1 H NMR Interpretation Using the NMR Mosaic. NMR Spectra contain THREE Pieces of Information Chemical Shift –Information about functionality Integration.

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Presentation transcript:

1 H NMR Interpretation Using the NMR Mosaic

NMR Spectra contain THREE Pieces of Information Chemical Shift –Information about functionality Integration –Number of hydrogen MAKING the peak Multiplicity (splitting) –Number of NEIGHBOR hydrogens ALL THREE must be used to solve spectrum

Chemical Shifts OH, NH Alkene Adjacent to Oxygen Adjacent to Cl, Br, I Adjacent to double bond Alkane-like Aromatic Aldehyde hydrogen Carboxylic acid hydrogen

Integration Rise of integral line indicates relative number of hydrogens 2 2 3

Multiplicity See one more peak than neighbor hydrogens –0 hydrogens gives singlet –1 hydrogen gives doublet –2 hydrogens gives triplet –3 hydrogens gives quartet

Steps for Solving 1 H NMR Spectra 1.Calculate integration for each peak a.#H = peak integration x (total # H’s / total integration) b.Smallest peak is often 1H c.Peaks ~1  are often 3H (methyl) 2.Determine number of adjacent hydrogens from splitting - Number of peaks = n+1, where n = number of adjacent hydrogens - Attach appropriate static cling(s) 3.Determine presence of functional group(s) - Attach functional group static cling(s) - Choose functional group Mosaic piece(s)

Calculate # H’s for each peak C 3 H 7 Cl

Calculate # H’s for each peak C 3 H 7 Cl 2H 2H3H

Make NMR Mosaic Pieces C 3 H 7 Cl 2H 2H3H

Make NMR Mosaic Pieces : C 3 H 7 Cl H | ─C─ | H

| ─C─ | H CH 2 Make NMR Mosaic Pieces : C 3 H 7 Cl

H | ─C─ | H CH 2 Funct. Grp. Make NMR Mosaic Pieces : C 3 H 7 Cl

X- H | ─C─ | H CH 2 Funct. Grp. Make NMR Mosaic Pieces : C 3 H 7 Cl

X- H | ─C─ | H CH 2 Funct. Grp. Make NMR Mosaic Pieces : C 3 H 7 Cl H | ─C─ | H

X- H | ─C─ | H CH 2 Funct. Grp. Make NMR Mosaic Pieces : C 3 H 7 Cl H | ─C─ | H CH 3

H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 CH 3 Make NMR Mosaic Pieces : C 3 H 7 Cl

H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 CH 3 H | H─C─ | H Make NMR Mosaic Pieces : C 3 H 7 Cl

H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 CH 3 H | H─C─ | H CH 2 Make NMR Mosaic Pieces : C 3 H 7 Cl

H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 CH 3 H | H─C─ | H CH 2 1-chloropropane Make NMR Mosaic Pieces : C 3 H 7 Cl

C 6 H 12 O 2

H | ─C─ | H Funct. Grp. CH ─ O ─

C 6 H 12 O 2 H | H─C─ | H Funct. Grp. H | ─C─ | H Funct. Grp. CH ─ O ─ O || ─ C ─

C 6 H 12 O 2 H | H─C─ | H Funct. Grp. H | ─C─ | H Funct. Grp. CH H | ─C─ | CH 3 CH 2 CH 3 ─ O ─ O || ─ C ─

C 6 H 12 O 2 H | H─C─ | H Funct. Grp. H | H─C─ | H CH (2 of these) H | ─C─ | H Funct. Grp. CH H | ─C─ | CH 3 CH 2 CH 3 ─ O ─ O || ─ C ─

C 6 H 12 O 2 : Isobutyl acetate ─ O ─ O || ─ C ─ H | H─C─ | H Funct. Grp. H | H─C─ | H CH H | ─C─ | H Funct. Grp. CH H | ─C─ | CH 3 CH 2 CH 3 H | H─C─ | H CH

C 7 H 14 O 2

─ O ─ H | ─C─ | Funct. Grp. CH 3

C 7 H 14 O 2 ─ O ─ H | ─C─ | Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. O || ─ C ─

