Class Exam for Lecture

There are five types of interactions within and between molecules. Intramolecular interactions include covalent and ionic bonds. Intermolecular interactions include van der Waals s forces, dipole-dipole, and hydrogen bonds. Table 1 lists the typical energies for these interactions. 

What type of bonding holds together the compound MgCl2  

Why do the boiling points of the noble gases increase as the period increases  

The bonds are stronger because larger atoms are more polarizable as period increases. 

With few exceptions, enantiomers cannot be separated through physical means. When in racemic mixtures, they have the same physical properties. Enantiomers have similar cliemi cal properties as well. The only chemical difference between a pair of enantiomers occurs in reactions with other chiral compounds. Thus resolution of a racemic mixture typically takes place through a reaction with another optically active reagent. Since living organisms usually produce only one of two possible enantiomers, many optically active reagents can be obtained from natural sources. For instance S)-(+Hactic acid can be obtained from animal muscle tissue and (S)- -)-2-methyl-l-butanol, from yeast fermentation. 

In the resolution of a racemic acid, a solution of (R)-phenylcthylamine is reacted with a racemic mixture of phenylchloroacetic acid to form the corresponding salts. The salts are then separated by careful fractional crystallization. Hydrochloric acid is added to the separated salts, and the respective acids are precipitated from their solutions. 

Resolution of a racemic base can be accomplished in the same manner with tartaric acid. 

Quinine, n natural anti-malarial, is commonly used as an optically active reagent to resolve acidic enantiomers. How many chiral carbons exist in the quinine molecule drawn below  

If the product is the naturally occurring lactic acid, which of the compounds below could be a reactant  

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