Introduction to Organic Chemistry

Introduction to Organic chemistry

1.1 Chemistry of carbon1.2 Types of organic compound

1.3 Applications of organic compound

INTRODUCTION TO ORGANIC CHEMISTRY

Organic chemistry is a chemistry of carbon compounds. Example : methane, DNA, urea, DDT (insecticide), penicillin , nicotine, aspirin etc..

But not all carbon compounds are organics. Example :

carbonate (CO32-; cyanide (CN-), bicarbonate (HCO3

-), carbon dioxide and carbon monoxide.

Organic chemistry is the study of compounds that contain carbon. It is one of the major branches of chemistry.

The history of organic chemistry can be traced back to ancient times when medicine for human extracted from plants and animals to treat members of their tribes.

In ancient era, it was produced willow bark which was used as a pain killer, (willow bark contains acetylsalicylic acid, the ingredient in aspirin )- Organic Chemistry.

Organic chemistry was first defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius. He classified chemical compounds into two main groups:

i. Organic: if they originated in living or once-living matter, and

ii). Inorganic: if they came from "mineral" or non-living matter.

In 1828, Frederich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound).

Wöhler mixed silver cyanate and ammonium chloride to produce solid silver chloride and aqueous ammonium cyanate:

He then separated the mixture by filtration and tried to purify the aqueous ammonium cyanate by evaporating the water.

Chemistry of Carbon

The carbon family, Group 14 in the p-block, contains carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and flerovium (Fl). Each of these elements has only two electrons in its outermost p orbital: each has the electron configuration ns2np2.

Catenation is the linkage of atoms of the same element into longer chains.  Catenation occurs most readily in carbon, which forms covalent bonds with other

carbon atoms to form longer chains and structures. Catenation is the reason for the presence of the vast number of organic compounds

in nature.

1. Carbon-carbon bonds are strong, long chains or rings of carbon atoms bonded to one another are possible.

2. Diamond and graphite are two familiar examples: a. Diamond lattice being a three-dimensional network of carbon atoms, b.Graphite more closely resembles a planar network.

3.Carbon is not unique in forming bonds to itself because other elements such as boron, silicon, and phosphorus form strong bonds in the elementary state. But with the combination of hydrogen carbon affords a remarkable variety of carbon hydrides (Hydrocarbons)

4. Carbon forms bonds not only with itself and with hydrogen but also with many other elements, including strongly electron-attracting elements

WHY ORGANIC CHEMISTRY SPECIAL?

TYPES OF ORGANIC COMPOUNDS

Organic compound: An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. Such as carbides, carbonates, simple oxides of carbon (such as CO and CO2), etc.

There are three generally accepted sources of organic compounds:

SOURCES OF ORGANIC COMPOUNDS

2. Living organismsoThe chemical compounds of living things are known as organic compounds because of their association with organisms and because they are carbon-containing compounds. oAmong the numerous types of organic compounds, four major categories are found in all living things: carbohydrates, lipids, proteins, and nucleic acids3. Invention/Human ingenuityoAntibiotics, aspirin, vanilla flavoring, and heart drugs are examples of substances that no longer have to be obtained directly from nature, they are manufactured in laboratories from organic starting materials. oEach year over 250,000 new chemical compounds are discovered  and many of these are products of scientists' imaginations, exploration.o Plastics are excellent examples of substances that are the product of invention - they are not found anywhere in nature.

1. carbonized organic matter: o Carbonization is the term for the conversion of an organic

substance into carbon or a carbon-containing residue through pyrolysis or destructive distillation.

o Example: the generation of coal gas and coal tar from raw coal. Fossil fuels from vegetable matter, coal to produce coke. the charcoal making process, etc.

Property Organic compound Inorganic compound

Bonding with molecule Usually covalent Often ionic

Forces between molecules

Generally weak(Intermolecular force)

Quite strong(Electrostatic force)

Normal physical state

Gases, liquids or low-melting-point solids

Usually high-melting-point solids

Flammability Often flammable Usually non-flammable

Solubility in water Insoluble SolubleConductivity Non-conductor Conductor

Rate of chemical reaction Slow and complex Fast and simple

Properties of typical organic and inorganic compound

Name Of OrganicCompounds

Origin Usage

ProteinsExample :a) Enzymesb) Hormones

From animals a) As a structural materialsb) As a biological catalyst and regulators

Fats and OilsExample :a) Triglyceride b) Paraffin Oils c) Almond Oils

From animals and vegetables

To store energy

VitaminsExample :A, B Complex, C, D, E and K

From food For healthy growth and functioning

Naturally Occurred Organic Compounds

Items Examples Usage

Plastics Poly (ethene), Perspex.

For packaging, plastic bags, as a substitute for glass.

Medicines andDrugs

Tranquilizer, Analgesic and Bactericide.

To treat tropical diseases such as Trypanosomiasis or Sleeping Illness and Malaria.

Pesticides Dichlorodiphenyl trichloroethane( DDT )

To kill houseflies and other insects.

Dyes Methylene blue Give colour to the material.

Synthetic Organic Compounds

Type of organic compoundHomocyclic organic compound.docx

Hetero-cyclic organic compound.docx

Homocyclic-aromatic organic compound.docx

Hetero-aromatic organic compound.docx

Saturated

Unsaturated

Aromatic● CLOSE rings of Carbon atoms. ● Contain a benzene ring. Example: Benzene

Aliphatic● OPEN chains of Carbon atoms.● Unbranched or Branched ● Contain Single, Double or Triple bonds. Example: ethane (CH3–CH3) ethene / ethylene (CH2=CH2) ethyne / acetylene ( )

Alicyclic● CLOSE rings of Carbon Atoms. ● Rings form the shape of POLYGON (triangle, square, rectangle or etc). Example: Epoxide

CC CCOO

HH

HHHH

HH

HH

HH

HCHC CHCH

Functional groups: an atom or group of atoms which determine the chemical and physical properties of an organic compound.

