Background
Bethmann was the oldest son of the Nassovian administrator Simon Moritz Bethmann (1687–1725).
Bethmann was the oldest son of the Nassovian administrator Simon Moritz Bethmann (1687–1725).
Johann Philipp apprenticed in a trading enterprise in Leipzig from 1730 to 1735, then worked in Nantes and later for his uncle Jakob Adami.
Their brother Johann Jakob carried on the family name in Bordeaux, where he became a merchant and shipowner. In 1746 they assumed control of the trading enterprise Jacob Adami, which became the Gebrüder Bethmann bank in 1748. In 1762 they purchased the Basler Hof mansion and premises from the Patrizier Johann Friedrich Maximilian von Stalburg, which Johann Philipp expanded with further acquisitions in 1787/88.
In 1762 Johann Philipp married Katharina Margarethe Schaaf (1741–1822).
He was elected a member and in 1785 director of the "College of the 51", id est (that is), the body of delegates to the Frankfurt city council. In 1786 he was appointed by Joseph II, who had the House of Bethmann underwrite most of his bond issues, to the office of "imperial counselor" (Wirklicher Kaiserlicher Rat).