December 07, 2022, 02:12:11 AM
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Topic: Alcohols in H-1 NMR  (Read 186 times)

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Offline Babcock_Hall

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Alcohols in H-1 NMR
« on: October 31, 2022, 11:36:35 AM »
We recently resynthesizes a primary alcohol, which I discussed in a different thread.  The two spectra were very similar, except for the following.  The -CH2-OH group near 3.80 ppm was a triplet in the first synthesis but a slightly broadened quartet in the second synthesis.  In the first synthesis a very broad signal appeared at 1.6 ppm.  In the second synthesis we observed two very broad, non-Lorentzian signals, one at 2.5 and the other at 1.8 ppm.  Our interest is in being certain that the two syntheses produced identical compounds.

In the past I have occasionally seen three-bond coupling between the HOR hydrogen and the hydrogens on the adjacent carbon, but not always.  It is my understanding that the rate of exchange of HOR hydrogens is a function of any catalyst that might be present.  We gave away the first batch to another laboratory; otherwise, we would perform an internal standard experiment.

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