GChemPaint/C3/Aromatic-Molecular-Structures/English

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Visual Cue Narration

Slide Number 1

Title Slide

Hello everyone.

Welcome to this tutorial on Aromatic Molecular Structures in GChemPaint.

Slide Number 2

Learning Objectives

In this tutorial, we will learn to

1. Convert Cyclohexane to Cyclohexene

2. Convert Cyclohexene to Benzene

3. Substitute Hydrogen of Benzene ring with other atoms

4. Substitute Hydrogen of Benzene ring with group of atoms

5. Merge two molecules

Slide Number 3

System Requirement

Here I am using

Ubuntu Linux OS version. 12.04

GChemPaint version 0.12.10

Slide Number 4

Pre-requisites

To follow this tutorial you should be familiar with,

GChemPaint chemical structure editor.

If not, for relevant tutorials, please visit our website.

Switch to GChemPaint application. I have opened a new GChemPaint application. Switch to GChemPaint application.
Let's first add a six membered cycle to the Display area.
Click on Add a six membered cycle tool>>Click on Display area. Click on Add a six membered cycle tool.

Click on the Display area.

Click on Add a bond or change the multiplicy of the existing one tool Click on Add a bond or change the multiplicity of the existing one tool.

Add two bonds on every corner of the cycle.

Click and drag the bonds to proper position. Position the bonds in such a way that no two bonds touch each other.

To do so, click and drag the bonds to proper position.

Let's display Carbon atoms at the corners of the cycle.
Right click on any one of the corner>>A Submenu appears Right click on any one of the corner,

A Submenu appears.

Select Atom >>click on Display symbol. Select Atom and then click on Display symbol.

Likewise add Carbon atoms at all corners of the cycle.

Press capital H on the keyboard. To add Hydrogen atoms to the bonds,

Press H on the keyboard.

Click on Add or modify an atom tool>>Click on all the bond positions. Click on Add or modify an atom tool

Click on all the bond positions.

Point to the Hydogen atoms. Again, see to it that no two Hydrogens overlap each other.

The obtained structure is Cyclohexane(C6H12).

Let's copy and paste the structure
Press CTRL+A to select the structure >>Press CTRL+C to copy>>Press CTRL+V and paste Press CTRL+A to select the structure.

Press CTRL+C to copy and

Press CTRL+V and paste.

Point to the structure. Let's convert the second Cyclohexane structure to Cyclohexene.
Click on the Eraser tool >>

delete one of the hydrogen bonds of the adjacent carbon atoms.

Click on the Eraser tool.

Delete one hydrogen bond from each of the adjacent carbon atoms.

Click on Add a bond or change the multiplicity of the existing one tool>>

click the bond between deleted hydrogen bonds.

Click on Add a bond or change the multiplicity of the existing one tool.

Then click on the bond between deleted hydrogen bonds.

Point to the structure. A double bond is formed.

The obtained structure is Cyclohexene(C6H10)

Let's convert Cyclohexene to Cyclohexadiene and then to Benzene.

Ensure that Current element is Carbon.

Click on the Eraser tool >>

delete one of the hydrogen bonds of the adjacent carbon atoms.

Click on the Eraser tool.

Delete one hydrogen bond from each of the adjacent carbon atoms.

Click on Add a bond or change the multiplicity of the existing one tool Click on Add a bond or change the multiplicity of the existing one tool.

Then click on the bond between deleted hydrogen bonds.

Point to the bond. A second double bond is formed.

The obtained structure is Cyclohexadiene(C6H8).

Likewise let's repeat the process to form the third double bond.

The obtained structure is Cyclohexatriene or Benzene(C6H6)

Slide Number 5

Assignment

Here is an assignment.

Draw the structures of:

1.Cyclobutane and Convert to Cyclobutadiene

2.Cyclopentane and Convert to Cyclopentadiene.

Your completed assignment should look like this.

Let's now learn about Benzene derivatives.
Slide Number 6

Benzene Derivatives

Functional groups can substitute hydrogens in Benzene to derive various chemical compounds

Functional groups that can substitute Hydrogen of Benzene are F, Cl, Br, I or OH, NO2, CH3.

Let's copy and paste the Benzene structure twice on the Display area.
Click on Select one or more objects tool >>select Benzene structure. Click on Select one or more objects tool to select Benzene structure.
Press CTRL+C to copy >> Press CTRL+V twice to paste. Press CTRL+C to copy and Press CTRL+V twice to paste.
Drag the overlapping structures aside Position the structures side by side on the Display area.
Let's Substitute Hydrogen atom of the first Benzene structure with F.
Press F on the keyboard. Press F on the keyboard.
Click on Add or modify an atom tool>>

Click on H to Substitute it with F.

Click on Add or modify an atom tool.

Click on H to Substitute it with F.

The structure obtained is Fluorobenzene.

Next let's Substitute the hydrogen of the second Benzene with a group of atoms.
Click on Add or modify a group of atoms tool>>

Click on the Hydrogen atom.

