How many carbon and hydrogen signals in a methyl para substituted benzene ring? What about ortho and meta methyl groups?
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How many carbon and hydrogen signals in a methyl para substituted benzene ring?
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2 signals for hydrogen
1 signal for all hydrogens in the benzene ring (all 4 are equivalent)
signal for methyl hydrogens
3 for carbon
2 for benzene ring (carbons connected to substituents are both symmetric and in this case the 4 carbons not connected to substituents are all symmetric as well)
1 for methyl carbons
1 signal for all hydrogens in the benzene ring (all 4 are equivalent)
signal for methyl hydrogens
3 for carbon
2 for benzene ring (carbons connected to substituents are both symmetric and in this case the 4 carbons not connected to substituents are all symmetric as well)
1 for methyl carbons
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A. Ortho-xylene
4 C signals
3 H signals
singlet (6H) -- from the methyl groups attached to carbon #1 and #2
doublet (2H) -- from carbon #3 and #6
triplet (2H) -- from carbon #4 and #5
B. Meta-xylene
5 C signals
4 H signals
singlet (6H) -- from the methyl groups attached to carbon #1 and #3
singlet (1H) -- from carbon #2
doublet (2H) -- from carbon #4 and #6
triplet (1H) -- from carbon #5
C. Para-xylene
3 C signals
2 H signals
singlet (6H) -- from the methyl groups attached to carbon #1 and #4
singlet (4H) -- from carbon #2, #3, #5, and #6 -- they're all equal.
Note - if the two substituents were different and para, for example -- (p) chlorotoluene = 1-chloro-4-methyl-benzene)
You'd have 4 C and 3 H signals.
Also, it's pretty tough to distinguish splitting patterns of substituted benzene rings because they're all so close. However, my ochem professor freehand drew the H NMR that showed the substituted benzene splitting pattern and we were tested over it that way.
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