Acids and Bases

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Reaction Intermediates

Now that we know about various electronic effects, let’s learn the Intermediates found in organic chemistry reactions.

For this we must understand the difference between reaction intermediate and transition state.

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And learn about intermediates in organic reactions:

  1. Carbocations
  2. Carbanions
  3. Free Radicals
  4. Carbenes

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Here we would know about the various effects due to the bonded pairs in organic molecules.
Types of electronic effects we would deal with are:

  1. Inductive
  2. Electromeric
  3. Mesomeric (or Resonance)

 

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  • More Examples of Resonance
  • Hyperconjugative effects

Various types of reactions in organic chemistry are also introduced here:

 

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Amino acids, peptides and proteins: Learning 1

Amino acids: Structure and classification, stereochemistry and their acid base behaviour

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The slides explained in the video are given below:

Slide2Source:https://commons.wikimedia.org/wiki/File:Bdna.gif

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Source: https://commons.wikimedia.org/wiki/File:Insulin_1AI0_animation.gif

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Stereochemistry…Lesson 2

We shall now move on the internal aspects of Optical isomerism. Before proceeding  we must understand and learn to view molecules in 3-D space. For this, one needs to know the different Projection formulae (representation of 3-D structures on a 2-D surface like paper or board).

These are of many types:

  1. Wedge-Dash
  2. Fischer Projections
  3. Newmann Projections (used for Conformations)
  4. Sawhorse Projections (used for Conformations)

Let’s learn them one by one.

Wedge-Dash

Pankaj_Khanna_presentation 2nd lecture Final

When rotated this may be converted to:

Pankaj_Khanna_presentation 2nd lecture Final 2

Fischer Projection Formulae

This is the best followed convention for representing 3-D structures in 2-D.

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However, few rules are to be followed:Slide13Slide14Slide15

(* to get the answer to Why??? please see video @27:18 min. – 32:44 min.)

Although the remaining two types Newmann Projection and Sawhorse Projection formula are mainly used for Conformation analysis but we need these for making Fischer formula of two chiral center systems.

Thus,

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Slide show 1

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Slide show 2

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Slide show 3Slide31Slide32

Finally the last concept of racemic mixture:Slide33

 

 

 

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