organic chemistry - Relative rate of hydrolysis of the carbon chlorine bond in thioethers and ethers

I am solving problems based on rates of hydrolysis of compounds but I don't have a general approach to such questions.

Which of the following compounds undergoes hydrolysis faster than the second under comparable conditions? It may be acid catalysed or base catalysed hydrolysis but the conditions must remain the same for each pair.

In my view since oxygen is more electronegative than sulfur, hence hydrolysis should be easier for second. But I am not sure about it.

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see part 3 here

Answer

This is a classic case of neighboring group participation. The hydrolysis of the thioether is significantly faster because the sulfur can displace the chlorine to give a three member ring with a sulfur in it. The ring is quite reactive and will easily be opened by water.

For reference, you can also look at a compound like mustard gas. It has the same functional groups and is so reactive that is a war gas.