South Africa contributes to 31% of the world fluorospar reserves, however, locally these resources have have up intil this point been largely underutilized. This underutilization prompted the establishment of the Fluorine Expansion Initiative (FEI) program aimed at the development of commercial processes making use of these resources. Our research group joined the FEI consortium in 2014 where our research focuses on the development of flow-based processes towards fluorine containing pharmaceuticals and intermediates. Chantal’s research involves the development of flow-based methods for the preparation of aryl fluorides and hydrazines and has led to the development of an economical greener continuous flow process for the preparation of the non-steroidal anti-inflammatory (NSAI) Celecoxib.
The automated flow synthesis of fluorine contai
2. Improved batch and flow syntheses of the nonsteroidal anti-inflammatory COX-2 inhibitor celecoxib
Chantal Scholtz and Darren L. Riley, Reaction Chemistry and Engineering, 2021, 6, 138-146
The comparison of an improved conventional batch mode synthesis of the nonsteroidal anti-inflammatory COX-2 inhibitor celecoxib with its flow chemistry alternative is reported. The stepwise and continuous flow synthesis of celecoxib was achieved by means of a Claisen condensation to access 4,4,4-trifluoro-1-(4-methyl-phenyl)-butane-1,3-dione followed by a cyclo-condensation reaction with 4 sulfamidophenyl-hydrazine hydrochloride to obtain the pyrazole moiety. A batch process was developed with improved work-up and purification (90% yield). This was successfully translated to flow in yields of 90–96% with greatly shortened reaction times (20 h vs. 1 h) and reduced chemical exposure.
1. A concise, rapid and high yielding flow synthesis of aryldiazonium tetrafluoroborates
Chantal Scholtz and Darren L. Riley, Arkivoc, 2020, v, 119-128
A concise, rapid and high-yielding flow synthesis of aryl diazonium tetrafluoroborate salts is reported. The flow approach has been achieved by means of a diazotization reaction to access unstable aryl diazonium chloride salts in situ, followed by reaction with sodium tetrafluoroborate, to afford the corresponding aryldiazonium tetrafluoroborates in isolated yields of 64-100%.
* Regional issue – Organic Chemistry in South Africa*
- SAAWK Conference, Pretoria, South Africa, November 2017: A continuous flow synthesis of aryl hydrazines and aryl fluorides, C. Scholtz, D.L. Riley
- South African Fluorine Symposium, Cape Town, South Africa, 2016: The Use of Flow Technology for the Manufacture of Fluorine Containing Compounds, C.Scholtz*, D.L. Riley Poster Prize
- 2016 Frank Warren Conference, Rhodes, South Africa, December 2016: A continuous flow synthesis of the anti-inflammatory COX II inhibitor Celecoxib, C. Scholtz*, D.L. Riley
- SAAWK Conference, Potchefstroom, South Africa, November 2016: ‘n Deurlopende vloeisintese van die anti-inflammatoriese COX-II stremmer Celecoxib C. Scholtz, D.L. Riley. Poster Prize
- Bi-National Organic Chemistry Conference, Stellenbosch, South Africa, December 2014: The Use of Flow Technology for the Manufacture of Active Pharmaceutical Ingredients (API’s), C. Scholtz*, D.L. Riley