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Alicia's Masters Thesis
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Ugi NMR Analysis
To prove that Boc-Glycine reacts with TFA to produce tert-butyl trifluoroacetate.
Weighed 175mg (1mmol) Boc-Gly-OH and dissolved it in 900uL of CDCl3. A HNMR of the aminoacid was obtained. To it 100uL of Trifluoroacetic acid was added. The reaction was monitored for about the first 20mins by NMR spectroscopy.
Boc-Gly (175mg/ 900uL CDCl3)
(100uL / 900uL CDCl3)
Boc-Gly / TFA 03min
(175mg / 100uL in 900uL CDCl3)
Boc-Gly / TFA 09min
Boc-Gly / TFA 16min
Boc-Gly / TFA 20min
Over a period of time it is clear that the t-buyl group of the aminoacid is lost and another peak at 1.56ppm starts emerging. This is similar to what has been observed in
. However, because there is 10 fold more boc compound for the same amount of TFA, the reaction is much slower.
Boiling point of tert-butyl trifluoroacetate in the literature has been found to be 83C.
t-butyl trifluoroacetate is formed by the addition of TFA to Boc-Glycine
19:15 : Made up a solution of Boc-Glycine in CDCl3 and obtained a HNMR
20:00 : Added 100uL TFA to the solution
20:03: Obtained HNMR
20:09 : Otained HNMR
20:16 : Obtained HNMR
20:20 : Obtained HNMR
1.Removal of t-butoxycarbonyl protecting groups with trifluoroacetic acid. (Lundt, Johansen, Volund, Markussen)
Int J Pept Protein Res. 1978 Nov;12(5):258-68
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