Question

1)Draw the structure of the compound that matches the following simulated DEPT 13C NMR spectra below. The molecular formula of the compound is C4H8O.

2) For light with a wavelength of 3.00 ?m, calculate the corresponding wavenumber value.... Answer is in cm-1

3) Mass spectral analysis of 1-cyclohexylpropan-2-one results in several fragmentation pathways. Complete the mechanism below and give the major products for the McLafferty rearrangement pathway. Include all nonbonding electrons and charges.

Answer 1

2-wave lenth(lemda)=3m wave no=1/lemda=1/3=.33x10^-2cm^-1

3-McLafferty rearrangement

The McLafferty rearrangement is a reaction observed in mass spectrometry. It is sometimes found that a molecule containing a keto-group undergoes ?-cleavage, with the gain of the ?-hydrogen atom. This rearrangement may take place by a radical or ionic mechanism.

The predominant cis elimination observed in every case is consistent with the substantial integrity of the cyclohexyl ring prior to fragmentation, and with a cyclic transition state for hydrogen abstraction. CH3CO+ is fragmentation between the 2 and 3 carbons and the rearrangement ion is fragmentation between the 3 and 4 carbons where the gamma hydrogen transfers to the oxygen and the electrons from the double bond between the oxygen and the 2 carbon transfer to form a more stable double bond between the 2 and 3 carbon.

--------------------->CH2=COHCH3 +cyclohexene CH2-C-Me 1-NMR is not given in question

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