Introduction to Organic Chemistry
Organic chemistry is the chemistry of carbon compounds. Due to the ability of carbon to form chains of atoms, and for other atoms or groups of atoms to be attached to these chains, there are a huge number of carbon compounds.
All organic compounds contain carbon together with one or more other elements such as hydrogen, oxygen, nitrogen, sulphur and the halogens.
Normally every compound of carbon is an organic compound. Even after discovering that these compounds could be synthesized in the laboratory, the definition that they are organic (of organic nature, that is, they originate from living things) has been retained. However, for conventional and historic reasons, some of the simpler compounds such as carbon dioxide (CO2) carbonates, carbon monoxide (CO3) are usually studied with other non-carbon compounds in Inorganic Chemistry.
Difference between Organic from Inorganic Chemistry
Distinguish organic from inorganic chemistry
Organic chemistry is the chemistry of carbon compounds. All organic compounds contain carbon and other elements such as H, O, N, S and the halogens.
Normally every compound of carbon is an organic compound. Examples of organic compounds/substances are plastics, milk, carbohydrates, lipids, proteins, sugar and hydrocarbons. Inorganic substances includes table salt, CO2, diamond, iron and water.
The Importance of Organic Chemistry in Life
Explain the importance of organic chemistry in life
Carbon is the most unusual atom. It has the ability to join up to itself and form very long chains of atoms. Without this ability, life on Earth would not exist because the molecules that make our bodies contain mostly long chains of carbon atoms.
All living things contain carbon compounds. Raw materials such as oil and coal, derived from living things, are also based on carbon. Our modern society is very much dependent on organic chemistry to make the fuels and materials that we use in every day of our lives. In particular, polymers, large molecules obtained from alkanes, have very widespread use. Without alkanes from crude oil our transport system would be impossible.
We also need various fractions obtained from crude oil (petrol, diesel, kerosene, oil, natural gas, etc.) to run motor vehicles and other machines to simplify our work and life.
In brief, the compounds obtained from crude oil have thousands of different uses, for example:
acids form a homologous series of the general formula CnH2n+1COOH (or
CnH2n+1CO2H), where n = 1, 2, 4, etc. for successive members of the
group. All these acids have the characteristic functional (carboxyl)
group, –COOH, attached to a hydrocarbon chain.
- milk (lactic acid)
- citrus fruits (citric acid);
- tobacco (nicotinic acid); and
- tea (tartaric acid).
acids are named as if they are derived from alkanes by the replacement
of one hydrogen atom by the –COOH group. The two lowest members,
containing one atom and two carbon atoms respectively, are:
successive members of the series have molecular formulae which differ
by –CH2 It is important to remember that every carboxylic acid molecule
contains the functional group –COOH which is called the carboxyl group.
other organic compounds, carboxylic acids also exhibit isomerism.
Isomers of carboxylic acid are a result of branching of the hydrocarbon
end (R) rather than the position of the carboxyl group in a molecule of
the carboxylic acid. More isomers of the carboxylic acids can be created
by branching the hydrocarbon end in as many different ways as possible.
the branched alkyl group, followed by the name of the acid to which the
alkyl group is attached. For example, in the case above (rule no.2):
- the alkyl group is methyl;
- it is attached to carbon number and
- the acid to which it is attached is butanoic acid,CH3CH2CH2COOH
case there occurs more than one alkyl groups in the compound the
prefixes di(2), tri(3), tetra(4) etc (as it was the case in alkanes) may
be used. For, example in the compound
- there are two methyl groups, one attached to carbon number 2 and the other to carbon number 3; and
- they are both attached to butanoic acid chain.
isomerism is found in this homologous series. Isomerism in carboxylic
acids begins from butanoic acid, C3H7COOH. The first three members of
the series do not show isomerism because their hydrocarbon ends do not
form branches. The following are the structures and names of the isomers
of carboxylic acids up to five carbon atoms:
- Butanoic acid, C3H7COOH or C3H7CO2H or CH3CH2CH2COOH
- Pentanoic acid, C4H9COOH
inorganic acids, their solutions contain H+ ions. The presence of H+
ions give the solutions acidic behaviour, that is, their solutions
affect indicators, just like the inorganic acids do.
inorganic acids, carboxylic acids react with metals, alkalis,
carbonates, and hydrogen carbonates to form salts. For example:
reaction between carboxylic acids and alcohols is called
esterification. The acids will react reversibly with alcohols to form
sweet–smelling esters. Concentrated sulphuric acid is a catalyst for the
reaction can be reversed to recover an acid and alcohol again by
boiling the products (an ester + water) with a mineral acid (HCl or
H2SO4) or with an aqueous alkali (KOH or NaOH) as a catalyst.
are manufactured for use as solvents, food flavourings, and fragrance
for perfumes and beauty products. Ethyl ethanoate is just one example of
many esters. The esters usually have strong and pleasant smells. Many
of these compounds occur naturally. They are responsible for the
flavours in fruits and for the scents of flowers. Fats and oils are
naturally occurring esters used for energy storage in plants and
animals. Some of the naturally occurring esters include:
- vegetable oils e.g. palm oil, groundnut oil, cashewnut oil, olive oil, sunflower oil, etc; and
- animal fats.
oils are formed from fatty acids and an alcohol called glycerol (also
called glycerine). Fatty acids are carboxylic acids with long chains of
carbon atoms. They are called “fatty” because the long chains repel
water, making them immiscible with water. Glycerol or glycerine (or
propane–1,2,3-triol) has three –OH groups. This is how fatty acids and
is made by heating animal fats or vegetable oils with sodium hydroxide
solution. The oils react with the solution of sodium hydroxide and break
down to form glycerol and the sodium salts of their fatty acids. These
salts are used as soap. The reaction equation is:
process is known as saponification. The soap you buy is made from a
blend of different oils. When soap dissolves in water it ionizes thus: