9. The compound c60 (Mw 720), also know as Buckminsterfullerene or \"Bucky Balls
ID: 530326 • Letter: 9
Question
9. The compound c60 (Mw 720), also know as Buckminsterfullerene or "Bucky Balls" can be isolated from the soot that forms when creating an electric arc between two graphite electrodes in an atmosphere of helium gas. The molecule is spherical with 32 faces, 12 of which are pentagons and 20 of which are hexagons. The molecule displays a single resonance in 13C NMR. In addition to C60 another compound can be isolated from the soot the MW 724. During the formation of the spherical structure an approximate sphere having a "hole" forms, and subsequently closes to the final structure. (20 pts) Given the information, answer the following: a) Calculate the intensity of the M+1 peak of C60 as a percent of the molecular ion 720 100%). b) Would you expect to see a significant M+2 peak? Explain. c) why the 13C NMR only shows one resonance. d) Propose a structure for the 724 weight product. Note that you needn't draw out the full structure; simply explain it in a sentence. C60 or Buckminsterfullerene.Explanation / Answer
a). If the M+/Z peak of appears at 720 is 100 % the one appears at (M+1) peak will be there with an intensity of 0.67 %. since the natural abundance of C13 is 1.1 %.
If 100 carbon atoms are there in molecule we will get an intensity of 1 %, in this case, 60 C atoms are there and intensity will come as 0.67.
b). No, the probability of M+2 peak is negligible. the abundance ofC14 is less than 0.0001 %. Thus for 60 C atoms, its contribution will not come in the mass spectra
C). Each carbon atom in fullerene is bonded to three other sp2 hybridized C atoms and their chemical environment are similar. thusall the C atom shows only one resonanace in C13 NMR
d). In the case of 724 compound, it is bonded to 4 hydrogen atoms it is opened at one end
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.