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Biocatalytic enantiomeric resolution of L-menthol from an eight isomeric menthol mixture through transesterification
| Content Provider | Semantic Scholar |
|---|---|
| Author | Brady, Dean Reddy, Shavani Mboniswa, Butana Andrew Steenkamp, Lucia Hendrina Rousseau, Amanda L. Parkinson, Christopher J. Chaplin, J. A. Mitra, Robin Kumar Moutlana, T. Marais, Stephanus Francois Gardiner, Neil Stockenstrom |
| Copyright Year | 2012 |
| Abstract | Abstract The four diastereomers of menthol and their enantiomers, namely dl -menthol, dl -neomenthol, dl -neoisomenthol and dl -isomenthol, were synthesised by the hydrogenation of thymol to yield an eight isomer liquid menthol. A suitably selective lipase was sought to preferentially esterify l- menthol in organic solvent, hence simplifying separation from the diasteromeric mix through distillation. From an initial screen a commercial Pseudomonas fluorescens lipase (Amano AK) was selected, and vinyl acetate was chosen as a suitable irreversible acyl donor for transesterification. The reaction reagent ratios were optimised, and an enantiomeric excess (ee) of l- menthol of greater than 95% was reproducibly achievable at a conversion of 30% dl -menthol (0.68 M) at ≤50 °C. On the basis of the composition of liquid menthol the reaction had a diastereomeric excess (de) of 82%. The enzyme was recycled 150 times in 5 ml batch reactions using liquid menthol and achieving an overall yield of 184.3 g dl -menthol/g commercial enzyme preparation. The by-product acetic acid, formed by hydrolysis of menthyl acetate, was found to cause a high degree of enzyme inactivation. The resolution reaction was scaled up 400 fold to 2 L and the enzyme recycled 38 times with an average conversion of the available l- menthol of 59% and a volumetric productivity of 1.2 g/L/h. |
| Starting Page | 1 |
| Ending Page | 10 |
| Page Count | 10 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/j.molcatb.2011.10.011 |
| Alternate Webpage(s) | http://researchspace.csir.co.za/dspace/bitstream/handle/10204/5641/Brady_2012.pdf?isAllowed=y&sequence=1 |
| Alternate Webpage(s) | https://doi.org/10.1016/j.molcatb.2011.10.011 |
| Volume Number | 75 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
