Question

Question 3 1 pts Indicate those of the following statements that are correct for the spectra below Note: The mass 67 peak in the mass spectrum is labelled incorrectly: the correct mass should be 65 Instead.) R Spectrum quid fim) 4000 3000 1600 1200 100 Mass Spectrum No significent UV absorption above 220 nm 405 B3 M+. C2H4C2 80 120 160 200 240 280 m/e 13C NMR Spectrum protan couped proton decoupied 200 160 120 40 0 (ppm) H NMR Spectrum 200 MHE. Co,uin 22 20 Pem 8 (ppm) O The IR spectrum is consistent with the presence of a C-Cgroup in the molecule. The mass spectrum peak at mass 83 is consistent with the loss of a methyl group o The carbon-13 spectrum indicates that all carbons in the compound are equivalent, fragment. and that all carbons are directly attached to two protons. The proton NMR indicates that a group representing three protons is next to a group containing a single proton. The proton NMR indicates that a group representing one proton is next to a group containing two protons. The compound is CH2X CH2X where X is CI or Br O The compound is CH3 CHX2 whXis Cl or Br

Answer 1

ANSWER:

All the answers were given after the careful analysis of the given spectrums for the respective functional groups, fragmnets/groups and for the nature of carbons and hydrogens.

The correct statements are given below.

• The mass spectrum peak at mass 83 is consistant with the loss of a methyl group fragment (i.e.) the peak at mass 83 is formed by losing a methyl group fragment (M-15 or M-CH₃) from the peak appeared at mass 98 which is known as Molecular ion peak (M^+.).
• The proton NMR indicates that a group representing three protons is next to a group containing a single proton. This is attributed to the peak appeared around 2.00 ppm as a doublet. This should belongs to a -CH₃ group (3H) which is next to -CH group (i.e.) to the atom with one hydrogen.
• The compound is CH₃CHX₂ where X is Cl or Br (i.e.) The structure of the compound with CH₃CHCl₂ is in fully agreement with all the given spectrums such as no prominent peaks in the IR spectrum, two kinds of non-equivalent protons in the proton NMR will give two peaks and also two non-equivalent carbons in the compound will give two peaks in the ¹³C-NMR spectrum.

And all the remaining statements are wrong such as

• The IR spectrum is consistent with the presence of C=C group in the molecule because it didn't showed any peak around 1600 cm^-1 which belongs to the C=C stretching vibrations.
• The ¹³C-NMR spectrum indicates that all the carbons in the compound are equivalent and all the carbon atoms are directly bonded to two protons. If this is correct, there should be only one peak in the spectrum with triplet multiplicity which hasn't observed.
• The proton NMR indicates that a group representing one proton is next to a group containing a two protons. If this is correct, the peak should appear as triplet but it appeared as a quartet in the spectrum.
• The compound is CH₂XCH₂X where X is Cl or Br. This is also wrong because according this structure, the compound should show only one peak in the proton NMR and only one peak in the ¹³C-NMR which is not observed in the above spectrums.