C 7 H 14 O 2 ─ O ─ H | ─C─ | Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. O || ─ C ─ H | ─C─ | H CH 2 CH 3

C 7 H 14 O 2 ─ O ─ H | ─C─ | Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. O || ─ C ─ H | ─C─ | H CH 2 CH 3 H | H─C─ | H CH (2 of these)

C 7 H 14 O 2 ─ O ─ H | ─C─ | Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. O || ─ C ─ H | ─C─ | H CH 2 CH 3 H | H─C─ | H CH (2 of these) H | H─C─ | H CH 2

C 7 H 14 O 2 : Isopropyl butyrate H | ─C─ | H CH 2 CH 3 H | ─C─ | H CH 2 Funct. Grp. H | H─C─ | H CH H | H─C─ | H CH H | H─C─ | H CH 2 ─ O ─ O || ─ C ─ H | ─C─ | Funct. Grp. CH 3

C 6 H 12 O 2 Cl

─ O ─ H | ─C─ | H Funct. Grp. CH 3

C 6 H 12 O 2 Cl ─ O ─ H | ─C─ | H Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. X-

C 6 H 12 O 2 Cl ─ O ─ H | ─C─ | H Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 Funct. Grp.

C 6 H 12 O 2 Cl ─ O ─ H | ─C─ | H Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 Funct. Grp. H | ─C─ | H CH 2

C 6 H 12 O 2 Cl ─ O ─ H | ─C─ | H Funct. Grp. CH 3 H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 Funct. Grp. H | ─C─ | H CH 2 H | H─C─ | H CH 2

C 6 H 12 O 2 Cl: Ethyl 4-chlorobutyrate ─ O ─ O || ─ C ─ H | ─C─ | H Funct. Grp. CH 3 H | H─C─ | H CH 2 H | ─C─ | H CH 2 Funct. Grp. X- H | ─C─ | H CH 2 H | ─C─ | H CH 2 Funct. Grp.

NMR Mosaic Simplifies Interpretation of Complex Multiplets Adjoining pieces specify connectivity Interpretation is no longer “impossible”

Example: C 4 H 9 Cl

X- H | ─C─ | Funct. Grp. CH 3 CH 2

Example: C 4 H 9 Cl X- H | ─C─ | Funct. Grp. CH 3 CH 2 H | ─C─ | H Undetermined Splitting

Example: C 4 H 9 Cl X- H | ─C─ | Funct. Grp. CH 3 CH 2 H | ─C─ | H Undetermined Splitting H | H─C─ | H CH

Example: C 4 H 9 Cl X- H | ─C─ | Funct. Grp. CH 3 CH 2 H | ─C─ | H Undetermined Splitting H | H─C─ | H CH H | H─C─ | H CH 2

Example: C 4 H 9 Cl X- H | ─C─ | Funct. Grp. CH 3 CH 2 H | ─C─ | H Undetermined Splitting H | H─C─ | H CH H | H─C─ | H CH 2

Example: C 4 H 9 Cl X- H | ─C─ | Funct. Grp. CH 3 CH 2 H | H─C─ | H CH H | H─C─ | H CH 2 H | ─C─ | H CH CH 3 2-chlorobutane

NMR Mosaic Helps Students Catch Mistakes Mosaic pieces no longer match Focus students on incorrectly interpreted peaks

Example: C 3 H 7 Cl

H | H─C─ | H CH 2 H | ─C─ | H CH 3 H | ─C─ | H CH 2 Funct. Grp. X- Incorrect Match ↑

Example: C 3 H 7 Cl H | H─C─ | H CH 2 H | ─C─ | H CH 2 Funct. Grp. X- Corrected Piece Matches H | ─C─ | H CH 2 CH 3

Steps for Solving 1 H NMR Spectra 1. Calculate integration for each peak 2. For each peak: Choose correct base Mosaic piece based on integration - Determine number of adjacent hydrogens from splitting and add static cling tab(s) to base piece - Determine presence of functional group(s) - Add functional group static cling(s) - Choose appropriate functional group Mosaic piece(s) 3. Put Mosaic pieces together, making sure all colors match and all functional group chemical shifts match.