(Solved): Each question includes a MS, IR, C-NMR and H-NMR. - Use the MS to determine the Mass and possible e ...

Expert Answer

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The parameters are given; From the mass spectrum, the molecular mass of the unknown compound = 74

Molecular ion peak(M), m/z 74 even mass indicates that in a given molecule even number of nitrogen atoms or zero number of nitrogen atoms should present, [M+1]; m/z 75 relative isotopic ratio contributes to 13C isotope presence of several carbon atoms present in given unknown, [M+1] each carbon atom contributes 1.1 % to [M+1] peak; in a given molecule, 4 carbons are presented [M+1] = 4.5 % to [M] ion peak.

m/z i.e.59, [M -  ] ; [M -15] the elimination of   , alpha cleavage of alcohol.

m/z i.e.45, [M -  ] ; [M -29] the elimination of   , alpha cleavage of alcohol. it is a base peak Highest relative peak intensity in the MS spectrum

Based on mass spectrum fragments combined to give a molecular formula for an unknown compound   



Molecular formula =   from this first we should find the Index of Hydrogen Deficiency (HDI) degrees of unsaturation

The formula for degree of unsaturation or HDI =

{ 2 + 2x(no . of carbon atom) - (no. of Hydrogen atoms) + (no. of Nitrogen atoms) -(no .of halogen atoms )}/2

= { 2+ 2 (4) - 10}/2
                                                        = 0 Degree of unsaturation