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Topic: Halogenation of a carboxylic acid using SO2Cl2  (Read 2859 times)

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Offline AWK

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Re: Halogenation of a carboxylic acid using SO2Cl2
« Reply #15 on: January 23, 2021, 01:28:17 PM »
There is no mention of DMF, but the reaction concerns the preparation of acid chlorides and anhydrides by the action of SO2 + Cl2 on carboxylic acid salts, and the products may be acid chlorides or anhydrides depending on the proportion of reactants. The salts are wetted with ethyl acetate before reaction.
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Offline rolnor

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Re: Halogenation of a carboxylic acid using SO2Cl2
« Reply #16 on: January 24, 2021, 03:51:51 AM »
I dont understand how this is relevant for the question from Meter?

Offline AWK

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Re: Halogenation of a carboxylic acid using SO2Cl2
« Reply #17 on: January 24, 2021, 04:31:45 AM »
It all started with the question (which is in the title of the thread) whether SO2Cl2 can be used to synthesize acid chlorides. Meter showed a reaction that also includes DMF (he claims the reaction is from Wikipedia).
You started a discussion about the advisability of using DMF, and then the discussion went sidetrack.
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Offline rolnor

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Re: Halogenation of a carboxylic acid using SO2Cl2
« Reply #18 on: January 24, 2021, 08:11:38 AM »
Thats true. I think many reagents can be used to make acyl halides, including SO2Cl2. It looked as if they used DMF as solvent and that seems strange to me.

Offline wildfyr

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Re: Halogenation of a carboxylic acid using SO2Cl2
« Reply #19 on: January 24, 2021, 07:02:57 PM »
I've personally always used thionyl chloride, and its pretty much failsafe. Its more of a hassle to handle and get rid of than oxalyl chloride, but its also probably a more powerful chlorinating reagent. A "drop" of DMF was always suggested to me for making acyl chlorides or sulfonyl chlorides, but I never really compared with/without the DMF.

I've usually chlorinated in neat thionyl chloride, but sometimes done 1 eq in a solvent like DCM. When doing that I actually probably leave out the DMF. No accounting for my decision :P

Offline rolnor

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Re: Halogenation of a carboxylic acid using SO2Cl2
« Reply #20 on: January 24, 2021, 07:52:05 PM »
Yes thionyl chloride is good, for benzoic type acids reflux can be used, not nessecary with aliphatic acids I think.

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