HCl replacing OH ?

[510586]

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Can someone explain when HCl replaces an OH with a Cl on alcohols? Is it only for secondary and tertiary alcohols? I know it can do secondary but not sure about primary, as we usually use SOCl2 and PCl3 for those

 

[virtualmaster999]

I believe this is how it works:

HCl/HBr: works on all types of alcohols, and can cause rearrangements
SOCl2: primary/secondary
PCl3: methyl, primary, secondary, with inversion of configuration.

I believe that's how it is...someone correct me if Im wrong.

 

[510586]

I believe the bottom 2 are sp2 but I am not sure.

 

[DAT Destroyer]

Can someone explain when HCl replaces an OH with a Cl on alcohols? Is it only for secondary and tertiary alcohols? I know it can do secondary but not sure about primary, as we usually use SOCl2 and PCl3 for those

The reaction is the basis for the Lucas test. Cl is not so great as a nucleophile, hence we use the Lewis acid ZnCl2 to accelerate it. We use it for secondary and tertiary alcohols. Primary alcohols do NOT react since this reaction involves carbocation formation.

Hope this helps.

Dr. Romano

 

[510586]

The reaction is the basis for the Lucas test. Cl is not so great as a nucleophile, hence we use the Lewis acid ZnCl2 to accelerate it. We use it for secondary and tertiary alcohols. Primary alcohols do NOT react since this reaction involves carbocation formation.

Hope this helps.

Dr. Romano

Thanks!

 

[510586]

The reaction is the basis for the Lucas test. Cl is not so great as a nucleophile, hence we use the Lewis acid ZnCl2 to accelerate it. We use it for secondary and tertiary alcohols. Primary alcohols do NOT react since this reaction involves carbocation formation.

Hope this helps.

Dr. Romano

But it works for Br because it is a larger so better nucleophile in protic solvents? This page said it works for Br as an SN2. http://pnorris.people.ysu.edu/Mechanisms/nucsub.html