5. Chirality

Convert the following Fischer projections to perspective formulas

(c)

(d)

(a) There is only one ketotriose, called dihydroxyacetone. Draw its structure.

(b) There is only one aldotriose, called glyceraldehyde. Draw the two enantiomers of glyceraldehyde.

For each set of examples, make a model of the first structure, and indicate the relationship of each of the other structures to the first structure. Examples of relationships: same compound, enantiomer, structural isomer.

(c)

Which of the following compounds are chiral? Draw each compound in its most symmetric conformation, star (*) any asymmetric carbon atoms, and draw any mirror planes. Label any meso compounds. You may use Fischer projections if you prefer.

(e) (R,R)-2,3-dibromobutane

(f)

Draw a Fischer projection for each compound. Remember that the cross represents an asymmetric carbon atom, and the carbon chain should be along the vertical, with the IUPAC numbering from top to bottom.

(e)

a. Are d-erythrose and l-erythrose enantiomers or diastereomers?

b. Are l-erythrose and l-threose enantiomers or diastereomers?

For each pair, give the relationship between the two compounds. Making models will be helpful.

(e)

(f)

For each structure,

1. draw all the stereoisomers.

2. label each structure as chiral or achiral.

3. give the relationships between the stereoisomers (enantiomers, diastereomers).

(a)

Give the stereochemical relationships between each pair of structures. Examples are same compound, structural isomers, enantiomers, and diastereomers. Which pairs could you (theoretically) separate by distillation or recrystallization?

(a)

(b)

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

c.

d.

For each pair, give the relationship between the two compounds. Making models will be helpful.

(g)