Question

An unknown compound gives the following spectral data. MS (m/z): 91, 108 and 122 (molecular ion) 1H NMR (Έ): 7.05(2H, d), 6.78 (2H, d), 3.7 (3H, s), 2.26 (3H, s) (HINT: the copound does not contain N, S, or any halogen) (a) (10 pts) Propose a structure that is consistent with this information. For full credit, explain how the information provided above was used in finding the structure. (b) (4 pts) Propose a structure for the signal seen at m/z = 91 in MS.

Answer 1

MS peak at 91 indicates the presence of benzyl group in the molecule

in H-NMR, two doublets at 7.05 and 6.78 suggests the presence of benzene rings and it is di substituted

A singlet due to 3H's at 3.7 suggests a methyl group attaached to oxygen

A singlet due to 3H's at 2.26 suggests a methyl group attached to benzene ring

based on above analysis the structure of compound may be written as