Chemistry is the study of matter and its changes.
Organic chemistry is the branch of chemistry that studies substances containing carbon.
Organic chemistry, as a separate branch of chemistry, originated at the beginning of the nineteenth century.
A large number of compounds, presently classified as organic, existed long before life as it is now known. Research on organic compounds lagged behind that of inorganic chemistry because natural organic substances are very complex and their reactions are hard to understand. However, certain specific properties were known. For example, the ancient Sumerians learned to brew beer and understood its unique effect on the body. Also, sour wine with its acidic properties was well known and useful in ancient times.
Simply put, organic compounds contain carbon (and other atoms); inorganic compounds do not contain any carbon atoms.
It was not until modern chemical techniques for isolating pure substances were discovered, that organic chemistry finally attracted serious attention. Credit must be given to Carl Wilhelm Scheele (1742-1786) who isolated oxalic, uric and citric acids.
In the beginning, no distinction was made between mineral and biological substances. However, as more and more compounds were isolated, the difference was so evident that a distinction was established. Torbern Bergman was the first to make this distinction. Afterwards, Jacob Berzelius (1779-1848) was the first to use organic chemistry as a term; he proposed a classification system for organic compounds in 1807.
Most of the credit is given to Friedrich Woehler (1800-1882) for the span that took organic chemistry into the modern era. Until then, it was believed that no substance produced by the body, or a living organism, could be reproduced synthetically in a laboratory. Woehler destroyed this theory. In 1828, he reported to have synthesized urea (accidentally!) in the laboratory by heating ammonium cyanate. It was then recognized that most organic substances could be synthesized. There was no longer any doubt that these substances possessed a certain "vital force". Since this event, thousands of organic compounds have been, and will be, synthesized in laboratories.
Hydrocarbons are compounds which contain only carbon and hydrogen atoms. For example, C2H6 is a hydrocarbon.
In saturated hydrocarbons, each carbon atom is bonded to four other atoms; each hydrogen atom is bonded to only one other atom.
Saturated hydrocarbons are called alkanes. They contain carbon-carbon bonds and carbon-hydrogen bonds.
The names of hydrocarbons consist of two parts.
The first part of the name (prefix) indicates the number of carbon atoms in the chain. The ending of the name (suffix) indicates that the compound is a saturated hydrocarbon (an alkane), which is “-ane”.
A hydrocarbon with 1 carbon atom has the prefix meth-
A hydrocarbon with 2 carbon atoms has the prefix eth-
A hydrocarbon with 3 carbon atoms has the prefix prop-
A hydrocarbon with 4 carbon atoms has the prefix but-
A hydrocarbon with 5 carbon atoms has the prefix pent-
A hydrocarbon with 6 carbon atoms has the prefix hex-
A hydrocarbon with 7 carbon atoms has the prefix hept-
A hydrocarbon with 8 carbon atoms has the prefix oct-
A hydrocarbon with 9 carbon atoms has the prefix non-
A hydrocarbon with 10 carbon atoms has the prefix dec-
So, the alkane with one carbon is named with the prefix "meth-" plus the suffix "-ane", to produce the word "methane".
You should memorize the names and the abbreviated structures of the first ten alkanes.
Often, one of the hydrogen atoms of an alkane is replaced with another atom (or group of atoms), such as bromine, chlorine or oxygen. The remaining portion of the alkane is called an alkyl group. The alkyl group is named after the identity of the alkane it comes from. The "-ane" of the alkane's name is removed and replaced by "-yl".
For example, one of the hydrogen atoms of methane (CH4) can be replaced by one chlorine atom to form CH3Cl. The new compound is called methyl chloride; the CH3- is the "methyl" group.
For the compound CH3-CH2Cl, there are two carbon atoms in its chain. The prefix used for this number of carbons is eth-; therefore, the name of this compound is ethyl chloride.
Because there are so many possible organic compounds, a method has been developed in order to systematically name all organic compounds. There are rules which must be understood and followed.
The first rule states that we must begin by identifying the longest sequence of carbon atoms in the compound. This is named after the appropriate alkane.
The second rule states that you must number the carbon atoms in the longest chain. Since there are two ends to each chain, there will always be two different ways to number a chain.