Development of an optimized process for commercial production of (-) ambrafuran

Abstract

Ambergris is a large lump excreted by whales, when exposed to sunlight, air and sea water, it oxidatively decomposed through inorganic reactions to form different compounds including (-) ambrafuran. (-) Ambrafuran is a highly fragrant compound and it is considered to be a stronger perfume ingredient than other constituents in ambergris. It is used as a fixative agent to stabilize perfumes by reducing the rate of evaporation of volatile substances. A two-step process for production of (-) ambrafuran starting from sclareol was developed at CSIR for an industrial partner, Teubes cc. The current commercial production of (-) ambrafuran entails a chemical process consisting of at least 8 steps and require very harsh chemicals and elevated temperatures. In the current study, relevant technologies for the optimization of a process for commercial production of (-) ambrafuran were investigated. The project objective has been to optimize fermentation conditions on laboratory scale for the conversion of sclareol to an intermediate diol using the microorganism Hyphozyma roseoniger and to subsequently test different zeolites for conversion of diol to (-) ambrafuran. Production of ambradiol was achieved in potato dextrose broth media in 13 days compared to a patented method which took 16 days. The method was also scaled-up in a 2 L fermentation bioreactor and the yield of 93% was achieved after 24 hours of reaction. Following the initial use of the zeolite CBV320, two new zeolites (CFG-1 and ZD0614) were identified which have the potential to convert ambradiol to (-) ambrafuran without undergoing an activation process. Zeolite CFG-1 have been recognized to be highly effective for converting the intermediate ambradiol to the resulting (-) ambrafuran. One of the greatest outcomes of this research project is that the amount of zeolite required per substrate has been reduced from between 1:6 and 1:9 to 1:2. The substrate concentration has been increased from 5 mg/mL to 100 mg/mL which also resulted in the reduction of the volume of solvent required for the cyclodehydration step. The study allowed for scale-up and following further optimisation on larger scale should result in a process on commercial scale.