These calibration curves are the same used in our previous study. To obtain yields for mixtures of compounds 6, 7, 8, 9 and bromo-m-xylene, calibration curves were constructed for each compound by GC-FID using n-dodecane as an internal standard. Authentic samples of compounds 6, 8, 9 and bromoxylene were bought from commercial sources, while compound 7 was synthesised and calibrations corrected for homocoupled impurity 2,2',6,6'-tetramethyl-1,1'-biphenyl. To construct each calibration curve, known amounts of each compound (approximately 0.01 mmol -0.1 mmol)