Cassella AG, formerly Leopold Cassella & Co. and Cassella Farbwerke Mainkur AG, commonly known as Cassella, was a German chemical and pharmaceutical company with headquarters in Frankfurt am Main. Founded in 1798, in the Frankfurt Jewish Alley by Leopold Cassella, Cassella operated as an independent company until 1995, and was one of many predecessor companies of today's Sanofi. Its main products were dyes, drugs, cosmetics and various other chemical products. From 1949, Cassella focused increasingly on pharmaceuticals and cosmetics rather than its former primary focus, dyes. Much of its history is closely associated with the Gans family, a prominent family of industrialists and philanthropists and former owners of Cassella. History The company was founded as a spice store inside the Frankfurt Jewish Alley in 1798 by the Jewish businessman Leopold Cassella and his brother-in-law Isaac Elias Reiss, and was originally named Cassel & Reiss. In its early years, the company focused on importing luxury goods from India, China and South America, and Cassel and Reiss also founded a sugar refinery in 1812. Himself childless, Cassella accepted Ludwig Aaron Gans as a partner in 1828, and the company became known as Leopold Cassella & Co. Gans was married to Cassella's niece, and the Gans family rose to great prominence as industrialists and philanthropists in Frankfurt in the following century. The family converted from Judaism to Protestantism in the late 19th century, and several family members were ennobled. In the 19th century, Cassella primarily traded with dye. In 1870, Friedrich and Leo Gans founded a dye factory at Mainkur in Fechenheim with their brother-in-law Bernhard Weinberg and the chemist August Leonhardt, called Frankfurter Anilinfarbenfabrik von Gans und Leonhardt. In 1894, the dye factory was merged with the Leopold Cassella & Co. dye wholesale company. The Cassella dye factory was the largest employer of Fechenheim, employing around 3,000 people by 1914, and was the world's largest producer of synthetic dyes by the turn of the century. In 1900, Arthur Weinberg established a pharmaceutical division of the company, and collaborated closely with his friend Paul Ehrlich, the founder of chemotherapy. In 1925, Cassella merged into the new IG Farben trust, with Cassella co-owners Leo Gans and Arthur von Weinberg joining its supervisory board. After World War II the company was reestablished as Cassella Farbwerke Mainkur AG and the rebuilding under Richard von Szilvinyi and Werner Zerweck's leadership proved very successful, making the company the