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A Level Chemistry Organic > Aldhydes And Ketones(optical isomerism > Flashcards

Aldhydes And Ketones(optical isomerism Flashcards

1
Q

What does partial oxidation of primary alcohol form

A

It results an aldehyde forming

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2
Q

What does oxidation of a secondary alcohol

A

Results in a forming a ketone

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3
Q

What is the oxidizing agent used in the oxidation primary alcohol and secondary alcohol and aldehydes

A

Potassium dichromate in sulphuric acid (gentle warming needed)

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4
Q

What happens to the potassium dichromate

A

The orange colour reduced to green

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5
Q

What is the symbol for oxidation

A

[O]

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6
Q

Give the simplified equations for oxidation reactions

A

R-CH2OH+[O]–R-CHO +H2O

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7
Q

Give the oxidation reaction for secondary alcohol

A

R1-CH(OH)-R2+[O]–R1-CO-R2+ H2O

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8
Q

When oxidised further what do aldehydes produce

A

Carboxylic acid

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9
Q

What two tests can help distinguish between aldehydes and ketones

A

Tollens reagent

Feelings solution

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10
Q

What occurs when aldehydes and ketones react with tollens reagent

A

Aldehydes- tollens reagent is reduced and a grey silver mirror forms (carboxylic acid formed)

Ketones-no reaction

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11
Q

What happens when fehlings solution reacts with an aldehyde or ketone

A

Aldehydes- it’s reduced from the blue copper to red brick red precipitate on gentle warming

Ketone- no reaction

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12
Q

What reducing agent is used to reduce aldehydes and ketones to alcohols

A

NaBH4 sodium tetrahydroborate

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13
Q

What symbol shows reduction

A

[H]

2[H] in equation

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14
Q

Give the simplified equation for the reduction of aldehyde

A

R-CHO + 2[H]-> R-CH2OH(primary alcohol)

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15
Q

Give a simplified equation for reduction of ketone

A

R1-CO-R2 +2[H]->R1-CH(OH)-R2 (secondary alcohol)

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16
Q

What reducing agent is used to reduce carboxylic acids

A

LiAlH4

17
Q

What reactions do carbonyls undergo

A

Nucleophilic addition

18
Q

What nucleophile undergoes nucleophillic addition with carbonyls in reduction

A

HCN

19
Q

Give the simplified equation for when HCN is reacted with carbonyls in reduction

A

R1-CO-R2 + HCN->R1-C(CN)(OH)-R2

20
Q

What is produced when carbonyls undergo reduction with HCN

A

Hydroxynitrile

21
Q

Write out equation for reduction by NaBH4 to make alcohols

A

R1-CO-R2+ 2[H]->R1-CH(OH)-R2

22
Q

What is chirality

A

When 4 different groups are attached to one carbon

23
Q

What are optical isomers (enantiomers)

A

They are two non superimposable mirror images

24
Q

How can optical isomers be distinguished

A

By passing plane polarised light through a liquid containing a chiral molecule

25
Q

What do chiral molecules do to plane polarised light

A

They cause it to rotate equally but in opposite directions

One in clockwise rotation
One in anti-clockwise rotation

26
Q

Define optically active

A

A substance which can rotate plane polarised light

27
Q

What is a racemic mixture

A

When optical isomers are found together in equal amounts

28
Q

What reactions do chiral substances undergo

A

Electrophillic addition
Nucleophillic addition
Nucleophillic substitution

29
Q

When a chiral substance is produced by an addition reaction what is it

A

It’s a racemic mixture

30
Q

Why is a racemic mixture produced when by an addition reaction

A

As the attacking nucleophile or electrophile will attack the polar C-O bond planar molecule above and below in equal proportions

31
Q

What happens when a chiral substance undergoes nucleophillic substitutions

A

It only produces a single enantimor as the attacking species only attacks from one side

32
Q

Give the reagents involved in nucleophilic addition of carbonyl

A

KCN
HCL

Room temperature

33
Q

Why is HCn generated insitu and give the equation

A

As it’s a very toxic gas

KCN +HCl->HCN KCL

A Level Chemistry Organic (13 decks)

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