Predict the first order splitting patterns of the indicated proton in the following molecules:
CH3CH2CH3
(the H in CH2 is selected)
a) quintet
b) quartet of quartets
c)septet
To determine the first order splitting patterns of the indicated proton, we need to examine the neighboring protons. In this case, we are focusing on the proton in CH2, which is connected to two other protons.
a) Quintet:
To determine if the proton will exhibit a quintet splitting pattern, we count the number of neighboring protons. In CH3CH2CH3, the proton in CH2 has two neighboring protons from the two methyl (CH3) groups. If a proton has two neighboring protons, we can use the n+1 rule to determine the splitting pattern. In this case, 2+1 equals 3, which does not match the expected value for a quintet splitting pattern. Therefore, this option is incorrect.
b) Quartet of quartets:
To determine if the proton will display a quartet of quartets splitting pattern, we again count the number of neighboring protons. In CH3CH2CH3, the proton in CH2 has two neighboring protons from the two methyl (CH3) groups. However, we also need to consider the neighboring protons of the neighboring protons. Since each of the methyl (CH3) groups has three neighboring protons (one hydrogen on the same carbon and two hydrogens on adjacent carbons), we multiply 3 by 2 (the number of methyl groups) to obtain 6. Again, using the n+1 rule, 6+1 equals 7. This matches the expected value for a septet. Hence, this option is incorrect.
c) Septet:
To determine if the proton will exhibit a septet splitting pattern, we count the number of neighboring protons. In CH3CH2CH3, the proton in CH2 has two neighboring protons from the two methyl (CH3) groups. Since each methyl (CH3) group has three neighboring protons, we multiply 3 by 2 (the number of methyl groups) to obtain 6. Using the n+1 rule, 6+1 equals 7, which matches the expected value for a septet. Therefore, this option is correct.
Thus, the correct answer is:
c) Septet