Answer Happy

Spectral Problems Instructions 2. Assign the proton and carbon and IR spectra Identify at least two p 1. Identify the compounds for each group of spectra (mass, proton, carbon and IR fragmentations on the mass spectrum. HINTS ANS TIPS: 1. Finding a molecular formula using mass percentages For element Z mass % Z therefore... #2 A (#Zx atomic wt Z) x 100% MW of compound mass % Z x MW of compound atomic wt Zx 100 2. If all of the elements do not add up to 100 %, the remaining element is probably Nitrogen. 3. Odd Molecular Weights (MW) indicate the presence of an odd number of nitrogen atoms. 4. The MW can be obtained by looking at the molecular ion (MI) or by looking at the second to last peak visible in the mass spectrum. See Appendix for common fragmentations. 5. Units of unsaturation (# of rings and/or double bonds) may be obtained from the molecular formula in the following way: (Example: C,H₁3NF₂0₁) D in a) For the purpose of this calculation, find effective number of H. For each halogen, add 1 H. D For each nitrogen, subtract IH. Oxygen has no effect on this calculation. So C₂H₁NF₂O, becomes CH₁4 JUST FOR THIS CALCULATION). b) Find how many H the compound would have if it were saturated (remember a saturated hydrocarbon is C,H.2). CH₁>CH c) Units of unsaturation C Saturated H-Actual H 2 1 (ring or double bond) 5. For compounds with N, look to see if a nitro group (NO₂) is present. 16-14 2

IH 200 180 160 140 120 100 80 60 q - 40 ЗН ZO D

12 100 100- 80. 60 40 20 0 10 MI = 98 119-NU-4372 20 5000 %C24.5; %H-4.09; %CI=70.4 30 40 50 2000 60 70 NAVENUMBER 80 1500 90 100 1000 mptit 110 120