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Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 1

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Isomeric Trichlorobenzenes

Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 2

1,2,3 1,2,4 1,3,5


Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 3

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Isomeric Tetrachlorobenzenes

Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 4

1,2,3,4 1,2,3,5 1,2,4,5


Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 5

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Structures of Dichloropropane Isomers

Line Formulas:

Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 6

Condensed Formulas:

CH3CHClCH2Cl CH3CCl2CH3
CH3CH2CHCl2 ClCH2CH2CH2Cl


Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 7

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Help for Question 1

You must consider the symmetry of a molecule when predicting the number of nmr signals expected. Each unique set of equivalent carbon atoms should give a characteristic signal, distinct from all other signals. The dashed red lines through the following structures indicate planes of symmetry.

Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 8

Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 9

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Help for Question 2

You must consider the symmetry of a molecule when predicting the number of nmr signals expected. Each unique set of equivalent carbon atoms should give a characteristic signal, distinct from all other signals. The dashed red lines through the following structures indicate planes of symmetry.

Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 10

Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 11

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Help for Question 3

Since these compounds all have a three carbon chain, it should be clear that the number of structurally distinct carbon atoms must be either two or three. After all, there are two end carbon atoms and one in the middle. If the end carbons are different there will be a total of three different carbons; but if the end carbons are the same there will only be two different carbons. The same analysis applies to the number of structurally distinct groups of hydrogen atoms. Additional information about the hydrogen groups may be obtained from the splitting patterns (n+1 rule).


Virtual Textbook: Practice Problems — Basic NMR Spectroscopy Discussion, figure 12

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