5 Stereochemistry

Organic Chemistry: Structure and Function

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Stereochemistry Part 1 Lecture supplement: take one handout from the stage
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Stereochemistry: What is It? Isomers Molecules with same chemical formula but different spatial arrangement of atoms Constitutional isomers Differ in sequence of atom connectivity Urea CH 4 N 2 O H 2 N NH 2 O Ammonium cyanate CH 4 N 2 O N H H H H O C N Jöns Jakob Berzelius, 1830
Background image of page 2
3 Stereochemistry: What is It? Isomers Same sequence of connectivity, but can be interconverted by rotation around a single bond rotate around C2-C3 bond Butane C 4 H 10 Eclipsed conformation Conformational isomers Are other isomers possible? Tetrahedral carbon. .. click on movie to play Butane C 4 H 10 Staggered conformation
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Historical Background Timeline A: Light 1678: Christiaan Huygens discovers plane-polarized light many vibrational planes nonpolarized light one vibrational plane plane-polarized light light beam Iceland spar crystal (natural CaCO 3 )
Background image of page 4
5 Historical Background Timeline A: Light 1815: Jean Baptiste Biot notes some natural substances rotate plane-polarized light polarization plane shifted tube of liquid organic compound or solution plane-polarized light Optically active : the ability to rotate plane-polarized light Optically inactive : does not rotate plane-polarized light
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Historical Background Timeline A: Light Dextrorotatory : rotates plane-polarized light in a clockwise direction (+) Levorotatory : rotates plane-polarized light in a counterclockwise direction (-) Optical activity (-)-Nicotine N N H CH 3 (+)-Methamphetamine CH 3 N H 3 C H H
Background image of page 6
7 Historical Background Timeline B: Tartaric Acid Tartaric acid Racemic acid OH OH HO HO O O 1828: Joseph Louis Gay-Lussac shows tartaric acid and racemic acid are isomers 1819: Paul Kester isolates racemic acid from tartar From Latin racemus : bunch of grapes 1769: Carl Wilhelm Scheele examines tartar (deposited in casks during wine fermentation); isolates tartaric acid
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
8 Historical Background Timeline B: Tartaric Acid 1838: Biot notes racemic acid is optically inactive 1832: Jean Baptiste-Biot notes tartaric acid is optically active 1847: Louis Pasteur separates ammonium sodium salt of racemic acid into (+) and (-) crystals
Background image of page 8
9 Historical Background Timeline B: Tartaric Acid O Na O NH 4 HO HO O O Ammonium sodium racemate optically inactive (+)-tartaric acid optically active identical to Scheele’s tartaric acid (-)-tartaric acid optically active Pasteur’s separation of racemic acid Quantity: equal Optical activity: equal but opposite Conclusion: Racemic acid is a 1:1 mixture of two optically-active substances separate crystals
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10 Historical Background Timeline B: Tartaric Acid 1853: Pasteur investigates mesotartaric acid Mesotartaric acid OH OH HO HO O O Artificial, optically-inactive isomer of tartaric acid Cannot be separated into (+) and (-) forms Tartaric acid isomers have different biological properties 1854: Pasteur notes a certain plant mold metabolizes (+) but not (-)-tartaric acid
Background image of page 10
11 Historical Background Timeline C: Tetrahedral Carbon A molecule having a tetrahedral carbon atom with four unequal attachments exists as a pair of isomers.
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 40

5 Stereochemistry - Stereochemistry Part 1 Lecture...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online