Organic Chemistry Ch 2. Isomers

Question 1

Structural isomers

Answer 1

Share only a molecular formula, have different chemical and physical properties

Question 2

Confirmational isomers

Answer 2

Differ by rotation around a single sigma bond

Question 3

Staggered confirmations

Answer 3

Have groups of 60° apart as seen in a Newman projection

Question 4

Anti staggered molecules

Answer 4

The two largest groups are 180° apart

Question 5

Gauche staggered molecules

Answer 5

The two largest groups are 60° apart

Question 6

Eclipsed confirmations

Answer 6

Have groups directly in front of each other as seen in a Newman projection

Question 7

Totally eclipsed confirmation

Answer 7

Two largest groups are directly in front of each other and strain is maximized

Question 8

Angle strain

Answer 8

Created by stretching or compressing angles from their normal size, creates a strain in cyclic molecules

Question 9

Torsional strain

Answer 9

Created from the clips and confirmations, also creates a strain in cyclic molecules

Question 10

Non-bonded strain

Answer 10

Interactions between substituents attached to nonadjacent carbons, also creates a strain in cyclic molecules

Question 11

Cyclic molecule strain

Answer 11

Angle strain, torsional strain, and non-bonded strain, cyclic molecules will usually adopt non-planer shapes to minimize the strain

Question 12

Axial substituents

Answer 12

Substituents attached to cyclohexane that are sticking up and down from the plane of the molecule, create more non bonded strain

Question 13

Equatorial substituents

Answer 13

Substituents attached to cyclohexane in the plane of the molecule, typically where the largest substituents are

Question 14

Configurational isomers

Answer 14

Can only be interchanged by breaking in reforming bonds

Question 15

Enantiomers

Answer 15

Non-superimposable mirror images unless have opposite stereo chemistry at every chiral carbon, have the same chemical and physical properties except for rotation of plane polarized light and reactions in a chiral environment

Question 16

Optical activity

Answer 16

Refers to the ability of a molecule to rotate plane polarized light, D or plus molecules rotate light to the right and L or minus molecules rotate light to the left

Question 17

Racemic mixtures

Answer 17

If equal concentrations of an ant hammers will not be optically active because the two enantiomers rotations cancel each other out

Question 18

Meso compounds

Answer 18

Have an internal plane of symmetry and also will be optically in active because the two sides of the molecule cancel each other out

Question 19

Diastereoisomers

Answer 19

Are non-mirror image stereoisomers, they differ at some but not all chiral centers, have different chemical and physical properties

Question 20

Cis trans isomers

Answer 20

Or some type of diastereoisomers in which groups differ in position about an immovable bond such as a double bond or a cyclo alkane

Question 21

Chiral centers

Answer 21

Have four different groups attached to the center carbon

Question 22

Relative configuration

Answer 22

Is the stereo chemistry of a compound in comparison to another molecule

Question 23

Absolute configuration

Answer 23

What is the stereo chemistry of a compound without having to compare it to other molecules, uses the Cahn-Ingold-Prelog priority rules

Question 24

Cahn-Ingold-Prelog Priority rules

Answer 24

Priorities given by looking at the atoms connected to the chiraol carbon or double bonded carbon, which ever has the highest atomic number gets highest priority, if there’s a tie one moves outward from the chiral carbon double bond until the tire is broken

Question 25

Z alkene

Answer 25

Occurs at the highest priority substituents are on the same side of the double bond

Question 26

E alkene

Answer 26

Occurs is the highest priority substituents are on the opposite sides of the double bond

Question 27

Determining stereo centers configuration

Answer 27

Putting the lot lowest priority group in the back and drawing a circle from 1 to 2 to 3 and descending priority

Question 28

R stereocenter

Answer 28

If circle is counterclockwise

Question 29

S stereocenter

Answer 29

If circle is clockwise

Question 30

Fischer diagrams

Answer 30

Vertical lines go into the page of the plane (dashes), horizontal lines come out of the plane of the page (wedges), switching one pair of substituents in a fisher diagram inverts the stereo chemistry of the chiral center, switching to pairs retains the stereo chemistry, rotating 90° inverts the stereo chemistry of the chiral center, rotating 180° retains the stereo chemistry