[RaInBowDaSh1488]

I've been having some trouble synthesizing an alkyl halide from a carboxylic acid. At first, I thought I was generating some impurities while reducing the acid, but this doesn't seem to be the case. The alcohol seems to be very pure.

I am using thionyl chloride to chlorinate the said alcohol, but TLC shows some side reactions taking place. Strangely, some of these seem to disappear with time. I am able to recover some of the desired product, but I am losing quite a bit to side reactions.

My first question is whether or not the chlorosulfite intermediate is practically stable enough to be seen on TLC.

Also, is it possible that moisture could contribute to side reactions in chlorination with socl2? I refluxed with the top of my condenser open. I've read a good amount of literature and it seems like many chlorinations with socl2 don't mention any thing to keep out atmospheric moisture. I'm not sure if I should focus more on eliminating exposure to air by running the reaction under nitrogen or maybe looking into my solvent which maybe a bit wet.

I've also been running this reaction without any base present. Should a base like pyridine be included in general when using thionyl chloride or is it only need in certain situations?

All and all, I am just not sure how much I should change when I attempt this reaction again. I'd like to minimize side reactions. I know I am going to try and assure my solvent is completely dry, but I am not sure if I should consider adding some pyridine or running the reaction under nitrogen. Any advice would be much appreciated!

[Dan]

It is probably worth doing the reaction with freshly distilled SOCl₂ under an inert atmosphere to see if it helps.

Personally, I would suggest going through a mesylate, imidazolesulfonate or triflate and displacing it with tetrabutlyammonium chloride.

You will be able to monitor (and isolate if you want) the sulfonate and see how it behaves in the displacement. It adds another step, but it could be telescoped or even made into a one-pot procedure.

[opsomath]

This is probably not what you want to hear, but I have never had any trouble with this reaction. (Just to clarify, you said "alkyl hilide from a carboxylic acid". You meant "acid chloride" right?)

I always ran this reaction neat in refluxing SOCl2, no solvent, which makes it fast and clean and eliminates worries about solvent wetness. I always did it under nitrogen to keep out water which would hydrolyze the product. Then I always removed excess SOCl2 by distilling it off under atmospheric pressure (again under nitrogen) and then got the last traces of SOCl2 out with high vacuum in a LN2 trap.

[Babcock_Hall]

@OP, Is your starting material a carboxylic acid or an alcohol?  Different portions of you post suggest different things.

[RaInBowDaSh1488]

Sorry for the ambiguity. I am synthesizing a halide from a carboxylic acid, but I am reducing the acid in order to chlorinate the alcohol.

The major side reaction occurring appears to be the halide reacting with the alcohol to form an ether. Would addition of a base possibly help to discourage formation of the ether?