Organic chemistry

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ORGANIC CHEMISTRY
The word organic refer to the substance which originated from the plants and animals remains.
The substance which originated from the body of the living organism such as plant and animal is
grouped to the group of the organic compounds, but those substances which came from minerals
are referred to as inorganic compounds. E.g. of organic compound petroleum (crude oil), the
food we eat such as starch, glucose, protein and other product like kerosene, alcohol, diesel,
petrol these are examples of the organic compounds; All above compounds they contain carbon
atom, Example glucose – C6 H12 06
DISTINCTION OF ORGANIC CHEMISTRY FROM INORGANIC COMPOUNDS
- Most substances are made of carbon atoms, when you heat dry wood completely the black
residue seen is due to the presence of carbon atoms in it. Other organic compounds include dyes,
drugs, papers, plastics and textiles.
In contrast, inorganic compounds contain very small quantity of carbon or not having it at all.
Around 25% of all global substances are inorganic compounds. Examples of inorganic
compounds are
(i) All oxides eg sulphur dioxide, carbon dioxide and aluminium oxide
(ii) All carbonates eg. Calcium carbonates , sodium carbonates , Iron II carbonate and
copper carbonate
(iii) All hydrogen carbonates eg. Sodium hydrogen carbonate
(iv) All sulphates eg.ammonium sulphate , Sodium sulphate and copper II sulphate
(v) All Chlorides eg. Hydrochloric acid (HCL) , sodium chloride (NaCL) and Iron III
chloride .
GENERAL PROPERTIES OF ORGANIC AND INORGANIC COMPOUNDS
Some specific properties of sodium chloride(inorganic compound ) and hexane(organic
compound)
d) are listed in a table below. Consider the following comparisons of typical organic and
inorganic compounds,
- Melting point :Organic compound have relatively low melting points, like hexane and ethanol
are liquid at room temperature. Most inorganic salts, by contrast have high melting points.
- Solubility : Most organic compounds are insoluble in water but are soluble in organic liquids.

- Density Most organic liquids are less dense than water and like oil they float on top of water if
we attempt to dissolve them
- Flammability : Organic compound are flammable some are highly flammable. Some, like
gasoline, form explosive mixtures with air and must not be used near an open flame. Inorganic
compound are non flammable. Some, such as water and sodium bicarbonate () are even used in
fighting fires.
- Bonding Properties of organic compounds are related to the fact that they are composed of
molecules with covalent bonds. Inorganic compound is ionic . Water solutions of ionic
compounds conduct an electric current, But water solutions of molecular substances those having
covalent bonds are non-conductors.
Comparison of an organic and inorganic compound:
SOURCES OF ORGANIC COMPOUNDS:
There are three main sources of organic compounds.
Namely:
1 Petroleum and coal: these substances provide compounds which can be used in their simple
forms.
2 Plants and animals: glycogen is an example of organic compound found in animals. Starch and
cellulose are organic compounds found in plants.

3 Synthetic organic compounds: some organic compounds are synthesized, for example
nylon and polysters. Others include synthetic rubber colours,dyes, fibres such as artificial sisal
fibres and synthetic acids, alcohols, ethers and amines.
APPLICATION (importance) of studying organic chemistry
They includes:
1. Applied in the food used by human beings and other living organisms
Example protein, carbohydrates, lipids, all these contain carbon atom
2. Applied in fuel industries in the production of fuel e.g. Petrol, kerosene, petroleum,
Benzene – C6H6, diesel, all these are organic compounds
3. Applied in the pharmaceutical industries in the drugs, chemical synthesis e.g.
erythromycin, tetracycline panadol, aspirin etc.
4. Applied in the plastic material production in the industries, e.g. plastic bags, trough,
sandals PVC (polyvinylchloride) used in plastic pipes, electrical wires insulators all these
are organic compound
CRACKING
This is the process of breaking down the complex compound to form the simplest compound
which is more useful
E.g. complex compound → simplest compound
Less useful more useful
Example
TYPES OF CRACKING
There are
1. Thermal cracking – Is the cracking that heat is used to break down the complex compound to
form the simplest compound which is more useful

