Organic Chemistry by R.T Morrison Free chemistry books

Organic chemistry is the chemistry of the compounds of carbon. The misleading name “organic” is a relic of the days when chemical compounds were divided into two classes, inorganic and organic, depending upon where they had come from. Inorganic compounds were those obtained from minerals; organic compounds were those obtained from vegetable or animal sources, that is, from material produced by living organisms. Indeed, until about 1850 many chemists believed that organic compounds must have their origin in living organisms, and .consequently could never be synthesized from inorganic material. These compounds from organic sources had this in common : they all contained the element carbon. Even after it had become clear that these compounds did not have to come from living sources but could be made in the laboratory, it was convenient to keep the name organic to describe them and compounds like them. The division between inorganic and organic compounds has been retained to this day. Today, although many compounds of carbon are still most conveniently isolated from plant and animal sources, most of them are synthesized. They are sometimes synthesized from inorganic substances like carbonates or cyanides, but more often from other organic compounds. There are two large reservoirs of organic material from which simple organic compounds can be obtained ‘.petroleum and coal. (Both of these are “organic” in the old sense, being products of the decay of plants and animals.) These simple compounds are used as building blocks from which larger and more complicated compounds can be made. We recognize petroleum and coal as the fossilfuels, laid down over millenia and nonreplaceable, that are being consumed at an alarming rate to meet our constantly increasing demands for power. There is, fortunately, an alternative source of power nuclear energy but where are we to find an alternative reservoir of organic raw material? What is so special about the compounds of carbon that they should be separated from compounds of all the other hundred-odd elements of the Periodic Table? In part, at least, the answer seems to be this: there are so very many compounds of carbon, and their molecules can be so large and complex. The number of compounds that contain carbon is many times greater than the number of compounds that do not contain carbon. These organic compounds

have been divided into families, which generally have no counterparts among the inorganic compounds.

Organic molecules containing thousands of atoms are known, and the arrangement of atoms in even relatively small molecules can be very complicated. One of the major problems in organic chemistry is to find out how the atoms are arranged in molecules, that is, to determine the structures of compounds.

There are many ways in which these complicated molecules can break apart, or rearrange themselves, to form new molecules; there are many ways in which atoms can be added to these molecules, or new atoms substituted for old ones. Much of organic chemistry is devoted to finding out what these reactions are, how

they take place, and how they can be used to synthesize compounds we want. What is so special about carbon that it should form so many compounds? The answer to this question came to August Kekule in 1854 during a London bus ride.

Carbon atoms can attach themselves to one another to an extent not possible for atoms of any other element. Carbon atoms can form chains thousands of atoms long, or rings of all sizes; the chains and rings can have branches and crosslinks. To the carbon atoms of these chains and rings there are attached other atoms, chiefly hydrogen, but also fluorine, chlorine, bromine, iodine, oxygen, nitrogen, sulfur, phosphorus, and many others. (Look, for example, at cellulose on page 1126, chlorophyll on page 1004, and oxytocin on page 1 143.) Each different arrangement of atoms corresponds to a different compound, and each compound has its own characteristic set of chemical and physical properties. It is not surprising that close to a million compounds of carbon are known today and that thousands of new ones are being made each year. It is not surprising that the study of their chemistry is a special field. Organic chemistry is a field of immense importance to technology: it is the chemistry of dyes and drugs, paper and ink, paints and plastics, gasoline and rubber tires; it is the chemistry of the food we eat and the clothing we wear. Organic chemistry is fundamental to biology and medicine. Aside from water, living organisms are made up chiefly of organic compounds; the molecules of “molecular biology” are organic molecules. Ultimately, biological processes are a matter of organic chemistry.