Figure 5: Evolution of Billups–Birch reductive addition.
From: Confined propagation of covalent chemical reactions on single-walled carbon nanotubes
Correlated (a) Raman spectra, (b) degree of functionalization as determined from weight loss in thermogravimetric analysis and water solubility (b, inset) as functions of reaction cycles for a HiPco-SWNT sample after 0–20 cycles of functionalization with Br(CH2)5COOH. The excitation line was 632.8 nm. The degree of functionalization increased as a linear function of reaction cycles. The functionalized nanotubes became water soluble at a threshold functional density of ~3.5% and thereafter increased linearly as a function of reaction cycle. (c) Effect of terminating groups on the reaction propagation probed with Raman spectroscopy. (6,5)-Enriched CoMoCat SWNTs were used for this study. The data were fitted by a rational function in the form 
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