Suitable reaction conditions were initially optimised using ATR-IR (Supporting Information), as a rapid method for visual assessment of reaction efficiency. The bulk DS and regioselectivity of reaction was followed using a novel solution-state NMR protocol . This is clearly illustrated by comparing the acetate regions (~2 ppm) in the diffusion-edited 1 H spectra for the representative samples, with varying reaction conditions (Figure ) -by peak fitting the 6-OAc (mono and diacetate) vs the 6-OAc (CTA), a value for % selectivity for CTA (%CTA) can be calculated (Supporting Information). Mild reaction conditions (100 vol% Ac2O -1 day) showed formation of 6-acetate under non-catalytic conditions (no pyridine), consistent with fibril surface only reactivity, as has been demonstrated previously . The pyridine-containing mixtures (62.5 vol% -1 day & 25 vol% -5 days) show the formation of CTA, consistent with the topochemical transformations involved in commercial bulk catalytic heterogeneous acetylations . Multiplicity-edited heteronuclear single-quantum correlation (HSQC) nuclear magnetic resonance (NMR) spectroscopy for the intermediate conditions, using 62.5 vol% Ac2O (Figure ), clearly showed the presence of 2 & 3-acetylation, consistent with previous literature assignments and supporting the apparent diffusion-edited 1 H NMR selectivity's shown.