3.3.7 ande 3.3.8 Optical Isomerism and aldehydes and ketones Flashcards

1
Q

Name the 2 types of isomerism

A

Structural isomerism
Stereoisomerism

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2
Q

Name the 3 types of structural isomerism

A

Positional isomerism
Chain isomerism
Functional isomerism

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3
Q

Name the 2 types of Stereoisomerism

A

Geometrical isomerism - E/Z
Optical isomerism

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4
Q

Structural isomerism definition

A

Same molecular formula but different structural formula

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5
Q

Stereoisomerism definition

A

Same structural formula
Bonds arranged differently in space

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6
Q

What are the key points of optical isomerism?

A
  • Carbon centre bonded to 4 different groups (chiral centre)
  • Forms 2 isomers that are mirror images (pair of enantiomers)
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7
Q

Non-superimposable mirror images definition

A

Bonds don’t line up with each other when on top of each other

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8
Q

What is optimal isomerism?

A

Optical isomers rotate a plane off polarised light, one isomer will rotate it anti clockwise, the other clockwise

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9
Q

Chiral definition

A

4 different groups on 1 carbon

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10
Q

Chiral centre definition

A

A central carbon bonded to 4 different groups

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11
Q

Stereogenic centre definition

A

A central carbon bonded to 4 different groups

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12
Q

Enantiomer definition

A

A single optical isomer

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13
Q

Enantiomerically pure definition

A

A sample with 1 optical isomer

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14
Q

Optically active definition

A

A sample with 1 optical isomer

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15
Q

Racemic mixture definition

A

A sample with both optical isomers in equal amounts

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16
Q

What are the properties that all optical isomers have in common?

A
  • Melting and boiling point
  • Solubility in a range of solvents
  • Mr value
  • Peaks in their NMR spectrum, IR and mass spectrum
17
Q

What is the case study for optical isomers?

A

Thalidomide

18
Q

Why is it not possible to produce an optically active sample?

A

In a lab all drugs are produced in a racemic mixture and so will rotate a plane in polarised light equally in opposite directions

19
Q

Equation for an aldehyde to a primary alcohol

A

CH3CHO + 2[H] –> CH3CH2(OH)

20
Q

Equation for a ketone to a primary alcohol

A

CH3C(CH3)O + 2[H] –> CH3CH(OH)CH3

21
Q

What is the reagent for the reduction of aldehydes and ketones?

A

NaBH4 (reducing agent)

22
Q

What is the mechanism for the reduction of aldehydes and ketones?

A

Nucleophillic addition

23
Q

What is the nucleophile in the reduction of aldehydes and ketones?

A

Hydride
H:-

24
Q

What is the condition needed for the reduction of aldehydes and ketones?

A

Dilute acid

25
Q

Equation for the reduction of propane to propane-1-ol

A

CH3CH2CHO + 2[H] –> CH3CH2CH2OH

26
Q

Equation for the reduction of butane to butan-2-ol

A

CH3CH2COCH3 + 2[H] –> CH3CH2CHOCH3

27
Q

What is the reagent for the reaction of aldehydes and ketones with :CN-?

A

KCN and dilute HCl

28
Q

What is the mechanism for the reaction of aldehydes and ketones with :CN-?

A

Nucleophillic addition

29
Q

What is the nucleophile for the reaction of aldehydes and ketones with :CN-?

A

:-CN

30
Q

What is the condition needed for the reaction of aldehydes and ketones with :CN-?

A

Acidic

31
Q

What is the name of the product when aldehydes and ketones react with :-CN?

A

Hydroxynitriles

32
Q

Why can nucleophillic addition to aldehydes and asymmetrical ketones result in a racemic mixture of optical isomers

A
  • The bonding is about a C=O planar group in an aldehyde and ketone is planar
  • This means there is a 50:50 chance of the nucleophile attacking from one side of the molecule or the other
  • Resulting in equal proportions of each optical isomer, forming a racemic mixture