Multiplicity and integration ratio determination. Select the multiplicity for th

Question

Multiplicity and integration ratio determination. Select the multiplicity for the indicated proton signal. Structure A methyl singlet singlet Structure A methylene singlet Singlet Structure B methyl triplet triplet Structure B methylene quartet quartet quartet structure C methyl doublet doublet Structure C methylne septet septet Structure D methyl singlet singlet Structure D methylene singlet single Give the integration ratio for the actual number of "different" hydrogens with the most downfield resonating proton listed first in the integration ratio. The sum of the numbers that make up the ratio should be the same as the number of hydrogens in the molecule. (Input the ratio format using a colon to separate numbers like 2:6) Structure A 2:6 2:6 Structure B 2:3 2:3 Structure C 1:6 1:6 Structure D 2:9 2:9 Give the number (write a number, not a word) of carbon signals that would appear in the^13 C NMR spectrum for Structure A 3 3 Structure B 2 2 Structure C 2 2 Structure D 3 3 Solution or Explanation Use the n + l multiplicity rule to determine what is on the adjacent carbon or carbons and the integration to determine how many of each type of proton you have.

Explanation / Answer

Part 1:
Number of signals = Number of neighboring proton to couple + 1

Structure A: Methyl will have singlet as these methyl group dose not have any neighboring proton to couple.
Structure A: Methylene will have singlet as these methyl group dose not have any neighboring proton to couple.
Structure B: Methyl will have triplet as this methyl group has two neighboring proton to couple.
Structure B: Methylene will have quartet as these Methylene group has 3 neighboring proton to couple.
Structure C: Methyl will have doublet as this methyl group has one neighboring proton to couple.
Structure C: Methylene will have septet as these Methylene group has 6 neighboring proton to couple.
Structure D: Methyl will have singlet as these methyl group dose not have any neighboring proton to couple.
Structure D: Methylene will have singlet as these methyl group dose not have any neighboring proton to couple.

Part 2:
Structure A: there are 6 methyl and 2 methylene protons hence intigration ration will be 2:6
Structure B: there are 3 methyl and 2 methylene protons hence intigration ration will be 2:3
Structure C: there are 6 methyl and 1 CH protons hence intigration ration will be 1:6
Structure D: there are 9 methyl and 2 methylene protons hence intigration ration will be 2:9

Part 3:
13C NMR spectrum will have different set of carbons. It will show same signal for equivalent carbons.

Thus,
Structure A: there are 3 different sets of carbons (two methyl group are equivalent hence it will have same ppm value and will show one peak), hence it gives 3 signal
Structure B: there are 2 different carbons hence it shows two signals
Structure C: there are 2 different sets of carbons, hence it shows two signals (two methyl group are equivalent hence it will have same ppm value and will show one peak).
Structure D: there are 3 different sets of carbons, hence it shows threesignals (three methyl group are equivalent hence it will have same ppm value and will show one peak).

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