Discussion on the reaction mechanism for the preparation of acyl chlorides from phosphorus trichloride
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Recently, while researching different products, I came across one that uses phosphorus trichloride to produce sulfonyl chlorides; it’s a bit hard to understand. Could everyone help me analyze it? Sulfonation of the benzene ring is carried out using an excess of chlorosulfonic acid, after which phosphorus trichloride is added to produce the sulfonyl chloride. Once the reaction is complete, it is slowly poured into ice water, resulting in the precipitation of benzenesulfonyl chloride (with the substituent). This acyl chloride is relatively stable and does not decompose in water. 1. May I ask what reactions occur here? Could you please write down the reaction equations? 2. What phosphorus compound is formed when phosphorus trichloride reacts with benzenesulfonic acid? 3. May I use phosphorus trichloride oxide instead of phosphorus trichloride? Costs are not considered here; only the reaction itself is analyzed. If possible, what would the reaction equation be? 4. May I ask, how many chlorines are typically involved in the reaction for phosphorus trichloride and phosphorus oxytrichloride? It’s really troublesome when calculating molar amounts. . . Thank you all:handshake
Phosphorus trichloride cannot be replaced by phosphorus oxychloride when forming acyl chlorides. Theoretically, the molar ratio of phosphorus trichloride to acid should be 1:3, but in practice this ratio is not achieved; it is usually around 1:2.5.
Thank you! In other words, after thorough reaction of phosphorus trichloride with acid, 3 moles of acyl chloride and 1 mole of phosphorous acid are produced, right?
Theoretically, yes. . . . . . . . . . .
Using thionyl chloride might be better