Cassella
Historic German chemical and pharmaceutical company best known for synthetic dyes, pharmaceuticals and cosmetics.
Last updated August 25, 2026
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Overview
Cassella was a German chemical and pharmaceutical company whose history began in 1798 with a spice and luxury-goods business in Frankfurt am Main. Founded by Leopold Cassella and his brother-in-law Isaac Elias Reiss, the original enterprise traded imported goods from India, China and South America. It later expanded into sugar refining and, increasingly, the wholesale and manufacture of dyes. The business became Leopold Cassella & Co. after Ludwig Aaron Gans joined as a partner in 1828. The Gans family subsequently became central to Cassella's ownership, management and industrial development. Cassella's decisive transformation took place in the second half of the nineteenth century. In 1870, Friedrich and Leo Gans, Bernhard Weinberg and chemist August Leonhardt established a dye factory at Mainkur in Frankfurt's Fechenheim district. The factory was combined with Leopold Cassella & Co.'s dye-wholesale operations in 1894. By the early twentieth century, the Mainkur works had become one of the world's most important synthetic-dye operations and Fechenheim's largest employer. It employed approximately 3,000 people by 1914 and was described as the world's largest producer of synthetic dyes around the turn of the century. The company also developed a pharmaceutical research capability. Arthur Weinberg established a pharmaceutical division in 1900 and worked closely with Paul Ehrlich, an important pioneer of chemotherapy. In 1925, Cassella was absorbed into IG Farben, the large German chemical trust. Cassella-related shareholders and industrialists, including Leo Gans and Arthur von Weinberg, held positions on IG Farben's supervisory board. After the Second World War, the business was re-established as Cassella Farbwerke Mainkur AG. Under the leadership of Richard von Szilvinyi and Werner Zerweck, it rebuilt production and research rapidly. Pharmaceutical research was restored in 1949, and the company increasingly shifted its strategic emphasis away from traditional dyes toward pharmaceuticals and cosmetics. It had already exceeded its prewar production level by 1951 and employed about 2,000 people in the early 1950s. The company became highly regarded by investors during that decade. Ownership changed during the postwar consolidation of the German chemical industry. BASF, Bayer and Hoechst each acquired a 25.1 percent controlling stake in the mid-1950s. Hoechst later acquired the BASF and Bayer holdings in 1970, and the company adopted the name Cassella AG in 1978. Cassella continued operating as a separate company until 1995, when it was integrated into Hoechst and the remaining minority shareholders were bought out. Its cosmetics activities were discontinued, while the Jade cosmetics subsidiary in Fechenheim was sold to L'Oréal. Cassella subsequently became part of the corporate lineage leading from Hoechst to Aventis and then Sanofi. Hoechst merged with Rhône-Poulenc in 1999 to create Aventis, and Aventis merged with Sanofi-Synthélabo in 2004; the combined company was renamed Sanofi in 2011. Although the Cassella operating company disappeared, the name retained local industrial significance in Frankfurt. In 2012, AllessaChemie obtained rights to the Cassella trademark and restored the historic logo as a rooftop neon sign at the former Cassella site. Allessa became part of the WeylChem group in 2013, while the Cassella name continued primarily as a historical and site-related identity rather than as the original independent chemical company.
History
Cassella originated in 1798 as Cassel & Reiss, a Frankfurt business established by Leopold Cassella and Isaac Elias Reiss in the city's Jewish Alley. The enterprise initially imported luxury products from overseas markets and later participated in sugar refining. Its industrial direction changed after Ludwig Aaron Gans joined as a partner in 1828, producing the name Leopold Cassella & Co. and beginning the long association between the company and the Gans family. During the nineteenth century, the business developed a strong position in dye trading. In 1870, Friedrich and Leo Gans joined Bernhard Weinberg and chemist August Leonhardt in establishing a dye factory at Mainkur in Fechenheim. The factory was merged with Cassella's dye-wholesale operation in 1894. This combination created a major German synthetic-dye producer. The Mainkur works became Fechenheim's largest employer and employed roughly 3,000 people by 1914. Around the turn of the century, Cassella was regarded as the world's largest synthetic-dye producer. Cassella broadened into pharmaceuticals in 1900, when Arthur Weinberg created a pharmaceutical division. The division's work was associated with Paul Ehrlich, whose research helped establish modern chemotherapy. In 1925, Cassella was incorporated into IG Farben. The Gans and Weinberg industrial families remained represented in the wider group's governance, although Cassella no longer operated as an independent enterprise in its earlier form. Following the Second World War, the company was reconstructed as Cassella Farbwerke Mainkur AG. Richard von Szilvinyi and Werner Zerweck led the rebuilding effort, and production recovered quickly. Pharmaceutical research resumed in 1949, supported by a new laboratory. From this period onward, Cassella's strategic profile shifted toward pharmaceuticals and cosmetics, while dyes became less central than they had been before the war. The company surpassed prewar production by 1951 and became a prominent postwar German industrial stock. In the mid-1950s, BASF, Bayer and Hoechst each acquired a 25.1 percent controlling interest. Hoechst took over the BASF and Bayer stakes in 1970, consolidating control. The legal name became Cassella AG in 1978. Cassella remained separately identifiable within the Hoechst sphere until 1995, when it was integrated into Hoechst and the remaining minority interests were acquired. The cosmetics department was closed, and the Jade subsidiary in Fechenheim was sold to L'Oréal. The corporate lineage continued through Hoechst's 1999 merger with Rhône-Poulenc to form Aventis, followed by Aventis's 2004 combination with Sanofi-Synthélabo and the adoption of the Sanofi name in 2011. Cassella therefore became one of the historical predecessor identities within the modern Sanofi corporate lineage. The Cassella name was revived as a trademark and local industrial symbol in 2012, when AllessaChemie secured trademark rights and reinstated the historic logo at the Frankfurt site. Allessa later joined WeylChem in 2013. The original Cassella company is defunct as an independent operating entity, although its name remains connected with the historic chemical works and the Frankfurt industrial district.
