Ch_322a_9.06

Ch_322a_9.06 - causes a general downfield shift in the H resonance but the shift does not correlate with X C H 3-X C H 3-CH 3 C H 3-I C H 3-Br C H

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Shielding Effects and Chemical Shifts Shielding causes an upfield shift while deshielding causes a downfield shift in a resonance. 0 ! 10 0 Hz TMS most H resonances fall within this range shielding deshielding
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The Inductive Effect of Substituent Groups Nearby electronegative groups decrease the electron density and reduce the usual shielding due to circulating electrons. ! 0.88 2.16 2.68 3.35 4.26 increasing deshielding (CH 3 -) The presence of an ! -electronegative group causes a downfield shift in the H resonance in line with the expected inductive effect. C H 3 CH 2 - X C H 3 CH 2 - I C H 3 CH 2 - Br C H 3 CH 2 - Cl C H 3 CH 2 - F !" ! + ! ( CH 3 CH 2 -) 1.75 1.80 1.58 1.58 The presence of a ! -electronegative group
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: causes a general downfield shift in the H resonance, but the shift does not correlate with X . C H 3-X C H 3-CH 3 C H 3-I C H 3-Br C H 3-Cl C H 3-F !" ! + electronegativity Inductive Influence of Oxygen on the Chemical Shift O H H H H H H H H tetrahydrofuran ! 3.75 ! 1.85 Quiz 9.06 Which H resonance is the most downfield in the NMR spectrum of I? CH 3 OCH 2 OCH 2 CH 2 CH 3 A B C D E Inductive effects are additive . If one !-oxygen atom causes a downfield shift in the resonance of an H atom, two -oxygen atoms will cause a larger downfield shift....
View Full Document

This note was uploaded on 07/22/2009 for the course CHEM 322AL taught by Professor Jung during the Summer '07 term at USC.

Page1 / 4

Ch_322a_9.06 - causes a general downfield shift in the H resonance but the shift does not correlate with X C H 3-X C H 3-CH 3 C H 3-I C H 3-Br C H

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online