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Topic: Why is this answer correct? (MS, alpha cleavage of t-butanol)  (Read 1266 times)

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Offline janos1220

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Why is this answer correct? (MS, alpha cleavage of t-butanol)
« on: February 19, 2024, 09:24:12 AM »
The exam question was: How many signals for the fragments attributed to alpha cleavage do you expect in the mass spectrum after collision-induced fragmentation of tert-butanol?

My answer would be one signal (C3H6OH+), because the other product (CH3•) is not detectable. The correct answer is 2. Am I missing something?

Offline Babcock_Hall

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Re: Why is this answer correct? (MS, alpha cleavage of t-butanol)
« Reply #1 on: February 19, 2024, 11:19:32 AM »
I agree that a methyl radical will not be observed by mass spectrometry.  However, experimentally more than one fragment is observed in the NIST mass spectrum.  Can you think of other stable cations that are possible?  I am not sure whether or not these other cleavages are what was expected in this question.
« Last Edit: February 19, 2024, 11:30:33 AM by Babcock_Hall »

Offline janos1220

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Re: Why is this answer correct? (MS, alpha cleavage of t-butanol)
« Reply #2 on: February 19, 2024, 01:03:02 PM »
I think the prof thought of the signal caused through inductive cleavage too

Offline Babcock_Hall

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Re: Why is this answer correct? (MS, alpha cleavage of t-butanol)
« Reply #3 on: February 19, 2024, 01:36:05 PM »
That terminology is not particularly familiar to me.  However, I thought about creation of a tertiary-butyl cation, which could be generated in such a process.

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