[1] De Mun was born in Port-au-Prince, Saint-Domingue to an aristocratic family originating from the Southwest of France.
[4] While trading in Mexico, de Mun was imprisoned alongside A. P. Chouteau for 48 days in Santa Fe, leading the group to file a claim against the Mexican government for confiscated goods worth $30,000.
[9] In 1820, de Mun moved with his family to Cuba, where he had purchased a large coffee plantation.
They returned to St. Louis in 1831 and De Mun was made recorder of deeds for the county.
[10] In 1812, de Mun married Isabella Gratiot, the daughter of Charles Gratiot Sr. and Victoire Chouteau and the granddaughter of Pierre Laclède, the founder of Saint Louis (Missouri); they had three daughters.