Van’t Hoff-Le Bel theory

Also, in 1890 Fischer had proven that the reduction of fructose with sodium amalgam yields a mixture of mannitol and sorbitol and pointed out that this conformed with the van t HofF-Le Bel theory (19). It seems, therefore, that the idea of asymmetric induction was clearly in a state of incubation prior to his publication of the relative configurations of the sugars in 1891. 

Henderson-Hasselbalch equation lahn-Teller effect Lee-Yang-Parr method Lineweaver-Burk method Mark-Houwink plot Meerwein-Ponndorf theory Michaelis-Menten kinetics Stem-Volmer plot van t Hoff-Le Bel theory Wolff-Kishner theory Young-Laplace equation Ziegler-Natta-type catalyst... 

Using the van t Hoff-Le Bel theory as a guide, Fischer extended his cyanohydrin syntheses from the work with xylose and arabinose to researches on all the other aldoses that were available in quantity at that time the list consisted of glucose, mannose, galactose, rhamnose, lactose and maltose. The experimental results with the disaccharides... 

It became evident soon after the beginning of the project in 1884 that the van t Hoff-Le Bel theory predicting the tetrahedral nature of the saturated carbon atom was critical to the solution of the problem, and that acceptable conventions for the description and representation of acyclic... 

Henderson—Hasselbalch equation Jahn—Teller effect Lineweaver—Burk method Mark-Houwink plot Meerwein—Ponndorf theory Michaelis—Menten kinetics Stern—Volmer plot van t Hoff—Le Bel theory Wolff—Kishner theory Young—Laplace equation Ziegler—Natta-type catalyst... 

As a point of reference, consider that in Marckwald s time the van t Hoff - le Bel theory of tetrahedral carbon was accepted, but what we now know as an sp2 or trigonal carbon, was not. It was thought, at least by some, that the fourth site of a carbonyl carbon was an unoccupied site on a tetrahedron. For example, under the term asymmetric induction in the first collective index of Chemical Abstracts, we find reference to a paper (8 3431 ) entitled Preparation of / benzaldehyde through asymmetric induction. .. (E. Erlenmeyer, F. Landesberger, G. Hilgen-dorff Biochem. Z. 1914,64, 382-392). The formula for benzaldehyde was PhCHL.OL, where L indicates an unoccupied position. 

Almost simultaneously, the French chemist Joseph Achille Le Bel (1847-1930) published a similar suggestion. The tetrahedral carbon atom is sometimes referred to as the Van t Hoff-Le Bel theory. 

Most important of all, there was no blinking the facts. Compounds possessing asymmetric carbon at--oms (those connected to four different types of groupings) possessed optical activity, while those that did not possess such atoms did not. Furthermore, the number of optical isomers was always equal to the number predicted by the Van t Hoff-Le Bel theory. 

Fischer showed that each such sugar had four asynometric carbon atoms, and that on the basis of the Van t Hoff-Le Bel theory, there should therefore be sixteen optical isomers. These isomers should be arranged in eight pairs in each pair one isomer should rotate the plane of polarized light clockwise to exactly the extent the other isomer rotates it counterclockwise. 

Fischer proceeded to work out the exact arrangement of the atoms in each of the sixteen isomers. The fact that exactly sixteen isomers of the 6-carbon sugars have been found, divided into eight pairs, is strong evidence for the worth of the Van t Hoff-Le Bel theory. This same accuracy in prediction holds in the case of other types of sugars, of amino acids, and of any other types of compound. 

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