Organic acid and bases

Question 1

How do you prepare carboxylic acids?

Answer 1

1. Oxidation of primary alcohol using strong oxidising agent (H2CrO4)
2. Grignard reagent addition to CO2
3. Nucleophilic substitution of primary halide with CN then addition of acid

Question 2

What is the acidity of carboxylic acids?

Answer 2

Moderately weak acids

Question 3

How does acidity of carboxylic acids compare with alcohols?

Answer 3

Carboxylic acids are more acidic as the carboxylate anion is more stable due to spread of charge across partial positive C due to C=O bond

Question 4

How does the acidity of a parent acid relate to the stability of the conjugate base?

Answer 4

More stable conjugate base = stronger acid = lower pKa

Question 5

How do electron donating substituents affect the strength of acids?

Answer 5

Electron donating groups decrease the stability of the conjugate base making the acid weaker

Question 6

How do electron withdrawing substituents affect the strength of acids?

Answer 6

Electron withdrawing substituents stabilise the conjugate base making the acid stronger

Question 7

What is resonance stabilisation?

Answer 7

stabilisation of an ion due to delocalisation e.g. phenols

Question 8

How does the acidity of phenols compare to carboxylic acids and alcohols?

Answer 8

The phenoxide ion is more stable than the alkoxide ion but less stable than the carboxylate anion therefore

Carboxylic acid > Phenol > Alcohol

Question 9

How do EWG and EDG affect acidity of phenols?

Answer 9

The more delocalised a charge is the more stable and the more stable the conjugate base the more stronger acid

Question 10

Are amines acidic or basic?

Answer 10

Amines are basic as they can use lone pair to accept protons

Question 11

Are anilines acidic or basic?

Answer 11

They are basic but much less compared to amines because their lone pair is delocalised into the ring making it less available

Question 12

Are amides acidic or basic?

Answer 12

Neutral