Identifying an extra NMR peak in silyl protection reaction

I protected a phenol with the TIPSCl/triethylamine procedure. The product was isolated by column (hexanes/EtOAc) and shows an extra singlet at 1.05 ppm in $$\ce{CDCl3}$$, integrating to ~10 H. Whatever this is I cannot find in under UV or various TLC stains ($$\ce{KMnO4}$$, vanilin, PMA). The integration of the peak goes smaller after one more column. Any suggestions? Thanks!

• Is there a corresponding bonus peak in the 13C? – orthocresol May 30 at 20:36
• Found two extra peaks in the aliphatic region, 18.1, 17.8, 14.6, 14.2,12.4. I know two of these are the isopropyl and a CH3 from an ethyl, did not assign them though. – Wah May 30 at 20:41

I believe some of your triisopropylsilyl chloride may be hydrolyzed triisopropylsilylol, $$\ce{((CH3)2CH)3SiOH}$$. That may gives you $$\delta$$ 1.04 and 12.4 (for $$\ce{C}$$ attached to $$\ce{Si}$$) in $$\mathrm{^1H}$$- and $$\mathrm{^{13}C}$$-NMR spectra, respectively. Compare the spectral values in Ref.1 and 2 (see below; corresponding $$\ce{^{13}C}$$ values are in red):