• Hydrolysis?is the breakdown of a compound using?water
• The ease of hydrolysis for different organic compounds may differ
• For example, the ease of hydrolysis, starting with the compounds most readily broken down, is: acyl chloride > alkyl chloride > aryl chloride
• This trend can be explained by looking at the?strength?of the C-Cl

Strength of C-Cl bond in acyl chlorides

• Acyl chlorides are hydrolysed most readily at?room temperature
• This is because the carbon bonded to the chlorine atom is also attached to an oxygen atom
• There are two?strong electronegative?atoms pulling electrons away from the carbonyl carbon, leaving it very?δ⁺
• The C-Cl bond is therefore?weakened?and?nucleophilic attack?of the carbonyl carbon is much more?rapid

The hydrolysis of acyl chlorides occurs most readily

Strength of C-Cl bond in alkyl chlorides

• The carbonyl carbon in alkyl chlorides is only attached to?one electronegative?atom which pulls electrons away from it
• This carbon atom is therefore not very?δ⁺?and the C-Cl bond is stronger than the C-Cl bond in acyl chlorides
• The hydrolysis of alkyl chlorides, therefore, requires a?strong alkali?(such as OH^-) to be?refluxed?with it
• An OH^-?ion will hydrolyse the alkyl chloride as it a?stronger nucleophile?than H₂O

The hydrolysis of alkyl chlorides requires a strong nucleophile

Strength of C-Cl bond in aryl chlorides

• In aryl chlorides, the carbon atom bonded to the chlorine atom is part of the?delocalised π bonding system?of the benzene ring
• One of the lone pairs of electrons of the Cl atom?overlaps?with this?delocalised?system
• The C-Cl bond, therefore, has some?double-bond character?causing it to become?stronger
• As a result, the C-Cl bond is difficult to break and?hydrolysis?will?not occur

Due to the strong C-Cl bond in aryl chlorides, these compounds will not undergo hydrolysis