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Ch. 14 - Structural Identification 1: Infrared Spectroscopy and Mass Spectrometry
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Mullins 1st EditionCh. 14 - Structural Identification 1: Infrared Spectroscopy and Mass Spectrometry문제 43b
13장, 문제 43b

Identify the peaks in the mass spectrum of octan-4-one that correspond to (b) the McLafferty rearrangement.
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검증된 단계별 안내
1
Understand the McLafferty rearrangement: This is a reaction in mass spectrometry where a molecule undergoes a rearrangement involving the transfer of a hydrogen atom and the cleavage of a bond, typically resulting in a neutral molecule and a radical cation.
Identify the structure of octan-4-one: Octan-4-one is a ketone with the formula C8H16O. The carbonyl group is located at the fourth carbon in the chain.
Locate the gamma hydrogen: In the McLafferty rearrangement, a hydrogen atom three carbons away from the carbonyl group (gamma position) is involved. For octan-4-one, identify the gamma hydrogen relative to the carbonyl group.
Illustrate the rearrangement: Draw the mechanism showing the transfer of the gamma hydrogen to the carbonyl oxygen, resulting in the cleavage of the bond between the alpha and beta carbons, forming a double bond and a neutral alkene molecule.
Determine the mass of the resulting fragments: Calculate the mass of the radical cation and the neutral alkene formed from the McLafferty rearrangement. These masses correspond to the peaks you would observe in the mass spectrum.

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주요 개념

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Mass Spectrometry

Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio of ions. It helps identify the composition of a sample by generating a mass spectrum, which displays the masses of fragments. Understanding how molecules break apart and form ions is crucial for interpreting these spectra.
추천 영상:
01:25
How to Read a Mass Spectrum

McLafferty Rearrangement

The McLafferty rearrangement is a specific fragmentation pattern observed in mass spectrometry, particularly in carbonyl compounds. It involves a hydrogen atom transfer from a gamma-carbon (three carbons away from the carbonyl group) to the carbonyl oxygen, followed by cleavage of the bond between the alpha and beta carbons, resulting in a stable enol and a neutral alkene.
추천 영상:
06:08
Definition of Claisen Rearrangement

Fragmentation Patterns

Fragmentation patterns in mass spectrometry refer to the specific ways in which a molecule breaks apart into smaller ions. These patterns are influenced by the structure of the molecule and the stability of the resulting fragments. Recognizing these patterns, such as the McLafferty rearrangement, is essential for deducing the structure of the original compound from its mass spectrum.
추천 영상:
08:06
Common Splitting Patterns
관련 실천
교과서 질문

The base peak in Figure 14.51 has m/z 45. Suggest a molecular formula and a structure for this fragment.

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교과서 질문

Identify the peaks in the mass spectrum of octan-4-one that correspond to (a) α-cleavage.

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교과서 질문

Suggest three ways that the following tertiary amine can fragment by α-cleavage. At which m/z would you expect to see peaks corresponding to these fragments?

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교과서 질문

Based on Hooke's law, choose the bond in each pair that you expect to vibrate at a higher wavenumber.

(e) C=N vs C≡N

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교과서 질문

2-Methylnonan-4-one can undergo two different McLafferty rearrangements. Draw the products of each of them.

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교과서 질문

Assign the structure based on the mass spectrum and IR spectrum shown.

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