Functional Groups

IMPORTANCEIMPORTANCE

All the member of a particular homologous series have:

1. Same general formula eg : CnH2n+1OH 2. Same functional group : same chemical reactions. Eg : all alcohols contain –OH group.

3. Each member differs from the next member by a constant –CH2.

4. As the molecular size increase, the boiling points increase.

HOMOLOGOUS SERIES

Alkane Nomenclature

Formula of organic compounds

● Molecular formula ● Empirical formula● Structural formula● Condensed formula● Bond-line formula

Organic compounds can be complexA system is needed that shows structure. We want something that is easy to read.

Example: Glucose, C6H12O6

C6H12O6

Molecular formulaCH2O

Empirical formula

Empirical formulaSimplest ratio number of atoms of each element in a molecule.

Molecular formula :Actual number of atoms of each element in a molecule.

Structural Formula: Shows all atoms in the bonds, Bonds are represented as line

Condensed Formula: Shorthand way of writing Molecular formula

Bond-line formulaRepresent structure between carbon-carbon bonds.Atoms other than carbon and hydrogen are called heteroatoms.

CHCH33CHCH22CHCH22CHCH3 3 is shown asis shown as

CHCH33CHCH22CHCH22CHCH22OHOH is shown asis shown as

Isomers

Structural isomers Stereoisomers

Isomers are different compounds that have the same molecular formula.

Classification of isomers

n-pentane 2-methylbutane

2,2-dimethylpropane

Structural isomers

C5H12

Example

CHCH33CHCH22CHCH22CHCH22CHCH22CHCH33

n-hexanen-hexane

C6H14

(CH(CH33CHCH22))22CHCHCHCH33

3-Methylpentane3-Methylpentane

(CH(CH33))22CHCH(CHCHCH(CH33))22

2,3-Dimethylbutane2,3-Dimethylbutane(CH(CH33))33CCHCCH22CHCH33

2,2-Dimethylbutane2,2-Dimethylbutane

(CH(CH33CHCH22))22CHCHCHCH33

2-Methylpentane2-Methylpentane

Stereoisomer

Compound with the same molecular formula and structural formula but with different arrangement of their bond in space.

HH33CC

CC CC

CHCH33

HH

HHHH

CHCH33

CC CC

HH33CC

HH

cis-2-butene trans-2-butene

cis (large groups on same side)

trans (large groups on opposite sides)

Naming of organic compound according to IUPAC system1 Identify the longest carbon chain. This chain is called the parent chain

2 Identify all of the substituents (groups appending from the parent chain).

3 Number the carbons of the parent chain from the end that gives the substituents the lowest numbers. When comparing a series of numbers, the series that is the "lowest" is the one which contains the lowest number at the occasion of the first difference. If two or more side chains are in equivalent positions, assign the lowest number to the one which will come first in the name.

4 If the same substituent occurs more than once, the location of each point on which the substituent occurs is given. In addition, the number of times the substituent group occurs is indicated by a prefix (di, tri, tetra, etc.).

5 If there are two or more different substituents they are listed in alphabetical order using the base name (ignore the prefixes). The only prefix which is used when putting the substituents in alphabetical order is iso as in isopropyl or isobutyl. The prefixes sec- and tert- are not used in determining alphabetical order except when compared with each other.

6 If chains of equal length are competing for selection as the parent chain, then the choice goes in series to: A. the chain which has the greatest number of side chains. B. the chain whose substituents have the lowest- numbers. C. the chain having the greatest number of carbon atoms in the smaller side chain. D. the chain having the least branched side chains.

7 A cyclic (ring) hydrocarbon is designated by the prefix cyclo-which appears directly in front of the base name.

prefix Length of Carbon

Meth 1

Eth 2

Prop 3

But 4

Pent 5

Hex 6

Hept 7

Oct 8

Non 9

Dec 10

1. Longest chain is 6 - hexane2. Two methyl groups - dimethyl

3. Use 2,5-dimethylhexane

EXAMPLE

Types of Organic Reactions

General

Addition Substitution Elimination Rearrangement

Specific

Hydrogenation Esterification Oxidation Hydrolysis

Addition: Two substances react together to form a single substance.

Ethane Bromoethane

Substitution (SN2 reaction): An atom or a group (leaving group) in a

molecule is replaced by another atom or group (nucleophile / electrophile).

Elimination: Removal of atoms or groups of atoms from a saturated molecule to form an unsaturated molecule.

Rearrangement: Migration of an atom, a group of atoms or a bond from one atom to another within molecule to form its isomer.

Hydrogenation•Addition of hydrogen to a multiple bond to form a single bond substance.

+ H—H+ H—HCC CC HH CC CC

HH HH

HH HH

HH

HH

HH

HH

HH

Pt

Ethylene Ethane

Hydrogen

Hydrogenation of alkane

Esterification: Acid-catalyzed ester formation between alcohol and carboxylic acid.

CHCH33COCHCOCH22CHCH33

OO

++ HH22OOCHCH33COHCOH

OO

++ CHCH33CHCH22OHOHHH22SOSO44

refluxEthanoic acid Ethanol Ethyl ethanoate

Fischer esterification

Oxidation: An increase in the number of bonds between carbon and oxygen and/or a decrease in the number of carbon-hydrogen bonds.

Hydrolysis•Chemical process in which a molecule is split into two parts by the addition of a molecule of water.

(CH3)3C–Br + H2O (CH(CH33))33C–OH + HBrC–OH + HBr

tert-Butyl alcohol alcoholtert-Butyl bromide Hydrogen bromide

Applications of Organic Compounds