OPTICAL ISOMERS/ALDEHYDES AND KETONES Flashcards

1
Q

Aldehydes —> carboxylic acid

A

Reaction: oxidation
Reagent: accidified potassium dicromate
Condtion: Reflux

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2
Q

Chemical TESTS to distinguish between aldehydes & ketones

A

1.
Tollen’s reagent
Aldehyde: silver mirror
Ketone: NVC
2.
Felling’s solution
Aldehyde: brick red ppt
Ketone: NVC

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3
Q

Why nucelophilic addition reaction of KCN, followed by dillyte acid, can produce a mixture of enantiomers (3 marks)

A

C=O planar
50:50 chance of nucelophile attaching from both sides
Results in equal proportions of each optical isomer formed so racemic mixture

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4
Q

Type of reaction that produces primary alchols from aldehydes

A

Reduction

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5
Q

Type of reaction that forms secondary alchols from ketones

A

Reduction

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6
Q

Mechanisms for:
Aldehyde ——> primary alcohols
(3marks)

A

Nucelophilic addition
NaBH4
Condition: acidic solvent

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7
Q

Mechanism for:
Ketone——>secondary alcohol
(3 marks)

A

Nucelophilic addition
Reagent: KCN & HCl
Condition: acidic solvent

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8
Q

Definition: strreoisomerism

A

Same structural formula different arrangement of atoms in space

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9
Q

What are optical isomers? (1 mark)

A

Non-superimposable mirror images

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10
Q

What is optical isomerism? (4 marks)

A

Molecules with chiral centres
Non-superimposable mirror images
Rotate plane of polarised light in opposite dirrection
One isomer rotates it clockwise and the other anticlockwise

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11
Q

How racemic mixtures are formed and why they are optically inactive (6 marks)

A

C=O planar
Nucleophilic artack
50:50 chance H attacking from either side
Exsists in 2 chiral form
Equal amount of enantiomer mixture formed
Optical isomers rotate plane of polarised light equally
Racemic mixture effects cancel

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12
Q

Chiral

A

Pair of optical isomers

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13
Q

Chiral centre

A

C attached to 4 different group

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14
Q

Enantiomer

A

Each optical isomer

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15
Q

Enantiomerically pure

A

Sample with 1 optical isomer

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16
Q

Optically active

A

Rotate plane of polarised in 1 dirrection only

17
Q

Racemic mixture

A

Mixture contains equal quantities of enantomers