Chapter 20.7: Stereoisomerism II: Configurational Isomerism Flashcards Preview

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Flashcards in Chapter 20.7: Stereoisomerism II: Configurational Isomerism Deck (24):
1

define stereoisomers

molecules in which the atoms are bonded in the same order, but have different spatial arrangement

2

define configurational isomersim

a type of stereoisomerism in which atoms or functional groups are connected in the same sequence, but there is a difference in spatial locations of atoms or groups

3

the only way to interconvert configurational isomers is to...?

break the covalent bonds

4

What are the two categories configurational isomers can be divided into?

Enantiomers
Diastereomers

5

define enantiomers

two molecules that are nonsuperimposable mirrior images of one another

6

define diastereomers

configurational isomers that are not mirror images

7

cis means...?

same side

8

trans means...?

opposite sides

9

define cis-trans isomersim

cis-isomers have the same functional group on the same side of a bond and trans-isomers have the same functional groups on opposite sided of the bond

10

what type of isomers are cis and trans isomers?

diastereomers (under the broader category of configurational isomers)

11

define E, Z system

the protocol for assigning stereochemical configuration of an alkene with three or more different groups

12

what are the priority of substituents determined by?

by Cahn-Ingold-Prelog rules

13

what are the three Cahn-Ingold-Prelog rules?

1. priority is first determined on the basis of the atomic mass of the atoms that are directly bonded to the carbons in the double bond
2. if the atoms are directly attached to a double-bonded carbon atom are the same, then the second atoms of the substituents are compared. again the priority assigned on the basis of atomic mass. if there is no difference in priority among the second atoms, then third atoms are considered, and so on.
3. if a substituent contains a double or triple bond, then multiply bonded atom is treated as if it were two or three atoms bonded atom is treated as if it were two or three atoms bonded to the same carbon atom.

14

define chirality

the type of isomersim in which molecules are nonsuperimposible

15

define chirality center

a carbon atom with 4 different substituents in a tetrahedral arrangement

16

define optical activity

the ability of chiral compounds to rotate the plane of plane-polarized light

17

define dextrorotary isomer (the d isomer)

the enantiomer that rotates plane-polarized light CLOCKWISE

18

define levorotatory (the l isomer)

capable of rotating the polarization of light COUNTER CLOCKWISE

19

define racemic mixture

an equimolar mixture of two enantiomers that does not rotate the plain of polarization at all

20

what is the only physical property that is not identical between enantiomers?

the way they interact with plain polarized light

21

define absolute configuration

the exact three-dimensional spatial arrangement of atoms at a chirality center

22

define R, S system

the protocol for assigning stereochemical configuration of a chirality center

23

what is the configuration if 1-3 is clockwise according to the R, S system?

R

24

what is the configuration if 1-3 is counterclockwise according to the R, S system?

S