Introduction to Organic Chemistry

Macromolecules

These are large molecules that are necessary for all life processes

Carbohydrate

These macromolecule is made up of carbon, hydrogen and oxygen

Saccharide

The unit structure of carbohydrates.

Monosaccharide

They are simple sugars such as glucose

Disaccharide

They are chains of two simple sugars such as lactose

Polysaccharide

they are chains of more than two simple sugars such as cellulose

Nucleic Acids

They are polymers made from the monomers called nucleotides. Examples are DNA and RNA

Effects of Impurities

They increase the boiling point and reduce the melting point

Melting points of impure compounds

They have a wider melting point range that is relatively lower

Melting points of pure compounds

they have a smaller melting point range that is relatively higher

The higher the molecular weight...

...the higher the boiling point.

What is Boiling point

It is the temperature at which vapor pressure of a liquid equals the atmospheric pressure.

Boiling sticks/Stones/Chips

Used to prevent super heating.

For an impure substance...

...The temperature during boiling/melting does not remain constant.

Refractive index "n"

The measure of how much a ray of light bends as it travels from one medium to another.

Formula for refractve index

Speed of light in vacuum/speed of light in given sample

Abbe-3L refractometer

this is used for measuring the refractive index of a sample.

Factors that influence the choice of a purification method

Stability of the compound. Amount of impurities present. Physical state of the compound. Nature of the compound.

Purification of compounds

The separation of the components of a compound and the removal of impurities.

Purification Method

Distillation. Re crystallization. Sublimation. Chromatography. Extraction.

Organic Chemistry

The study of all carbon compounds and the reaction it undergoes in exception of carbonates (CO32-), cyanide (CN-) and oxides

Catenation

The property of certain elements, such as, carbon to form rings, chains or branched structures with other atoms of the same element

The ability catenate....

...decreases down the group

Elements with the Catenation property

Carbon, Silicon, Gallium, Tin, Lead (all group 4 elements)

If there are four atoms bonded to a carbon atom e.g CH4 (Methane)

The shape is tetrahedral. Bond Angle is 109.5 degrees

If there are three atoms bonded to the central atom e.g C2H2 (Ethene)

The shape is trigonal Planar. The bond angle is 120 degrees

If there are two atoms bonded to the central atom e.g C2H2 (Ethylene)

The shape is linear. Bond angle is 180 degrees

Source of Formic Acid CH2O2

Ants, Sting of bees

Source of Ethylene C2H4

Plants

Use of Ethylene C2H4

Promotes ripening of fruits

Examples of Macromolecules

Protein, Carbohydrate, Nucleic Acids.

Metabolism

this refers to chemical reactions in cells that change food into energy

Proteins

Macromolecules that are polymers of amino acids.

Chromatography

a technique for the separation of a mixture by passing it through a stationary phase in which the components move at different rates while being carried by the mobile phase

In Chromatography, the component that travels the least distance…

…is the least soluble/polar to the solvent

In Chromatography, the component that travels the most distance…

…is the most soluble/polar to the solvent

Theory of Chromatography

1. Solubility of the compounds in the mixture

2. It uses the different polarities of the stationary phase and mobile phase

3. Compounds attracted to the stationary phase will move slower than compounds attracted to the mobile phase.

common substances used in the stationary phase of chromatography

Silica gel, and alumina

Substance used in the mobile phase

any solvent that can move through the stationary phase and carry components of the compound.

Retardation Factor

(distance traveled by solute) / (distance traveled by solvent)

Types of chromatography

1. Gas chromatography

2. Thin-layer chromatography

3. Column chromatography

Column chromatography

The chromatography method used to separate a single compound from a mixture.

Gas Chromatography

The chromatography method used to separate small quantities of volatile mixtures

Some carrier gas used in Gas Chromatography

Helium and Nitrogen

High Pressure Liquid Chromatography (HPLC)

A chromatographic technique that uses high pressure to separate and analyze compounds in a liquid sample based on their interaction with a stationary phase.

Thin Layer Chromatography (TLC)

an affinity-based chromatography method used to separate compounds in a mixture.

Uses of Chromatography

1. For Identifying poisons and drugs

2. To determine the purity of a given substance

3. To detect traces of unlawful dyes and other additives in foodstuffs.

Sublimation

is the process where a substance transitions directly from a solid to a gas without passing through the liquid phase.

Distillation

This is the process used to separate components in a liquid mixture through a selective evaporation and condensation method.

Types of Distillation

1. Simple Distillation

2. Vacuum Distillation

3. Fractional Distillation

4. Steam Distillation

Simple Distillation

The distillation method used when the boiling points of the samples vary widely, usually greater 25 degree Celsius

Fractional Distillation

This distillation method is used when the difference in the boiling points of the samples is very small.

Ways to increase the efficiency of Fractional Distillation

1. Increasing the length of the fractionating column

2. Increasing the surface area of the beads in contact.

Vacuum Distillation

The distillation method used to separate samples that decompose before reaching their boiling points by decreasing their boiling points.

Steam Distillation

This distillation is used for separating samples that are heat sensitive and are nearly insoluble in water

Heat sensitive substances…

…decompose before reaching their boiling points.

The method used to extract fragrant compounds for perfumes, essential oils, and those used in food processing and skincare products is…..

…Steam Distillation.

Recrystallization

• Purification method to get super clean crystals!

• Dissolves impure solid in hot solvent, then cools it down.

• The pure stuff forms crystals, leaving gunk behind in the solution.