Product Development Story
2. MAOC, AOC Development Story
MAOC, AOC Development Story
It was known that the reaction of acrylic acid or methacrylic acid with thionyl chloride or phosphorus pentachloride yielded the corresponding acid chlorides. However, the methods require aftertreatment for SO2 and phophine-containing wastewater. In addition, there is some sulfur and phosphorus contamination of the product.
We have the technology to convert carboxylic acids to the corresponding acid chloride using benzotrichloride via a chlorine-oxygen exchange reaction. When the chlorine exchange reaction was applied to acrylic acid or methacrylic acid, many various hydrogen chloride adducts were formed.
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Synthesis from the corresponding carboxylic acid using thionyl chloride afforded a large amount of acid anhydride.
A literature search revealed a method using ortho-phthaloyl chloride (OPC) as a chlorine source. OPC is one of our main products.
When this method was applied to methacrylic acid, methacryloyl chloride (MAOC) was obtained in very good yield.
While considering how to reduce the cost of the MAOC manufacturing method, the idea of using benzoyl chloride (BOC) instead of OPC came up. BOC is also one of our major products.
In an old report (H.C.Brown, JACS 1938), a synthetic method for acid chloride with BOC as a chlorinating agent was reported, but we were unaware of any recent use. We assume that the method requires the removal of benzoic anhydride, and that acid chlorides having high boiling points are difficult to handle.
The method using BOC is convenient to adapt to the synthesis of acid chlorides that can be easily distilled off, and with MAOC, this is exactly the case. Based on this method, we have completed a so-called "reactive distillation method" in which methacrylic acid is added dropwise into heated BOC, and the resulting MAOC is immediately distilled away. This allowed for high-purity MAOC to be obtained without catalyst or contamination. A synthetic method of high-purity acryloyl chloride (AOC) from acrylic acid was also established.
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