Click on Add or modify a group of atoms tool.

Click on any one of the Hydrogen atom.

Point to enclosed Hydrogen. Observe that Hydrogen is enclosed in a green box with a blinking cursor.
Delete Hydrogen and type capital CH and 3. Remove Hydrogen and type capital CH and 3 and click anywhere on the Display area.

The obtained structure is Methyl benzene.

Click on the hydrogen of third Benzene structure. Likewise let's click one of the hydrogens of third Benzene structure.
Delete Hydrogen and type capital NO and 2 in a green box Remove Hydrogen and type capital NO and 2 in a green box

The obtained structure is Nitrobenzene.

Slide Number 7

Benzene Ring Positions

Let's now see Carbon positions in the Benzene ring.

Six Carbon atoms are numbered from 1 to 6 in Benzene.

All the six positions are equivalent before Hydrogen is substituted.

Slide Number 8

Electron Density

Electron density of ring changes, when Hydrogen is substituted by a functional group.

Electron density of the ring is dependent on the Substituent.

Slide Number 9

Carbon Positions

A mono-substituted compound of Benzene can be substituted at-

1 & 4- called as Para positions

2 & 6- called as Ortho positions

3 & 5- called as Meta positions.

Let's now substitute Methylbenzene structure with another Methyl group.
Click on Add or modify a group of atoms tool>>

Click on the Hydrogen atom.

Click on Add or modify a group of atoms tool.

Click on the second Hydrogen position of the ring.

Type CH3 in the green box Substitute Hydrogen in the green box with CH3.

The new structure obtained is ortho-Xylene.

Let's substitute Nitrobenzene with a Carboxylic(COOH) group.
Click on Add or modify a group of atoms tool>>

Click on the Hydrogen atom.

Click on Add or modify a group of atoms tool.

Click on the fourth Hydrogen position of the ring.

Substitute the Hydrogen in the green box with COOH Substitute Hydrogen in the green box with COOH

The new structure obtained is para-Nitrobenzoic acid.

Press CTRL+Z Press CTRL+Z to undo the process.
Likewise Substitute third Hydrogen position with NO_2 to get meta-Dinitrobenzene.
Slide Number 9

Assignment

Here is an assignment.

Draw seven Benzene structures.

Substitute one of the Hydrogens of:

1)first Benzene with Br.

2)second Benzene with I.

3)third Benzene with OH.

4)fourth Benzene with NH2.

5)fifth Benzene with C2H5.

Slide Number 10

Assignment

Also Substitute:

1)two of the Hydrogens of the 6th Benzene with Cl atoms.

2)1 and 4 Hydrogen positions of the 7th Benzene with COOH group.

Your completed assignment should look like this.

Now let's learn to merge two structures.
Click on Create a new file icon on the toolbar. Let's open a new window.

Click on Create a new file icon on the toolbar.

Click on the Add a four membered cycle tool>>

Click on the Display area.

Click on Add a four membered cycle tool.

Click on the Display area twice.

Click on Select one or more objects tool >>

select the second structure.

Click on Select one or more objects tool to select the second structure.
Drag the structure and place it close to the first structure>>

Press CTRL+A to select structures.

Drag the structure and

place it close to the first structure such that they touch each other.

Press CTRL+A to select the structures.

Point to the tool Merge two molecules tool becomes active.
Click on Merge two molecules tool to merge the molecules. Click on Merge two molecules tool to merge the molecules.

Drag the structure to observe the merging.

<pause>

Let's summarize what we have learnt.
Slide Number 11

Summary

In this tutorial we have learnt to

1. Convert Cyclohexane to Cyclohexene

2. Convert Cyclohexene to Benzene

3. Substitute Hydrogen of Benzene ring with F

4. Substitute Hydrogen of Benzene ring with CH_3, NO_2.

5. Merge two four membered cycles

Slide Number 12

Assignment

As an assignment

1. Merge two Benzene molecules

2. Merge two Pentane structures

3. Merge Cyclopentane and Cyclohexane

Your completed assignment should look like this

Slide Number 13

Acknowledgement

Watch the video available at this URL.

http://spoken-tutorial.org/What_is_a_Spoken_ Tutorial

It summarizes the Spoken Tutorial project

If you do not have good bandwidth, you can download and watch it

Slide Number 14 The Spoken Tutorial Project Team:

Conducts workshops using spoken tutorials

Gives certificates to those who pass an on-line test

For more details, please write to

contact@spoken-tutorial.org

Slide number 15 Spoken Tutorial Project is a part of the Talk to a Teacher project

It is supported by the National Mission on Education through ICT, MHRD, Government of India

More information on this Mission is available at this link

http://spoken-tutorial.org/NMEICT-Intro ]

This is Madhuri Ganapathi from IIT Bombay signing off. Thank you for joining.

Contributors and Content Editors

Madhurig, Nancyvarkey