. This rearrangement finally results in the formation of an olefin without any charge and an enol radical cation as products. A radical cation is a cation with an unpaired electron. An example of McLafferty rearrangement in aldehydes is shown below (Figure 2). In the mass spectrum of pentane, the presence of a peak at M-15 most likely is due to the loss of what radical from the molecule? McLafferty Rearrangement. The transfer of a hydrogen atom of molecular ion from gamma (γ) position to the carbonyl functional group or unsaturation followed by the cleavage of the Cα-Cβ bond to give a neutral alkene and enol radical cation in mass spectrometry is called the McLafferty Rearrangement. By observing the peak at 44 in the mass spectrum, we can confirm the structure of n-pentanal. So, the (m/Z) value gives the actual mass of the cationic species. Spectra of straight-chain aldehydes show other characteristic peaks as well, e.g. B. After ionization, a radical cation breaks apart into a cationic piece (which is seen by the mass spectrometer’s detector) plus a neutral radical piece (not seen by the detector). 6-membered transition state = loss of alkene This rearrangement finally results in the formation of an olefin without any charge and an enol radical cation as products. . A. Pentanal. The resultant molecular ion undergoes a special type of rearrangement. The hydrogen at gamma (γ) position transfers to the carbonyl functional group followed by the hemolytic cleavage of the Cα-Cβ sigma bond. The McLafferty rearrangement is a characteristic fragmentation of the molecular ion of a carbonyl compound containing at least one gamma hydrogen (see alpha hydrogen). American chemist Fred W. McLafferty observed that the Gamma (γ) hydrogen to a carbonyl compound undergoes rearrangement when the compound is converted into a molecular ion in a mass spectrometer. Cleavage of the bond in β position: E53. Also McLafferty Rearrangement where possible! The mechanism for the above reaction can be drawn via a cyclic transition state followed by the homolytic cleavage of the Cα-Cβ bond. The peak of Enol radical cation is observed at (m/Z) = 44 in the Mass spectrum of n-Pentanal. Select all that apply. butyl radical. Select all that apply. Figure 2: McLafferty rearrangement in n-Pentanal. Cleavage of the bond in α position: E54. position. a molecule containing a keto-group undergoes β-cleavage, with the gain of the γ-hydrogen (gamma) atom, this rearrangement may take place by a radical or ionic mechanism . Mass spectrometry is an analytical method used to identify and characterize the molecules of a sample. The McLafferty rearrangement is a characteristic fragmentation of the molecular ion of a carbonyl compound containing at least one gamma hydrogen (see alpha hydrogen).