The phrase "when mentioned" is correct and commonly used in written English.
It is typically used to refer to something that has been previously mentioned or will be mentioned later in the sentence or text. Example: "The new policy has been met with mixed reactions. Some employees support it, while others have expressed concerns when mentioned at the staff meeting."
"Coax", when mentioned, is a soundalike for some COKES.
When mentioned in a baseball context, the phrase "it's early" usually has a negative connotation.
The notion of a citizen's arrest is something of a joke these days -- ridiculed, when mentioned at all.
When mentioned in China, which is rarely, bad weather or Russian treachery are usually blamed for this disaster, and both are knowledgeably dismissed by Yang.
Programs that were once laughable when mentioned with Connecticut or even Rutgers — St. John's, Georgetown, Syracuse — grew in recent years into tournament-caliber teams.
Wood now has the satisfaction not only of retaining her seat on the court of the Southern District of New York but of being married to Richardson, whose name, when mentioned in the newspapers, is generally preceded by words like "investment banker," "wealthy," or "gazillionaire".
The sources of these are provided in the text when mentioned.
Aquinas, when mentioned, is treated with respect and FitzRalph follows him on a number of important points.
When mentioned, a user is notified by the Twitter API, and the mentioning tweet is displayed on the user's feed.
The NX is still an enigma wrapped in a mystery, after first being revealed as a project currently in progress at Nintendo back in March when mentioned by Nintendo CEO Satoru Iwata.
Sometimes known as an "ordinary language", sometimes as an "analytic" philosopher, Ryle even when mentioned in the same breath as Wittgenstein and his followers is considered to be on a different, somewhat idiosyncratic (and difficult to characterise), philosophical track.
