organic chemistry 2: isomers

[...] have the same chemical formula but have a different stereochemical arrangement of their atoms

isomers

[... isomers] have identical chemical formulas but differ structurally

constitutional (structural) isomers '

• the share only a molecular formula. have different physical and chemical properties

[...] are connected in the same order but differ in 3D orientation

stereoisomers

A/an [...] is when four different groups are attached to a central carbon

chiral center

For n number of chiral carbons, there are [...] possible stereoisomers

2ⁿ

[... isomers] differ by rotation around a single σ bond

conformational isomers

This Newman projection shows [...] conformation

anti

• the carbons attachments are no opposite ends, 180 degrees apart

This Newman projection shows [...] conformation

gauche

• the carbon attachments are 60 degrees apart

This Newman projection shows [...] conformation

eclipsed

• less favorable because it fores more interactions between the front and back attachments, creating more strain

An [... bond] is a bond which is perpendicular to the axis of the ring

equatorial bond

• the bond lies along the equator of the chair

An [... bond] is a bond which is parallel to the axis of the ring

axial bond

• straight up and down

The two categories of [... isomers] are enantiomers and diastereomers

configurational isomers

• can only change from one form to another by breaking and reforming bonds

[...] are stereoisomers that are non-superimposable and are mirror images of each other

enantiomers

• same chemical and physical properties, expect for rotation of plane polarized light

Optical activity is the ability of a molecule to [...] plane-polarized light

rotate

A/an [...] mixture is a 50:50 mixture of two enantiomers

racemic

• not optically active because the light rotations cancel out

[...] have an internal plane of symmetry

meso compounds

• will be optically inactive because the two sides of the molecule cancel each other out

[...]are stereoisomers that are non-superimposable and are not mirror images of each other

diastereomers

• not mirror images

Cis functional groups are on [...] side

Trans functional groups are on [...] sides

the same sides

opposing sides

[.. configuration] gives the stereochemistry of a compound relative to the D- and L- forms of glyceraldehyde

relative configuration

• in a fischer projection, look at the highest numbered chiral carbon

• if -OH is on the right then its a D-sugar. If -OH is on the left then it is an L-Sugar

The stereochemistry of the α-carbon in all eukaryotic amino acids (except glycine) is [...] 

L

[... configuration] gives the stereochemistry of a compound without having to compare to other compounds

absolute configuration

Cahn-Ingold-Prelog priority rules are rules for [...]

naming stereoisomers

• priority is given by looking at atoms connected to the chiral carbon or double-bonded carbons. whichever has the highest atomic # gets highest priority

In the E-Z naming system for alkenes:

(Z) has the highest priority on [...] side(s)

(E) has the highest priority on [...] side(s)

the same

opposite

In Fischer projections:

Vertical lines go to [...] of the page

Horizontal lines [...] page

vertical lines go back of the page

horizontal lines come out of the page

vertical lines are like dashes

horizontal lines are like wedges