Investigation revealed that residual formaldehyde could be present in the coupling partner, prolinol (MR84908). Setting tight control on formaldehyde greatly improved the catalyst activity. When present at 1.5% by weight, the reaction required 88 hr to reach completion. Moreover, the in process HPLC analysis showed low purity of the intermediate and substantial generation of an impurity resulting from hydrolysis of the aryl chloride (~10% a/a). At 0.2% formaldehyde however, MR84907 reacted fully within 15 hr (0.6% residual MR84907).