Cycloalkanes

ring strain

instability of a molecule based on abnormal bond angles

60 degrees

cyclopropane inner bond angle

118 degrees

cyclopropane outer bond angle

88 degrees

cyclobutane inner bond angle

110 degrees

cyclobutane outer bond angle

108 degrees

cyclopentane bond angle

109.5

cyclohexane

2

how many chair conformations for every cyclohexane?

boat conformation

always higher energy than either chair

ring flip

switching the positions of carbon 1 and 4 vertically

stearic/flag-pole interactions

repulsion between atoms or groups in a molecule due to physical size or spatial arrangement

axial

straight up or straight down

equatorial

diagonally up or diagonally down

axial down, equatorial up

diagonal carbon in top of chair conformation (6 or 5)

axial up, equatorial down

top left carbon in chair conformation (5 or 4)

axial up, equatorial down

top right carbon in chair conformation (1 or 6)

axial down, equatorial up

bottom left carbon in chair conformation (4 or 3)

axial down, equatorial up

bottom right carbon in chair conformation (2 or 1)

axial up, equatorial down

diagonal carbon in bottom of chair conformation (3 or 2)

up

wedge

down

dash

favored

more equatorial

favored

larger group equatorial

same (both up or both down)

cis

opposite (one up, one down)

trans

1. largest groups in equatorial 2. number of equatorial positions

order of priority

two attachments

cis and trans can only be used with…