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4 Mnemonic rules

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NMR Multiplet Interpretation
This chapter is in the book NMR Multiplet Interpretation
4 Mnemonic rulesBelow is the list of the mnemonic rules previously discussed for a quick reference.Mnemonic Rule I:(a) For every first-order1H multiplet, the sum of the integral values of each peak within themultiplet should be equal to the numerical value of the last assignedsegment. (b) Note that according to the2nrule, the full sum of the segments always equals2n, wherenis the number of J-coupling constants (NJ) or thenumber of neighboring protons to which the H of interest, represented by the multiplet, is coupled to.Mnemonic Rule II:The distance between the very first peak {1} in a first-order1H multiplet and the second peak {2}(depicted as 1→2) will always equal the value of the smallesttrue coupling constant in any multiplet (J1→2=J12).Mnemonic Rule III:The distance between the very first peak in a first-order1Hmultiplet{1}andtheverylastone{2n} will always equal the sum of all true coupling constants in the multiplet (J1→2n=J1+J2+J3+...+Jn=JΣ).Mnemonic Rule IV:If the numerical value of the last assigned segment {2n} is placed on top of the J-tree dia-gram and split according to the propagation of the J-tree branches, then the final products of the values ob-tained at the bottom of the branches should always equal (↔) the integral values (peak intensities or≈peakheights) of each peak in the multiplet.While learning the interpretation of1H NMR spectra, it can be challenging to see theobvious connection between adt(doublet of triplets) and aq(quartet), for example.Theabundanceoftheexamples,thevariability in the terminology (dt,tt,dq,dtd,ttd, . . ., etc.), and the absence of a systematic approach can further complicate under-standing. Table 4.1 helps to visualize the relationship between the number ofJ-couplingconstants (n), derived fromthe 2nrule, their magnitude, and it provides a systematichierarchy illustrating all possible combinations ofSimple First-Ordermultiplets:d,t,q,and so on.15For simplicity and practicality, Table4.1 summarizes such relationship onlyfor the multiplets with:1(one)J-coupling constant for ad(doublet)2(two)J-coupling constants for add(doublet of doublets)3(three)J-coupling constants for addd(doublet of doublet of doublets)4(four)J-coupling constants for adddd(doublet of doublet of doublet of doublets)5(five)J-coupling constants for addddd(doublet of doublet of doublet of doublet ofdoublets).Complex First-Order multiplets can be viewed as an overlapping combination of Simple First-Order multiplets:dtdmultiplet is a combination of adoublet(d), atriplet(t), and anotherdoublet(d).https://doi.org/10.1515/9783110793017-005
© 2025 Walter de Gruyter GmbH, Berlin/Boston

4 Mnemonic rulesBelow is the list of the mnemonic rules previously discussed for a quick reference.Mnemonic Rule I:(a) For every first-order1H multiplet, the sum of the integral values of each peak within themultiplet should be equal to the numerical value of the last assignedsegment. (b) Note that according to the2nrule, the full sum of the segments always equals2n, wherenis the number of J-coupling constants (NJ) or thenumber of neighboring protons to which the H of interest, represented by the multiplet, is coupled to.Mnemonic Rule II:The distance between the very first peak {1} in a first-order1H multiplet and the second peak {2}(depicted as 1→2) will always equal the value of the smallesttrue coupling constant in any multiplet (J1→2=J12).Mnemonic Rule III:The distance between the very first peak in a first-order1Hmultiplet{1}andtheverylastone{2n} will always equal the sum of all true coupling constants in the multiplet (J1→2n=J1+J2+J3+...+Jn=JΣ).Mnemonic Rule IV:If the numerical value of the last assigned segment {2n} is placed on top of the J-tree dia-gram and split according to the propagation of the J-tree branches, then the final products of the values ob-tained at the bottom of the branches should always equal (↔) the integral values (peak intensities or≈peakheights) of each peak in the multiplet.While learning the interpretation of1H NMR spectra, it can be challenging to see theobvious connection between adt(doublet of triplets) and aq(quartet), for example.Theabundanceoftheexamples,thevariability in the terminology (dt,tt,dq,dtd,ttd, . . ., etc.), and the absence of a systematic approach can further complicate under-standing. Table 4.1 helps to visualize the relationship between the number ofJ-couplingconstants (n), derived fromthe 2nrule, their magnitude, and it provides a systematichierarchy illustrating all possible combinations ofSimple First-Ordermultiplets:d,t,q,and so on.15For simplicity and practicality, Table4.1 summarizes such relationship onlyfor the multiplets with:1(one)J-coupling constant for ad(doublet)2(two)J-coupling constants for add(doublet of doublets)3(three)J-coupling constants for addd(doublet of doublet of doublets)4(four)J-coupling constants for adddd(doublet of doublet of doublet of doublets)5(five)J-coupling constants for addddd(doublet of doublet of doublet of doublet ofdoublets).Complex First-Order multiplets can be viewed as an overlapping combination of Simple First-Order multiplets:dtdmultiplet is a combination of adoublet(d), atriplet(t), and anotherdoublet(d).https://doi.org/10.1515/9783110793017-005
© 2025 Walter de Gruyter GmbH, Berlin/Boston

Chapters in this book

  1. Frontmatter I
  2. Preface VII
  3. Contents XI
  4. Foreword 1
  5. 1 Introduction 2
  6. 2 Simple First-Order 1H NMR Multiplets: Pascal’s Triangle 4
  7. 3 Complex First-Order 1H NMR Multiplets: Infographic Walk-Through 8
  8. 4 Mnemonic rules 52
  9. 5 Exercises 58
  10. 6 Classification of Protons in 1H NMR Spectra 158
  11. 7 1H NMR Multiplet Prediction: 1H, 1H Coupling 178
  12. 8 19F NMR Multiplet Prediction: 19F, 19F and 19F, 1H Coupling 210
  13. 9 1H NMR Multiplet Prediction: 1H, 1H and 1H, 19F Coupling 224
  14. Appendix 237
  15. Acknowledgments 245
  16. References 247
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https://doi.org/10.1515/9783110793017-005

Chapters in this book

  1. Frontmatter I
  2. Preface VII
  3. Contents XI
  4. Foreword 1
  5. 1 Introduction 2
  6. 2 Simple First-Order 1H NMR Multiplets: Pascal’s Triangle 4
  7. 3 Complex First-Order 1H NMR Multiplets: Infographic Walk-Through 8
  8. 4 Mnemonic rules 52
  9. 5 Exercises 58
  10. 6 Classification of Protons in 1H NMR Spectra 158
  11. 7 1H NMR Multiplet Prediction: 1H, 1H Coupling 178
  12. 8 19F NMR Multiplet Prediction: 19F, 19F and 19F, 1H Coupling 210
  13. 9 1H NMR Multiplet Prediction: 1H, 1H and 1H, 19F Coupling 224
  14. Appendix 237
  15. Acknowledgments 245
  16. References 247
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