Organic ChemistryFor

1st Grade Students

Tishk International University

Faculty of Science

Medical Analysis Department

Prof. Dr. Faiq H.S. Hussain

Lecture 1

2Introduction

In the early nineteenth century, scientists classified all known compounds into two categories:

Inorganic compoundsWere derived from nonliving sources

(minerals and gases)

Organic compoundswere derived from living organisms

(plants and animals)

Organic compounds were often difficult to isolate and purify, and upon heating, they decomposed

more readily than inorganic compounds.

Organic compounds: are those compounds containing carbon atoms.

The food that we eat and the clothes that we wear are comprised of organic compounds.

Our ability to smell odors or see colors results from the behavior of organic compounds.

3Organic Chemistry in Life

Pharmaceuticals, pesticides, paints, adhesives,

and plastics are all made from organic

compounds.

In fact, our bodies are constructed mostly

from organic compounds (DNA, RNA,

proteins, etc.) whose behavior and function

are determined by the guiding principles of

organic chemistry.

The responses of our bodies to

pharmaceuticals are the results of reactions

guided by the principles of organic chemistry.

4

Organic chemistry is the scientific study of the structure, properties, composition,

reactions, and synthesis of organic compounds.

Organic compounds are molecules composed of carbon (C) and hydrogen (H), and may

contain any number of other elements.

Many organic compounds contain nitrogen (N), oxygen (O), halogens (X= F, Cl, Br, I), and

more rarely phosphorus (P) or sulfur (S).

Organic Compounds

5Why Carbon is quite important?

The properties of carbon make it the backbone of the organic molecules which form living matter

• Carbon is a such a versatile element because it can form 4 covalent bonds.

• Carbon skeletons can vary in length, branching, and ring structure.

• The functional groups of organic molecules are the parts involved in chemical reactions.

6Formation of chemical bonds

• Atoms form bonds in order to obtain a stable electronic configuration, i.e. the electronic

configuration of the nearest noble gas, in which they have eight electrons in outer shell and

obeying the octet rule.

• Carbon, has four outer-shell electrons, its impossible to lose or gain 4 electron because very

high energy required for this purpose, therefore, carbon is sharing electrons with other

elements to obtain the stable electronic configuration and conform octet rule.

7Hydrocarbons

Hydrocarbons

AromaticAlkenes Alkynes

Compounds containing only Carbon and Hydrogen

All bonds between Carbon and hydrogen

are single

Bonds between Carbon and hydrogen

are double or triple

Saturated Hydrocarbons Unsaturated Hydrocarbons

Ethane

Exam

ple

Alkanes and

cycloalkanes

Ethene Ethyne Benzene

8Alkanes

• Alkanes, the simplest hydrocarbons, are found in all shapes and sizes and occur widely in nature.

• Alkanes are aliphatic hydrocarbons having only C – C and C – H.

• They are also called saturated hydrocarbons because they have the maximum number of

hydrogen atoms per carbon.

• Alkanes have the molecular formula CnH2n+2 (where n = an integer) and contain only linear and

branched chains of carbon atoms.

For example: n=1, C1H(2*1+2) C1H4 more preferred as CH4

9

• The nomenclature of alkanes ends by ANE.

• For example, methane, ethane, hexane, octane, etc.

Alkanes

10

• When an Alkane is attached to a long chain molecule, it is changed to an Alkyl group, the suffix

Alkyl group

Alkane Structure

Methane CH4

Ethane CH3CH3

Propane CH3CH2CH3

Butane CH3(CH2)2CH3

Pentane CH3(CH2)3CH3

Hexane CH3(CH2)4CH3

Heptane CH3(CH2)5CH3

Octane CH3(CH2)6CH3

Nonane CH3(CH2)7CH3

Decane CH3(CH2)8CH3

Alkyl Structure

Methyl –CH3

Ethyl –CH2CH3

Propyl –CH2CH2CH3

Butyl –CH2(CH2)2CH3

Pentyl –CH2(CH2)3CH3

Hexyl –CH2(CH2)4CH3

Heptyl –CH2(CH2)5CH3

Octyl –CH2(CH2)6CH3

Nonyl –CH2(CH2)7CH3

Decyl –CH2(CH2)8CH3

ANE is converted to YL.

11Cycloalkanes

• Cycloalkanes have molecular formula CnH2n and contain carbon atoms arranged in a ring.

• Think of a cycloalkane as being formed by removing two H atoms from the end carbons

of a chain, and then bonding the two carbons together.

• Simple cycloalkanes are named by adding the prefix cyclo- to the name of the acyclic

alkane having the same number of carbons.

12Physical properties of alkanes

• Alkanes are completely NON–POLAR.

• Boiling points of alkanes are lower than those of almost any other type of compound of the same

molecular weight, because interactions between alkane molecules consist only of very weak

dispersion forces.

• Boiling and melting points of alkanes increase as molecular weight increases.

• Alkanes containing 1 to 4 carbons are gases at room temperature.

• Alkanes containing 5 to 17 carbons are colorless liquids.

• High-molecular-weight alkanes (those with 18 or more carbons) are white, waxy solids.

For example, the wax found in apple skins, is an unbranched alkane with molecular formula C27H56

13Importance of alkanes

• Many alkanes occur in nature, primarily in natural gas and petroleum. Both of these fossil

fuels serve as energy sources, formed from the degradation of organic material long ago.

• They are used in preparation of LPG (Liquefied petroleum gas) (propane and butane).

• 2,2,4-Trimethylpentane is used as an additive to increase the octane rate of gasoline.