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A-level Chemistry > Carbonyl Compounds > Flashcards

Carbonyl Compounds Flashcards

1
Q

What are carbonyl compounds?

A

Compound with a C=O bond, they can either be aldehydes or ketones

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2
Q

Are carbonyl’s soluble in water?

A

Only the smaller carbonyls because they can form hydrogen bonds with water

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3
Q

What can aldehydes be oxidised to?

A

Can be oxidised into carboxylic acids

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4
Q

What are the aldehydes oxidising reagent?

A

Acidified potassium dichromate & tollens reagent

= K2Cr2O7

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5
Q

Can ketones be oxidised?

A

No

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6
Q

How do we test for ketones and aldehydes?

A

-we can use Brady’s reagent (2,4-DNP) (it has to be warm)

  • both ketones and aldehydes give an orange ppt
  • so you have to purify the solutions by recrystallisation, then measure the melting point and compare with a publish value/ data so see if it’s a ketone or aldehyde
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7
Q

what can aldehydes and ketones be reduced to?

A

Ketones- secondary alcohol

Aldehydes- primary alcohol

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8
Q

What is the reducing agent for ketones and aldehydes?

A

NaBH4 (but in chemical reactions & mechanism represent it as H-)= hydride

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9
Q

What are the steps to a reduction mechanism of ketones and aldehydes?

A
  1. Curly arrow breaks double bond & H- attacks the carbon
  2. Then the lone pair of electrons on the oxygen molecules bond to the hydrogen on water & curly arrow breaks bond between the hydrogen and water
  3. Resulting in a formation of an alcohol (primary or secondary)
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10
Q

What reacts with carbonyl compounds to form hydroxynitriles?

A

Potassium cyanide

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11
Q

What are the steps to the mechanism where potassium cyanide reacts with a carbonyl to form a hydroxy nitrile?

A
  1. Curly arrow breaks the double bond between the carbon and oxygen & the CN- ion attacks the carbon atom
  2. Then a curly arrow goes from the oxygen lone pair to the hydrogen atom on the H2O molecule
  3. Then a hydroxynitrille is formed
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12
Q

What is potassium cyanide represented as in an equation with a ketone or aldehyde?

A

H+

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13
Q

What happens when a ketone and aldehyde react with potassium cyanide ?

A

Aldehyde - C-N bonded to carbon on the end of the chain

Ketone- C-N bonded to the carbon in the middle

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14
Q

What are the risks of using potassium cyanide?

A

-it’s an irritant and is very dangerous if inhaled

-when it reacts with moisture it can form toxic gases

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15
Q

How do we distinguish between aldehydes and ketones by using tollenes’ reagent?

A
  1. Get silver nitrate
  2. Add a few drops of NaOH which forms a pale brown ppt
  3. Add a few drops of dilute ammonia until the ppt dissolves
  4. Add aldehyde/ Ketone to rollers Reagan g in a hot water bath
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16
Q

Why isn’t a Bunsen burner used when testing for aldehydes and ketones?

A

Because aldehydes and ketones are flammable

17
Q

What are the results of aldehydes and ketones when adding tollens reagent?

A

Aldehydes= reduced to silver which coats the inside of the flask

Ketone- no silver ppt formed

18
Q

What is the functional group of an acid chloride?

A

O
||
C —Cl

19
Q

What are the positives of using acid chlorides?

A
  • very reactive on their own
20
Q

What are the negative of using acid chlorides?

A

-corrosive
- expensive
-forms harmful products

21
Q

What is the functional group of acid anhydrides?

A

O O
|| ||
C — O— C

22
Q

What are the positives of using acid anhydrides?

A

-cheaper

-less corrosive

  • safer products
23
Q

What are the negatives of using acid anhydrides?

A

-less reactive than acid chlorides

24
Q

What does an acid anhydride + water form ?

A

Forms a carboxylic acid and hydrochloric acid

25
Q

Describe the mechanism for acid chlorides plus nucleophiles?

A
  1. Curly arrow breaks double bond between oxygen and carbon on acid chloride & curly arrow from lone pair of the nucleophile to the carbon
  2. Then curly arrow from oxygen with 2 lone pairs forming a double bond & curly arrow from hydrogen to positive molecule on the nucleophile
  3. Curly arrow from bond between carbon and chloride
  4. Product is formed with HCL
26
Q

What is the product when an acid chloride reacts with alcohols?

A

An ester and HCL

27
Q

What’s the product when acid chloride reacts with ammonia?

A

Primary amide + HCl

28
Q

What’s formed when an acid chloride reacts with an amine?

A

N- substituted amide + HCL

29
Q

How do you name N substituted amides?

A

N- (group which would’ve been a hydrogen) number of carbons bonded to- amide

30
Q

How do you name amines?

A

Hydrocarbon group- an amide

31
Q

What is the mechanisms call involving carbonyls and a nucleophile?

A

Nucleophilic addition

32
Q

What happens when a carboxylic acid reacts with SOCl2?

A

Forms an acyl chloride + SO2 + HCL

A-level Chemistry (15 decks)

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