2. Catalytic cracking – Is the cracking that catalyst is used to break down the complex compound
to form the simplest compound which is more useful
DISTILLATION OF CRUDE OIL
A crude oil refinery is a group of industrial facilities that turns crude oil and other inputs into
finished petroleum products. A refinery's capacity refers to the maximum amount of crude oil
designed to flow into the distillation unit of a refinery, also known as the crude unit.
The diagram above presents a stylized version of the distillation process. Crude oil is made up of
a mixture of hydrocarbons, and the distillation process aims to separate this crude oil into broad
categories of its component hydrocarbons, or "fractions." Crude oil is first heated and then put
into a distillation column, also known as a still, where different products boil off and are
recovered at different temperatures.
Lighter products, such as butane and other liquid petroleum gases (LPG), gasoline blending
components, and naphtha, are recovered at the lowest temperatures. Mid-range products include
jet fuel, kerosene, and distillates (such as home heating oil and diesel fuel). The heaviest
products such as residual fuel oil are recovered at temperatures sometimes over 1,000 degrees
Fahrenheit.
The simplest refineries stop at this point. Although not shown in the simplified diagram below,
most refineries in the United States reprocess the heavier fractions into lighter products to
maximize the output of the most desirable products using more sophisticated refining equipment
such as catalytic crackers, reformers, and cokers.

Distillation tower
HYDRO-CARBONS
Hydro-carbons are organic compounds that contain only carbon and hydrogen atoms. For
example, methane(CH4), ethane(CH3 - CH3 ) and ethyne(CH ≡ CH), each one contains in it the
atoms of carbon and hydrogen only. Basing on the number of bonds between carbon to carbon
atoms, there are three families of hydro-carbons. These are alkanes, alkenes and alkynes. Some
of hydro-carbons are saturated while others are unsaturated. Compounds are said to be saturated
if the carbon to carbon atoms is only the single bond.
Example of:
Saturated hydro-carbons.

On the other hand, unsaturated compounds are those whose molecules contain either double or
triple bounds between carbon to carbon atoms. For example:
Un-saturated hydro-carbons
From the above information, alkanes are saturated organic compounds while both alkenes and
alkynes are unsaturated organic compounds.
HOMOLOGOUS SERIES
Homologous series is a series of compounds related to each other. A group of compouns forms
a homologous series if there is a constant increment of change in molecular structure from one
compound in the series to another or
Homologous series: Is a group of compounds which possess the same general formular
and the members of homologous series differ from the next by group.
The following are characteristics of members that belong to the same homologous series.

(i) All members in the same family conform to a general molecular formula.
For Example:
- All alkanes conform to a formula CnH2n+2
- All alkenes conform to a formula CnH2n
- All alkynes conform to a formula CnH2n-2
*Where n is a an integer and can be 1 ,2, 3 ,4 .....
(ii) Each member differs in molecular formular from the next by CH2
Each member differs from the next by CH2
(iii) All members show similar chemical reactions though varying in strength eg. The reaction of
methane and ethane with chlorine, respectively
(iv) The physical properties of members change gradually in the same direction along the
series eg. In alkane CH4 is a gas at ordinary temperature while C5H12 is liquid at ordinary
temperature.

NOTE:
(v) General methods of preparation are known which can be applied to any member of the
series.
Example of hydrocarbons in the families of alkanes, alkenes and alkynes have been given in
tables below
Examples of alkanes as hydro-carbons

Hydro-Carbons of Alkenes

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STRUCTURES OF THE HYDRO-CARBONS
There are two types of structure of hydrocarbons. These are condensed and open structure
Condensed and open structure of alkenes.

