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Chemical Reactivity > Unit 6 > Flashcards

Unit 6 Flashcards

aldehydes, ketones and alcohols

1
Q

What is an aldehyde?

A

Has a c=o at the end of a molecule

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2
Q

What is a ketone?

A

Has a c=o in the middle of the molecule

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3
Q

What are some properties of aldehydes and ketones?

A

Polar
miscible with water
volatile

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4
Q

What is the suffix for an aldehyde?

A

Al

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5
Q

What is the suffix for a ketone?

A

one

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6
Q

How can you make an aldehyde from a primary alcohol?

A

By adding PCC (weal oxidising agent)

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7
Q

How can you make a ketone from a secondary alcohol?

A

potassium dichromate and sulphuric acid. (K2cr207 & h2so4) acidic conditions are best can just put (H+)

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8
Q

What can ozonolysis be used for?

A

To find the position of a double bond

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9
Q

What is ozonolysis?

A

Splitting of a double bond and inserting oxygens creating two carbonyl derivatives. Two molecules with c=o will be formed

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10
Q

What is PCC

A

A weak oxidising agent that is selective so can be used to oxidise a primary alcohol to an aldehyde

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11
Q

How can you produce benzaldehyde? (using chlorine)

A

React methylbenzene and chlorine in UV (form free radical) light then reflux to get benzaldehyde

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12
Q

How can you reduce benzoyl Chloride to get benzaldehyde? (aromatic)

A

Reduce benzoyl chloride using hydrogen and palladium catalyst mixed with barium sulfate

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13
Q

Why do addition reactions take place on aldehydes and ketones?

A

the c=o is polar as o is very electronegative. This slight positive charge on the C allows for nucleophilic attack which breaks the double bond (pi) and means H+ can be attached to the o (OH) as its down in acidic conditions

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14
Q

How do aldehydes and ketones react with water?

A

to form diols/hydrates but they arent very stable

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15
Q

What happens when you react an aldehyde with a alcohol?

A

Form an ether it can be used to protect ketone groups from further reaction

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16
Q

What colour does Na2Cr207 turn in the presence of an aldehyde

A

Goes from orange to green

17
Q

Ketones are very hard to oxidise true or false?

A

True

18
Q

Why is there difference in reactivity between aldehydes and ketones

A

Aldehyde is more reactive. as its less sterically hindered

less inductive groups (e- donating trying to stabilise) so the carbon centre is more + than in a ketone

19
Q

Test for the carbonyl group? (aldehyde or ketone)

A

2-4 dinitrophenylhydrazine. If theres aldehydes or ketones present there will be an orange precipitate formed

20
Q

Test for aldehydes?

A

Tollens reagent. Clear solution will turn like a silver mirror.
Can also use Fehlings solution which will turn from blue to orange

21
Q

What happens if you condensate two aldehydes?

A

you make an aldol (2 functional groups)

22
Q

What do alcohols contain?

A

OH hydroxyl group

23
Q

what are primary secondary and tertiary alcohols

A

Primary- Carbon with the OH is bonded to 1 other C
Secondary- Carbon with the OH is bonded to 2 other Cs
Tertiary- Carbon with the OH is bonded to 3 other Cs
Phenol- bonded to benzene

24
Q

What numbers correspond to Ortho?

A

1,2

25
Q

What numbers correspond to Meta?

A

1,3

26
Q

What numbers correspond to para

A

1,4

27
Q

How do you get from an alkene to an alcohol?

A

An acid catalyst and water

28
Q

How do you get from a carboxylic acid to a alcohol?

A

Lithium aluminium hydride in acidic conditions

29
Q

How do you get from a halogen alkane to an alcohol?

A

Sodium hydroxide

30
Q

Why do alcohols have high boiling points?

A

Hydrogen bonding and permanent dipole to dipole attractions

31
Q

Small alcohols are miscible in water but this decreases with the size of the alkyl group

A

Alkyl group is non polar. The polar hydrogen bonds between OH is what makes it miscible so if you increase non polar bit you decrease solubility

32
Q

Alkyl group decreases acidity in alcohols, why?

A

more Ch3 bonds push electrons to the O

33
Q

Halogens increase acidity in alcohols, why?

A

They pull electrons towards themselves making H+ even more positive

34
Q

Why is phenol more acidic than another alcohol?

A

Phenol is much more stable as the delocalized electrons can distribute the charge. Because it is stable it doesn’t mind losing the H as much. Also the H gets even more positive

35
Q

Reduction of aldehydes and ketones using sodium borohydride gives what?

A

Alcohols

36
Q

How can you get and alcohol from aldehydes and ketones?

A

Reduce them using sodium borohydride

37
Q

Reacting an alcohol with sulfuric acid gives?

A

An alkene

38
Q

Reacting an alcohol with sodium dichromate and sulfuric acid gives what?

A

Carboxylic acid

39
Q

Reaction of an alcohol with PCC gives?

A

An aldehyde

Chemical Reactivity (11 decks)

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