- 2013
Allessa joins WeylChem
[1]Allessa becomes part of the WeylChem group of companies.
- 2012
Cassella trademark and logo are revived
[1]AllessaChemie secures trademark rights and displays the historic Cassella logo at the Frankfurt-Fechenheim site.
- 2011
The combined group adopts the Sanofi name
[1]Sanofi-Aventis is renamed Sanofi.
- 2004
Aventis merges with Sanofi-Synthélabo
[1]The transaction creates the wider corporate lineage that later becomes Sanofi.
- 1999
Hoechst enters the Aventis corporate lineage
[1]Hoechst merges with Rhône-Poulenc to form Aventis.
- 1995
Cassella is integrated into Hoechst
[1]Cassella ceases operating as a separate company, and its remaining minority shareholders are bought out.
- 1978
Company name changes to Cassella AG
[1]The postwar company adopts the shorter Cassella AG name.
- 1970
Hoechst consolidates control
[1]Hoechst acquires the Cassella shares previously held by BASF and Bayer.
- 1951
Production exceeds the prewar level
[1]The rebuilt company surpasses its prewar production volume.
- 1949
Pharmaceutical research is restored
[1]Postwar pharmaceutical research resumes and the company's emphasis begins moving from dyes toward pharmaceuticals and cosmetics.
Products and positioning
Historically positioned as a major German industrial chemical enterprise, initially led by synthetic dyes and later increasingly focused on pharmaceuticals and cosmetics.
Specialty chemicals
Synthetic dyes
Synthetic dyes were Cassella's defining industrial product for much of the nineteenth and early twentieth centuries. The Mainkur works in Frankfurt-Fechenheim grew into a major international dye operation after its establishment in 1870 and its combination with the company's dye-trading business in 1894. Dye manufacturing remained the company's historic foundation even as later management shifted resources toward pharmaceuticals and cosmetics.
Pharmaceuticals · 1900
Pharmaceuticals
Cassella established a pharmaceutical division in 1900 under Arthur Weinberg and maintained an association with the research of Paul Ehrlich. Pharmaceutical research was re-established after the Second World War in 1949, supported by a new laboratory. From that point, pharmaceuticals became an increasingly important part of Cassella's business profile and helped replace dyes as the company's principal strategic focus.
Cosmetics and personal care
Cosmetics
Cosmetics formed part of Cassella's postwar diversification as the company moved beyond its traditional dye business. The cosmetics department was later discontinued when Cassella was integrated into Hoechst in 1995. Its Jade cosmetics subsidiary in Fechenheim was sold to L'Oréal, ending the activity as a Cassella-controlled business.
Cosmetics
Jade
Jade was Cassella's cosmetics subsidiary based in Frankfurt-Fechenheim. It was divested to L'Oréal after Cassella's integration into Hoechst in 1995. The sale marked the separation of one of Cassella's consumer-facing businesses from the historic chemical company.
Brand decisions
2012
Revival of the Cassella trademarkOtherBackground
Although the original company had been integrated into Hoechst, the Cassella name retained historical significance at the Frankfurt-Fechenheim chemical site.
Action taken
AllessaChemie secured trademark rights and restored the traditional Cassella logo as a rooftop neon sign.
Aftermath
The action re-established Cassella as a local historical and site-related brand rather than reviving the former independent chemical company.
1995
Integration into HoechstStrategyBackground
Cassella had operated under Hoechst control following the consolidation of ownership.
Action taken
Hoechst integrated Cassella, bought out the remaining smaller shareholders and discontinued the Cassella cosmetics department.
Aftermath
The Jade cosmetics subsidiary was sold to L'Oréal, and Cassella ceased to exist as an independent operating company.
1970
Hoechst consolidates its Cassella holdingsM&ABackground
BASF, Bayer and Hoechst had each acquired a controlling minority stake in Cassella during the mid-1950s.
Action taken
Hoechst acquired the holdings previously owned by BASF and Bayer, giving it consolidated control of Cassella.
Aftermath
Cassella remained a separately identified company for several more decades but became firmly aligned with Hoechst.
1949
Shift toward pharmaceuticals and cosmeticsStrategyBackground
After the postwar reconstruction of Cassella Farbwerke Mainkur AG, the company reassessed the balance between its traditional dye operations and newer research-led businesses.
Action taken
Cassella restored pharmaceutical research, built a new laboratory and increasingly emphasized pharmaceuticals and cosmetics rather than dyes.
Aftermath
The change shaped Cassella's postwar identity and made pharmaceuticals and cosmetics more prominent before the company was absorbed into Hoechst.
Recent events
- 2013
Allessa becomes part of the WeylChem group[1]
M&A
Allessa, the company associated with the renewed Cassella trademark presence, became part of the WeylChem group of companies.
- 2012
AllessaChemie secures Cassella trademark rights[1]
Other
AllessaChemie obtained rights to the Cassella trademark and began restoring the historic Cassella identity at the Frankfurt-Fechenheim site.
- 2012
Historic Cassella logo returns as a rooftop neon sign[1]
Other
The traditional Cassella logo was displayed again on the roof of the Cassella building in Frankfurt-Fechenheim.
Sources1 sources
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