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prakhar_galaxy

Sir plz explain the product of this rxn with complete mechanism

Rxn is:

PROPANE-1,3-DIOL reacts with SOCL₂,HEAT

hope u r getting my ques

Thanx in advance

madhusudan.chavan

33490

Propane-1,3-diol on reaction with SOCl₂ should form 1,3-dichloropropane; a reaction similar to monohydric alcohol where OH is replaced by Cl.

The mechanism is as follows

..

R¾O¾H + O=S(¾Cl)¾Cl ® R¾O⁺¾H

½

O^-¾S¾Cl ® R¾O¾S(¾Cl)=O + HCl

½

Cl

S_N²

H⁺Cl^- + R¾O¾S(¾Cl)=O ® Cl^d-?.R?.O^d-¾S(¾Cl)=O

®RCl + O^-¾S(¾Cl)=O ® SO₂+ Cl^-

prakhar_galaxy

It is also the ques of test

I hav also thought the smae answer sir but it was not dat

So i am again posting the ques along with answer ,plzz explain it with the mechanism

Thanx

madhusudan.chavan

HO¾CH₂¾CH₂¾CH₂¾OH + O=S(¾Cl)¾Cl ®

H¾O⁺¾CH₂¾CH₂¾CH₂¾OH

ï - HCl

O^-¾S(¾Cl)¾Cl ®

CH₂¾CH₂¾CH₂

ï ï

O¾S(=O) OH

ï

Cl ®

CH₂¾CH₂¾CH₂

ï ï

O¾S(=O)¾O⁺¾H

ï -HCl

Cl ®

CH₂¾CH₂¾CH₂

ï ï

O¾S(=O)¾O

As explained in the earlier mechanism for formation of corresponding chloride the intermediate is formed by the reaction of thionyl chloride instead of being attacked by Cl^- by S_N², the lone pair of electron on second OH attacks the sulphur atom to form the intermediate as shown above which loses the HCl to give six membered ring.This is the possible mechanism for the formation of the product shown by you.

Thank you for correcting me. Initially it appears to be a simple reaction of thionyl chloride and alcoholic OH. If the reaction is with only one mole of thionyl chloride there 3-chloro ?1-propanol should be formed along with the above mentioned product. The % of each product will depend on the reaction condition. I have my own doubt about the stability of the cyclic product as sulphur is attached to three more electronegative atoms.

The problems posted by you are really challenging , keep it up; do share such problems with me.

prakhar_galaxy

thanx sir
i will keep discussingmy ques with u

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