Question

Could you help me interpret some spectra data for an Unknown Amine? Included is a Proton nmr, Carbon nmr, IR, and mass spec. Chloroform solvent (CDCl3) was used in the nmr. Any tips?

W.NNR EPS Amme Samph 0 3 7 6 5 4 ppm 8 7.256 7.239 - 7.217 60'0 96 0 6.568 6.546 00 -5.294 0.01 -3.654 0.94 - 1.585 2 0.18 000 0 0.08

Answer 1

The unknown is p-bromo aniline ( 4-bromo aniline), M.F: C₆H₆BrN

Mass:

1:1 intensity ratio of signals at m/z 171 & m/z 172 is an indication of presence of bromine isotopes

171 - 92 = 79 ------------> bromine atom mass

IR:

3475 & 3383 cm-1, two strong and sharp bands are characteristic of primary amine N-H stretching

1613 cm-1, strong band further supports N-H bending

1181 cm-1, medium band is due to C-N stretch

503 cm-1, strong due to C-Br stretch

1400 - 1600 cm-1, medium-weak, multiple bands are due to aromatic sp2 C=C stretch

HNMR and CNMR:

77.0 ppm 1:1:1 triplet in CNMR is due to CDCl₃ solvent peak

HNMR - 0.0 TMS peak, other two small peaks are (5.3 & 1.6) are impurities.

HNMR NH2 NH CNMR Br Assign. Shift (ppm) ppm Assign 7.214 doublet, 2H 6.542 doublet, 2H 3.35 singlet, 2H 145.48 131.93 116.70 110.03

Hope this helped you!

Thank You So Much! Please Rate this answer as you wish.("Thumbs Up")