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Organic chemistry and synthesis A2 > Isomerism > Flashcards

Flashcards in Isomerism Deck (20):
1

Another word forEZ isomerism
And what is needed for it to occur?

Geometric isomerism

A carbon - carbon double bond to prevent rotation, and 2 different groups attached to the carbon atom

2

What is optical isomerism

When isomers have the same molecular and structural formula, but have a different affect in the plane of polarised light

3

What are enantiomers

Non super impossible mirror images

4

Why can't a carbon atom that's part of a double bond or a carbonyl (C=O) atom not be chiral?

Due to the mirror image relationship and the fact isomers can't be superimposed on eachother, it can't be chiral as the carbons only have 3 Different atoms or groups attached

5

How does optical isomerism arise?

It arises from molecules which have 4 different atoms or groups of atoms attached to the tetrahedral carbon (chiral)

6

Describe an optically active compound (enantiomer)

It has the ability to rotate the plane of polarised light left or right, amount of rotation is measured by a polarimeter

7

What is an equivocal mixture of 2 different enantiomers called?

Race mate

8

Why is a race mate (equinmolar mixture of 2 enantiomers) optically INACTIVE?

Because the rotating effect of one enantiomer cancels out the effect of another

9

What is the separation of a race mate into component enantiomers called?

Resolution

10

What is a stereoisomer?

Have same molecular and structural formula but atoms arranged differently in space

11

How can you distinguish between enantiomers?

Rotate the plane of polarised light in opposite directions

12

What is the amount of rotation measured using?

A polarimeter

13

Ratio of an equinmolar mixture of 2 enantiomers (racemate)

1:1

14

An equinmolar mixture of 2 enantiomers is optically inactive- why?

The rotating effect of one enantiomer cancels out the effect of another

15

Define an enantiomer and its ability

Non superimposable mirror images

Has the ability to rotate the plane of polarised light left or right

16

Is an enantiomer optically active or inactive?why?

Active !
Because it has the ability to rotate the plane of polarised light left or right

17

Give some examples of Carbons / compounds that aren't Chiral

Why?

C=O
C=C
Benzene


Due to the mirror image relationship and the fact isomers cannot be superimposed on eachother - must have 4 different atoms attached to the tetrahdral (chiral) Carbon!

18

What is meant by a compound that shows optical activity

Has ability to rotate the plane of polarised light in opposite directions

19

Why is something optically inactive

Rousting effect of one enantiomer cancels out affect of another

20

What is meant by the term enantiomer

An optically active isomer that had the ability to rotate the plane of polarised light in opposite directions