organic chemistry - lecture-notes.tiu.edu.iq
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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.