Isophthaloyl chloride turns red in color
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I’m reaching out to those who are involved in the production of phthaloyl chloride to ask if anyone has encountered the problem of the product turning red – or experienced any serious consequences as a result. I haven’t found any relevant literature on this topic. Do any of you have any good suggestions?
Have iron ions entered? We don’t produce it, but we have used acyl chlorides; once, when it was drawn up and added drop by drop, a slight red color was observed at first. .
There is suspicion that iron ions are the cause, but the mechanism is unknown – why does it turn red? I want to look up some information, but I can’t find it.
Acyl chlorides generally contain hydrogen chloride, and hydrogen chloride reacts with iron. Did you use iron pipes or containers at some step?
Yes, the container is made of glass-lined material. Since the container’s coating cracked, it is suspected that iron ions were to blame. Do you know how iron ions cause the solution to turn red? Or are there any other reasons?
When visiting other manufacturers, they use carbon steel equipment for producing phthaloyl chloride – including distillation kettles, distillation towers, and pipelines, all of which are made of carbon steel. However, strict sealing requirements apply; no air is allowed to enter at all. :)