Intramolecular Sn2 reactions

[Andrea93]

Hi!

I can't solve this question:

 

I think it's a intramolecular Sn2 reaction

But that can occor only with "trans isomer"

 

So in the first one  what is the product?

Does  NaOH  deprotonate the  -OH group or give a Sn2 reaction on the carbon bonded with Cl? (Usually acid-base reactions are faster than Sn2 ones)

 

I have the same doubt for the last one.

 

 

Some help?

Thanks!!

[hypervalent_iodine]

For the last one, why are you ignoring the actual substrate in the reaction? 

[Andrea93]

15 hours ago, hypervalent_iodine said:

For the last one, why are you ignoring the actual substrate in the reaction? 

Yes...but I don't know what happens

 

The NaOH,so the OH- only deprotonates the alcoholic OH- of the substrate or gives a Sn2 reaction with the carbon bonded witch Br??

 

I have tue same doubt for the first one...I don't now if it is the correct product..same thing: the nucleophile OH- attacck the carbon bonded with Cl or it gives an acid-base reaction with the alcoholic group ?Or both?

 

Thanks

[chemgreger]

Quote

I'm new here and I know I'm a bit late, but I'm having trouble seeing why any of those reactions would be a ring closing. I know it could theoretically happen because NaOH is a strong base, but still isn't strong enough for deprotonation of those particular alcohols. I would imagine for the first you would get the trans diol. And for the second a mixture of cis diol product and the epoxide. All that assuming SN1 isn't even being considered. If anyone could help me here, I saw this and I too am a bit confused.