Optical Isomerism Flashcards

1
Q

What kind of molecules show optical isomerism?

A

Chiral molecules (4 different groups attached)

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2
Q

What is a racemic mixture or racemate?

A

When a substance has a 50/50 mix of two enantiomers

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3
Q

What is an enantiomer?

A

An optical isomer

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4
Q

Optical isomerism is a form of what type of isomerism?

A

A form of stereoisomerism

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5
Q

How do enantiomers differ?

A

In their effect on plane polarised light and their reaction with other chiral molecules

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6
Q

What does a polarimeter do?

A

Measure how the plane of light is rotated when polarised light is passed through a sample

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7
Q

How does the electrophilic addition of HBr to but-2-ene form enantiomers?

A

The intermediate formed is a trigonal planar.

Br is equally likely to attack from above as below, thus forming the enantiomers (and therefore a racemate)

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8
Q

Why is optical isomerism important to consider in medicine and drugs?

A

Most of the reactions that occur in the body are very shape specific. Therefore, often only one enantiomer will have an effect.

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9
Q

Many drugs are optically active, with only one enantiomer having an effect. However, many drugs are racemates. Why?

A

Only one has an effect, so (in most cases) other is not harmful
Cheaper to not separate

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