Synthesis and Characterization of TMZ Esters

Acetonitrile (HPLC grade: ≥99.9%), water (HPLC grade: ≥99.9%), acetic acid (HPLC grade: ≥99.7%), citric acid monohydrate (HPLC grade) and dimethyl sulfoxide (reagent grade) were purchased from Fisher Scientific, Horsham, UK. Sodium phosphate dibasic (HPLC grade: ≥99.0%), sodium acetate (HPLC grade: ≥99.0%), phenol (reagent grade: >99%) and p-cresol (reagent grade: >98%) were purchased from Sigma-Aldrich, Gillingham, UK. PLE was purchased from Sigma-Aldrich, St. Louis, MO USA. 4-Nitrophenol (reagent grade: >97%), 4-Chlorophenol (reagent grade: >98%), 4-Hydroxybenzonitrile (reagent grade: >97%) and 4-Methoxyphenol (reagent grade: >99%) were sourced from Alfa Aesar, Haverhill, MA, USA. All reagents sourced from external suppliers were used without further purification. The TMZ esters were synthesised, purified and characterised following standard procedures [18 (link)]. The purity of each synthesised TMZ ester was also estimated to be at least 95%, using ¹H NMR.