Source: Paula Bruice Ed. 2017 Pg.877
From this excerpt, we infer that formyl chloride is unstable. But how does that affect the reaction in any way? Is it just mentioned as a point to note or does it have an effect on the reaction. And if acetyl chloride is unstable why is acyl chloride stable?
Also note that I do realise that this is a duplicate of Stability of formyl chloride
But we’ve not used water in Gatterman Koch reaction as reasoned by @SimpliFire in the thread. So how does it remain unstable even when water is not involved.