This PPT is about organic chemistry , sterochemistry , and also define polarimeter . Any mistake or for guide , then contact me , send me comment, give your feedback must

1. OPTICALACTIVITY
PRESENTED BY
MUHAMMAD DEEN
FURQAN UL HASSAN
QASIM ALI
ZEESHAN FAROOQ
USAMA BIN SAJJAD
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2. CONTENTS
OPTICAL ACTIVITY
THEORY OF OPTICAL ACTIVITY
INTRODUCTION
PLANE POLARISED LIGHT
POLARIMETER
INSTRUMENTATION
APPLICATIONS
CHIRALITY
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3. OPTICALACTIVITY
It Has found that magnitude of rotation depend upon the following factors:
 Nature of Substance
 Length of liquid column ( l ) through which light passes
 Concentration of the solution
 Nature of the solvent
 Temperature of the solution (t)
 Wavelength of the light used
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4. • The Rotatory Power of a given solution is generally expressed as specific rotation.
• It is the number of degrees of rotation of plane polarized light produced by one
gram of the substance per ml.
• The measurements is carried out at temp using sodium light.
[α] = specific rotation, T = temperature,
 λ = wavelength, θ= optical rotation,
c = concentration in g/100ml, l = optical path length in dm.
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5. Optical Activity Regular
(unpolarized) light vibrates in all directions
 Plane-polarized light: Light composed of waves that vibrate in only a
single plane
 Obtained by passing unpolarized light through a polarizing filter
 Optical Activity when plane polarized light passes through a solution containing a single
chiral compound
 The chiral compound causes the plane of vibration to rotate
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6.  Optical Activity Compounds “that rotate the plane of polarized
light to the right (clockwise) are called dextrorotatory.”
 d(+) IUPAC convention
 “Compounds that rotate the plane of polarized
light to the left (counterclockwise) are called levorotatory.”
 l(-) IUPAC convention
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7. INTRODUCTION
o Optical Activity Polarimetry is a laboratory technique that measures the interaction
between a compound and plane polarized light.
o Polarimetry is one of the important instrumental methods employed in analysis.
o This measures the rotation of the polarized light as it passes through an optically
active compound.
o This technique involves the measurement of change in the direction of vibration of
polarized light when interact with an optically active compound.
o A substance is said to be optically active if it rotates the plane of the polarized light.
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8. PLANE POLARISED LIGHT
• According to wave theory of light,
“An ordinary ray light is considered to be vibrating in all planes at right angle to
the direction of propagation. If this ordinary ray of light is passed through a Nicol prism, the
emergent ray has its vibration only in one plane.”
This light having wave motion in only one plane is known as Plane Polarised Light.
•NICOL Prism – Iceland Spar
Calcite ( CaCO3 form ) (or) Polaroid
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10. o A plane polarized light which consists of two components of fixed magnitude rotating
in opposite directions to one another
o The right circulatory polarized light
o The left circulatory polarized light
o Plane polarized light is the vector sum of these two components
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11. INSTRUMENTATION
 Optical activity may be detected & measured by an instrument → Polarimeter
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12.  A polarimeter consists of a polarized Light source
 Sodium vapor lamp
 Polarizer
 Quartz prism
 Material
 Analyzer
Light source – Sodium vapor lamp
Analyzer– another Nicol prism aligned to intercept the linearly polarized ray as it emerges from the sample
solution
Nicol prism aligned to intercept the linearly polarized ray as it emerges from the sample solution,
a graduated circle- to measure the rotation angle and sample tubes
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15. APPLICATIONS
Quantitative application
 If the specific rotation of sample is known its concentration in the solution can be estimated.
Qualitative application
 Optical activity is the only parameter available for distinguishing between D and L isomeric forms.
Saccharimetry
 Important practical application of polarimetry
 Determination of high conc. of sugars
 Visual saccharimeters called Polaroscopes
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Chirality
 A property of asymmetry important in several branches of science.
 The word chirality is derived from the Greek (kheir), "hand," a
familiar chiral object.
 An object or a system is chiral.
 If it is distinguishable from its mirror image
 That is, it cannot be superposed onto it.

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How do you identify chirality?
 Look for carbons with four different groups attached
to identify potential chiral centers.
 Draw your molecule with wedges and dashes and then draw a mirror image
of the molecule.
 If the molecule in the mirror image is the same molecule, it is achiral.
 If they are different molecules, then it is chiral.

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CHIRAL MOLECULE

19. CHIRAL MOLECULE
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21. REFERENCE
• HTTPS://WWW.GOOGLE.COM/SEARCH?Q=CHIRALITY+DEFINITION&RLZ=1C1CHBF_
ENPK766PK766&OQ=CH&AQS=CHROME.0.35I39L2J69I60J69I61J69I60L2.3272J0J7&SO
URCEID=CHROME&IE=UTF-8
• HTTPS://WWW.POWERSHOW.COM/VIEWHT/51FED4-
ZTC5Y/OPTICAL_ACTIVITY_POWERPOINT_PPT_PRESENTATION
• HTTPS://WWW.SLIDESHARE.NET/RAJ_BHAGWAT/POLARIMETRY-59864226
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THANK YOU
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