Question

4) Unknown 428 (29.30% C,5.74% H) 4000 3600 3200 2800 2400 2000 1800 1800 1400 1200 1000 300 600 100- Relative Intensity 10 20 30 40 50 60 80 90 100 110 120 70 m/z peo ppm 10 ppm

Answer 1

Mass

Percentage of carbon = 29.30%

Percentage of hydrogen = 5.74%

Empirical formula calculation

Atomic ratio of carbon = 29.30 / 12 = 2.44

Atomic ratio of Hydrogen = 5.74 / 1 = 5.74

Dividing each number with the smallest number (C:H)= (2.44/2.44): (5.74/2.44)

(C:H)= (1 : 2.3)

Molecular formula = empirical formula * 3= C3H7

Mass spectra indicates presence of bromine Thus Molecular formula is C3H7Br

Mass spectra

M+ = 122, 124 (1:1) presence of bromine

M-79 ( loss of bromine) peak, that is (M = 43) is observed in mass spectrum

1H NMR spectra

4.2 (septet, 1H) proton attached to six proton (two equivalent CH3)

1.8 (d, 6H) Two equivalent CH3 attached to CH

All above data indicates following structure

Br 2-bromopropane