Chapter 4: Alkanes and Cycloalkanes

How do you identify relative energy of conformations?

1) Draw a Newman projection 2) Draw all three staggered conformations and determine which has the fewest or least severe gauche interactions 3) Draw all three eclipsed conformations and determine which one has the highest energy interactions

How do you draw a chair conformation?

1) Draw a wide V 2) Draw a line going down at a 60° angle ending just before the center of the V 3) Draw a line parallel to left side of V ending just before left side of V 4) Draw line parallel to line from step 2, going down exactly as low as that line 5) Connect the dots

How do you draw axial and equatorial positions?

1) Draw all axial positions as parallel lines, alternating in directions 2) Draw all equatorial positions as pairs of parallel lines

How do you draw both chair conformations of a monosubstituted cyclohexane?

1) Draw chair conformation 2) Place substituent in axial position 3) Draw ring flip and axial groups become equatorial

How do you assemble the name of a bicyclic compound?

1) Identify bicyclo parent and indicate how bridgeheads connect 2) Identify and name substituents 3) Number parent chain (start with longest bridge) and assign locant to each substituent 4) Assemble substituents alphabetically

How do you assemble the systematic name of an alkane?

1) Identify parent 2) Identify and name substituents 3) Number parent chain and assign locant to each substituent 4) Arrange substituents alphabetically

How do you identify and name complex substituents?

1) Identify parent 2) Place numbers on complex substituent, going away from parent chain 3) Treat entire group as a substituent on a substituent

How do you draw Newman projections?

1) Identify three groups connected to front carbon atom 2) Identify three groups connected to back carbon atom 3) Assemble Newman projection from two pieces obtained in previous steps

How do you draw both chair conformations of a disubstituted cyclohexane?

1) Using number system, determine location and configuration of each substituent 2) Place substituents on first chair using information from step 1 3) Draw second chair skeleton and place substituents using information from step 1

How do you draw the more stable chair conformation of polysubstituted cyclohexanes?

1) Using numbering system, determine location and configuration of each substituent 2) Using information from step 1, draw both chair conformations 3) Assess energy cost of each axial group

How do you identify the parent chain?

1. Choose the longest chain 2. In a case where two chains compete, choose chain with more substituents

How do you identify and name substituents?

1. Identify parent chain 2. Identify all alkyl substituents connected to parent 3. Name each substituent using names in Table 4.2

How do you identify constitutional isomers?

Constitutional isomers have different names. If two compounds have the same name, they are the same compound.