Question

Interpret the IR and NMR spectra for an unknown substance. Label all peaks and protons. Correctly Identify the compound and draw its structure.

The unknown compound may be one of the following:

1,2-dichloropropane         2-chloro-2-methylpropane                1-bromobutane                

2-bromobutane                 1-bromo-3-methylbutane                 bromocyclohexane

ethanol                               1-propanol                                      2-propanol

1-butanol                           2-butanol                          2-methyl-2-propanol

n-pentane                           2,2,4-tri-methylpentane                toluene

1,2-dimethylbenzene          1,3-dimethylbenzene     1,4-dimethylbenzene

ethylbenzene                      n-butylbenzene                            2-butylbenzene

isobutylbenzene                 cyclohexene                      alpha-methylstyrene

10 NAME 15 VENUMBERS COPYRIGHT 1992 -3 và DOL 140 120 100 80 60 40 20 PPM

Answer 1

IR data

750 cm-1 indicates C-H wag stretch observed in ortho substituted benzene ring

1500 cm-1 indicates C=C stretch

2900 cm-1 indicates aliphatic C-H stretch

1H NMR data:

7.1-7.2 (4H)

2.3 (s, 6H) two equivalent CH3

¹³C NMR data:

138 ppm presence of quaternary aromatic carbon

130 ppm presence of aromatic carbon

128 ppm presence of aromatic carbon

20 ppm presence of aliphatic carbon

All above data indicates following structure

о-хylene