When was Pascal Olivier Count de Negroni born?

There is no historical record of a Pascal Olivier Count de Negroni. It's possible you are thinking of the Negroni cocktail, which was invented in Florence, Italy, but there is no documented connection to a person named Pascal Olivier Count de Negroni.

The cocktail's origin story is often attributed to Count Camillo Negroni, an Italian nobleman, who asked a bartender to strengthen his Americano cocktail by substituting gin for soda water. This story is often disputed, but it remains the most popular origin story.