part of inorganic chemistry because of their properties.

ORGANIC CHEMISTRY AS A SEPARATE SUBJECT

Organic compounds obey the same fundamental laws of chemistry that hold for inorganiccompounds. However, they are studied as a separate discipline because of the following reasons :

Large Number of Compounds. There are approximately 150,000 known inorganic compounds and this number is not rapidly increašing. On the other hand, there are over 35 million known organic compounds and several thousand new compounds are synthesized each year. If the study of 10 miHion organic compounds was included with that of carbon under inorganic chemistry,it would throw the subject out of balance.
Unique Chemical and Physical Properties. There are marked differences between the composition, structure, and properties of organic and inorganic compounds (Table 1.1) which make

their study as a separate branch more practical and useful.
Unique Character of Carbon. Carbon has the ability to bond successively to other carbon atoms to form chains of varying lengths and shapes. This property of carbon is called Catenation and

Is responsible for the variety and large number of organic compounds.

SOURCES OF ORGANIC COMPOUNDS

Historically, as has been mentioned, all organic compounds at one time came from plants or animals. Many of our most important substances are still derived from these sources directly or indirectly.

Plants and Animals. Many organic compounds are obtained directly from plant or animal sources by suitable methods of isolation. A few familiar examples are carbohydrates (cellulose, sugars,starches), proteins (silk, wool, casein, food proteins), fats and oils (cottonseed, soybean oils, lard,butter), alkaloids (quinine, morphine, strychnine), hormones, vitamins, perfumes, flavors, resins.
Natural Gas and Petroleum. Natural gas and petroleum are now the major sources of organic compounds. They are used as fuels and also, through synthetic organic reactions, for the

production of hundreds of useful organic substances such as solvents, synthetic rubber, explosives,and plastics.
Coal. Coal is another major source of organic compounds. It yields coke and coal-tar on pyrolysis or destructive distillation. More than 200 organic compounds have been directly isolated from coal-tar. These coal-tar products form the starting materials for the manufacture of thousands of useful aromatic compounds, including perfumes, drugs, dyes, photographic developers, and others.
Fermentation. Fermentation is defined as the production of chemicals by the action of microorganisms. By employing appropriate organisms hosts of useful substances are produced including alcohols, acids, vitamins, and antibiotics.
Synthesis. Simple organic compounds derived from petroleum or coal have been converted into thousands of useful materials by synthetic methods. Many examples might be cited of synthetic organic compounds replacing those obtained from natural sources, such as dyes, rubber, fibres, plastics, drugs, vitamins. In many cases the synthetic materials are superior to the natural compounds replaced.

For example, synthetic dyes are superior to those of natural origin. In other cases the synthetic materials

are entirely unknown in nature and fill the requirements not satisfied from any other source. Examples are ether, glycol, aspirin, and the sulpha drugs. Synthetic organic chemistry touches almost every phase of life.