Haarmann Reimer process

Since several decades, for the manufacturing of synthetic menthol, two industrial processes are employed the Haarmann-Reimer Process and the Takasago Process. BASF has developed a third one, which has recently gone into use. 

The starting material for the Haarmann-Reimer process is m-cresol, which is alkylated with propene. Hydrogenation then produces the racemates of menthol, neomenthol, isomenthol and neoisomenthol. Although the boiling points lie... 

Menthol is obtained industrially starting from cresol according to the Haarmann-Reimer process, which involves a classical resolution of the racemate. 

Epimerization is one central part of the Haarmann, Reimer process and proceeds via a stepwise change of either the isopropyl group or the alcohol group [isomenthol neomenthol menthol (and vice versa)]. The epimerization to menthol only is limited by thermodynamic constraints. 

Haarmann Reimer (Holzminden, Germany) in collaboration with Rolf Schmid s group at the University of Stuttgart developed a process based on the resolution of racemic menthol esters, such as acetate or benzoate esters. The team employed several lipases such as Candida cyclindracea which resulted in enantio-selectivities up to 100% e.e. (Bomscheuer, 2002). 

Once mycelia have been separated via continuous filtration from exhausted production media, citric acid may be recovered by using three different methods, such as direct crystallization upon concentration of the filtered liquor, precipitation as calcium citrate tetrahydrate, or liquid extraction. Since molasses are extremely rich in impurities, direct crystallization cannot be applied unless very refined raw materials, such as sucrose syrups or crystals, are used. The precipitation process (that is based on subsequent addition of sulfuric acid and lime to clarified fermentation broths) is used by the great majority of world citric acid manufacturers, including Archer Daniels Midland Co. (ADM) in the United States. Liquid extraction with mixtures of trilaurylamine, n-octanol, and Cio or Cn isoparaffin was used by Pfizer Inc. in Europe and Bayer Co. (formerly Haarmann Reimer Co., subsidiary of Miles) in the Dayton (OH, USA) and Eikhart (IN, USA) plants only (Moresi and Parente, 1999), even if such plants might have been shut down in 1998. 

The company of Haarmann Reimer was established in the nineteenth century by the two entrepreneurial German chemists whose names the company bears. The Reimer in question is the same man who gave his name to the Reimer-Tiemann reaction and, indeed, many of the company s original products were produced by the Reimer-Tiemann or similar reactions. The process that they use to produce L-menthol is shown in Scheme 4.21. 

Qualitative and quantitative evaluations of an odor furnish odor profiles for classification that are amenable to electronic data processing. The Haarmann Reimer odor cycle according to U. Harder provides a good foundation as does the further developed odor landscape according to J.-N. Jaubert For the odor classes, see table. 

Fiege, H., Wedemeyer, K., Bauer, K.A., Krempel, A., Molleken, R.G. Further development of a classical process for the synthesis of aromatic hydroxyaldehydes In Croteau, R., Ed. Fragrance Flavor Subst., Proc. Int. Haarmann Reimer Symp., 2nd 1979 (Pub. 1980), 63, D PS Verlag, Pattensen... 

Symrise A process for making enantiomerically pure (-) menthol from a mixture of menthol isomers. Formerly called the Haarmann and Reimer process. Developed by the German company Symrise, which acquired Haarmann and Reimer. The proprietary heterogeneous catalyst (not described) contains nickel. 

Vanillin has been known as a flavouring substance since about 1816, and by 1858 the pure chemical had been obtained from ethanolic extracts of vanilla beans. It was not until 1872 that Carles established its correct formulation and in 1874, Tiemann and Haarmann reported it as 3-methoxy-4-hydroxy-benzaldehyde (Fig. 3.60). Finally, Reimer synthesized vanillin from guaiacol and thus proved its chemical structure. For many years, the most important source of vanillin was eugenol, from which it was obtained by oxidation. Today, the major portion of commercial vanillin is obtained by processing waste sulfite liquors, the rest through fully synthetic processes starting from guaiacol [21 ]. 

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