HNMR readings (chem shift + j vals)

NMR characterizes molecules based on how their electrons interact with magnetic fields. The more "deshielded" a proton is, the more it's electron cloud is interacting with the magnet.

KEY SHIFT TRENDS

1. Hs near/attached to electronegative atoms will be more deshielded than whatever group they are bucketed into (ex. alkane range, aromatic proton range, etc.)

2. Resonance will make atoms more deshielded, since pi bonds have an induced magnetic field that amplifies the magnet NMR detection

3. In addition, increased s character in attached atoms (ex. carbon) are more deshielding since they act as electronegative centers, pulling electron density from H (alkyne Cs are a special exception)

4. Hydrogen bonding usually has an average deshielding affect (somewhere in the high alkanes) since the molecules often don’t form as strong H bonds with each other due to structure

5. DESHIELDING GROUPS/AFFECTS COMPOUND!!!

alkane Hs

0-4ppm. 2-4 is more deshielded, 0-2 is less deshielded.

alkene Hs

5-6ppm

aromatic protons

7-8ppm

aldehyde H (O=C-H)

11-10ppm

carboxylic acid H (O=C-OH)

12-10ppm

H-[En]

2-6ppm

alkyl C-H

0-2 ppm (not near any electroneg atoms or conjugation)

H-C-C-H J coupling value (if the Hs are in 2 diff equiv groups)

7-8Hz

alkene cis Hs J coupling val

around 10Hz

geminal Hs (just Hs connected to same C) but with diff equiv groups have a J value of…

2Hz

trans alkene Hs J value is…

around 15Hz

ortho Hs (Hs 3 bonds away on a ring) have a coupling value of…

7-8Hz

meta Hs (Hs 4 bonds away on a ring) have a J value of…

2Hz

splitting in an unsubbed benzene ring is….

multiplet. too much complex splitting to distinctly count peaks