This seminar presentation discusses Fischer and Newman projections, two methods for representing the 3D structures of molecules in 2D. It outlines the definitions, advantages, and disadvantages of each projection, along with key stereochemical aspects and rules for proper representation. The conclusion emphasizes the utility of these projections in illustrating chirality and chemical conformations.

1. TUMKUR UNIVERSITY
DEPARTMENT OF STUDIES AND RESEARCH IN ORGANIC CHEMISTRY
Seminar on
FISCHER AND NEWMAN PROJECTIONS
Presented By
Rakshitha S (P11AZ22S104037)
I MSC, I Sem
Department of studies and research in Organic Chemistry
Tumkur University, Tumkur.
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2. CONTENTS
 INTRODUCTION
 DEFINITION AND RULES OF FISCHER PROJECTION
 ADVANTAGES AND DISADVANTAGES
 SOME STEREOCHEMISTRY ASPECTS
 DEFINITION AND RULES OF NEWMEN PROJECTION
 ADVANTAGES
 CONCLUSION
 REFERENCES
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3. INTRODUCTION
Projection formulas:
The molecules can be visualized and represented on a paper by several projection formulae
1.Wedge-dash projection
2.Newman projection
3.Fischer projection
4.Sawhorse projection
5.Haworth projection
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4. Rules for showing the arrangement around the asymmetric carbon
 In this representation, bonds are solid lines, The bonds are placed vertical and
horizontal to each other
Fischer projection:
In 1891,Emil fischer devised a method of representing the 3D structures of
molecules in 2D Structures on a plane (Paper) by convention, horizontal line
represent bonds projecting from the plane of paper towards the observer and
vertical line represent away from the observer .
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5.  The intersection of vertical and horizontal line is called stereocenter
 Maximum number of the carbon chain is present in vertical line(Longest carbon chain)
Horizontal line is coming out of the plane of the paper(towards the observer)
and vertical line is going back behind the plane of paper( away from the observer)
 In fischer representation most oxidized carbon atom is placed on top of the vertical line
Ex:1
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6. 2.
Advantages
To represent chairal molecule
It is used to represent molecules and compounds , especially structure of monosaccharides and amino acids
To differentiate between pair of enantiomers
To differentiate between D and L molecules
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7. Disadvantages
 These projections can be rotated only in certain specified way
 Fischer projection represent only in the eclipsed form
 In compound more than one stereocenters, fischer projection implies an eclipsing relationship of group attached
to stereocenter but staggered is more stable than eclipsed
Some stereochemical aspects when rotate the fischer projection
 In 180 degree rotation in the plane gives the same stereo chemistry
It allowed and identical
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8. In 90 degree rotation in the plane gives the inverted stereochemistry
It is not allowed and not identical
Exchanging any two position gives the inverted stereochemistry
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9. Newman projection
In 1952,Newman devised a way to draw chemical conformational and views a carbon-carbon
chemical Bond from front carbon is represented as dot and back carbon is represented as
circle.
It easy to assess the dihedral Angle between two bonds one at each carbon atom
Rules for representing the molecules in newman projections
In this representation molecule is viewed along the bond joining the two carbon atoms
The front carbon shown by three solid lines that is “Y”
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10. The back carbon is shown by a circle with a three bonds pointing out from it
Combining the front and back carbon results in the eclipsed newman projection which on rotating
through 180 degree results to get staggered newman projection
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11. The three groups on the carbon atoms are shown as being to bonded to dot or circle
by an angel 120 degree to each other
In newman projection formula all the parallel bonds are eclipsed
But in case of all anti parallel bonds are staggered
The dihedral angel in eclipsed is zero degree
The dihedral angel in staggered is 180 degree or 60 degree
Example 1:
Ethane
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12. Advantages
Newman projection is that they are easy to draw and clearly show the relationship among
substituents on the different carbon atom
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13. CONCLUSION
Fischer projection formula are used to represent the molecules from the 3D to 2D
To the chirality of a molecule and distinguish between o pair of enantiomers
Newman projection is useful to visualizes the conformation of a chemical bond from front to back
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14. REFERENCES
1.Stereochemistry conformation and mechanism(8th edition) by P S kalsi
2.Stereochemistry by Alex v ,Ramani,Leo A,Stanley
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15. THANK YOU