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Condensed and open structure of alkynes
NAMING HYDRO-CARBONS.
1 NAMING ALKANES
Nomenclature: Is the system of naming. The naming in alkanes is according to the (IUPAC)
International Union of Pure and Applied Chemistry.
Rule 1: Naming of alkanes, ends with suffix –ane-

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Rule 2: In naming alkanes the name is determined by the parental chain (Longest chain of
carbon atoms)
Eg (1)
- The longest chain consists of 4 carbon atoms.
- Its name is Butane.
(2)
- The longest chain consists of 3 carbon atoms
- Its name is Propane.
Rule 3: Number the carbon atoms of the parent chain starting from the end nearer to a
substituent group
Eg (1)
(Substituent group) (Substituent group)
- Wrong numbering Correct numbering
Rule 4: If the substituent group attached in a long chain a carbon atoms, the substituent group
named according to their position in which occurs.
- The most number should be lowest as possible.
- In naming the substituent group named first followed with the name of a parental chain.
Example of substituent group are:
F – Fluoro

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I – Iodo
CL – Chloro
Br – Bromo
Rule 5: If substituent group divides the parent chain into two identical parts start numbering
from either end.
ie Wherever you start the carbon atom with a substituent group is given number 3.
Thus, any one is correct.
Rule 6: Separate numbers from each other by commas (,) and separate numbers from
names by hyphen (-)
Rule 7: If the identical substituent groups are present in the parent chain, use prefixes
di for two groups, tri for three groups and tetra for four groups.

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Rule 8: If there are two or more different substituent groups name them
alphabetically.
(2) NAMING ALKENES
All rules in naming alkanes are applied used in alkenes except the following modifications.
(i) The suffix “ane” in alkane replaced by suffix – “ene” in alkene.

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(ii) In naming alkenes the parent chain is determined by a double bonds or must include double
bonds
(iii) In writing the name of a parent chain the position in which the double bond occurs should be
indicated. Make sure the number is smallest as possible
3 NAMING ALKYNES:
All rules in naming alkenes are used in naming alkynes except the suffix “ene” in alkenes is
replaced by suffix – “yne”
ISOMERISM OF HYDRO- CARBON
Compounds that have the same molecular formula but different structural formula are called
isomers. This phenomenon is known as isomerism. Isomerism is defined as the occurrence of
two or more compounds of the same molecular formula but different molecular structures. For
example, four carbon atoms can be joined in two ways
(i) An unbranched chain of four
Or
(ii) A branched chain having the fourth atom joined to the middle of three other atoms

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All above unbranched and branched chains have each one four carbon atoms. In that case they
have the same molecular formula. However the arrangement of those atoms differs between the
two. That is, they have different molecular structures and regarded as the two isomers.
WORK EXAMPLES:
Write down the isomer of the following hydro carbons.

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PROPERTIES OF HYDRO-CARBON
ALKANES: A hydrocarbon contains hydrogen and carbon only. Alkanes are hydro-carbons with
the formula .
PHYSICAL PROPERTIES OF ALKANES
Some physical properties of first 4 alkanes are given in the table below. Notice the fairly regular
increase in melting point, boiling point, and density as the number of carbon atoms increase. As
shown in the table at room temperature alkanes having 1 to 4 carbon atoms per molecule are
gases. The alkanes are insoluble in water.
Table show: physical properties of selected alkanes are

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CHEMICAL PROPERTIES OF ALKANES
The alkanes are the least reactive of all organic compounds. They are unreactive towards strong
acids.(such as sulphuric acid ) and strong bases such as sodium hydroxide)
Alkanes do undergo a few very important reactions, including combustion. Some of the
chemical properties of methane are as follows:
1. Combustion. Methane burns in air with the faintly luminous frame, forming carbon
dioxide and water. A mixture of air and methane is explosive.
2. Chlorine in free radical substitution. A mixture of methane and chlorine explodes when
placed in bright sunlight or when sparked.
In diffused sunlight the substitution of hydrogen occurs slowly and in steps as shown below:

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U.V is ultra-violent light:
In this reaction, each time one hydrogen atoms in methane becomes replaced by a chlorine atom.
This type of reaction is substitution reaction. The substitution reaction is the reaction in which
the hydrogen atom of a hydrocarbon become replaced by a new functional group.
All saturated hydro – carbons (alkanes) undergo substitution reaction (chain reaction) because
the reaction stops when all hydrogen atoms become replaced.
Chain reaction of methane with fluorine is very explosive it is moderate with bromine and
methane does not react at all with iodine. Iodine is a metal in the halogen group.
ALKENES: The general formula of alkenes is in which n=2 or more.
Table showing boiling point and the number of carbon atoms
PHYSICAL PROPERTIES
Ethene is a gaseous at room temperature and pressure, colourless, almost insoluble in water and
slightly less dense (Vapour density = 14) than air (Vapour density= 14.4)
CHEMICAL PROPERTIES
(1) COMBUSTION: Ethene burn (explodes) in air if a light (or electric spark) is applied. The
product on combustion are carbon dioxide and steam, but the flame tend to be smoky from
unburnt carbon became of its highly proportional(about 86%) of carbon
2.ADDITION REACTIONS:

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Ethene gives a number of addition reactions in which two hydrogen atoms are taken into
combination per molecule of ethene of form a single product .Ethene is said to be unsaturated.
Consider the following addition reactions
(1) With chlorine or bromine
Ethen combines rapidly to give an oil liquid 1,2 – dichloro ethane
(2) With hydrogen iodide
Ethene combines rapidly with hydrogen iodide(Vapour) at ordinary temperature to produce
iodoethane.
The gases HBr and HCL combine similarly but more slowly.
(3) With concentrated sulphuric acid.
- Ethene is absorbed rapidly by this acid at room temperature to form ethyl hydrogen
sulphate
- The reaction is reversed at about 180Ëšc liberating ethene.
(4) With hydrogen;
- Ethene combines with hydrogen if the two are passed over finely divided nickel(catalyst) at
about 200Ëšc. The product is the alkane called ethane
ALKYNES

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PHYSICAL PROPERTIES
Ethyne is a colourless gas, almost insoluble in water and having a sweet smell when pure. It is
slightly less dense than air (vapour density is 13; vapour density of air is 14.4)
CHEMICAL REACTIONS
Having a carbon - to – carbon triple bound in its structure, ethyne is an unsaturated compound. It
gives a number of addition reactions; combining with two moles of the reagent as shown below.
(i) With bromine.
-At ordinary temperature ethyne combines rapidly with bromine, forming
tetrabromoethane
- Thus, bromine vapour is decolourized
- Chlorine gives a corresponding reaction to form carbon and hydrogen chloride
(ii) With Hydrogen:
- If passed with twice its own volume of hydrogen over nickel(catalyst)
at about 200ËšC ethyne forms ethane.
(iii) With halogen acids
- Ethyne combines readily with hydrogen iodide at room temperature to form diiodoethane,
- The reaction with hydrogen chloride is very slow.
(iv) With acidified potassium manganate VII solution
- At room temperature, with shaking, ethyne quickly decolourizes this solution (ie reduces it)
with the formation of ethanedioic acid (oxalic acid)

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- Oxalic acid is a colourless, crystalline and toxic organic compound.
ALCOHOL
Alcohol is an organic compound which have the functional group of “-OH” which is known as
alcohol group.
HOMOLOGOUS SERIES
Have got the general molecular formula of R-OH where R= Alkyl group since alkyl group =
The general molecular formula of alcohol can be represented in two ways.
eg. For methanol
Hence:
Molecular formula of alcohol can be:
Where “n" starting from 1,2,3 . .. ... .....n
The adjacent members differ from one another by group only.

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NOMENCLATURE OF ALCOHOL
All rules in naming alkanes are applied in alcohol except the suffix “ane” in alkane replaced by
suffix “anol” in alcohol.
Eg (1) Ethane ------- Ethanol
(2) Heptane ------- Heptanol

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Organic chemistry

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